Deschutes River: Operators will try a cooler mix to meet temperature goals
By Quinton Smith
Operators of a massive new water tower at Round Butte Dam near Madras agreed Friday to again release more cold water into the lower Deschutes River because of concerns they were not always meeting permitted temperatures.
It is the second change in the mix of water from the Round Butte Dam project in the past two weeks by Portland General Electric and the Confederated Tribes of Warm Springs, owners of the three dams and reservoirs near Madras in central Oregon.
The new $110 million water-mixing tower at Round Butte Dam was part of the dam’s re-licensing and designed to aid the reintroduction of salmon, steelhead and bull trout into the three rivers that flow into Lake Billy Chinook. The tower attracts migrating juvenile fish by taking cold water from the bottom of the lake and mixing it with warmer water at the top and then releasing it downstream.
But so far, downstream releases are warmer than in the past and are being blamed by fishermen and others for rising water temperatures in the lower 100 miles of the highly popular trout and steelhead river. They argue the warmer water is changing the biology of the lower river, is harder on native steelhead, and is affecting fishing guides’ livelihoods by hampering fishing success in July and August.
In July the released mixture of water was 15 percent cold water from the bottom of Lake Billy Chinook and 85 percent warm water from the top. On July 27, after a week of missing the permitted water temperature, PGE adjusted the cold water percentage to 17 percent. Then as scheduled Aug. 1 it went to a release of 30 percent cold water and 60 percent warm water. Plans called for 40 percent cold water releases during September and 50 percent in October.
But PGE senior biologist Don Ratliff said the 30/70 mix was still not meeting permit temperatures last week, so the utility agreed Friday to jump ahead to a 40/60 percent mix over the next 10 days. The release will be held at 40/60 through October, Ratliff said, using the same amount of cool, deep water from Lake Billy Chinook but concentrating it more in the warmer month of August.
The agreement came during a conference call Friday that included representatives of the Oregon Department of Fish and Wildlife, the Department of Environmental Quality, the Warm Springs tribes and PGE –a group that meets regularly to advise the utility on water and fish issues. The change was announced late Friday on PGE’s Deschutes Passage website.
Although PGE was within overall compliance limits, the advisory group asked “What’s the right thing to do?” Amy Stuart, Deschutes watershed manager for the department of fish and wildlife, said Saturday. Stuart said the jump to the 40 percent mix of cold water is expected to keep releases below permitted levels through September.
The two state agencies say they are taking a more flexible approach to PGE’s operations during the first year of the water mixing tower because the project got a late start this year and because not enough cooler water has accumulated yet in Lake Billy Chinook. Starting in November and through the winter, PGE said releases will be concentrated from the lake’s surface so additional dense, cool water can be accumulated at the bottom through the winter and aid water temperature management in the lower Deschutes next summer.