Engineering Approaches to Ecosystem Restoration

Initiatives taken in Thames Region over the last two decades have led the way towards achieving a sustainable water environment in the United Kingdom (UK). Single-function design, presented as a fait accompli to the public, progressed to environmentally sensitive river management, then to floodplain and catchment/watershed management, in just five years of concentrated effort, much of which has been documented. This paper describes the key points from this experience, which serve as background for the current initiatives. These have increasingly emphasised the prevention of further problems through influencing land use decision-making processes, rather than continuing to spend many times more resources on trying to mitigate the effects of poor decisions, after their implementation. At the same time, there has been a strong European emphasis on river restoration; brief examples are given of river rehabilitation programmes in the UK, Denmark and Germany.

Urbanization, flood control, land clearing, and agricultural practices have extensively degraded and disturbed aquatic systems throughout the Northeast. In particular, urban development profoundly impacts the hydrology, morphology, water quality, and biodiversity of streams. Maryland, recognizing the connection between healthy streams and a healthy Chesapeake Bay, developed a comprehensive strategy to restore the tributaries of the Chesapeake Bay watershed. Baltimore County has embarked on one of the most ambitious stream restoration programs to date. The restoration of Spring Branch is a hallmark of their program. Located in the Piedmont Plateau physiographic province, Spring Branch drains approximately 489 acres to the Loch Raven Reservoir, one of several drinking supply reservoirs for the Baltimore metropolitan region. Throughout the last 50 years, the watershed of Spring Branch has undergone intense development. Today, single family homes, on ¼ to ½ acre lots interconnected with curb and gutter roads, blanket the landscape. Impervious surfaces account for more than 50% of the watershed, and, due to the age of the development, stormwater management is absent (typical of northeastern suburban development). On average, 25% of the area contributing stormwater runoff enters the stream via overland flow (non-point source) and 75% via storm drain inputs (point source). The large percentage of drainage area attributable to point sources suggests that the rate of storm runoff entering the stream channel can be described with short, rapid peak hydrographs. These peaks, commonly called "pulse inputs," tend to discharge storm water into the stream channel more quickly and with a greater intensity than streams draining a forested watershed.

To mitigate the effects of urban development on tributaries of Accotink Creek within the City of Fairfax, Virginia, the City began a program to stabilize and restore the eroding stream channels. The design methods used in the stream restoration incorporate the design philosophies of bioengineering and stream morphology. In addition to providing stability to the stream, restoration created stream habitat, added to the riffle/pool complexity, expanded the riparian buffers, improved meander patterns, reduced sediment loads, and improved temperature conditions in the streams. The City has successfully completed restoration of 3.9 miles of stream channel.

Rapid growth of Anchorage, Alaska severely impacted the many creeks that flow through the city. These creeks have resident populations of Dolly Varden and rainbow trout as well as anadromous populations of all five species of Pacific salmon. Impacts ranged from increased peak flows resulting from a more impervious watershed to decreased low flows caused by filling riparian wetlands and decreased habitat diversity for fish created by straightening of the creeks and removal of vegetation. To correct these problems, in the 1980s the city started a program to attempt to restore the habitat values of the creeks while improving flood conveyance of the channels. This paper discusses the results of HDR's restoration work done to date and experience gained from these projects.

This paper describes historic reconstruction research performed as part of a riverine riparian restoration design. The restored riparian area is proposed to be a design element within a new urban riverfront park/pedestrian corridor along the Willamette River in Portland, Oregon.

A study was conducted to assess the influence of woody debris on the resistance to flow that may be expected in small, third, and/or fourth order stream channels. A stream site was identified that had naturally matured with growth and debris. Flows were conveyed through the channel, with and without debris, and manning's n values were determined. The results indicated that the resistance to flow with debris increased nearly 40% over the no debris condition.

A new method has been developed for the determination of Manning's n and hydraulic roughness values for shrubs and woody vegetation. This method involves the measurement of horizontal plant density, stem diameter, and the height and width of the leaf mass of a typical plant. Investigation has shown that the force value necessary for the calculation of plant stiffness modulus (E_s) is linearly related to the stem area of a plant and varies from one plant variety to another. An simple example of the calculation of Manning's n values using the method is presented.

Aquatic plants convert mean kinetic energy into turbulent kinetic energy at the scale of the plant. This energy transfer, linked to stem-wake generation, affects both the vegetative drag and the plant-induced turbulent diffusivity. Drawing on this phenomenological link we develop a model which couples these flow parameters. Experimental observations are presented which support the link between canopy diffusivity and canopy drag. The study extends previous models of vegetative resistance by incorporating the dependence of drag coefficient on population density.

An artificial wetland was created to receive effluent containing relatively low concentrations of nitrogen and phosphorus from the Numana Fish Hatchery, located in a semi-arid environment near Pyramid Lake, Nevada. Detailed inflow and outflow observations were obtained throughout the study period. Fluorescent dye tracer pulse tests were conducted to establish travel times which were subsequently used to implement a Lagrangian water quality sampling program. Dye tracer results were also used to define longitudinal dispersion within the system. Water quality monitoring of the constructed wetland system was conducted in April and August 1995, with additionally follow-up sampling in late September and early December of 1997. The collected data were also used to calibrate and verify a water quality mathematical model (WASP5). The complex WASP5 model, including site specific calibration, was then tested against simple wetland design equations. The predictions of both total and ammonia nitrogen removal made by WASP5 were generally superior to the simple design expressions.

This paper documents the performance of a newly built subsurface-flow constructed wetland system for wastewater treatment, during the initial and start-up period, under a variety of loading and operating conditions associated with northern climates. The results indicated that effective and sufficient CW seasonal removals of TSS, VSS, CBOD₅, COD, and fecal coliform were achieved. Temperature appeared to affect CBOD₅ and COD removal rates. Furthermore, nitrogen and phosphorus reductions were not as effective and varied with wastewater temperature.

This paper presents the planning, design and first year of operating experience for the award-winning Manila CSD Wastewater Treatment Facilities. The facilities were constructed to replace a failed community leachfield system. The influent is septic tank effluent from a STEP system operated by the District. Treatment of the septic tank effluent at the wastewater treatment plant occurs via two Surface Aerated Facultative (SAF) lagoons followed by three Free Water Surface (FWS) wetland cells. Disposal is through rapid infiltration basins which discharge to groundwater. With the exception of the first few months when the wetland vegetation was becoming established and the biota were developing in the lagoons, the plant performed well. Although peak flows exceeded the expected design flow rates due to exceptionally heavy winter storms, the plant provided effective treatment and disposal at all times.

The performance of both surface and subsurface flow constructed wetlands present challenges to the designer because of natural biological processes leading to seasonal fluctuations in performance. The three systems described demonstrate both the problems and successes in designing wastewater treatment systems for the removal of BOD, TSS and nitrogen using constructed wetlands. Wetlands provide an attractive, low cost, low energy use alternative, but the designer must take into account both the advantages and the limitations.

Tampa Bay is Florida's largest open-water estuary and home of one of the world's busiest ports. Estuaries are among the world's most productive ecosystems and activities within contributing watersheds impact their health. Ecosystem planning on a watershed scale is the utilization of abiotic communities in such a way as to minimally impact the biotic communities within a specific hydrologically defined geographic area. Decisions within a watershed based on ecosystem needs can lead to a successful restoration and preservation program. The Alligator Creek Watershed encompasses 5,691 acres in a highly urbanized setting crossing several jurisdictional boundaries. The creek has been channelized, redirected and encroached upon to the extent that much of its five mile course bears little resemblance to its original state. Impacts of extensive urbanization have contributed to the degradation of the watershed's natural resources, as well as those of the receiving water body, Tampa Bay. In an effort to restore and protect the natural resources, the Southwest Florida Water Management District, City of Clearwater, Pinellas County and the City of Safety Harbor have joined forces to develop a watershed management plan. With the assistance of Parsons Engineering Science, Inc., the Alligator Creek Watershed Management Plan identifies the causes and sources of flooding, water quality degradation, and habitat loss within its 5,691 acres. The plan recommended solutions to alleviate the problems; these solutions included restoring habitat, reducing impervious surfaces, planning alternative land uses, administering pollution reduction programs, implementing capital improvement projects such as stormwater retrofitting programs, and encouraging public involvement and awareness.

The Allen's Creek Rehabilitation project is on a 27 acre site located within Allen's Creek watershed. This watershed consists of 4,682 acres of predominantly residential and commercial land use. Historically, the site was a floodplain marsh and forest dominated by red maple (Acer rubrum) and bay (Persea spp.) trees. Over recent decades, portions of the site were dredged for borrow material, filled with construction debris, and mined for peat. These impacted areas are dominated with nuisance and exotic vegetation such as Brazilian pepper (Schinus terebinthifolius), willow (Salix caroliniana), and cattail (Typha spp.). The remnant floodplain where peat mining occurred has been invaded by air potato (Discorea bulbifera) and Brazilian pepper (Schinus terebinthifolius). The site is platted and owned by the City of Clearwater and Pinellas County. An elementary school, middle school, and high school are all within walking distance and children frequently traverse the site to school. The purpose of the project is three-fold: management of surface water runoff to Allen's Creek, including attenuation of instream peak flow rates; biological treatment of surface runoff, restoration of the natural floodplain in such a manner as to maintain a balance among and improve wildlife utilization of uplands, open water and intermediate habitats; and provision for an educational opportunity for the public. Watershed studies have identified flooding issues, water quality degradation, and natural habitat loss that can be relieved and reduced through a restoration and treatment project.

The source of water, sediment and many water quality constituents for large rivers and wetlands is typically found in upland contributing watersheds. This is particularly evident for the topographically complex landscapes of the interior Pacific Northwest and Great Basin regions, where meltwater from high-elevation snowpacks is the primary water source for rivers traversing extensive semiarid lowlands. These conditions are demonstrated for a rangeland watershed system in which hydrologic regime of headwaters and mid-elevation sectors is intimately linked to streamflow and channel processes in low-elevation, higher-order stream reaches. Adequately understanding hydrologic and ecosystem characteristics of the source watershed is requisite to comprehensive, successful river or wetland restoration and management.

Streams and rivers are dynamic systems which are undergoing constant change. Some of the changes can be accelerated by watershed development which result in negative impacts to infrastructure and the environment. Engineers have been increasingly asked to mitigate these damages and restore streams to more natural systems where the ecosystem is again favorable. Once tasked with environmental restoration of a stream, an engineer must determine the appropriate methodology to achieve this goal. Often this requires narrowing the focus of the project's geographic area, gathering field data, identifying the project's problem areas and finally producing a design. This task is often more difficult and time consuming than it first appears. The Baltimore District of the U.S. Army Corps of Engineers has been involved in several river and stream restoration studies in the mid Atlantic area. These areas are both urban and suburban areas. Each project has presented its own unique opportunities and difficulties. A team comprised of many professional disciplines determines the needs associated with the project. The team will then determine the overall approach to data collection and site selection. Finally, a project that fits the requirements and desires of the study team can then be designed. The current paper will outline the steps used by the Baltimore District to determine the purpose, location, and general type of environmental restoration projects. Of particular interest in the current paper will be the planning process, goal setting and data collection leading to a conceptual design. The lessons learned from these studies may prove useful in future studies involving stream restoration and stream bank protection.

Planning and design of tidal wetlands should consider inlet characteristics, sedimentation, hydraulics, biology, and water quality, while addressing structures, utilities and material disposal. Wetland restoration requires the coordinated efforts of planners, biologists, and engineers. Studies must be conducted to optimize project features and costs, minimize adverse impacts, and determine future maintenance requirements. This paper presents general planning and design considerations based on experience from recent tidal wetland restoration projects.

Reclamation proposes to preserve archaeological site 24BE529 from erosion by the Red Rock River in southwestern Montana. The Red Rock river is naturally meandering towards site 24BE529, slowly eroding the bank containing the resource. Federal historic preservation laws require Reclamation to address the impact. The preservation plan calls for the installation of three or four Bendway Weirs, also called Thalweg Displacing Barbs. The order of construction excludes all equipment activity in the stream. The barb materials will be large stones, up to 24 inches (61 cm) in diameter, quarried nearby. The bank buttressing material will be smaller stones, less than 12 inches (30 cm) in diameter. A top soil will be placed on both the finished barbs and the bank buttressing material. The soil will be seeded with native grasses and willows, forming a natural looking bank.

Streams and rivers are dynamic systems which are undergoing constant change. In most cases these changes are gradual; however, the changes can be accelerated by development in the watershed. The increases in rate and duration of runoff which accompanies urbanization has resulted in the rapid destabilization of countless miles of streams. The resulting bank erosion, bed degradation and bed aggradation has threatened infrastructure that is immediate to the stream and has adversely impacted water quality and the environment. The Baltimore District of the U.S. Army Corps of Engineers has been involved in several river and stream restoration studies in the mid Atlantic area. The initial phase of these studies involve a rapid assessment of areas within the watershed to determine target areas for work. A combination of biologic and engineering field investigation, GIS analysis, and hydrologic analysis has been used in this assessment and analysis. The analysis is conducted by a multidiciplined team with diverse expertise in areas such as biology, ecology, hydrology, hydraulics/geomorphology, and real estate. A visual hydraulic assessment is made sufficient to qualitatively categorize the bed and bank stability as well as the bank erosion potential. The current paper will primarily focus on the hydraulic engineering environmental channel stability field assessment of existing conditions that was developed for use in these studies.

Hydraulic geometry techniques, which were developed in the 1950s, have undergone a renewed popularity in the last five years. It has been suggested by many that these relations can be used to check field data, to assess channel condition, and to design channel re-alignments for stream restoration projects. There has also been recent interest in developing new hydraulic geometry relations for local watersheds, both for design and for regulatory use in evaluating channel modifications. Although hydraulic geometry relations are useful, they can easily be mis-applied. A combination of hydraulic geometry theory and analytical techniques can result in a cost-effective design method which is adapted to site-specific conditions. The use of hydraulic geometry relations alone for final design of channel re-alignments has severe limitations.

As part of the North Expansion of the Nike World Campus, a 1200 meter reach of Cedar Mill Creek was incorporated into the center of the Campus. The project utilized several stream restoration techniques and wetlands creation to construct a high flow bypass channel. The resultant solution preserved or enhanced the existing vegetation along the creek's low flow channel while improving the creek ability to convey the regulatory flood.

Suburban streams are experiencing problems such as erosion, sedimentation, and loss of wildlife habitats. Causes include residential and commercial developments and limited stormwater management. Streams in Cheswick Park are subject to all of these conditions and need restoration. This project focuses on stabilization of the channels using bioengineering techniques and the restoration of riparian and benthic habitats. This ongoing project involves three phases: existing conditions assessment and planning, restoration, and evaluation. The first phase includes stream classification using the Rosgen system, riparian habitat and benthic surveys, hydrologic analyses, and an inventory of stormwater networks. The restoration phase includes plantings and stream bank stabilization techniques. The evaluation phase will include riparian habitat and benthic surveys, and a stream system survey. This project was conducted as a private/public partnership between government agencies, private industry, and volunteer organizations.

A multi-agency task force planned, designed, and installed four bioengineering treatments with two additional modifications for stabilizing and restoring a 90-m reach of the Chena River in downtown Fairbanks, Alaska. Volunteer citizens were also involved in the installation. The goal of the project was to illustrate to private landowners and businesses various low-cost methods of controlling bank erosion that would also be beneficial for salmonid habitat and improve aesthetics.

A theoretical analysis is presented that forms the basis for determining ballast requirements for LWD habitat structures. Limited field testing of the analysis indicates good agreement with the theory. Tentative design curves have been developed. A monitoring and assessment program is currently underway to test the stability of LWD structures, and to verify the proposed design curves under a range of field conditions.

A model for pool and scour hole development in gravel-bed streams based on the size of an obstruction developed in the Pacific northwest is tested in southwest Montana. Analysis of the data suggest that the general form of the empirical relationships may be valid but the coefficients for the equations differ. Variations may be due to measurement error, differences in stream setting and character, woody debris removal, or some other unrecognized source of variability.

We collected peer-reviewed and grey literature related to rock (rip-rap) revetment and channelization impacts to aquatic organisms. In general, the literature reflected agreement that the impacts of channelization (with or without rock revetment) are severe and long-lasting, often reducing fish populations and habitat to levels significantly below those prior to construction. The effects of rip-rap alone on fish populations were less clear; although some studies show that rock revetments reduce and degrade natural bank features, other research outlines the use of rip-rap in stream restoration projects to provide constructed habitat features in channelized rivers. Recognizing the inherent impacts associated with these types of construction projects, and reviewing the accepted conventions for impact reduction, are very important for inclusion into future planning efforts.

Concrete armor units can be used in place of riprap in rivers for channel revetment; structures including spurs, groins and weirs; and for prevention of local scour. The units have primarily been used in ocean applications where the complex shape increases the stability of the unit. The limited information available on river installations indicates that increases in stability resulting from shape are insignificant when units are placed on the bed of a channel, while some increase is noted when units are placed on a slope. The implications of porosity, stability and placement of concrete armor units with respect to river designs are presented. An equation for designing concrete armor units for local scour prevention is included. Riprap equations are recommended for designing channel revetment, spurs, groins, and weirs until further research is available on concrete armor units in a river system.

Described is a field pilot study wherein environmental data and biological response were measured for 13 posts along Harland Creek, Mississippi in July–October, 1996. Highest levels of mean net photosynthesis were associated with posts planted at moderate elevations in silty sands. Photosynthetic activity was lower for posts in sands and gravels at higher elevations and for those in sandy gravel at very low elevations. Biomass for posts planted at moderate elevations was sensitive to soil texture: aboveground and root biomass from posts in silty sand were about six times greater than from posts in slightly more cohesive soils.

Installed and naturally colonizing vegetation performs a critical role in the long-term stability of bioengineered streambanks, especially when biodegradable erosion control fabrics are used for initial surface erosion protection. However, data on the limits of vegetal reinforcement are not well understood, particularly in regard to natural channels. Summaries from related studies on the shear stress resistance of grass-lined channels conducted in the last 50 years are presented. Although few studies consider sufficient factors necessary for direct application to current bioengineered streambank design, these data provide conservative guidelines to determine limits of vegetal streambank treatments. Vegetal resistance to shear depends on factors such as stem density, plant stem height, uniformity of plant cover, plant rooting habits, and soil erodability. Recommendations for future research include the need to obtain performance data on constructed bioengineered treatments and the associated vegetal resistance of native herbaceous and woody plant species commonly used in streambank bioengineering.

In natural settings, vegetation has long been empirically understood to provide surficial erosion protection and soil reinforcement. It is becoming more common to design engineered stabilization treatments which rely on vegetation, either alone or in conjunction with other materials. However, experimental research data which quantitatively address the soil reinforcement contribution of plants have been scarce to date. This paper seeks to identify the range of conditions where plants have been shown to be suitable for erosion control designs and to describe some of the common benefits of applying vegetation for stabilization purposes. Research methods and preliminary findings of an on-going investigation into the shear stress resistance contribution of various common riparian plant species are presented.

An integrated wetland treatment system was designed and constructed at the Upper Blackfoot Mining Complex in west-central Montana to treat metal-enriched, acidic drainage from two inactive mines. Treatment system design considered complexities of site topography and climate, mine drainage chemistry and flow, and engineering stability in order to meet NPDES discharge restrictions. Treatment system flow-through was initiated in the fall of 1996. Functioning of the start-up system demonstrates its capacity for efficient, passive treatment of iron in the pretreatment array and zinc in the wetland cells. Further improvement in metals retention efficiency is expected as the wetlands mature and further optimization is realized as a result of operation and testing.

Previous studies have demonstrated that detention ponds in series with constructed wetlands can reduce phosphorous loads to receiving waters and improve water quality. Significant land acquisition and engineering costs, however, dictate that a predictive model be applied to analyze the effectiveness of pond/wetland systems on water quality in large watersheds. Such a model was developed for the series of 12 reservoirs that comprise New York City's Croton water supply system. Potential detention pond/wetland sites in the watershed of each reservoir were preliminarily identified based on a review of available maps. The viability (less than 5% slope, a source of water, and no significant wetlands) of the potential sites were verified in the field and approximate boundaries of the 46 viable sites were located using a Global Positioning System (GPS). The land use within the catchment of each site was delineated on geographic information system (GIS) maps.

Monitoring data collected from the subsurface flow wetland system in Minoa, NY (3 units, approx. 60 x 30 x 0.75 m, HRT = 1.3 to 11.4 days), which began treating primary municipal wastewater during January 1996, was evaluated using multivariate statistical techniques. Nine factors accounted for 88.99 % of the variance among 27 monitoring variables. Overall, the most significant factor was "organic biotransformation". The significance of the factor to performance was demonstrated by a multiple regression model to predict COD removal as a function of HRT, temperature, and influent concentrations of COD and TKN; the model accounted for nearly 93% of the variability in COD removal by the system (multiple R²=0.9292, N=164) during the 17 month monitoring period. Work is ongoing to improve empirical and fundamental mathematical models of wetland performance to provide better tools for future systems design.

A decision support system, Constructed Wetland Decision Support System, CWDSS, was developed to aid in the design of wetland treatment systems for agricultural runoff waste streams. The program functions as a screening tool, allowing the user to choose various designs options to determine which treatment system is best for a particular site. This paper presents an example application of CWDSS for a small feedlot farm.

A pilot subsurface constructed wetlands system in a cold climate region was monitored from late October 1996 to early September 1997 for BOD₅, TSS, FC, NH₃/NH₄-N, NO₂/NO₃-N, TP, and TOC. The system components are: an upflow anaerobic filter with an automatic dosing siphon tank, a vertical (down flow) aerobic filter, a constructed subsurface wetland followed by an automatic dosing siphon tank, and infiltrators. In general, reduction of BOD, FC, TSS, and TP is observed as the effluent passes through the system, and reduction was higher in the summer than in the preceding winter and spring. Significant nitrification is not observed.

Subsurface flow constructed wetlands are notorious for their inability to transform ammonia into nitrites, and nitrates, thereby preventing the completion of the nitrogen cycle. By providing a separate and distinct aerobic environment in a series of filter components, the nitrification step in the cycle is enhanced, prior to application to the wetland filter, where denitrification occurs.

Stormwater runoff has been identified as a major source of pollutant load to both McKay Bay and Tampa Bay. The Southwest Florida Water Management District and the City of Tampa has developed a stormwater management plan that will help protect this valuable resource. This paper discusses a risk-based approach that was used to identify contaminants of concern in stormwater runoff as well as to prioritize management actions based on the contribution of various factors to overall risk.

Ocean tidal action was permanently restored to Batiquitos Lagoon after three years of construction on December 7, 1996. The lagoon was restored as off-site mitigation to replace deepwater marine habitat disturbed by the construction of cargo terminals in outer Los Angeles Harbor. The project removed 1.15 million cubic meters of sand from the lagoon and deposited the sand on the beach as nourishment. The project provided habitat for fish, shore birds, and several rare and endangered species of birds and included the construction of two new bridges, two short jetties, 16 ha of nesting habitat, and 146 ha of subtidal and intertidal habitat.

Elevations of mean high water (MHW) and the high tide line (HTL) were determined at four wetlands located along the southern end of the Laguna Madre, Texas, by applying standard Section-404 procedures of the Clean Water Act and by reference to water level at a nearby tide gauge. The Section-404 evaluation involved visual identification of vegetation and saturation of the soil. The average of five visual estimates of the MHW elevation agreed within 2 cm (0.8 inch) with MHW given by the tide gauge. The elevation of the HTL was found to lie 0.31 m (1 ft) above MHW, corresponding to an annual exceedance between 2.8 and 7.7 percent for each of 3 recent years. It is concluded that experienced personnel can apply visual indicators at tidal wetlands adjacent to the southern Laguna Madre to estimate reliably MHW and the HTL. The procedure of referencing the elevation of the HTL to MHW determined by a local tide gauge appears applicable to other tidal wetlands.

Constructed wetlands provide a low cost and effective means of treating wastewater. When dealing with large flows the land requirements for constructed wetlands become very high, thus limiting their use for treating large flows of wastewaters. Deep wastewater treatment ponds can be used in conjunction with constructed wetlands to handle medium to large sized wastewater flows. In this manner a low cost and efficient natural wastewater treatment system is obtained. In this paper the role of wastewater pretreatment ponds is examined by studying the behavior of key hydrometeorological variables in the waste stabilization pond at Boxelder Sanitation District which is located 5 miles east of Fort Collins, Colorado, 40° N, at an elevation of about 4980 ft. An attempt has been made to identify causal relationships among the various hydrometeorological variables by time series modeling.

Developing management strategies for sustainable riverine ecosystems, including finding practical solutions for endangered aquatic species preservation, requires an improved understanding of riverine ecosystem behavior under stress. This research seeks to provide a methodology to quantify temporal and spatial changes in ecosystem health induced by environmental stresses. A mechanistic ecosystem response model will be utilized to quantify impacts of natural and anthropogenic stresses, singly or in combination, on sensitive aquatic species. This ecosystem response model is being created by incorporating an ecological routine into an existing hydrodynamic and water quality modeling framework. Initial application of the ecosystem response model investigates impacts of flow regime, water temperature, and salinity on survival, growth, and migration of juvenile chinook salmon in the Sacramento River-San Francisco Bay-Delta system. Progress is reported on development and application of this methodology for determining relationships between stress changes and aquatic ecosystem responses.

This paper describes a sediment modeling assessment of a geomorphic channel design proposed for restoration and flood damage mitigation of a six mile tidally influenced reach of the Napa River. The model study employs the unsteady quasi-two-dimensional hydrodynamic and sediment transport model, MIKE 11, and the Rouse equation to calculate sediment transport, erosion and deposition at specific areas across the channel cross-section (i.e. the main channel, the marshplain and floodplain terraces) and a dry bypass channel, and to assess the morphologic stability of the channel. This modeling approach allows for the simulation of salient sediment transport processes including lateral and vertical sorting and distribution of sediments, resuspension due to riverine and tidal flows and local flushing of fine cohesive sediments during flooding.

The fabric-encapsulated soil (FES) method to provide bioengineered stream bank protection is described and discussed in the context of five projects constructed between 1991–96. This technique utilizes a stone toe protection, an internal gravel filter, soil lifts wrapped in biodegradable coir fabric, and an aggressive revegetation plan. Project reviews suggest that successful implementation of this technique relies, in part, on consideration for toe-of-slope protection, the lower limit of perennial vegetation, the relationship between fabric decay and plant establishment, the use of appropriate soils, and thorough construction oversight.

This paper describes two new experimental bioengineering techniques. One demonstration project has been constructed using each method. Additional projects are scheduled to be installed in 1998–99.

The role woody vegetation plays in restoring and protecting streambanks is widely recognized. In addition, it has a variety of environmental benefits, including providing overhanging cover, temperature modification, supplying organic debris, and providing streamside habitat for nesting areas and protected wildlife corridors. While this role has become well understood, concerns are often expressed regarding the use of woody vegetation in streambank protection relating to its resistance to erosion in channels with high velocities. This is especially true of streams in urban areas as well as those that have been relocated and/or shortened. Additionally, questions arise regarding how it is affected by ice and debris, and what guidelines are available for determining the lowest bank elevation for establishing vegetation.

Woven coir fabric is a biodegradable erosion control product that has become widely utilized in stream bank stabilization and soil bioengineering. Its primary advantages over non-woven coir, jute, or straw erosion control products are a high tensile strength and increased longevity, while still remaining cost-effective and easy to install. Fabric tensile strength provides initial bank stability while installed vegetation provides long-term resistance to erosional forces as fabric decomposes. Because woven coir fabric is often used on sites that experience high tractive forces that may also be difficult for vegetation establishment, the longevity of woven coir fabric is critical. Since little published data exists on actual rates of fabric degradation under field conditions, a study was undertaken in 1996 investigating installed longevity of 700 and 900 g/m² woven coir fabric. Samples of woven coir and qualitative site data were collected from 20 bioengineered stream banks projects constructed between 1989 and 1995. These samples were submitted to an independent geotextile testing laboratory for standardized ASTM tensile strength testing. To generate approximate degradation rates, tensile strengths of collected samples were then compared to test values of "new" fabric samples submitted by several coir suppliers.

When Wal*Mart Stores, Inc. proposed building a store in West Lafayette, Indiana, on commercially-zoned land, the company encountered opposition from area residents, primarily because the site bordered a wetland the community wanted to see developed into a habitat for indigenous species. Concerns over impacts of additional impervious areas on the quantity and quality of runoff prompted Wal*Mart to build an on-site biofiltration pond, a constructed wetland to treat nonpoint source (NPS) pollution in the first 1.27 cm (0.5 in) of runoff from the store's parking lot. To assess the chemical and sediment trap efficiency of this stormwater detention biofiltration pond, samplers were installed at the inlet and outlet. The purpose of sampling is to ascertain whether the constructed wetland is performing to specifications and to determine how performance varies seasonally as well as over a series of years as the wetland vegetation matures. Instruments at the inlet and outlet automatically measure water level, flow, pH, temperature, conductivity, and dissolved oxygen, and take water samples when a storm occurs. Samples are analyzed for common road contaminants such as salts and heavy metals. This approach provides more accurate data than standard "grab" analyses, as well as new insight into seasonal and long-term performance of constructed wetlands.

The purpose of this study is to evaluate the use of constructed wetlands as a best management practice (BMP) by comparison of selected design parameters and pollutant removal efficiencies for three wetland sites. Analysis of stormwater samples for total suspended solids (TSS), chemical oxygen demand (COD), total phosphorus (TP), orthophosphate (OP), and zinc (Zn) indicates a wide range of average removal efficiencies ranging from –30 % (export of pollutant) to greater than 80 % (removal of pollutant) with significant variations between the three sites monitored. Data was also collected to document vegetative diversity and utilization of the wetlands as a habitat. A field scale wetland model (currently under development) utilizing the U.S.E.P.A. Water Quality Analysis Simulation Program (WASP) is described, along with a geographic information system (GIS) that has been developed as a resource for model input and storage of data pertaining to wetland sites.

Two wet ponds built to detain and treat highway runoff were investigated to determine dredging maintenance schedules in Washington state. Each pond was located in a different climate, one with few significant snow events, the other with many major snow events. Results showed that the pond in the heavy snow climate required a more frequent dredging schedule due to application and subsequent runoff of sand and gravel. It was recommended that ponds in northern climates receiving large snow events be dredged every 2–3 years, as compared to the frequently stated 5–10 years suggestion.

The Water Resources Development Act (WRDA) of 1996 provides a new Congressional authority by which the U.S. Army Corps of Engineers may participate in the design and construction of ecosystem restoration and protection projects. In 1996, the U.S. Congress appropriated funds to initiate the Hocking River Basin Environmental Restoration Study under the Corps of Engineers General Investigations Program. The study is being conducted by the Huntington District of the Army Corps of Engineers. The Hocking River is located in southeastern Ohio, in the heart of the northern Appalachia coal mining belt. Streams throughout this region have been severely degraded by acidic drainage from mines abandoned prior to implementation of the Surface Mine Reclamation Act of 1977. The Hocking River Basin Environmental Restoration Study will ultimately lead to a unified watershed restoration plan to ameliorate aquatic habitat resources in this region.

The Mompano Dam Rehabilitation project integrates several techniques to achieve various watershed management objectives. These included dam safety, mitigation of increased runoff produced by development, and the maintenance of Beaver Lake as an important aesthetic and habitat resource. Innovative spillway geometry improved detention capacity while increasing conveyance for major storm events. The solution utilizes a new trapezoidal spillway while maintaining the existing spillway and fish ladder. The new spillway reduces discharge during small storm events due to its narrower opening. This improves downstream channel stability and improves aquatic habitat. The existing spillway becomes an overflow adding conveyance during the largest events (including the probable maximum flood or PMF). Maintaining the existing fish ladder allowed rapid project acceptance from regulatory agencies.

Development of water resources in the Colorado River Basin is complicated by, among other things, the fact that the river contains four native fish species listed as endangered under the Endangered Species Act (ESA). To address the issues related to resource development and compliance with the ESA, the states of Colorado, Utah and Wyoming have joined with the U.S. Department of Interior, Western Area Power Administration, and representatives of the environmental and water development communities, to form the Recovery Implementation Program for Endangered Fishes of the Upper Colorado River Basin (Recovery Program). The purpose of the Recovery Program is to facilitate recovery of the listed fishes, a goal greater than the avoidance of jeopardy required by ESA, while water development proceeds.

In 1991, Los Angeles Department of Water and Power in cooperation with Mono County, California, initiated a multi-year effort to restore the Owens River Gorge. Restoration is focused on developing riparian and aquatic habitat complexity using incremental increases in pulse and base flows. We use pulse flows low enough to prevent erosion of landforms and loss of channel sediments but sufficient to provide seed transport, germination, and hyporheic zone recharge. Monitoring vegetative response shows a large and consistent increase in riparian vegetation each year. Brown trout are responding rapidly to the restoration effort. From zero fish in 1993, brown trout increased by 50 percent between 1995 and 1996. Current trout catch rates of between 7.1 and 5.8 fish/hour demonstrate the success. The key to ecosystem recovery in the Gorge is a multiple-flow regime that allows nature to build and maintain riparian habitat and channel form.

The Oregon Department of Transportation (ODOT) developed the "Guide to Wetland Mitigation Issues for Transportation Designers" for the American Association of State Highway and Transportation Officials (AASHTO), published in September 1996. The manual provides a bridge of understanding between the specialized disciplines of wetland ecology and regulation and highway design. AASHTO recognizes a need to improve understanding and collaboration between highway designers and environmental staff. The manual is written in a readable, jargon-free style suited to the non-technical reader. It provides information on wetland functions, policy and regulations, mitigation options, the mitigation site development process and post-construction management. It was based on several years of practical experience gained in each phase of mitigation planning, design construction, planting and monitoring. The manual emphasizes practical options for wetland impacts avoidance and minimization, and sets out a step by step, multi-disciplinary approach to the mitigation site development process. It discusses the special issues relating to contractor selection and coordination, obtaining plant materials, accurate site grading for specific hydrological conditions, soil amendment, and planting techniques and timing. The guide has been applied by ODOT in numerous wetland mitigation sites, including its first mitigation bank at Dalton Lake, the subject of another paper at this conference.

Fifteen federal agencies are developing a of stream corridor restoration planning and design technology document to serve as a common reference for field resource managers and other technical specialists. Offering a scientific perspective, the document will emphasize least intrusive solutions that are ecologically derived and self sustaining.

Wetland and stream restoration projects are receiving increased government funding. Future restoration efforts will be focused on accelerating the pace of projects constructed "on-the-ground," with funding being dependent on a project's engineering and regulatory feasibility. Interdisciplinary conflicts in completing wetland or stream restoration projects often result in unexpected costs and schedule delays. This paper reviews the close, ongoing interaction between conventionally isolated project planning, engineering, and permitting processes for three restoration projects in California.

Success criteria for wetland restorations are generally tied to regional, site-specific goals. Although it would be a hopeless task to attempt to restore all wetland functions, certain criteria can be used to guide the restoration trajectories toward a desired end-point. For example, the restoration of coastal salt marshes serving as primary nurseries for finfish requires an appropriate balance between vegetated areas and the marsh drainage configuration. The former fuels the base of the food web, while the latter increases "edge", and thereby access to the marsh surface and enhanced exchange between marsh products and adjacent tidal creeks. In this paper, the requisite area of marsh required to replace fish "production lost" at a power plant is established, and a population model developed to estimate the actual number of fish of a particular species produced at the end of the growing season.

This report describes the project initiation and site identification phase of the proposed Mogensen Meadows Wetland Mitigation Bank. The project site is located along Plateau Creek in west central Colorado on a parcel of land owned by the Ute Water Conservancy District (bank sponsor). The unique qualities of the site were identified during environmental inventories performed as part of a Bureau of Land Management (BLM) Environmental Impact Statement (EIS). The site has historically been under intensive agricultural use and presently includes degraded wetlands, pastures and irrigated fields. It includes approximately 2.6 cubic feet per second (cfs) of water rights that could be used for wetland restoration. The bank sponsor has indicated a willingness to provide a long-term real estate arrangement to protect the area.

To restore diked salt hay farms along the Delaware Bay to functional salt marshes, we had to satisfy ecological requirements within the context of engineering specifications. Because the ecosystems are complex and there are uncertainties involved in ecosystem design and construction, we agreed to use Ecological Engineering to achieve functional salt marshes with normal ecological relationships to the adjacent Bay. This means establishing sufficient conditions to start development of the ecosystem, then allowing natural processes to complete the job. Meetings between hydrologists, ecologists, and engineers developed design criteria. Tidal channels of proper shape and size to provide habitat and flows of suitable velocities were to be excavated. Tidal flooding of the marshes was to achieve a hydroperiod to allow marsh plants to flourish, requiring designs calculated from tides during the growing season. Tidal inlets were designed so that armoring would not be needed to achieve stability. We chose different techniques for two sites. At one site the channels were to be overdredged and evolution to the final condition was to be by sediment deposition. At the other site, channels were underdredged and the final condition was to be achieved by scouring.

An investigation of the historical nature and use of tidal marsh drainage systems in the Delaware River Estuary was conducted as baseline information. Historical maps, aerial photographs, dike failure records, tidal range data, and present day tidal creek geomorphology provided the basis for analysis. These data, together with information on relative sea level rise, present an overview of the use and management of estuary tidal marshes. Select marsh systems are discussed to describe the restoration of tidal marshes following diked meadow land use. Restoration is depicted in terms of marsh system age. The prevalence of Phragmites australis in the Estuary has increased during this period of marsh restoration, now dominating many tidal watersheds by replacing or isolating more beneficial species, such as Spartina alterniflora. The pattern of P. australis spread is presented for two case study areas (Blackbird Creek in Delaware and Alloways Creek in New Jersey) based on aerial photography from 1930 to the present and is related through observations on site conditions and invasion pressure upon the survival of relic areas of S. alterniflora.

The adaptive management philosophy was applied throughout the design and construction phases of a project to restore approximately 10,000 acres of degraded salt hay farm wetlands on the Delaware River Estuary. Adaptive management involves setting goals, monitoring a project, and then modifying intervention and management strategies to meet the goals. Fifty years of diking have reduced marsh plain elevations, obliterated tidal channels, reduced Spartina alterniflora and increased Phragmites australis in marshes on the Delaware River Estuary. The restoration goal is to obtain a mixed salt marsh ecosystem dominated by Spartina alterniflora but with significant areas of Spartina patens high marsh. This paper will explore the application of adaptive management to the project construction phase.

Design of successful marsh restoration projects requires careful consideration of the hydroperiods of the marsh system. If the hydroperiods are poorly defined, the duration of inundation of marsh grasses will be either too long or too short, the restoration effort may be less successful. Fortunately, proper design based on understanding of nonlinear tidal hydrodynamic processes can enhance the likelihood of success of marsh restoration. Tidal marsh systems are strongly nonlinear hydrodynamic filters. Astronomical tides entering salt marshes via tidal inlets may be inherently linear, but they are distorted strongly once they enter the marsh. This nonlinear distortion results in strong spatially-varying tidal heights and tidal phases. One representation of the strong nonlinearity is the generation of overtides and harmonics of the fundamental equilibrium tidal constituents found offshore. These nonlinear processes must be understood when designing a marsh, since the marsh channel design and the extent of tidal flats will control this nonlinear response. There are several fundamental controls on the hydrodynamics of marsh nonlinearities, which control the hydroperiods. The first nonlinear control focuses on depth of the channel; the ratio of tidal amplitude to water depth is the first order control on the degree of nonlinear energy transfer from parent tides to harmonics. The second control is the ratio of the area of the marsh system covered by vegetated tidal flat versus that dedicated to deeper tidal channels. Other tertiary controls exist as well. By careful design of the depth of the marsh channels, and the relative area covered by tidal flat vegetation, different hydroperiods can be encouraged, enhancing marsh growth.

Opportunities and constraints are presented for the conceptual restoration of diked salt hay farms in Commercial Township to tidal marshes. The fundamental design philosophy was to restore physical processes at the site, which would result in a sustained and naturally functioning tidal marsh. The design criteria of channel morphology were based upon reference marsh data, historic conditions, and consideration of natural marshplain evolution. General assumptions and projections were made concerning anticipated patterns of site marshplain evolution, using a two dimensional hydrodynamic and cohesive sediment transport model. A comprehensive review of incremental changes in engineering design as implemented during the construction by the EEP is presented with associated justification. The role of the Adaptive Management process in site construction monitoring is reviewed with particular emphasis to the establishment of high marsh creation areas.

As part of the Estuary Enhancement Program (EEP) being undertaken by Public Service Gas & Electric (PSE&G), Woodward-Clyde International-Americas (Woodward-Clyde) was responsible for conducting the baseline studies and developing the restoration design for the degraded tidal salt marsh at both the Dennis Township Salt Hay Farm and the Maurice River Township Salt Hay Farm. Both engineering and ecological factors were considered in developing designs that focused on a natural restoration, minimizing the level of engineering and subsequent disturbance, while maximizing the potential for a successful, self-sustaining restoration. The key components of the design include the breaching of existing perimeter dikes and the excavation of new channels to allow the restoration of daily tidal flows; and the construction of upland diking to protect adjacent properties from flooding associated with normal tide conditions. The work included the use of two-dimensional hydrodynamic modeling to predict wetting and drying of the sites for various design alternatives. The model was also used to refine the channel configurations and evaluate the erosion and scouring potential in the channels and across the sites. Inherent in the final design are many ecological and physical criteria that may impact the success of the restorations. This work was conducted on a very fast track during 1994 and 1995.

An analytical method for determining the stable hydraulic geometry of restored river channels is presented and is offered as an alternative to intuitive or empirical methods. A design chart is produced, and its application to river restoration is demonstrated through application to a hypothetical river.

Spawning and rearing habitat for spring/summer chinook salmon in the lower Red River meadow has been severely degraded over the past 60 years due to ranching and mining activities. Restoration of the stream channel within four parcels of property in the lower meadow would greatly benefit resident and anadromous fish species. Red River is a tributary of the South Fork Clearwater River which is located in north central Idaho. Preparation of the project design package was based on the overall project design philosophy that the stream channel should be constructed and revegetated with native plant species to create conditions that allow the re-establishment of the dynamic equilibrium inherent to the meadow ecosystem. Using 1938 aerial photos, a comparison of historic and existing channel meander patterns was completed to identify the best alignment for the restored channel. Information needed to prepare the design package was collected and analyzed in a defined process to ensure all components were incorporated into the design. This project was managed by the Idaho County Soil and Water Conservation District and funded by Bonneville Power Administration. Interagency review and coordination was provided by Idaho Fish and Game, Nez Perce Tribe, Idaho Division of Environmental Quality and the Nez Perce National Forest.

Urban streams and wetlands are some of the most extensively degraded and disturbed aquatic ecosystems in the country. To assess the cumulative effects of urbanization and development, the watersheds of 22 small streams in the Puget Sound lowlands were extensively studied over a 3-year period. The watersheds included rural, suburban, and urban land uses. The study included detailed watershed characterization, in-stream habitat assessment, riparian zone surveys, macroinvertebrate sampling, hydrologic monitoring, and chemical water-quality analyses. The results suggest that resource managers should concentrate on the preservation of high-quality stream systems through the use of land-use controls, riparian forest buffers, and protection of critical in-stream salmonid habitat. Enhancement and mitigation efforts should be focused on watersheds where ecological function is impaired but not lost. It is apparent that restoration measures will probably be ineffective unless watershed-level disturbances such as changes in the hydrologic regime and loss of riparian forests are addressed in addition to addressing in-stream habitat features and water quality.

As part of environmental restoration activities subject to the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) at the former Loring Air Force Base (LAFB) in northeastern Maine, contaminated sediments from a high-value brook trout (Salvelinus fontinalis) stream and floodplain are being removed. In 1997, 50,387 cubic meters of contaminated sediments was removed from the East Branch of Greenlaw Brook (EBGB) and one of its tributaries, the Flight Line Drainage Ditch (FLDD). In 1998, another 46,000 cubic meters of sediment is expected to be removed from the EBGB. In total, approximately 2,500 linear meters of stream and 10 hectares of bordering floodplain wetland will be restored. This paper describes the process and methods used to develop and implement restoration.

Knowledge of the basic concepts of river ecology is fundamental to understanding the nature of human impacts on river systems and articulating sound restoration strategies. This article reviews the fundamental elements and processes that structure fluvial ecosystems: the physical setting, living organisms, and inputs and flow of energy. It also highlights those factors that maintain a high heterogeneity of habitats and ecological connectivity, resulting in higher biological diversity and productivity.

The main effects of regulation, channelisation, and diversion works on river ecosystems are a decrease in habitat diversity, and a shift from native to exotic biodiversity. To restore a river is to attempt to bring it back to high levels of ecological integrity - conditions as close as possible to those that unimpaired rivers would have had in the region, taking into account the prevailing socioeconomic, political, and technological constraints. When a river is highly managed, this goal is unrealistic, the objective should then be ecological health - that the river ecosystem provides services to society in a sustainable fashion, without degradation for future use, performing all of its functions properly, with minimal outside care. If the natural flow and water quality régimes are restored, and the channel is reconnected to its floodplain, a river left to itself will regain a high ecological integrity, without need for further intervention.

A design approach is suggested which may offer greater opportunities for satisfying multiple objectives in engineering design projects. The congruence of patterns in the human ecosystem with naturally occurring patterns in the landscape is offered as an ecological design model for better integrating an ecological aesthetic into the artificial environment, especially regarding the design of waterways and water edges.

Integrated Bank Protection is process for the design of streambank protection projects that protect and restore aquatic habitats. It is the assimilation of six concepts into the planning and design of river bank protection projects; mechanism of failure, cause of failure, risks of erosion and stabilization, and habitat condition and needs. Design tools are suggested for assessment of bank protection needs and selection of bank protection techniques. Concepts of lost opportunity impacts, channel confinement and shear stress/erodibility analyses are discussed.

It is known that intensive structural flood prevention measures often lead to further development in flood hazard areas, generating a need for yet more flood protection measures. This reciprocal pattern of development followed by river engineering has been exhaustively criticized by national policy experts, but persists as a model of growth in much of the U.S. Predictable increases in flood hazard and compromise of ecological floodplain integrity result, and, once embraced, a community loses the flexibility to manage floodplains for values other than real estate. The more dynamic fluvial behavior of gravel bed rivers in the western states makes flood prevention strategies more challenging, yet the relative lack of development on these floodplains may lend more opportunity to redefine floodplain management approaches. In this paper, the failures of national floodplain management programs are viewed through the lenses of two small river valley communities, Jackson Hole. Wyoming, on the Snake River and Livingston, Montana on the Yellowstone River. The authors suggest that traditional structural flood control approaches are inadequate for these communities, and that if natural resource values are important, local, rather than federal, regulation of flood prone areas will be necessary.

Montogomery County, Maryland used a flood mitigation alternatives analysis process to select a flood mitigatation alternative for a townhouse development which had repetitative flood damage from a nearby stream. By following standard problem solving techniques to select an alternative, Montgomery County was able to relatively quickly and cost effectively identify the "optimal" flood mitigation alternative.

The Corps of Engineers wetlands delineation manual states that a site must meet the wetland hydrologic criterion for water table depth and duration under average conditions, defined by the Corps to mean that those conditions occur in at least one of two years over a long term record. Because long-term water table records rarely exist for sites in question, water table measurements of a few months are often made to determine whether wetland hydrology exists. The decision as to whether those measurements reflect "average" conditions is usually based on whether rainfall during the measurement period is "average". This paper examines whether an assessment of hydrologic status based on satisfying a water table criterion in one of two years, on average, is the same as an assessment based on the same criterion, but applied only in periods with average rainfall. The reliability of a field method based on "average" rainfall was examined. The field method excludes from consideration water table records occurring during above average rainfall months when making hydrologic assessments. Results from the examination of the field method showed that by only considering water table records from average rainfall months, many sites which did have wetland hydrology were incorrectly identified as uplands. Sites which meet the hydrologic criterion under actual rainfall often do not meet the criterion when only months of "average" rainfall record are examined. Results indicate that a site that satisfies the wetland hydrologic criterion on a long term average may be much drier than a site meeting the criterion under "average" rainfall conditions.

In a tidal marsh plain, salinity and moisture distribution determine the sustainability of the ecosystem. These response patterns are modeled by the marsh plain equations, the governing equations for coupled flow and salinity transport in a saturated/unsaturated tidal marsh plain. The boundary conditions, whose combination is unique to a tidal marsh plain, are established, and evaporation and periodic inundation in a one-dimensional soil column is explored.

Storm flows from Arroyo Chico and its tributaries cause severe and frequent flooding to the central part of the City of Tucson, Arizona. Urban encroachment severely limits the rights-of-way needed for traditional flood-control measures such as channel improvements or levees. Further, the residents and their elected public representatives prefer maintaining the riparian characteristics of the local watercourses and the historic character of the surrounding neighborhoods. Consequently, stormwater detention is the method of choice. In cooperation with the U.S. Army Corps of Engineers, the City of Tucson and Pima County have developed a two-part regional detention project for Arroyo Chico. The first part, a multiple detention basin system integrated into an existing 18-hole municipal golf course is complete and operational. The second, and ongoing, part includes a multiple detention basin system located farther down in the watershed. The design of the lower, or "Park Avenue," detention basin includes mitigation, environmental restoration, and recreation. There are several configurations that provide opportunities to incorporate different types of habitat restoration and recreation. The project is a good example of siting a multi-objective flood control/restoration project in an urban area with a scarcity of open space. The challenge is to accommodate federal flood control design and environmental standards, as well as the desires of the local community.

The Limon Wetland is a pilot wetland-banking project for the Colorado Department of Transportation (CDOT). The main intent of the project is to develop a wetland banking memorandum of agreement (MOA). The intent of this MOA is to outline for the regulatory resource agencies how wetland banks will be done on future CDOT projects in Colorado. CDOT will use the created wetlands for mitigation credits on future transportation projects primarily in the upper Arkansas River watershed. We will present an overview of the project explaining major features and our design assumptions. A conclusion will be given presenting what we hope to learn from the project and CDOT future plans for the site.

The management goal at the 23.2 ha Dalton Lake wetland mitigation bank is enhancement of waterfowl habitat by controlling the non-native grass Phalaris arundinacea (reed canarygrass) and restoring Sagittaria latifolia (wapato). The project included extensive research on lake hydrology and plant community dynamics. Mitigation actions consisted of excavation of Phalaris from two areas totaling 1.2 ha, replanting Sagittaria and construction of a low weir to control water levels. Baseline monitoring established that higher water and a longer period of inundation reduces Phalaris vigor, but extreme high water in consecutive years also reduced Sagittaria cover dramatically. "Adaptive management" involving continued monitoring and water level manipulation will be needed to restore the native plant community.

A multi-disciplinary approach was used to design a saline wetland mitigation bank for The Burlington Northern and Santa Fe Railway Company (BNSF) to compensate for unavoidable wetland impacts associated with the upgrade and expansion of their Hobson Yard facility in Lincoln, Nebraska. The project was the first permitted mitigation bank in Nebraska. Development of the design concepts centered around a hydrologic analysis of the proposed 178.60-acre mitigation site to determine an appropriate water budget and source of saline conditions for support of the desired biological communities. Mitigation measures to restore the area's past hydrology included construction of low-level earthen embankments with outlet control structures, correction of headcut drainages, removal of drain tile systems and other agricultural practices, and clearing of woody vegetation. These measures serve to correct hydrological and land management parameters that are actively degrading the site and thereby allowing the existing saline wetland plant communities to expand into a larger area generally thought to correspond to the historic coverage of the wetland. The plan included consideration of long-term maintenance and operation of the site for continued success of the project.

This paper evaluates methods used in the environmental and hydraulic planning, design and evaluation for restoration of riverine wetlands along the Rio Grande in New Mexico. The environmental degradation brought on by anthropogenic changes in riparian and aquatic biological communities have made riverine wetland ecosystems one of the most important for conservation and restoration in the southwestern United States. The U.S. Army Corps of Engineers is planning to rehabilitate a flood control levee along 42 miles of the Rio Grande immediately below San Acacia, New Mexico. The flood control levee currently restrains the Rio Grande to a narrow floodplain that is perched as a result of sediment deposition. Opportunities for overbank flooding within the existing floodplain have further decreased due to localized scouring of the channel and regulated flows that lower spring peak discharges. The project area is important habitat for two endangered species, the Rio Grande silvery minnow (Hybognathus amarus) and the southwestern willow flycatcher (Empidonax trailii extimus). Aquatic habitat needs for silvery minnow include low velocity side channels and non-conveyance backwater areas. Low velocity flooded vegetation is a key for willow flycatcher nesting success and riparian habitat maintenance. The flood control project provides an opportunity to improve habitat for these endangered species by enhancing the structural diversity and ecological integrity of the floodplain.

The causes and mechanisms of erosion along wetland shorelines and channels are described. A checklist is provided summarizing information and documented experience regarding considerations in wetland erosion protection projects.

The U. S. Army Corps of Engineers (Corps) and its customers dredge to maintain 25,000 miles of navigation river, lake, and coastal channels, as well as numerous flood control projects, and as part of the permitting process for US Navy homeporting, private and public marinas, and for dredge-and-fill permitted projects. Only a tiny fraction of this has been considered for use in tubes, or involves tube projects for wetland restoration. However, the low costs associated with using tubes as breakwaters for wetland restoration and beneficial uses of dredged material projects have made it an area of intense discussion and concern. Virtually all of the wetland restoration tube projects constructed have involved recognized functions of wetlands such as fish and wildlife habitats, sediment management, and erosion control. In years past, the Corps generally used unconfined disposal with a primary purpose of navigation and channel maintenance; however, a secondary purpose resulted in the habitat creation and/or restoration on islands, wetlands, and along shorelines.

The U.S. Army Corps of Engineers Waterways Experiment Station (WES) is currently developing a systematic methodology for hydraulic design of channel restoration projects. The methodology incorporates both fluvial geomorphologic principles and engineering analysis. It includes use of hydraulic geometry relationships, analytical determination of stable channel dimensions, and a sediment impact assessment. The preferred design channel geometry is a compound channel with a primary channel designed to carry the effective or "channel forming" discharge and an overbank area designed to carry the additional flow for a specified flood discharge. Channel width may be determined by analogy methods, hydraulic geometry predictors, or analytically. Once a width is determined for the effective discharge, depth and channel slope are determined analytically by balancing sediment inflow from upstream with sediment transport capacity through the restored project reach. Meander wavelength must be determined by analogy or hydraulic geometry relationships. Assumption of a sine-generated curve then allows calculation of channel planform. The stability of the channel design should then be evaluated for the full range of expected discharges by conducting a sediment impact assessment. Refinements to the design include variation of channel widths at crossings and pools, variable lateral depths in pools, coarsening of the channel bed in riffles, and bank protection.

Stream meander restoration design is often based on empirical equations or other empirical information. The appropriateness of these methods depends on the local physiographic and hydrologic setting and on the ability of the method to adequately describe the planform geometry. Freely formed meander planforms can be described by two equations for the meander arc length and sinuosity. Regional regression equations can be used to verify the use of free-form meander dimensions or as the basis for meander design or stabilization.

Remediation of mine tailings from the channel and adjacent floodplain of 5 miles of Silver Bow Creek near Butte, Montana will require complete excavation and reconstruction of the floodplain and channel. Specific project objectives include reconstruction of a channel and streambanks which provide for dynamic stability through deformable streambanks while working within the constraints imposed by existing infrastructure. Specific design criteria were developed to achieve vertical stability, dynamic lateral stability, and reduced potential for channel avulsion. Based on estimated hydrology and sediment supply, criteria were established to facilitate a design process which begins with ensuring sediment continuity through channel grade and cross-section geometry and subsequently develops planform and floodplain characteristics.

The design of stable channels with mobile bed materials poses complex problems in hydraulic engineering, sedimentation and fluvial geomorphology. In addition, recent requirements to provide a range of aquatic and riparian environments capable of supporting a high biodiversity, recreational activities and possessing good aesthetics presents further challenges to the design engineer. Geomorphic engineering principles and procedures are outlined as a basis for incorporating natural channel variability into the Waterways Experiment Station (WES) river restoration design procedure.

Natural and constructed wetlands are being built in locations throughout the United States to improve the quality of stormwater runoff. However, substantial consideration must be given before such a project can be undertaken. This paper identifies some of the differences between constructed and natural surface-flow wetlands for stormwater treatment. Topics included in the discussion are: the objectives of stormwater wetlands, some physical and operational differences between natural and constructed wetland systems, the pollutant removal capability of stormwater wetland systems, and considerations for selection of wetland type for stormwater runoff treatment

Pinellas County and the Southwest Florida Water Management District's Surface Water Improvement and Management (SWIM) Department have jointly funded a project to retrofit an urban drainage basin for stormwater attenuation and treatment. This paper presents unique design features along with an effective combination of public education and environmental awareness that can easily be applied to other projects.

Storm water level of service (LOS) is a means of evaluating existing infrastructure and a basis for allocation of storm water resources. The challenge has been the determination of appropriate parameters for LOS evaluation. The management of storm water usually includes the reduction of flood risk and the improvement of water quality. There may be other objectives such as the protection of wetlands, water reuse, or the improvement of ground water recharge. While there is widespread agreement that water quantity and water quality objectives are linked, LOS criteria have, in most cases, been considered separately. The development of storm water LOS has been the purview of local government, and several different approaches have been proposed. While the objective seems to be a single parameter system that can be reduced to a letter grade from A to F, some have found it necessary to use multiple parameters to define the criteria. The maintenance status of the system has also been a level of service issue, and criteria for grading the maintenance status of a storm water facility have been proposed.

The bioengineered pond and wetland system on the site of the new Federal Medical Center in Devens, Massachusetts successfully combines stormwater quality and discharge control with ecological enhancement. Project designers created a series of three interconnected basins in an existing stream course. These ponds/wetlands are heavily vegetated to take advantage of vegetation's ability to improve water quality, stabilize soils and provide wildlife habitat. Specialized bioengineered, vegetated materials helped establish the vegetation quickly and reliably. The system is designed to regulate stormwater flow for events up to the 100-year storm for a watershed of 21.7 ha (55 acres). This project demonstrates that stormwater management systems can provide their engineering function while also providing ecological benefits, and that site development mitigation activities can indeed improve existing degraded natural resources.

Healthy, natural streams provide a wide variety of benefits. Streams can be thrown out of balance, and their beneficial functions degraded, if the amount of water or sediment they convey changes significantly. For example, upstream development can increase the frequency and volume of storm runoff and lead to stream degradation and erosion. The disciplines of hydrology, hydraulics, geomorphology, and biology can be applied to re-create stable, natural stream systems that function under new hydrologic conditions. Riparian vegetation plays a particularly important role in this process. Several case histories of stream restoration and water quality projects are described, with insights shared regarding techniques that have worked well in the Denver metropolitan area.

Anchorage, Alaska, is situated at 61° latitude, at the very northernmost extension of the Pacific Ocean. Centered on a broad peninsula between the Chugach Mountains and the marine waters of Knik and Turnagain Arms, the city receives 15–20 inches per year of precipitation, roughly half of which falls as snow. Anchorage is home to 260,000 people, with a convenient road network of over 3000 miles. The Municipality of Anchorage and State of Alaska Department of Transportation and Public Facilities expect to receive an NPDES permit for municipal storm water discharge from the USEPA by early 1998. The Municipality has been using wet pond sedimentation basins for BMP treatment of stormwater runoff and snowmelt for over a decade. Suspended solids are the primary contaminant of concern in Anchorage, based on the sensitivity of local salmon-bearing streams to increased sediment loadings and contaminants associated with sediments. Sediments are also particularly relevant in Anchorage storm water and melt water runoff, as a result of sanding of city streets to improve winter traction. These sedimentation basins have been documented as achieving removal of suspended solids as high as 80% during storm events.

EA developed a cost effective pollutant removal strategy which also converted a portion of the 30-m (100-ft) critical area buffer to a forested wetland filter strip. The strategy consisted of a wetland perimeter swale and berm system which collects surface water runoff and, through a series of level spreaders, directs the decanting storm water through a 30-m (100-ft) wide perimeter filter strip planted with wetland trees and shrubs. In order to establish the swale, berm and buffer area, it was necessary to remove areas of impervious paving in the buffer. Portions of the buffer area were made-land. Soil samples were collected and tested. The use of crusher run and limestone dust as a fill material resulted in relatively high soil pH values with a high buffering capacity. The removal of paved areas, inappropriate fill texture, and high soil pH values necessitated the import of topsoil on portions of the site. Plant species were selected on the basis of the soil test results and a set of functional attributes relating to wildlife habitat values. Evergreen species were selected to provide winter cover, species producing hard and soft mast were included, and other species were selected for their limb dropping and cavity forming propensities. Through the selection of eight canopy and six shrub species, this planting is expected to provide a variety of habitat for urban wildlife and water dependant species from the adjacent waterway. During the construction of the project, site supervision and monitoring during a heavy precipitation event demonstrated that the design is effective. The design has resulted in phosphorus removal in excess of the 10% required by the City Critical Area Program. In addition, birds have been observed flying into the canopy of the trees even before the planting was completed. This project was completed mid-October 1994 and water quality monitoring efforts proposed in conducted in 1997 indicate sediment and nutrient removal efficiencies higher than predicted by the Critical Area loading model.

The Sichuan Province of China is located in the Yangtze River Basin just east of the Himalayan Mountains, and is one of the most populated Provinces in the country. The Province is also a semi-tropical, productive agricultural area. This agricultural abundance is assisted by major irrigation projects, the largest one dating back to 300 B.C. (Min River, Dujiangyan) Water is abundant but poorly distributed throughout the year. Snowmelt is available in the late spring and over 75% of the annual rainfall occurs between May and September. There is currently little storage capacity available to provide for flow augmentation during low-flow periods. Most of the smaller streams tributary to the Yangtze are heavily polluted by a combination of raw sewage, industrial waste, urban and rural polluted runoff and other factors. The Sichuan Urban Environment Project (SUEP) was formulated by the Sichuan Provincial Government and the World Bank in an effort to recover these surface waters. However, the lack of adequate flow during dry periods makes it very difficult to develop cost-effective programs to meet desired ambient stream quality standards.

This paper will describe the importance in maintaining frequent coordination with regulatory agencies throughout the design process for mitigation projects, and specifically for the Maryland Route 100 project. This coordination resulted in an innovative preservation and creation area encompassing 10.7 hectares (26.5 acres) at the University of Maryland Horse Farm.

This project involved wetland permitting and mitigation design associated with a new bridge over the Cross Bayou Canal in Tampa Bay, Florida. Amelioration of wetland impacts was troublesome as very few sites existed for mitigation and the cost of land for mitigation was not a viable option. The project posed some permitting challenges as approval from three agencies was required for wetland delineation, permitting, and mitigation. The new bridge and road design incorporated several features to avoid and minimize wetland impacts. The plan called for replacing the vegetated freshwater upland ditches with a scrub/shrub wetland. Impacts to the estuarine habitats were compensated by enhancing the wetlands adjacent to the canal, removing exotic vegetation, and creating mangrove habitats. The avoidance, minimization, and compensation of wetland impacts was difficult due to the potential cost, limited available space, and the project area.

Hydrologic restoration aims to change the water regime in degraded areas to make the conditions experienced by the biological and physical systems more similar to those present before the degradation occurred. In order to determine reasonable goals or evaluate potential projects a non-traditional engineering design approach must be used. Continuous hydrologic modeling, using models such as HSPF, offers the potential to design and evaluate restoration projects based upon the goals of the project, expressed in terms of durations, magnitudes and seasonality of streamflows or water levels. The modeling effort can provide valuable information throughout the restoration process and has been used in applications of various scales, restoration goals and degrading processes. Two projects in Wisconsin and one in Washington are outlined here.

The calibration of a two-dimensional, steady-state seepage model (FastSEEP/SEEP2D) to estimate the subsurface seepage into the Everglades Nutrient Removal (ENR) Project was performed. The ENR Project is a 1544 ha artificial wetland constructed by the South Florida Water Management District (SFWMD) to begin the process of removing nutrients (especially phosphorus) from agricultural drainage and stormwater runoff before entering the Everglades. A 8.2-km reach of the L-7 levee is the divide between the ENR Project and Water Conservation Area 1 (WCA-1), an impoundment area, which maintains consistently higher stages than the ENR Project throughout the year. Calibration of the model was conducted by comparing instantaneous surficial seepage flows (42 events) collected at the toe of the L-7 levee to model predictions. After selecting the most appropriate simulation (K values) from the calibration process, the model was run to obtain the 42 simulated values of subsurface seepage. These seepage flows and the average stages (WCA-1 and ENR Project) were used to obtain a regression equation (r²=0.962). This equation has been used to estimate the daily subsurface seepage flow component of the ENR Project water budget. For the first two years of operation of the project (August 1994 through August 1996), subsurface seepage was estimated to account for 7.8 percent of the total inflow. Estimation of the seepage components of the water budget, which is intrinsically related to the nutrient budget, is crucial to evaluate the efficiency of nutrient removal in treatment wetlands.

The design of wetlands based on groundwater as the principal source of hydrology pose uncertainties in areas where erratic seasonal groundwater fluctuations exist. Under these conditions, the need for accurate prediction of the behavior of groundwater is of paramount importance. This paper presents a case history and a statistical approach adopted to model groundwater for a wetland created in a landscape position which does not allow for the use of surface water inputs.

Drainage channels in California have progressed from trapezoidal channels to multi-terraced corridors, primarily as a result of Federal and State wetland and other environmental requirements. The environmental benefits of these more complex channels are significantly greater than those that would have been present with the standard projects that would have been built at these sites and they have also generally provided the drainage benefits predicted. However, costs for two channels assessed in this analysis were much higher than trapezoidal channel projects originally proposed. Essentially, where the sponsor is willing to incur the higher capital costs and has an appropriate design which considers the relevant factors, multi-objective channels can meet all appropriate criteria and will assist the sponsor with permitting and other works.

The Mad River flows through the Brass Mill Center, a regional shopping center developed on the site of a former industrial mill complex in Waterbury, Connecticut. As part of a project to restore and enhance fisheries habitat in this river, the design team developed a design for a naturalistic fishway. The structure is essentially a "vertical slot" fishway fabricated using boulders. A major design challenge was the evaluation of hydraulic performance of this innovative structure.

A combined biological and engineering approach was taken to identify and repair anadromous fish passage problems at culverted stream crossings in Clark County, Washington. Culverts were inventoried and prioritized based on biological factors. Construction cost factors were assessed and compared to the benefits of improving passage to develop a relative ranking of passage projects. Hydrologic data were developed for ungauged culvert locations and hydraulic designs were prepared using the Hydrologic Engineering Center-River Analysis System (HEC-RAS) model.

Currently applied stream channel reclamation techniques utilized by placer-gold miners in Interior Alaska are frequently not successful in meeting reclamation goals required by various land management agencies. Upper basin channels with a gradient of one percent or greater are particularly at risk of failure after reclamation. Surveys were conducted on thirteen previously reclaimed streams in order to analyze each site's hydraulic capacity and fluvial stability. Morphological parameters were compared to established values which are generally considered to represent stable channels, using the Rosgen stream type classification system. Additionally, surveyed channel width and depths were compared with dimensions derived from relationships in the literature for hydraulically stable, gravel-bed streams. The Corps of Engineers HEC-RAS program and field data were used to model flood events and estimate velocities and shear stresses in the channels and overbanks. Analyses indicated that most stream channels were constructed with, or quickly developed. excessively large width-depth ratios, steep energy gradients, and low sinuosities. These factors, combined with low rates of natural revegetation common to subarctic climates, resulted in failure (continued erosion and bank instability) for most of the thirteen sites.

The Logan River downstream of Third Dam has been impacted by several past and present disturbances. Channel instability, eroding river banks, and reduced streamside vegetation have diminished the extent and quality of riparian-wetland areas and aquatic habitat. Studies were performed to determine if channel restoration would benefit the entire riparian corridor through holistic channel restoration practices. Existing conditions were determined for hydrology, morphology, sedimentology, riparian-wetland resources, and fish habitat. The conceptual design developed to restore the stream channel and floodplain would: restore four large meanders so natural fluvial processes could be used to re-establish riparian-wetland areas; increase channel length, channel sinuosity, radius of curvature, and meander length; stabilize eroding streambanks and eliminate the processes causing channel widening; and reduce pool-to-pool spacing to improve instream fish habitat. Approximately 0.53 hectare of riparian-wetlands and 0.23 hectare of aquatic habitat would be restored.

An investigation of nine Yazoo Basin discharge gauges was made, and relationships between the temporal density of the discharge data and computed sediment yield, and between discharge skewness and sediment yield were identified. Each of the nine gauges are in watersheds in which the hydrologic response has been affected by severe channel incision.

In 1985, the city of Roseville, Minnesota restored an ineffective wetland tributary to 33 hectare (ha) Lake McCarrons. The intent of the project was to treat runoff such that water quality in the lake would visibly improve. The "wetland treatment system" consists of two detention ponds and six low head wetland chambers. Studies documenting short- and long-term effectiveness show that the system now exports as much phosphorus as it receives, and is 20–50% less effective in the removal of most other pollutants than when it was new, and Lake McCarrons does not appear to be improving. Several "improvements" to the system by the city between the two study periods, and system aging are discussed to shed some light on the decline in effectiveness.

Once a viable wildlife habitat and recreational site, Lake Munson is now choked with aquatic vegetation, and sediments and trash are blocking the mouth of the lake creating a "delta". The Lake Henrietta basin, located upstream of Lake Munson, historically provided stormwater treatment for the natural flow through the system. Channelization through the Lake Henrietta basin and increased stormwater flows, the result of increased development, have led to the creation of the "delta" and the degradation of Lake Munson. Through more than ten years of investigations, studies, and master planning efforts, Leon County has identified five major objectives of the Lake Munson Restoration Program; to improve the water quality of stormwater entering Lake Munson, to restore the natural stormwater treatment ability of the Lake Henrietta basin, to improve the fishery quality and recreational value of Lake Munson, to improve the water quality of the discharge from Lake Munson to downstream waters, and to reduce flooding as much as possible in the Lake Munson system.

Kirkman's Cove Lake is a 65 ha (160 ac) reservoir located in Richardson County, Nebraska near the southeast corner of the state. The lake's 1,981 ha (4,896 ac) watershed is characterized by rolling terrain, steep slopes, highly credible soils, and predominantly agricultural land use. The stream network in the watershed is dense and experiencing severe streambank erosion. As a result, the lake is susceptible to high rates of sediment and nutrient loadings. These excessive loadings have resulted in rapid aging and eutrophication of the lake. To restore functional uses, improve water quality, and protect the lake against excessive loadings in the future, a comprehensive lake and watershed management plan was developed. The cornerstone of this plan was design of lake protection measures at the upper end of the lake to provide an effective, efficient means of reducing loadings to the lake. A multi-disciplinary design team of engineers and scientists developed the lake protection measures that consisted of: 1) a low-head earthen embankment across the main channel to the lake at the upper end of the lake, 2) a sediment/nutrient settling basin upstream of the embankment, and 3) wetlands along the channel's overbank areas. Construction of the lake protection measures was completed in the Spring of 1996. While too early to judge the level of success, preliminary results indicate that the system is functioning according to design objectives.

White phosphorus has been found to be the causal agent for massive waterfowl die-offs at the Eagle River Flats impact range on Ft. Richardson, Alaska. Research indicates that in-situ remediation of white phosphorus is possible if the sediments in which the contaminant persists can be desaturated and the temperature rises to where sublimation can occur. Several remediation methods have been studied at the Flats, the most promising of which is the pumped removal of ponded water using an automatic remote pumping system developed by the U.S. Army Cold Regions Research Engineering Laboratory (CRREL). This paper will describe the system, its deployment, and the results of the first year's study.

The role of quantitative measures of hydrology and hydraulic watershed properties and their impact on ecological risk assessment was investigated. Pearson correlation coefficients were examined between metrics of ecotoxicology and physically based parameters describing channel, velocity, and flow conditions at each test site. A total of 83 single value ecological endpoints at each site were used. Measures of benthic macroinvertebrate biodiversity, biological habitat condition, sediment toxicity, and in-situ clam toxicity were found to be weakly to moderately correlated with channel geomorphology, flow, and velocity field parameters. For each endpoint, between 30 and 54 test sites were surveyed.

Three field sites were monitored for water surface elevations during 1996 and 1997 and post high-water measurements of channel topography and structure position were compared using Terra Model for each year. The field locations included: St. Regis River, Montana; Zumbro River, Minnesota; and Sammamish River, Washington. Results from the St. Regis River and Sammamish River are reported here. Both 1996 and 1997 recorded higher than average flows at both sites with peak flows at 25 year recurrence period levels or greater. Topographic and photo surveys of the sites were used to measure the evolution of the channels and banks including patterns of deposition and erosion. Of the structures represented in these sites, including: boulder clusters, low flow deflectors, sills, and root wads, the boulder clusters showed the greatest changes in position or "instability" while the low flow deflectors effected the greatest local change in bed topography based on deviation from average cross sectional depths. The habitat enhancement projects were newly constructed in the Sammamish River in 1995 prior to the winter and spring peak flows.

As an element within watershed management activities, habitat creation and opportunities for habitat enhancement within urban watersheds are typically constrained by development that is directly adjacent to the channel's right-of-way—development that precludes channel widening due to the associated cost of real estate. However, multi-objective projects that include habitat creation may be implemented at various locations adjacent to rivers and streams through the diversion of streamflow into pockets of available rights-of-way. The current paper discusses this opportunity and its application to a habitat project within Mason Park in the County of Orange, California.

This paper summarizes the application of one-dimensional finite element hydrodynamic and water quality models to the lower Feather River in Northern California. The study was precipitated by a perceived need for cold water temperature in river reaches below Oroville Dam where salmon spawning occurs. Releases from Oroville Reservoir and Thermalito Afterbay were shown to have a dramatic effect on water temperatures in those sections of the river. The exact degree to which releases affect river temperature had not been determined prior to this study. Calibration and validation of the models were performed using field measurements of flow, meteorological conditions, and water temperatures obtained during August 1993, August 1994, and September 1994.

Reservoir temperature models of Trinity and Lewiston Lakes and a river temperature model of the mainstem Trinity River were used to evaluate the impacts of five proposed Trinity River Basin Fish and Wildlife Restoration Act flow alternatives. Initial results of temperature modeling indicate that most flow alternatives result in water temperatures that exceed downstream temperature requirements. The reasons for these results lie in the complex "plumbing" and operations of the Trinity Division. Temperature model simulations were then initiated to investigate and develop proposed mitigations for elevated release temperatures. Promising solutions include: shifting CVP diversion patterns so that the highest diversion rates occur during the summer period; maintaining higher carry-over storage capacity of Trinity Lake into the late summer; decreasing summer release temperatures to the Trinity Fish Hatchery; and using an auxiliary outlet to draw upon the deeper cool-water pool of Trinity Lake. Many of these temperature mitigation strategies provide benefits to other Trinity River stakeholders (e.g. higher summer-time lake levels for recreation, higher CVP diversions during peak power generation periods, and more timely diversions that will help meet summer-time Sacramento River and Bay-Delta flow and water quality objectives).

This paper describes the application of GLT (a 1-D transport model) to assess thermal and thermally-mediated biological impacts from a municipal discharge on a limestone trout stream near State College, Pennsylvania. Prominent features of this application are: 1) use of a simple, meteorologically-based temperature computation to fill gaps in hourly upstream temperature observations used as boundary conditions for the transport model, 2) very close agreement of computed and observed stream temperatures, and 3) use of a reduced form of a bioenergetic model for assessing thermal impacts on brown trout growth potential.

Massive summer fish kills in 1995 drew public attention to the deteriorating water quality in North Carolina's Neuse River Estuary. Nitrogen loading to the estuary has increased dramatically due to increases in population, agricultural activity, and livestock production. Widespread anoxia and fish kills have occurred occasionally in the Neuse River Estuary in the past, but occurred in both 1995 and 1996. In addition, problems associated with algal blooms and macrophytes are at all time highs. In response, the State has drafted regulations aimed at reducing nitrogen loading to the estuary by 30 percent. At the same time, the State has funded a research project to predict the water quality improvement that will result from reduced nutrient loading, and to plan for future management of the river basin. This three-phase project, referred to as MODMON (MODeling and MONitoring), will include collection of tightly coupled water quality, fisheries, hydrodynamic, and sediment data; application of a eutrophication model to predict the results of reduced nitrogen loading; and development of recommendations for longer-term development of a watershed-river-estuary water quality model focusing on management outcomes. Results from initial water quality monitoring showed the estuary to be intermittently anoxic even during "good" years such as 1997. The special characteristics of the predictive eutrophication modeling effort now underway are also discussed. These characteristics include a large database of water quality and ecosystem rate measurements, the existence of a multi-disciplinary monitoring effort, parallel short-term and long-term model development efforts, and incorporation of an uncertainty analysis into the process-based eutrophication model.

In recent years a steady decline in salmon populations has been reported in the Columbia River and its tributaries. Dams constructed to provide recreation, barge/tow access, power production, flood control, and many other regional benefits along the Columbia River system have been sited as one of the major contributors to the declining numbers of salmon. To address issues related to adult and juvenile fish passage at The Dalles Dam, a 1:80 scale physical model was constructed. The three dimensional undistorted physical model reproduces the dam features and the Columbia River for approximately 2.3 km (1.4 miles) upstream and 1.6 km (1.0 mile) downstream from the axis of the dam spillway. Spillway discharge is currently the primary method of fish bypass at The Dalles Dam. Until a permanent surface bypass collection facility or a juvenile bypass system is implemented, interim solutions can be utilized to improve fish passage survival rates. This paper discusses changes in dam operational procedures that were implemented at The Dalles Dam as a result of the physical model investigations.

Hydropower development and operations in the Columbia River Basin have contributed to the regional decline of anadromous fish populations. These fish, particularly the salmon and steelhead trout, hatch in fresh water, migrate to the sea, and return to their spawning grounds where most spawn their eggs and die. High concentrations of total dissolved gas (TDG), generated by spillway releases, can inflict the out migrating juveniles with a fatal condition known as gas bubble trauma.

This paper will discuss the use of a three-dimensional physical model of John Day Lock and Dam, Columbia River to investigate alternatives to improve fish passage at the structure. A 1:80 scale physical model of the site was constructed to investigate flow conditions developed under various operating procedures. The model reproduces the Columbia River from river mile 212.5 to 219.5. The hydraulic experiments investigate fish passage improvement measures required under the Columbia River Juvenile Fish Mitigation Program for the John Day Project. Experiments are being conducted to investigate spill patterns for juvenile fish, drawdown options, gate spill patterns for adult fish, proper location of a juvenile fish transportation facility, and flow conditions approaching the powerhouse intakes.

Large numbers of constructed wetlands for wastewater treatment (CWWT) are being built throughout the US using the "black box" approach of measuring influent and effluent, but not really understanding just what is happening inside the black box—the wetland. Since CWWTs have an important role to play in certain types of wastewater treatment (WWT), it is important to gain a better understanding of the biological, chemical and physical activity that is occurring within the wetland. With this knowledge, the advantages and the limitations can be much better defined and understood. To gain this knowledge, much additional research needs to be performed. This paper proposes that an organized effort be launched to develop a coordinated program for systematically planning, conducting and reporting the necessary research to gain the understanding that is needed. It also proposes that all of the stakeholders be involved in this coordinated effort. Finally, it proposes that the ASCE take the initiative to organize and help see this effort through to completion.

A habitat-driven approach to CWWT design is defined as designing the constructed wetland to maximize habitat values for a given site within the constraints of meeting specified treatment criteria. This is in contrast to the more typical approach of designing the CWWT to maximize treatment efficiency, and then, perhaps, adding wildlife habitat features. The habitat-driven approach is advocated for two reasons: (1) because good wetland habitat is critically lacking, and (2) because it is hypothesized that well-designed habitat will result in good, sustainable wastewater treatment.

Constructed wetlands for wastewater treatment (CWWT), in the challenging climate of Colorado, has encountered a number of difficulties. Among these is how and where to locate level control structures, building a CWWT in a very limited space, a lack of funds and experienced researchers to obtain performance data, a lack of understanding among regulators and the lack of experience in treating storm water with CWWTs. An extensive research program is seriously needed to document the processes and effectiveness of various biological, microbiological, chemical and physical components of CWWTs.

The Brookside rehabilitation project resulted in numerous improvements to urban stream corridor function. Alleviating chronic flooding problems in the immediate neighborhood by improving flood storage was accomplished by excavating more than 70,000 m³ from the floodplain. Oversteepened channel banks were regraded to lower angles and were lined with biodegradable geotextiles to provide temporary erosion protection until groundcover re-establishment. Bank slope regrading was adjusted to preserve as many existing lower bankside trees as possible. Eroding channel bends were either eliminated by flood storage excavation or were stabilized with biotechnical revetments which simultaneously provide aquatic habitat benefits.

The St. Johns River Water Management District (SJRWMD), the regional agency with authority over water resources, uses regulations, interagency planning, land acquisition and restoration to manage aquatic ecosystems in north central Florida. The Little Wekiva River, the largest tributary of the Wekiva River in the Orlando area of central Florida, has experienced rapid urbanization and degradation during the past 30 years. Heavy rains in 1994 focused attention on the problems in this basin. The SJRWMD established the Little Wekiva River Technical Working Group (The Group), consisting of government agencies, environmental advocacy groups and homeowners, in 1995 to develop and implement restoration strategies. These strategies are based on the ability of the Group to blend the technical expertise and vested interests of its members, and the ability of the members to reach consensus and influence public policy makers. This paper will illustrate the effectiveness of multidisciplinary, citizen-based, working groups, and discuss the evolution of the Group and the roles of its member organizations, the importance of citizen-based organizations in the development of public policy, and the development and implementation of the watershed plan. Updated information will be provided on specific project components that have been planned, designed and implemented, focusing on the effectiveness of pilot projects and innovative design strategies.

The Prince Memorial Greenway project involves habitat enhancement and urban design of a one half mile stretch of channelized Santa Rosa Creek. It is an extremely high profile, visible project with enormous potential for environmental upgrade, habitat appreciation and public use located in downtown Santa Rosa. To date, this project has consisted of preliminary design based upon an active public participation process, with extensive agency involvement, and environmental documentation. The design team, retained by the City of Santa Rosa, is moving forward with construction drawings based upon input from this essential preliminary design process. This paper will review that process: the importance of building consensus, identifying opportunities and constraints for the project, and effecting a positive public perception of the Creek revitalization.

Environmental considerations have made designing flood reduction projects increasingly difficult. The Napa River Flood Reduction Project is a model for balancing public safety with the environment. A geomorphically based floodway design with a restored ecosystem has been proposed for the Napa River. The system combines 100 year flood protection with environmental enhancement for the city of Napa, California.

In Florida, wetlands are often created from upland areas to offset natural wetland impacts that are incurred during the development of projects such as roads, shopping centers, or subdivisions. There has been some debate in Florida over whether or not wetland creation has been successful and if it should continue to be used in the permitting process to mitigate for wetland impacts. Over the past four years the St. Johns River Water Management District conducted an assessment of over two hundred wetland creation areas permitted in northeast (Duval County) Florida. This assessment consisted of planting survival, evidence of normal growth, percent coverage by appropriate species, hydrology, overall success criteria, and the degree of compliance with permit conditions. This paper will present the criteria and evaluation methods, findings of this assessment, and recommendations for improving the success of wetland creation.

In the conterminous United States, it is estimated that 53% of pre-settlement wetlands were lost between 1780 and 1980; in Illinois, as in much of the Midwest cornbelt, wetland loss climbs to 90% for the same period. While the loss of wetland acreage is less than in the past, a net loss of the wetland resource continues. Wetland compensation projects have contributed to this net loss both in subtle functional shifts of wetland types and outright project failure. In our experience, failures of compensation projects are often attributable to improper hydrologic conditions to sustain a wetland habitat. Poor site-selection, poor design, poor construction methods, and inadequate management can lead to improper hydrologic conditions. While it may be possible to overcome poor site selection with herculean efforts in engineering, construction, and management, increased costs and project failure usually ensue.

The Evaluation for Planned Wetlands (EPW) is a rapid-assessment procedure for use in determining whether a planned wetland has been adequately designed to achieve defined goals. EPW provides 1) a technique for assessing 6 wetland functions, 2) guidance in applying EPW throughout the various steps of the planning process, and 3) a method for calculating the size of the planned wetland required to meet planning/mitigation goals. A wetland assessment area (WAA) represents a designated wetland area to which the planned wetland (PW) will be compared. In many cases the wetland assessment area will be the wetland impact area of a project. The term planned wetland is used to describe a variety of related activities directed at providing wetland functions, e.g., wetland construction, restoration or enhancement. Thus, a planned wetland is a design or an implemented design for a constructed, restored or enhanced wetland. The steps to developing a planned wetland are jointly referred as the planning process.

The U. S. Army Corps of Engineers (Corps), partnering agencies, and regulatory permit applicants have restored, created, acquired, managed, and/or protected over one million acres of wetlands, including approximately 100,000 acres using dredged material, over the past three decades. These manmade wetlands may be on islands, on confined disposal facilities, along shorelines, in rivers and streams, in lakes and reservoirs, and a number of them provide habitats for rare and endangered species, as well as a myriad of other fish and wildlife. Prior to the early 1970's, the Corps "built" many wetlands incidentally to navigation and flood control projects, through the placement of dredged material adjacent to shorelines or during island creation when the Intercoastal Waterway System was constructed, while river, lake, and estuarine navigation channels were maintained, and when navigation channels were deepened and widened for various U. S. major rivers and ports. The Corps is also aware that it changed many wetlands during that same time period due to civil works projects in an era when there was little understanding of the occurring or cumulative impacts.

In 1997, in response to a national shift in environmental R&D, the U.S. Army Corps of Engineers (CE) initiated a new research program, the Ecosystem Management and Restoration Research Program (EMRRP). The EMRRP is sponsored by Headquarters, USACE, with program management and research conducted through the U.S. Army Engineer Waterways Experiment Station, Wetlands Research and Technology Center. The EMRRP is funded through the General Investigations fund of the CE. The program is designed to provide state-of-the-science methods and procedures to predict and analyze environmental impacts of Corps projects and activities with application toward ecosystem management and restoration. Ecosystem is defined by CE regulation as the dynamic and interrelating complex of plant and animal communities and their associated non-living environment. The EMRRP provides both short- and long-range solutions to problems in the following Corps mission areas: Environment, Navigation, Recreation, Regulatory, Support for Others, and Water Supply. Five specific stand-alone, yet interrelated, research work units within the program focus on the following research technology areas: (1) develop capabilities to predict ecosystem impacts, (2) develop ecosystem management and decision support systems, (3) develop rapid quantification and assessment methods, (4) investigate basic ecosystem processes, and (5) restore threatened and endangered species habitat.

An expanding mission in environmental management and restoration requires that the U.S. Army Corps of Engineers develop and apply effective models for predicting ecological responses to human impacts. Such models must couple physical and biological processes, and resolve differences in modeling approach, complexity and spatiotemporal resolution.

The best and most remembered stories are those told in parables, and the changes we are seeing in the Corps of Engineers are indeed the stuff of legends and fables. Goblins and demons, necessary parts of any fable, are the spirits of ecological complexity, human and societal demands, and fewer resources. The heros and champions are new and forward-looking authorities, research tools, and opportunities to implement them. This paper will showcase some of today's protagonists in the Corps, and forecast their victory in wetland and water resource dilemmas.

To meet dissolved oxygen standards on Segment 15 of the South Platte River, the Metro Wastewater Reclamation District has utilized combination of traditional and nontraditional approaches to ammonia management. The nontraditional approach includes improving the river channel to increase reaeration of flow. Channel improvements include addition of a drop structure designed to optimize reaeration and development of a stable channel gradient to eliminate a backwater pool upstream of a grade control structure. Ancillary improvements to the river channel include development of wetlands and secondary channels, and relocation and protection of infrastructure river crossings. Post-construction results indicate that the reaeration drop structure performs within 3 percent of its predicted performance and DO levels are well above standard.

During the early 1970's the City of Denver "re-discovered" the South Platte River that bisected the City and created the Platte River Greenway. Improvements included major cleanup efforts, miles of paved multi-use paths and the first urban whitewater boating facility in the nation. The City is now proceeding with another major plan for 1½ miles of linked riverside parks in Central Denver coupled with river improvements for enhancement of habitat and boating. Riverfront Park is being administered by the Mayor's South Platte River Commission, and will include nearly $25 million in improvements to five parks that border the river adjacent to downtown. Upstream of Riverfront Park, multi-objective flood control improvements are being installed to contain the 100-year flood flow and provide boating and habitat improvements.

This $11,000,000 river enhancement project is located at the northern edge of the City of Denver in the Globeville neighborhood. This high profile project, driven by the Mayor's Office and the Urban Drainage and Rood Control District, constructed a greenway trail, aquatic and terrestrial habitats, reclaimed and stabilized the river banks, constructed flood levees and floodwalls to provide 100-year flood protection, enhanced the wetland and riparian areas along the river, and provided educational signage throughout the project reach. This paper describes the project and provides insight into the need for public participation.

The phenomenon of hysteresis in sediment transport explains cycles of scour and fill as floodwaves pass fine grained deposits along the margins of incised river channels. Increased sediment load on the rising limb of floods modifies channel shape and can transform normally depositional eddy recirculation cells into scouring zones. This process was documented on a naturally flowing reach of the Colorado River upstream of Glen Canyon Dam annually, and more frequently downstream on the regulated river. Considering this powerful process is important when managing flows to restore river processes and riverine habitats.

A conceptual planning approach is given to restore natural ecosystem functions and processes for long reaches of large rivers. Ways are examined to provide compatibility with river corridor development and uses.

The Riverine Community Habitat Assessment and Restoration Concept (RCHARC) has been used for restoration planning and impact analysis for the main stem Missouri River and a number of rivers in the southeastern USA. The RCHARC contrasts depth and velocity distributions from a reference stream against distributions from different operational or channel alternatives in a target stream. The more nearly depth and velocity distributions of an alternative resemble distributions from the reference stream, the more highly that alternative is ranked. For the Missouri River application, the reference system was the historical river as defined by HEC-II analysis using historical (preproject) cross sections and historical mean monthly flows. For other applications, relatively unimpacted river reaches within the same basin have been used as the reference. This same approach can be employed to evaluate channel alternatives instead of flow alternatives for river restoration studies. The results of the analysis allowed the Corps of Engineers to rank operational alternatives by their ability to provide hydraulic habitat most likely to restore native warm water fishes. It was also used to develop design criteria for a major side channel restoration project on the Missouri River. The community-level perspective and whole-river descriptions used in the RCHARC facilitate assessments of ecosystem integrity of target systems.

Increased and nutrient rich runoff from urban and agricultural developments caused a degradation of water and sediment quality of the Indian River Lagoon in east central coastal Florida. One of the restoration plans being developed for the lagoon includes a 5,460-acre retention/detention area to manage storm drainage, and a 2,240-acre constructed wetland that filters nutrients and sediments transported by the runoff. Various plan components were optimized by hydrologic simulations using HSPF.

The Red Lake Watershed District (RLWD) began the Clearwater Nonpoint Study in April of 1992 as a cooperative effort with other governmental agencies, primarily because of local concern about the water quality of the Cleanwater River. Causes of degraded water quality within three reaches of the river were identified during a 2 year monitoring study. Goals and the direction for improving river water quality were established through public meetings and questionnaires. Activities underway to improve water quality include implementing conservation tillage Best Management Practices, establishing riparian buffer areas and waterway filter strips, constructing a nonpoint source treatment system for reducing sediment and nutrient loads in agricultural runoff, and stabilizing eroding banks. Implementation cost for the project during the next 3 years exceeds $560,000.

Delaney Creek is a highly disturbed, channelized creek that drains a 16-square mile area of industrial, residential, and agricultural areas in southern Hillsborough County, Florida. In order to improve on the poor water quality and wildlife habitat in the creek, the Hillsborough County Stormwater Department and the Surface Water Improvement and Management (SWIM) section of the Southwest Florida Water Management District joined forces to fund the design and implementation of the proposed Delaney Creek improvements. The project site is a 10.6-acre parcel including approximately 3.11 acres of channelized jurisdictional wetlands hydrologically connected by tidal fluctuations. The wetlands have the characteristics of an oligohaline marsh, supporting a mixture of true marine species and some typical freshwater species. Preliminary studies indicated that while the water quality in the creek was "fair," the creek had high levels of total suspended solids. The main objectives for the project were to maximize the residence time to reduce the amounts of total suspended solids in the creek flows, to preserve as much of the upland habitat as possible, to maximize the available wetland habitat, and to reduce downstream flooding. The project objectives were accomplished by constructing an oxbow shaped system on line with the main channel of the creek. The majority of the trees on the site were preserved on an island created in the center of the wetland.

Laboratory experiments were conducted to investigate the turbulence structure of flow through rigid vegetation. The vegetation was simulated by a uniform array of acrylic dowels mounted to the bed of an hydraulic flume. The flow rate in the flume was adjusted to create both partially submerged and fully submerged flows. Vertical profiles of the longitudinal and vertical turbulence intensities were studied at several locations within the array.

The complicated hydraulic processes occurring in flow through vegetation has prompted many research efforts over the course of past years. Recent interest in the positive environmental impact of wetlands has increased interest is fully understanding nutrient and sediment migration through these areas. Included in this article are results from laboratory models investigating flow through simulated riparian wetlands. Emphasis has been placed on measurement of turbulence intensity and statistical analysis of velocity profiles through various configurations of simulated vegetation.

Regulated rivers, as the Trinity River, often lose flow variation and are encroached by riparian vegetation. Riparian hardwood germination and establishment patterns on channel rehabilitation sites and the effects of maintenance flow releases from Lewiston Dam were quantified. On the Trinity River, riparian hardwoods germinate within 0.5 meters of summer baseflow water surfaces on substrates of coarse sand or finer. The upper germination limit corresponds to the edge of soil surface moisture 0.14 meters above the June 6, 1995 water surface. Channelbed scour within the active channel is attained by floods of 170m³/sec or greater. Riparian hardwood establishment is restricted to those parts of the channel not experiencing channelbed surface layer scour. Bank rehabilitation site re-encroachment has been prevented by annual channelbed scour, which has eliminated 90–100% of establishing seedlings. Within three years of a riparian hardwood's germination, maintenance flow releases must be of at least 170 m³/sec to scour the channelbed surface and restrict encroachment.

The Wetland Hydrologic Index (WHI) presented in this paper is a tool to evaluate relative impacts of river management scenarios on riparian wetland functions. WHI are calculated using matrix summaries of monthly stage exceedence frequencies for reference and alternative water management conditions and the elevation distribution of riparian wetland acreage. In a manner similar to the Habitat Suitability Index developed by the U.S. Fish and Wildlife Service, WHI are multiplied by wetland acreage to calculate the Wetland Hydrologic Unit (WHU). Comparisons of the WHI matrices and WHU for various scenarios allows river managers to rank scenarios for relative degree of impact to riparian wetland functions and to evaluate the impacts in terms of depth, duration, and season of inundation for affected wetland acreage.

An intensified hydroacoustic study of fishes in Bendway Weir fields of the Middle Mississippi River was conducted by the St. Louis District Corps of Engineers. The study focused on determining the positive impacts that Bendway Weirs have had on aquatic species, in particular; macro and micro invertebrates and fish. This paper will summarize the effort that has been set forth on the river. Several new data collection techniques will be discussed, including the hydroacoustics used for determining fish location and size, and a new methodology to collect actual fish specimens in deep, sediment laden water.

Waterways that are properly planned, rehabilitated, and regulated can be fully utilized to accommodate multiple activities. Conflict resolution is an essential issue which must be addressed in the management of waterways and waterfronts. This paper summarizes the recent rehabilitation and management, as well as history, of the Chicago River in Chicago, Illinois. The underwater and above water inspection, design, rehabilitation, maintenance, and operation of the historic Chicago River in Downtown Chicago will be discussed in this paper. The issues involved in fully utilizing an urban waterway while minimizing conflicts are also discussed in this paper.

Thompson Bend is located on the right descending bank of the Mississippi River between river miles 30.0 and 4.5 above the confluence of the Mississippi and Ohio Rivers. The river flows in a broad sweeping reverse curve in this reach, and encompasses approximately 10,000 acres of valuable agricultural land. At the throat of the bend, the overland distance is approximately one mile. The distance along the thalweg is approximately 1.4 miles. During flood events, the river naturally tries to take the shortest path, straight across Thompson Bend. The normal slope along the thalweg is 7 feet, or about 0.5 feet/mile. When flows cross the bend, the 7 foot drop occurs across approximately 2 miles, producing a slope approaching 3.5 feet/mile, depending on the Cairo gage. This paper will discuss in detail how this situation developed, what attempts have been made to control it; how it was severely tested in the Great Flood of 1993, and the floods since 1993. It will Illustrate that overbank scour can be controlled by vegetative efforts and well designed tree screens, and in conjunction with planting certain types of crops at key locations, can almost entirely eliminate surface erosion. It will discuss what is being planned for 1997 to further stabilize the scour and what long term goals are expected.

The UK Engineering and Physical Sciences Research Council (EPSRC) funded an eight-month study in 1996 to asses the current status of and gaps in knowledge regarding the use of vegetation to stabilise river banks. Results of this study are summarised, and thirty-five research topics are identified, which will help to direct funding priorities within the national research programmes. Multi-disciplinary cooperation is emphasised, as the complex interactions among the fluvial processes of flowing water, sediment transport and deposition, hydraulic and geotechnical the expertise of multi-functional research teams. These teams will need greater communication between disciplines, with river managers and the public to aid in implementing BMPs into river management practice.

The U.S. Army Corps of Engineers manages the construction and maintenance of myriad structures within its business areas of hydropower, recreation, environmental stewardship, coastal navigation and protection, flood control, and inland navigation. Since 1984 the Corps has been developing methodologies for rank ordering competitive budget items that must be funded with ever decreasing funds. One such methodology is the objective condition assessment of structures using condition index procedures. The condition index is a gauge of the physical deterioration of a structure and is designed to give uniform results on a Corps-wide basis. This paper presents an overview of the condition index, and condition indexing procedures and measurements for the array of inland navigation structures, including locks, dams, gates, operating equipment and riverine training structures such as stone dikes and revetment. The condition index is used as an M&R decision support tool at all levels of Corps management hierarchy. Other decision support criteria and data are discussed. New efforts in applying management based on performance measures are also addressed.

The last self sustaining riverine population of endangered razorback sucker occurs on the middle Green River, Utah. Since 1962, operations at Flaming Gorge Dam have reduced flow variability and altered timing and duration of flood peaks. These alterations in flow have resulted in poor production of young because of sedimentation at the primary spawning site during high flow years when dam releases are early and high compared to natural inflow. Furthermore, reduced connectivity to floodplain nursery areas results in poor survival of young post-emergence. It is hypothesized that reductions in peak flows have resulted in sediment being stored and transported at much lower flow ranges. Effective discharge has been reduced 44 percent from pre-dam conditions. Results of sediment transport analysis conducted using HEC-6 compared favorably with empirical cross section observations at the site in 1993 and 1996. Predicted sedimentation began at 200 m³s^–1 and resulted in 0.6 meters average deposition of sand in the spawning channel as flows approach 650 m³s^–1. Restoration of spawning and nursery habitat for this floodplain species is achievable through restoration of flow variability and timing at Flaming Gorge Dam and removal or modification of levees at floodplain nursery sites.

The Gunnison and Trinity Rivers are two western rivers with major reservoirs were downstream aquatic habitat must be relatively free of sediment. The Gunnison River is a gravel bed river with large loads of fine material. The discharge needed to maintain the river in the condition needed by Colorado squawfish varies from 210 to 484 cubic meters per second (cms) depending on the objective. The overall objectives will be met if the discharge exceeds 484 cms one in every three years, with one in every two years having a discharge of at least 354 cms, and two in every three years having a discharge of 354 cms for at least four days. The Trinity River has a gravel bed and the river transports large quantities of sand; fines (material ≤ 0.062 mm) are relatively unimportant. The Trinity River is spawning and rearing habitat for Chinook salmon. The streamflow required to flush sediment from the substrate is 190 cms. The discharge needed to transport sediment size which should be transported and not allowed to deposit on the stream bed (1 mm or smaller) is 70 cms. This discharge is required only when Grass Valley Creek (a tributary moving large quantities of sand) is transporting sediment to the Trinity River.

The Muddy Creek Task Force and the US Bureau of Reclamation constructed eleven grade control structures and more than three-hundred bank stabilization structures between 1994 and 1996 as part of the Muddy Creek Demonstration Stream Restoration project. Under Reclamation sponsorship, the US Geological Survey operates a water quality sampling station at Vaughn, Montana, below the restoration reach of Muddy Creek, and since 1995 at Gordon, Montana, above the restoration reach. Initial water quality data indicates a decline in sediment transport in Muddy Creek over the past 25 years. This paper is an analysis of the initial sediment transportation data from these two gaging stations.

Dimensional analysis and numerical modeling are combined to obtain a simple expression for estimating the capacity of vegetated open channels to transport suspended sediment under equilibrium conditions. The numerical model consists of a two-equation closure scheme of the k-ε type, with parameters calibrated using laboratory observations in an open channel with simulated vegetation. A simple power-type expression is found to provide a very good collapse of all the experimental data involving the Rouse number, the relative submergence, the particle Reynolds number and the dimensionless plant density as independent variables.

Freshwater wetlands are among the most important ecosystems on Earth. Saturated soils, standing water, and diverse biological species are characteristic components of wetland ecosystems and describe an ecosystem capable of complex interactions between the soil and sediment organic carbon and the overlying water. Such interactions include oxygen diffusion into the sediment, adsorption of solutes onto the sediment, and carbon utilization by sediment microbes. Freshwater wetlands serve as a sink for complex organics consisting of cellulose, lignin and chitin which require hydrolysis and degradation to a labile carbon for utilization by bacteria. Detrital material such as nucleic acids, proteins, amino acids and lipids are nutrient sources from lysed cells, decaying organisms in sediment habitats, or by-products from biotic metabolisms. With high microbial populations, compared to terrestrial environments, wetland soils are highly effective at consuming and processing labile, detrital litter. Such utilization of background organic matter has encouraged close evaluations of wetland systems and their applicability to reduce and utilize organic xenobiotic compounds released into the environment.

A study has been initiated to contribute to the development of process-based design approaches for constructed wetlands in cold climates. Eight bench-scale vegetated sub-surface bed wetland cells were placed in the climate-controlled environment of Montana State University's Plant Growth Center. Three each were planted with native cattail and bulrush, while two cells remained unplanted as a control treatment. Since April 1996 the cells have received a stream of synthetic wastewater at a rate of 30 ml/min, resulting in a hydraulic residence time of approximately 5 days. To date, the system has been operated at three separate influent concentrations and at various steady temperatures ranging from 4° C to 21° C. Samples drawn from influent and effluent once per residence time have been analyzed for the parameters COD, NH₄, PO₄, and SO₄. Concentration data are presented as a time series moving average for each water quality parameter. All treatments have displayed 80 to 90% COD removal efficiency at temperatures greater than 12° C. Emergent plants have had significant effects upon ammonia and phosphate removal efficiency. Only planted wetland cells exhibited significant long-term phosphate removal. Substantial sulfate removal was expressed in all treatment types at the higher wastewater strengths. Sulfate treatment efficiency was greatly reduced at the lower strength for planted treatments, attributed to increased oxygenation of the root zone. Due to significant water loss through evapo-transpiration, planted treatments generally display greatly improved removal efficiencies if measured on a mass rather than concentration basis.

Historical research was performed to characterize and quantity cultural and natural resource trends within the Tillamook Bay estuary on the Oregon Coast. The research documented a history of environmental changes in Tillamook Bay and its watershed since the time of the Euro-American settlement. A characterization of these changes was done by focussing on key indicators of environmental change, including sedimentation, water quality and estuarine, wetland and riverine habitat. The environmental history findings are intended to provide insight for future resource management decisions in the estuary, as part of the Comprehensive Conservation and Management Plan (CCMP) for the EPA Tillamook Bay National Estuary Project (TBNEP).

The paper reviews various causes of wetland loss and means, including justification, for their protection, enhancement and restoration in the light of institutional and social factors. Aspects of the UK situation are briefly examined, and related to the global interests in sustainable development, catchment management and source control methods.

Initiated in 1997, this program for development of proposed regulations for protection of the Delaware River Basin (Basin) waterway corridors is another step in the continuity of the Delaware River Basin Commission (Commission) programs to protect and enhance the waters and related resources of the Basin. This program builds upon existing flood plain regulations for Basin interstate riparian corridors and expands to protect all of the Basin waterway corridors.

Mill Creek, a tributary to the Mahoning River in northeastern Ohio, has suffered severe degradation of aquatic habitat due to nonpoint source pollution from its watershed. In addition, recreational use of Lake Newport, an impoundment on Mill Creek, has virtually ceased due to sediment accumulation. Plans to dredge Lake Newport have met with various regulatory and monetary obstacles over the past 20 years. Now, projects are underway to develop a watershed plan, obtain conservation easements for key riparian areas along Mill Creek, and to control sedimentation and enhance the development of wetlands in Lake Newport.

The use of the 1.5 year flood (annual maximum series) as the dominant, design discharge for stabilising and restoring channels is not supported by field data. For stable channels, bankfull return periods are not uniquely designed by this value, principally because the annual maximum series ignores lesser floods which transport sediment and cause morphological change as well as the duration of transport events. Given the close correspondence between bankfull flow and the effective discharge, defined as the flow that transports most sediment in the longer term derived from daily average flow data and associated sediment transport rates, it follows that bankfull flow will be more closely associated with daily flow exceedance durations than flood return periods as it accounts for both the magnitude and duration of all transport events. Its value varies between river environments reflecting regional differences in flow and sediment transport regimes.

This paper describes a geomorphic channel design proposed for a six mile tidally influenced reach of the Napa River. The design includes restoration of historic estuarine marshland and alluvial floodplain features to achieve 100-year flood damage mitigation objectives for the city of Napa and to allow for continued navigation use. The design demonstrates the compatibility of ecologic restoration and flood damage mitigation objectives when they are given equal weight in the design process.

The U.S. Army Corps of Engineers has been developing a hydrogeomorphic (HGM) approach for assessing wetland functions in the context of its Section 404 Regulatory Program. To date, the HGM approach has not yet been refined such that it can be rapidly applied, although regional guidebooks for its application are in progress. In lieu of a published guidebook, HGM concepts were used to develop a modified approach to assess riparian-wetland functions that would be affected by the reconstruction of Montana Forest Highway 73. Agencies participating in the Section 404 process adopted the modified approach and used it as a guide for determining the level of mitigation required to compensate unavoidable impacts to wetland functions.

The reference reach is a river segment that represents a stable channel within a particular valley morphology. The reference reach is used to develop natural channel design criteria based upon measured morphological relations associated with the bankfull stage for a specific stable stream type. Specific data on stream channel dimension, pattern, profile and channel materials are measured and documented. Channel morphological variables are analyzed and developed into dimensionless ratios by stream type. The morphological data collected are used for river assessment and extrapolation to disturbed or unstable reaches in similar valley types for the purposes of restoration, stream enhancement, stabilization, and stream naturalization schemes. A reference discharge utilizing the bankfull stage is required to maintain consistency for obtaining stream channel dimensions.

The San Benito River has experienced approximately 4.6 meters of degradation in the past 30 years. Bank failures are threatening water treatment facilities, and downcutting exposed a buried sewer line. The river was studied using both qualitative and quantitative methods. The primary variable effecting the river appears to be gravel and sand mining, which occurs in the river bed, banks, and terraces. A geomorphic analysis indicates that the river is in a state of disequilibrium. The river is a braided system with slopes smaller than normally anticipated. The thalweg of the SBR is lower than its tributaries. Processes indicating active bank erosion include undercutting, mass-movements, and soil tension cracks. A HEC-6T model was calibrated using conditions observed during the geomorphic analysis. The model predicts up to 2 meters of scour associated with the movement of a headcut at a proposed mine site. When combined with historic degradation rates, the channel is predicted to downcut at least 6.4 to 7.6 meters in the next 30 years.

Bioengineering techniques employing living vegetation and non-living organic materials, often in combination with hard structures, are an effective approach for channel stabilization while restoring some natural riparian functions. A good bioengineering design relies on careful analysis of hydrologic and geomorphic conditions to help the selection and location of vegetation, and other materials and the design of the channel form and cross-section. A case study located in Chicopee, Massachusetts demonstrates the integration of geomorphic considerations in bioengineering design in a highly incised urban channel where hard structure was originally planned. Monitoring for one year after construction shows positive results in terms of structural stability, sediment transport, vegetative development, and aquatic and terrestrial habitat.

A combined engineering/biological effort between several state and federal agencies resulted in restoration or environmental enhancement measures in three secondary channels of the Middle Mississippi River. The effort was achieved using micro modeling, a micro scale, physical sediment transport modeling methodology. This paper will outline the history of this environmental effort and describe the results of both model testing and recent construction implementation in the Mississippi River.

The paper presents design and construction considerations for restoration of aquatic and terrestrial habitat along the Missouri River at the Benedictine Bottoms Mitigation Site, near Atchison, Kansas. Site selection, environmental impact, and design considerations are also discussed.

Planting willow cuttings for streambank erosion control is an ancient technology, revived in recent decades as part of "bioengineering." Problems include difficulties with emplacement, and slumping can easily undermine the short cuttings normally used. We have implemented a new hydraulic jetting technique which can rapidly (20–30 seconds) open planting holes in silty/sandy streambank alluvium, which are 2 meters deep by 3–5 cm diameter. Slender dormant willow cuttings pushed into these holes extend to damp soil and can sprout roots their entire below-ground length. The technology consists of a specially machined jetting tip welded to a 2 meter length of ordinary 1.3 cm ½ inch) steel pipe. Two of these jetting pipes are connected to a portable high-pressure pump, drawing water from the stream and delivering it to the jets via sturdy garden hoses. A planting team of 4 is most efficient, with 2 persons jetting holes and 2 planting willows. At favorable locations, a team of 4 can harvest 1000–1500 slender willow cuttings per day and deep plant 1000 cuttings per day. All the equipment is portable and can be carried on muddy stream banks. The jetting equipment plus 1000 bundled willow cuttings fit into a pickup truck. When properly planted, survival rates for fully dormant spring plantings of sandbar willow consistently exceed 95% in Iowa.

The Mad River flows through the Brass Mill Center, a regional shopping center developed on the site of a former industrial mill complex in Waterbury, Connecticut. Historic uses had highly altered the river alignment and habitat. The project team implemented structural and vegetative measures to restore and enhance fisheries habitat in this river.

Stream systems are constantly changing. Some changes are the result of natural catastrophic events such as floods, debris flows, or fires in the watershed basin. Often times, however, the changes are a result of man-made activities such as urbanization within the watershed, development within the floodplain, and overgrazing of the river banks. These changes often result in the loss of riparian habitat, wildlife habitat, stream and bank stability, and changes in flooding conditions.

The technical paper outlines the planning process, design, construction, and post site evaluation of soil bioengineering measures used for stream restoration and streambank protection. The planning process involved several meetings with the landowner and representatives from town, state, and federal agencies to develop alternatives for the project and select the final measures. The soil bioengineering measures included stabilizing the toe of the streambank with combinations of rocks, logs, and root wads; protecting the upper bank with live stakes, brushlayers, plantings, and geotextile fabric; and installing stream deflectors. One project was installed under a formal contract with a bid schedule and construction inspection, and the other project was installed under the supervision of the designer using rental equipment. The projects have been installed for over a year and are holding up well.

Stream restoration, like other "green engineering", is popular in the media and academia. But without hands-on experience for practitioners, policy changes in conservation agencies, and the enlightenment of administrators and politicians, little restoration will actually happen "on the ground".

Field studies by fluvial geomorphologists provide valuable information about the existing characteristics, stability, and likely pattern of evolution of an alluvial river system . If the existing or future conditions are found to be unsatisfactory for ecological or land use reasons, restoration or enhancement measures may be attempted. Experience during the past two decades has shown that the greatest chance for successful ecological restoration occurs if the natural physical processes are accommodated, rather than forcing a local reach into an unnatural or static configuration. This restoration approach requires an understanding of the natural form of the river channel under dynamic equilibrium conditions. One of the design parameters is the concept of the dominant (or channel forming) discharge. Quantitative approaches for estimating the dominant discharge are presented and the reason for the robustness of this design parameter is demonstrated.

This paper outlines the need for field verification of bankfull discharge in urbanized watersheds. The term bankfull discharge as used in this paper refers to that discharge which just overtops the flood plain. The flood plain is defined as the relatively flat depositional surface adjacent to the river that is formed by the river in its current climatic and hydrologic condition.

A comparison of channel restoration design approaches using field indicators of bankfull and sediment transport analyses is presented on three (3) urbanized streams in White Marsh, Maryland. The results indicate the field selected bankfull and associated discharge were significantly less than flows determined to move the majority of the channel-forming sediments. As a result of the study, channel restoration design incorporated the channel forming flows determined from bedload collection data yet not readily observable from field indicators.

This paper explores public and media perceptions and understandings of the "100-year flood", discusses flooding as a regular and natural occurrence from a historical standpoint and documents flood damage trends, bringing into question the lessons we have really learned from the February 1996 flooding in the Pacific Northwest. Historic flood lessons learned by others are expressed to encourage us to learn from the past and plan for history to repeat itself.

Conventional flood control engineering techniques and approaches that have been traditionally been applied are now challenged by the public and no longer readily available as floodplain management tools. Increased awareness and concern regarding environmental degradation has resulted in protection of the riparian and river ecosystems. A variety of drainage related projects are required to provide habitat mitigation as a part of regulatory permit requirements. Natural floodplains typically provide the most appropriate location for constructing habitat replacement since this is a natural riparian ecosystem, especially in semi-arid areas. Incorporating environmental features into an active floodplain requires an understanding of the natural physical processes and stream mechanics, along with commonly encountered failure problems. General planning guidelines and a formalized design process adopt fundamental procedures to enhance the preservation of the natural floodplain characteristics. The recommendations include typical design considerations and site selection techniques addressing many primary concerns. Recent technology utilizing computer graphic visualizations facilitates the design development process and assists in the consensus building process with the community. Applying multi-disciplined planning guidelines to develop habitat mitigation within active floodplains assists in developing an implementable and successful long-term floodplain management project which addresses flood protection as well as providing environmental opportunities.

Large-scale wetland and river restoration projects carry with them substantial investments in Federal and State funds, as well as high environmental and economic costs to society. A well informed and participative society, especially the population in communities and regions directly affected by restoration activities, is essential to the smooth and trouble-free development of these projects as well as the long-term viability of the restored ecosystems. The restoration of the Kissimmee River and Lake Okeechobee ecosystems provides unique opportunities to involve the public in the restoration process both through formal education programs and activities, as well as through the participation of citizen groups, educators and the general public in outdoor educational activities related to ecosystem restoration. We detail five different programs which meet the educational needs of Okeechobee and neighboring counties on ecosystem restoration and related topics. We focus on the importance of interpretation and novel educational methodologies to effectively justify to society the need for environmental restoration projects. Special emphasis is made on the role of scientists, engineers and environmental interpreters in designing materials and activities that are scientifically solid, entertaining and educational.

The hydrogeomorphic (HGM) approach to wetland functional assessment has received considerable attention as a potential tool to enhance wetland resources inventories and mitigation practices. We conducted an investigation to develop preliminary HGM reference standards for low-order overbank flow dominated riverine wetlands in the Piedmont region of Georgia. The reference standards suggest specific wetland characteristics that should be more thoroughly investigated during the design and construction of mitigation wetlands in riverine settings in this region. It is anticipated that such consideration will ultimately lead to mitigation wetlands that are more capable of performing the natural ecosystem functions performed by the wetlands they are intended to replace.

Diamond Fork River, Utah has been used since 1915 to convey irrigation water from the Colorado River basin to areas along the Wasatch Front. These flows have increased summer base flows more than 10 times above natural levels and led to dramatic changes in channel and floodplain morphology. In 1939, Diamond Fork was a meandering, single-thread channel averaging 12 m in width. By 1952, the lower 6 km of the channel was braided, occupying the entire 150 m-wide valley floor. Concurrent with changes in floodplain morphology, there has been a 50 to 90 per cent reduction in the extent of riparian cottonwood forest. The remaining forest is dominated by late mature cottonwoods, with little survival into premature (2–7 yr) and early mature (8–30 yr) age classes. In contrast with previous patterns of establishment that were associated with frequent flood events, current cottonwood recruitment is limited to 50–100 year flood events. We are using analysis of a time series of aerial photographs, reconstruction of hydrologic data, and field studies of riparian vegetation structure and channel form to evaluate and recommend restoration flow regimes for Diamond Fork. The restoration objective is to provide an improved fishery, but the initially proposed flow regime did not address riparian needs, as it would have eliminated all potential for natural cottonwood establishment, or channel stability, as it did not consider flow duration or sediment transport. Recommended flow regimes need to consider the relation between hydrologic change and geomorphic process as well as the processes contributing to riparian establishment and maintenance.

HIDROVIA is a waterway project that, if completed, will require dredging and deepening of select reaches along the 3400 km De la Plata River basin. Fish diversity in the basin is great and dominated by detritivorous and bottom feeders. Large-sized, migratory species support valuable subsistence, commercial, and sport fisheries. In the upper Paraguay, dredging and anticipated increases in navigation traffic will severely impact shore-line habitats and likely affect fish fauna and mobilize shoreline sediments. In the middle and lower Paraguay Rivers and in the Paraná River, dredging should not affect upstream fish migrations and therefore we anticipate only minor effects on the fishery. Dredging and sediment disposal will not release significant levels of contaminants because sediments are dominated by medium and fine sands. However in De la Plata River, dominance of silt and clay elevates concentrations of contaminants that may be released by dredging thus increasing bioaccumulation in bottom-feeding fishes and benthic organisms. These effects could be more severe in estuarine spawning habitats used by several eurihaline fish species.

South American river basins have high fish diversity and contain many economically important migratory fish species. Approximately 140 dams have been built, and 280 dams are planned for the near future in De La Plata River basin. Adult fish passage facilities in the basin are restricted to a few low-head dams in Brazil that have pool-weir systems of modest effectiveness, passing primarily migratory species (e.g. Prochilodus). A historical reliance on stock maintenance through hatchery production has hindered development of fish passage technology. In the lower basin a Borland lock system was installed at Salto Grande Dam and fish elevators were installed at Yacyreta Dam. Both systems have limited success in passing migratory fishes. The limited success of fish transfer systems in the basin can be attributed to unquestioning acceptance of North American fish passage technology without consideration of the unique biology and behavior of South American fishes, inappropriate entrance geometry and location, and inadequate scaling of fishways relative to numbers of fish that must be passed to sustain stocks of migratory fishes. We advocate an integrated approach to develop and improve fishways based on ecological, hydraulic, and engineering criteria developed specifically for basin fishes supplemented by other strategies such as hatchery production and passage through navigation locks.

A study was performed to evaluate flood management benefits through floodplain restoration on the Willamette River in Oregon. An assessment of historic flooding and flood damages provided a context for developing conceptual restoration measures. The study was coincidentally released at the time of a 1996 flood event on the river.

A Geographic Information System-based, landscape-scale procedure was developed for inventorying and prioritizing candidate wetland restoration sites in coastal North Carolina. The procedure was based on the potential ecological significance of the sites throughout a region using fundamental ecological principles to determine the specific wetland functions they might perform within their watersheds. The watersheds used were 5,000 to 50,000 acre hydrologic units delineated by the Natural Resource Conservation Service (NRCS). The GIS data layers used in this procedure include (1)wetland boundaries and types, (2) soils maps, (3) land use/land cover, (4) hydrography, (5) watershed boundaries, (6) threatened and endangered species occurrences, (7) estuarine primary nursery areas, (8) water quality classifications, (9) NC priority protection areas, and (10) anadromous fish spawning areas.

Constructed wetland systems have the potential of providing a low cost and low maintenance wastewater treatment alternative for nitrogen removal. This paper describes a method developed to investigate denitrification as a nitrogen removal pathway in constructed wetlands. The method allows collection of information on rate limiting factors that can be used to improve the nitrogen treatment capabilities of these systems. A modified acetylene block method was developed to measure denitrification rates in the laboratory. This method was used to measure denitrification rates of soil cores from the effluent of a constructed wetland. Background denitrification rates as well as potential denitrification rates using sodium acetate were measured. The average background and potential denitrification rates were 5.06 ± 1.9 g N/m³/d and 18.0 ± 0.89 g N/m³/d, respectively. Average nitrate nitrogen loading and removal rates from water sampling during 1997 were 11.7 ± 3.1 and 4.01 ± 1.8 g N/m³/d, respectively.

The 1998 ASCE Wetlands Engineering and River Restoration Conference featured several panel discussions that were designed to draw upon the diversity of backgrounds present in the conference to promote a lively interaction and discussion. The discussion topics are issues that have generated debate and controversy among professionals involved in environmental restoration. The members of the panel were selected to provide a variety of view points and they were encouraged to involve the audience as much as possible. The current paper presents the results of the panel discussion titled "Do Ecologists and Engineers Have Differing Views of Stream Restoration?". Since few people possess all of the skills necessary to conduct a successful environmental study and design, an interdisciplinary team approach is necessary. The exact makeup of teams can vary, but successful restoration typically involves the application of engineering and ecological expertise. So the question of whether ecologists and engineers have differing views of restoration and how different these views are, is very relevant.

The terms Sustainable Development and Ecosystem Management have become widely used in recent years. Several specific definitions have been put forward, but there is not yet consensus on their meaning within the scientific or natural resources management communities. However, considerable progress is been made in their application to the appropriate management of the earth's resources. A workshop was convened on March 23, during the 1998 ASCE Wetlands Engineering and River Restoration Conference, to explore these two "buzz words"; what do they mean? are they useful?

This paper presents the conclusions of a discussion held on March 23, 1998 at the ASCE River Restoration and Wetland Engineering Conference. Over 100 restoration professionals participated in this discussion, of which approximately one-half to two-thirds identified themselves as civil engineers, with the rest including soil bioengineers, geomorphologists, hydrologists, biologists and others.

Over 60 persons participated in this discussion session. About 50% of the participants work with plant selection in one manner or another. Most of the participants were ecologists; a few were engineers and five (5) identified themselves as Geomorphologists. The session generated comments, questions, and conclusions related to plant selection.

During ninety minutes of lively discussions on the why, who, what, where and when about educating restoration specialists, the audience suggested ways in which it could be done.