Maintenance of inland and intracoastal waterways for navigation is essential for national and international trade, job creation, and national security. These waterways also provide hydropower, flood protection, municipal water supply, agricultural irrigation, recreation, and regional development. The US Army Corps of Engineers' role in maintaining and improving these waterways began in 1824 and, today, the Corps maintains over 12,000 miles (19,200 km) of waterways throughout the United States. Corps and contractor-owned dredges annually remove over 270 million cubic yards (cy) of sediment from over 150 projects in the United States.
Several types of dredges are typically used for excavating sediments to construct new waterways or maintain navigation depths in channels. Cutterhead pipeline, hopper, and mechanical dredges are the three primary types used throughout U.S. waterways. The type used depends on factors such as sediment type, location, environmental considerations, and wave conditions. The dredge type of concern with endangered sea turtle interactions is the hopper dredge.
Hopper dredging along the southeastern USA potentially impacts five species of threatened or endangered sea turtles. Documented incidental takes of loggerhead, green, and Kemp's ridley sea turtles have occurred during dredging since 1980 in more than 38 coastal channels from the Texas-Mexico border through New York. Over the past 24 years, the U.S. Army Corps of Engineers (USACE) and dredging industry have worked to develop protocols, operational methods, and modified dredging equipment to reduce dredging impacts to sea turtles. The success of these protection efforts is illustrated in the reductions in incidental takes compared to the increasing number of dredged channels monitored.
Engineering and biological studies were completed to develop a suite of protective tools to reduce hopper dredging impacts on marine turtles. These investigations have included sea turtle relative-abundance, behavioral, acoustic-detection and dispersal, and dredging equipment development. In addition to gaining valuable data for understanding sea turtle biology, these studies helped to establish environmental windows, draghead modifications, draghead turtle deflectors, and protection protocols such as trawling to relocate sea turtles (see Dickerson et al. 2004 for explanation of these protection measures).
The USACE Sea Turtle Warehouse was created to centralize and archive historical and future data regarding sea turtle impacts from hopper dredging activities for long-term continuity and evaluation of these data. Although the overall impacts to sea turtles from dredging activities is relatively small, the USACE and dredging industry is committed to the continued pursuit of efforts to further reduce dredging impacts on sea turtles.
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