INCORPORATING AQUATIC HABITAT RESTORATION/MITIGATION INTO DREDGING PROJECTS

摘要

A substantial portion of the world's dredging occurs in urbanized areas where aquatic habitats have been degraded by a range of necessary human uses. In recent years, urban waterfronts have been increasingly viewed as important habitat for a range of fish and wildlife species. For example, in Washington state the listing of Puget Sound Chinook salmon as threatened under the Endangered Species Act (ESA) has led to increased focus on restoring habitat in the individual sub-estuaries of Puget Sound, including the Puyallup River estuary in Commencement Bay. Navigation and remedial dredging provide unique opportunities for accomplishing cost-effective aquatic habitat restoration. These actions can be either mitigation for impacts to habitat caused by dredging or restoration in the absence of significant habitat impacts. In either case, the aquatic habitat that is constructed in conjunction with dredging is typically much higher quality than the existing altered habitat.This paper describes a number of large and small scale habitat restoration/mitigation projects that have been implement in Commencement Bay over the last 20 years in conjunction with dredging projects. Projects range from construction of beaches with dredge material to shoreline cutbacks to create salt marshes. Topics will include: technical biological criteria for designing and locating appropriate habitat; incorporating multiple non-habitat benefits into the restoration action such as beneficial use of dredge material; sequencing of dredging and restoration work to minimize costs; and lessons learned negotiating habitat design and location with federal and state resource agencies.This paper demonstrates the range of aquatic habitat restoration actions that can be incorporated into dredging projects, while providing practical advice on how to implement them in the challenging urban environment and regulatory process.