News Release
| Release Number: | 01-027 |
| Dated: | 3/7/2001 |
| Contact: | Public Affairs Office, 503-808-4510 |
Portland, Ore.--An Environmental Assessment detailing the benefits and impacts of potential fisheries construction work at Bonneville Lock and Dam on the Columbia River was released for public comment March 5, 2001.
Increased juvenile salmonid survival is the goal of possible juvenile bypass system changes inside the first powerhouse and a transportation flume that would guide migrating juveniles from the Oregon side of the Bonneville project to bypass facilities on the Washington shore. The timing of such construction is dependent on a regional decision-making process that prioritizes fish recovery work in the region.
The decision-making group includes the National Marine Fisheries Service (NMFS), U.S. Fish and Wildlife Service, Bonneville Power Administration, state fish and wildlife agencies of Oregon, Washington and Idaho, Northwest Power Planning Council, the Columbia River Inter-Tribal Fish Commission and the Corps.
The U.S. Army Corps of Engineers, Portland District, prepared the Environmental Assessment under provisions of the National Environmental Policy Act (NEPA), which ensures environmental effects of a project are carefully considered, and provides an opportunity for public participation. Under NEPA, the EA process must be completed before construction can begin. The Corps prepared the EA now to be ready to begin construction when and if a decision is made to proceed with the work.
The work outlined in the Environmental Assessment includes: improvements inside the powerhouse; ice and trash sluiceway modifications; trash boom construction; a dewatering structure; and a transportation/bridge flume beginning in Oregon, crossing over the Columbia River, and connecting to the existing unused flume which parallels the second powerhouse transportation flume in Washington. The unused flume was constructed at the same time as the second powerhouse flume because there were significant cost savings to doing it at that time. Fish traveling through the flume would be diverted into the smolt monitoring facility and from there through the existing outfalls to return to the Columbia River. The estimated cost for the entire project, including preliminary planning and design work, construction and post-construction monitoring, is $84.8 million.
Survival benefits of migrating juvenile salmon and steelhead are estimated to increase by 12 percent for spring migrants and as much as 25 percent for summer migrants. Survival of spring chinook migrants passing through the first powerhouse is expected to increase from 85 percent to about 97 percent. Rates of increased survival for summer chinook are even more positive, rising from a current rate of about 70 percent to about 95 percent.
The portion of the flume on Bradford Island would be nearly 1,300 feet long, with 360 feet of that length elevated, the rest buried underground. The total portion of the flume forming a bridge is about 1,200 feet. The bridge segment would be supported by 11 piers in the river set at 120-foot intervals, and by two smaller concrete piers on land. The bridge flume would be a maximum of 45 feet above the river.
Minimal environmental effects are expected. The major portions of the project, the dewatering facility and transportation flume on Bradford Island, are within habitats disturbed during dam construction in the 1930s, and more recently to construction of the existing juvenile bypass system in the 1970s and the new navigation lock in the late 1980s. On the Washington shore, habitat was disturbed by second powerhouse construction activities in the 1970s, and again for construction of the second powerhouse transportation flume in 1999. The environmental assessment includes information on impacts of the proposed work to endangered wildlife, fish and vegetation. The Corps has requested Water Quality Certification from Oregon and Washington.
The assessment also includes information on potential short- and long-term impacts to recreational opportunities, including fishing, near Bonneville Dam. Bank fishing access along the north side of Bradford Island would be affected during the two-year construction period. If funded, the flume could include a pedestrian walkway that would allow project visitors to walk above the Columbia River between Oregon and Washington.
Questions or comments regarding the Environmental Assessment should be addressed to Lynne Hamilton, Environmental Resources Branch, (503) 808-4772. Written comments on the EA must be mailed by April 4, 2001, to District Engineer, U.S. Army Corps of Engineer District, Portland, Attn: CENWP-PM-E, P.O. Box 2946, Portland, OR 97208-2946. In your response, please refer to public notice number CENWP-PM-E-01-02.
Construction and operation of juvenile bypass systems at both Bonneville powerhouses was included in the March 1995 NMFS Biological Opinion on operation of the Federal Columbia River Power System. Work at the second powerhouse, including a transportation flume, smolt monitoring facility and outfall structures was completed in 2000. Work at the first powerhouse was put on hold pending biological evaluations of extended length screens (in the turbine passage system), and surface bypass. The December 2000 NMFS Biological Opinion requires a decision between juvenile bypass system improvements and surface bypass at Bonneville Dam be made no later than January 2002.
This action is one of many being undertaken by the Corps to improve fish passage at its Columbia and Snake River dams. The Corps continues to work with its regional partners - government, public and private - to preserve the valuable fish runs on the Columbia and Snake rivers.