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Idaho, Oregon Send Snake River TMDL to EPA

by Mike O'Bryant
Columbia Basin Bulletin - September 12, 2003

Idaho and Oregon have sent a jointly developed Total Maximum Daily Load (TMDL) plan to the U.S. Environmental Protection Agency for approval.

The TMDL sets pollution load limits on a 221-mile section of the Snake River from the confluence of the Salmon River upstream to where the river no longer forms a border between the two states. That section of the river is on the water quality impaired 303(d) lists of both states.

The Oregon Department of Environmental Quality and the Idaho Department of Environmental Quality developed the TMDL. It includes daily load limits on point sources of pollution, such as the outfalls at sewage treatment plants and industry, including Amalgamated Sugar and Heinz on the river's shore in Oregon. It also includes non-point sources of pollution, such as agricultural runoff and Idaho Power's Hells Canyon complex of dams.

ODEQ Eastern Region Administrator Joni Hammond said the TMDL and the accompanying Water Quality Management Plan "are tools to build on existing efforts to improve water quality and to protect valuable natural resources in the Snake River drainage. Our goal is to accommodate the variability in the natural environment and enable land management to occur in such a way that minimizes water quality impacts and reduces pollutant loads from human manipulations."

According to the state DEQ offices, the TMDL describes the quantity of pollutants the section of Snake River can accept before violating the states' water quality standards. It found that most problems where limits are exceeded occur under summer low flow conditions when temperatures, dissolved oxygen and the presence of phosphorous are at their highest, said Dick Nichols, Oregon DEQ water quality manager in Bend. The entire length of the section of river is listed by both states as impaired for temperature. In addition, Idaho lists the river impaired for nutrients (131.5 miles), dissolved oxygen (69.6 miles), pesticides (12.5 miles) and sediments (131.5 miles). Although not listed in either state, the TMDL also addresses total dissolved gas, sometimes a problem when Idaho Power dams spill water.

Nichols said the water that comes out of Brownlee Dam is often cooler than the water that arrives in its reservoir.

"If you look at what goes into the Brownlee pool, a good part of the time it is cooler when it comes out than if the dam were not there," Nichols said. "However, that reverses in the fall."

Early fall is when chinook begin to spawn downstream of the dam and for several weeks, until cooler air temperatures quickly bring water temperatures down, the water released by Idaho Power exceeds the spawning criteria for temperature, he said. "Idaho Power hasn't addressed this yet," Nichols said.

The TMDL also fails to address dissolved oxygen below the dam during the spawning season. "Maybe we should have," he said. The power company may still have to address dissolved oxygen when relicensing the complex of dams, which it is in the process of doing now. Idaho Power would still have to apply to the states for water quality 401 certifications before its license can be approved by the Federal Energy Regulatory Commission, he added.

Upon approval of the TMDL by EPA, which Nichols said could be as soon as the end of September, ODEQ and IDEQ will give each point source of pollution 18 months to prepare a facilities plan to show how they will bring their facility into compliance with water quality laws. They would be given five years to fix the problem. Nonpoint sources will also have to prepare plans and make improvements, as well, but that could take longer.

Related Sites:
Idaho Department of Environmental Quality:
Oregon Department of Environmental Quality:
Snake River/Hells Canyon TMDL:

Mike O'Bryant
Idaho, Oregon Send Snake River TMDL to EPA
Columbia Basin Bulletin, September 12, 2003

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