Background: The Mid-Columbia River and Lake Roosevelt total dissolved gas TMDL is based on the federal Clean Water Act, state and tribal water quality standards, the National Marine Fisheries Service's 2000 biological opinion for the federal Columbia River power system, and continuous monitoring and special studies conducted by hydroelectric project owners on the river.
The TMDL/implementation plan identifies strategies for reducing total dissolved gas in the mid-Columbia/Lake Roosevelt from the Canadian border to the Snake River. For this project, ecology and the United States Environmental Protection Agency (EPA) will issue a joint TMDL, sharing responsibility depending on jurisdiction. EPA will lead the TMDL for Lake Roosevelt and tribal waters in the Columbia River. Ecology will lead for the state waters of the Columbia downstream of Grand Coulee Dam.
EPA works closely with ecology and provides technical review of all products produced by ecology. Ecology worked with the Spokane Tribe to develop the implementation plan to reduce TDG in the Columbia River and Lake Roosevelt.
Why is Elevated Total Dissolved Gas (TDG) a Problem? Saturation of the water with dissolved gases may result from either natural or human caused conditions. High concentrations of TDG negatively impact the health and survival of fish and other aquatic life. The primary source of elevated dissolved gas in the mid-Columbia/Lake Roosevelt is from water spilled at seven dams – Priest Rapids, Wanapum, Rock Island, Rocky Reach, Wells, Chief Joseph, and Grand Coulee – and from sources in Canada and the United States upstream of Lake Roosevelt.
Spill results from river flows exceeding the available capacity of the dam's powerhouse. Water is also spilled to assist fish passage. The mid-Columbia River's salmonid populations have declined significantly, and inadequate fish passage has been identified as one of the causes. The habitat – the lakes and rivers where fish live – also needs to be healthy for the fish populations to recover. This TMDL attempts to balance fish passage needs with the TDG levels necessary to protect habitat.
Federal Law Requires Cleanup of Polluted Waters: Federal law requires states to identify sources of pollution in water bodies that fall short of water quality standards and to determine how much pollution needs to be reduced for the water to remain healthy. Given this information, ecology, EPA, the Spokane Tribe and regional interests develop strategies for achieving the necessary reduction or elimination of pollution. The result is a water cleanup plan or TMDL, which identifies the allowable pollution levels from various sources. In the mid-Columbia/Lake Roosevelt, TDG levels at times violate the standards of the Colville and Spokane tribes and the state of Washington. This TMDL provides target levels and an implementation plan to reduce TDG to acceptable levels.
Public Comment Period and Hearings: Ecology, EPA, and the Spokane Tribe will review and consider all relevant comments received during the public comment period. Following this review, the TMDL and implementation plan may be modified. When complete, the TMDL will be sent to EPA for final approval. You will be notified of the final decision if you present either oral or written comments during the comment period. If you do not comment but wish to receive notification of ecology's final decision, please call or e-mail Ann Butler.
Mail written comments to Ann Butler, Washington Department of Ecology, P.O. Box 47600, Olympia, WA 98504-7600. Written comments on the proposed total maximum daily load and/or implementation plan must be received by 5 p.m. on March 18, 2004. Public hearings will be scheduled in Wenatchee and Spokane in mid-March - contact Ann Butler or ecology's website: http://ecy.wa.gov/programs/wq/wqhome.html - for details.