How Much is Too Much?: Challenges to Water Withdrawal and Consumptive Use Management
Publication: Journal of Water Resources Planning and Management
Volume 140, Issue 6
“Anyone who can solve the problems of water will be worthy of two Nobel prizes—one for peace and one for science.” (John F. Kennedy)
Implementation of the clean water act (CWA) has resulted in strict controls on discharges to streams, but laws and regulations on withdrawals from streams are often absent (Eheart 2004). The CWA has two basic approaches to protecting the nation’s waters; i.e., a technology-based end-of-pipe approach and a water quality-based approach. The technology-based approach is used to derive national pollutant discharge elimination system (NPDES) permit limits and the water quality-based approach is used to develop total maximum daily loads (TMDL) for achieving desired water quality. There is no similar federal law establishing permit limits and total load controls on water withdrawals and consumptive uses from streams. Although how much and when water can be withdrawn and consumptively used from a watershed is a conceptually simple issue, it is a scientifically and politically difficult one. Nonetheless, cumulative water use is one of the most important issues faced by contemporary water resources managers.
Water Withdrawal and Consumptive Use Regulation in the Susquehanna River Basin
The Susquehanna River Basin Commission (SRBC) is a federal-interstate compact commission responsible for coordinated management of the water resources of the (27,510-square-mile) Susquehanna river basin. The SRBC is uniquely suited to fulfill its mission of comprehensive planning, water supply allocation, and overall management of the water resources of the basin as its jurisdiction is defined by a watershed boundary rather than political boundaries (SRBC 1972). Under the authority of the Susquehanna river basin compact, and in concert with its member jurisdictions, the SRBC regulates groundwater withdrawal, surface water withdrawal, and consumptive water use in the basin. Consumptive use is broadly defined to be the loss of water because of a variety of processes by which the water is not returned to the waters of the basin undiminished in quantity. In general, the SRBC regulates ground and surface water withdrawals of (100,000 gal.) per day or more (peak consecutive 30-day average), consumptive uses and out-of-basin diversions of (20,000 gal.) per day or more (peak consecutive 30-day average), and into-basin diversions of any quantity. With the absence of federal law and regulations on water quantity, and in coordination with the states’ regulations, the SRBC has developed and implemented various regulations, policies, and plans over the last four decades tailored to water withdrawal and consumptive use management in the basin.
Some important water resources management measures embodied in these directives include consumptive use mitigation, passby flows, and withdrawal limits. Consumptive use mitigation is intended to eliminate artificial impacts caused by consumptive use during critical low flow events by returning flows to natural conditions to ensure water is available for downstream uses, including instream uses (SRBC 2008). Regulated projects comply with the mitigation requirement by discontinuing consumptive use, providing flow augmentation releases from storage, or paying a fee intended for development of water storage projects to provide mitigation. A passby flow is a prescribed streamflow level at which a regulated withdrawal must cease. It represents a minimum hands-off flow threshold to limit local withdrawal-induced adverse impacts during low flow events. Although consumptive use mitigation and passby flows address instream flow protection during low flow conditions, relying exclusively on minimum-threshold-based standards can result in elimination of flow variability and flat-lined flow hydrographs as water allocation pressure increases (Richter et al. 2012). Withdrawal limits can also be imposed on regulated withdrawals when individual or cumulative withdrawals are of significant magnitude to produce unacceptable levels of hydrologic alteration during seasonal flow conditions. Requiring consumptive use mitigation and passby flows for low flow protection, coupled with withdrawal limits to maintain natural flow variability for seasonal flow protection, provides a comprehensive approach to meeting instream flow protection objectives.
Water Withdrawal and Consumptive Use Management Challenges
To develop the specifications for these management measures, a basic question has to be answered: how much water use is too much? Certainly, the commonly faced water resources management challenges, such as uncertainty, multiobjectives, nonstationarity, and climate change are of importance and interest in answering the question. However, as they have been discussed extensively in the literature, this editorial focuses on specific challenges confronted in water withdrawal and consumptive use management from a perspective of developing and implementing regulations and policies based on sound science. These challenges include reliable, high-resolution water use data, balanced risk-based and ecosystem-based water resources management thresholds, definitive relationships between hydrologic alteration and ecological response, and prioritization of water uses.
Reliable High Resolution Water Use Data
Water use data are critical to making sound water allocation decisions to ensure that water supplies are reliable in the short term and sustainable over the long term. While the water resources community continues to be frustrated over diminishing funding for United States Geological Survey (USGS) streamgages, there is often little attention paid to water use data collection programs such as the USGS national water-use information program (NWUIP) (National Research Council 2002). The nation’s water use data are often collected at the state and local level by various organizations, which produces inconsistencies in data types, accuracy, spatial resolution, and temporal scale. Some agencies collect water withdrawal data but not consumptive use data. Discharge quantity data are often used to compute net water use. However, if discharge data are collected by a different entity and at a different spatial or temporal resolution, net water use summaries at the watershed scale can be erroneous. Accuracy of water use data can vary significantly based on whether the use is regulated, the quantities reflect permitted or monitored and recorded or estimated use, and the reporting is mandatory or voluntary. Spatial resolution of water use data can be a substantial limiting factor in evaluating water availability at the watershed scale. Discrepancies in facility versus source-based water use data and point-of-taking versus watershed unit versus political boundary water use data can constrain finer resolution analyses. Streamflow data collected by USGS often have daily, or even subdaily, temporal resolution. However, water use data at this fine temporal scale are not typically available. Varying temporal resolutions of water use data can considerably limit the value of the data.
Risk- versus Ecosystem-based Water Resources Management Thresholds
Traditionally, water resources professionals have developed and maintained water resources systems and related infrastructure projects using risk-based approaches. Planning and design criteria commonly incorporate statistical thresholds such as the 7-day 10-year low flow, 10-year baseflow, 100-year flood, and probable maximum flood. These risk-based standards have been applied by water resources managers for decades, are easy to communicate to the regulated community and general public, and have proven effective in guiding development of resilient projects. Contemporary environmental flow science has fueled a paradigm shift in which traditional thresholds are more commonly dismissed in favor of ecosystem needs-based approaches for managing and operating water resources systems (Poff 2009). Whereas it is certainly appealing to employ ecosystem-based methods to manage water withdrawals and consumptive use, it also demands firm demonstration of the instream flow requirements necessary to attain self-sustaining aquatic and riparian ecosystems. This is a science question but also a social preference. As difficult as it is to scientifically substantiate these ecosystem flow requirements, it is even more challenging to achieve consensus on an acceptable level of impact. The consensus building process can be particularly arduous if apprehensions about ecological protection are pitted against public health and safety concerns.
Relationship between Hydrologic Alteration and Ecological Response
To establish and implement standards for consumptive use mitigation, passby flows, and withdrawal limits, it is desirable to thoroughly understand the relationships between hydrologic alteration and ecosystem response. Although significant advancements have been made in the last few decades, firm, quantitative relationships between hydrologic alteration and ecological response have yet to be established. These relationships are elusive because of a sequence of intervening dynamic effects that are difficult to discern, from reduction in streamflow, to influence on water quality, to decrease in stage, to reduction in wetted area, to diminishment in habitat, and to negative ecological response, among other factors. Considering the intrinsic variability of hydrology and the propensity for ecosystem recovery, it is difficult to develop quantitative criteria for maximum acceptable hydrologic alteration. Aquatic and riparian ecosystems are influenced by so many varied factors, many of which are naturogenic, that it is a daunting task to isolate any aspect of hydrologic alteration as the principle cause of impacts without also considering changes to water quality, habitat, land use, and climate dynamics. Even if a relationship were discerned, how much negative ecological response is acceptable is not purely a scientific question.
Prioritization of Water Uses
One of the most contentious issues in water resources management is prioritization of water use. Ideologically, water withdrawals and consumptive use would be managed equitably among all competing water users. Western states follow prior appropriation doctrine which prioritizes water allocations for beneficial uses based on the seniority of the appropriation. Eastern states follow riparian rights doctrine which prioritizes water allocations for reasonable use by landowners whose property is adjoining to a body of water. Although the states are owners of the water, they have generally not prioritized water uses, nor have river basin commissions undertaken the challenging and controversial effort to prioritize in-basin water uses. Priorities are often relative and highly dependent on location and public acceptance. When jurisdictional and watershed boundaries do not coincide, it is more challenging to identify the priorities of various water use sectors and users (Sheer 2009).
It is attractive to prioritize water use based on its importance to society, including those uses for public health, safety, and welfare. For example, self-supplied residential and public water supply uses tend to be regarded as top priorities. Agricultural water use is also typically viewed as a priority over many other uses not as intrinsically linked to public health and safety. To the extent it provides for essential purposes such as heating, cooling, and healthcare, electric utilities have made a case for consideration as a priority water use. Lists of priority water uses are very susceptible to escalation and political disagreement. For all these reasons, developing a prioritization hierarchy for water uses during water supply shortfalls is challenging. If a higher priority water use is permitted and begins operating after existing lower priority water uses, and water availability is approaching management thresholds, which use should have its water allocation adjusted to ensure sustainability of the system? Or should all active water users be required to share the burden and reduce their use equally or proportionally so that the cumulative demand is managed in accordance with the sustainable yield. These are conceptually straight-forward but politically and operationally complex water management approaches that would require dynamic water use allocation programs and standards. The dynamic water use allocation programs would ideally incorporate adaptive management scheme and adjust all active water use allocation to balance water demand and safe yield if needed.
Water Resources Research
To appropriately address the aforementioned challenges, it is important that water resources managers are equipped with the best available science and tools. Research provides the scientific basis for sound water resources planning and management and improves how professionals monitor, model, analyze, and manage water resources systems. Water resources managers can benefit significantly from tracking contemporary advancements in water resources research, including both general studies and case-specific investigations. Having a firm grasp on the best available science allows practitioners to adapt and implement innovative management strategies to meet modern challenges. Water resources professionals also need scientifically defensible results to support their decisions on particular water resources issues as the decisions may be challenged by stakeholders and in court. Thus, it is also important for the research community to understand current and specific water resources management needs and challenges to undertake research initiatives with direct applicability to contemporary issues. For example, applied research focused on establishing definitive, quantitative relationships between hydrologic alteration and ecological response could dramatically improve the ability of water resources managers to answer the question how much is too much.
Acknowledgments
This editorial does not necessarily reflect the view of Susquehanna River Basin Commission, and no official endorsement shall be inferred. The authors would like to thank Dr. Patrick Reed of Cornell University for his encouragement and review of this work.
References
Eheart, J. W. (2004). “No river left behind: A call for regulation in a deregulating and misregulating era.” J. Water Resour. Plann. Manage., 10.1061/(ASCE)0733-9496(2004)130:5(357), 357–358.
Nationa Research Council. (2002). Estimating water use in the United States: A new paradigm for the national water-use information program, National Academy Press, Washington, DC, 176.
Poff, N. L. (2009). “Managing for variability to sustain freshwater ecosystems.” J. Water Resour. Plann. Manage., 1–4.
Richter, B., Davis, M., Apse, C., and Konrad, C. (2012). “A presumptive standard for environmental flow protection.” River Res. Appl., 28(8), 1312–1321.
Sheer, D. P. (2009). “Dysfunctional water management: Causes and solutions.” J. Water Resour. Plann. Manage., 1–4.
Susquehanna River Basin Commission. (1972). Susquehanna river basin compact, Susquehanna River Basin Commission, Harrisburg, PA.
Susquehanna River Basin Commission. (2008). Consumptive use mitigation plan, Susquehanna River Basin Commission, Harrisburg, PA.
Information & Authors
Information
Published In
Journal of Water Resources Planning and Management
Volume 140 • Issue 6 • June 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Feb 10, 2014
Accepted: Feb 20, 2014
Published online: Apr 11, 2014
Published in print: Jun 1, 2014
Discussion open until: Sep 11, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.