Balancing Engineering and Resource Agency Requirements to Create Shallow Water Habitat

Creation of Shallow Water Habitat as replacement for or mitigation for loss of SWH due to the filling or reclamation of harbor water areas with dredge material has become a critical component to the continued development of deep water port and harbor facilities, especially on the US west coast. In recent time, this began with the Federal Los Angeles Channel Deepening Project between 1979 and 1982 which deepened the harbor's main channel from its previous elevation of -35 ft (-10.7 m) MLLW to -45 ft (-13.7 m) MLLW. Due to the continued necessity for mitigation for loss of deep and shallow water areas, and to support beneficial disposal of dredge materials as channel depths continue to increase, policies have been formulated by the appropriate Federal and State Resource Agencies for compliance with various Federal and State Laws. As a result, additional SWH has been successfully constructed in the Port of Los Angeles as dredging projects have required and have demonstrated improved biological and fishery value over or greater than their previous deeper water depth. Recently, the Cabrillo Shallow Water Habitat (CSWH) has been constructed by the US Army Corps of Engineers (USACE) as part of the Federal Deep Draft Navigation Improvement Project. Design considerations for the on-going 50-acre (20.2 ha) CSWH Expansion include experience with the earlier phases of shallow water habitat construction, comments received during the public review process for the SEIS/SEIR, and knowledge of geotechnical characteristics of both the site and dredge material source areas. The successful completion of this project has required sequencing the placement of dredge materials at the CSWH, the use of construction methods which minimize disturbance of the dredge materials, and the development of a monitoring plan to ensure the future ecological benefit of the project. This paper will discuss how open communication and balancing the engineering and resource agency requirements have led to successful development of SWH.