PORTLAND - The U.S. Army Corps of Engineers has recently completed an underwater survey of an ocean dredged material disposal site at the mouth of the Columbia River.
The survey of the Shallow Water Site, also called Site "E," is performed as part of the Corps and Environmental Protection Agency's management and monitoring efforts. Occurring at the beginning of the crab fishing season, it also provides the Columbia River crab fleet information about ocean depth at that location.
"We provide the information from the survey as soon as possible each year as a courtesy to the crab fishing industry," said Doris McKillip, Corps project manager. "We want the crab fleet to have the most current information available when deciding to navigate across the site."
Last year, Corps disposal practices in the area were blamed for a fatal crab boat accident near North Jetty, prompting renewed calls from crabbers and others for better monitoring and efforts to avoid undersea mounding, which creates rough water on the surface.
During the 2002 dredging season, the Corps moved 1.5 million cubic yards of sand out of the mouth of the Columbia River navigation channel and into the shallow water site. Since Sept. 26, more than 350,000 cubic yards has eroded out of the site.
The Shallow Water Site extends west of the North Jetty and covers an area of 534 acres, or .84 square miles. Currently, ocean depths range from 45 feet, at the north side of the site, to more than 70 feet, at the south side. Results of the survey, completed Dec. 2, are available on the Internet at www.nwp.usace.army.mil/op/n/wh/channel_line.htm. Click on index number "0A."
The Corps mintains that the Shallow Water Site is necessary to effectively maintain the deep-draft navigation channel at the mouth of the Columbia River and is an environmentally valuable option because it keeps sand in the near shore-system, feeding nearby Benson Beach and northerly up the Long Beach Peninsula. Scientists with the state of Washington dispute this, saying that sediments dumped at these depths do not reach the beach.
Also a matter of some controversy is what effects this dumping has on juvenile crab. Some fishermen maintain that the crab are likely to be smothered. But the Corps takes the position that "Since the area also is a historically used site where sand is constantly shifting due to naturally caused high wave and current energy, impacts on aquatic organisms are minimized." To minimize potential impacts to crabs, the Corps stops using the western portion of the site after Aug. 15 each year when soft-shell crabs may begin moving into the area.
The Corps and the Environmental Protection Agency jointly manage ocean dredged material disposal sites to balance competing objectives, such as efficient dredging to maintain the navigable channel for all vessels, minimizing potential wave impacts, and retaining sand in the near-shore littoral system to slow coastal erosion.