Dworshak Flow Augmentationby Mike O'Bryant
With half of the juvenile salmon and steelhead migration still in the Snake River and while waiting for the spring freshet to begin, the Technical Management Team decided this week to continue high flow and spill from Dworshak Dam on the North Fork of the Clearwater River through Tuesday.
The flow augmentation from Dworshak is helping to maintain the somewhat higher flows at Lower Granite Dam on the Snake River that are needed to push juveniles downstream.
At last week's TMT meeting, the U.S. Army Corps of Engineers predicted it could maintain 15,500 cubic foot per second releases from Dworshak Dam through May 18. At that point it would have to drop flows abruptly to about 1.5 kcfs in order to assure refill of Dworshak Reservoir by June 30, a target set by NOAA Fisheries 2000 biological opinion for the Columbia River hydro system. The 15.5 kcfs flow includes about 10 kcfs through the powerhouse and over 5 kcfs of spill (limited by the total dissolved gas cap of 110 percent).
However, new information this week from the Corps predicts that the water supply in the North Fork Clearwater River basin will be higher (up from 1.9 million acre feet to 2.34 maf) than it predicted last week, allowing a few more days of higher flows. Still, flows from the dam will have to be cut by the middle of next week.
"Based on the information of a higher inflow April through July, we think flows can continue at least one more week," said Dave Wills, U.S. Fish and Wildlife. "With all the new snow, there is plenty of water for refill."
The BiOp, which was thrown out last week by a federal court, gives a higher priority to refilling Dworshak Reservoir so the water is available during the summer for flow augmentation, than it does for using that water for spring flow augmentation.
The Bonneville Power Administration, which says it is losing about $1 million per week due to the spill at the dam, believes the fisheries managers could be jeopardizing refill and flow augmentation for the summer juvenile migration. He believes the fisheries managers are counting on every last drop of water predicted by the Corps and that could be dangerous.
"I understand you want to keep as much water in the river for the smolts, but this feels like you're putting all your eggs in one basket. Whenever you put all your eggs in one basket, I get nervous," said John Wellschlager of BPA. "If you go another week and there still is no runoff, you'll have to pull the plug out from under the smolts."
Instead of dropping flows abruptly to 1.5 kcfs, Wellschlager suggested ramping down several thousand cfs sooner so the water would last longer while waiting for the spring runoff to begin.
Kyle Martin, a hydrologist for the Columbia River Inter-Tribal Fish Commission, said CRITFC and the Nez Perce Tribe in Idaho supports the higher flows that fisheries managers have recommended. One reason is because he predicts warm weather in the Clearwater Basin will begin early next week. That, he said, would kick off the spring freshet and Snake River water flow will rise at that point without the aid of Dworshak flow augmentation.
Rudd Turner of the Corps suggested keeping flows at 15.5 kcfs through May 20, then to begin ramping down flows at Dworshak Dam to 10 kcfs on May 21 and to the minimum flow of 1.5 kcfs May 23. With that operation and while waiting for the freshet, the Corps is predicting flows at Lower Granite Dam will gradually fall from the current 68 kcfs (the BiOp flow target is 80 kcfs) to about 58 kcfs then gradually creep up to 80 kcfs by the end of May. That's the conservative suggestion, Turner said.
Another ramping option, Turner said, is to hold the 15.5 kcfs flows through May 23, then drop flows to 10.5 kcfs on May 24, to 7.5 kcfs on May 25, 3.5 kcfs on May 26 and go to minimum flow on May 27. However, this operation could jeopardize refill, he said, and the Corps would want the request from the salmon managers in writing.
"Part of my job is to represent ratepayers," Wellschlager said. "This costs them about $1 million per week. The law is on the side of the fisheries managers, but I still need to put that on the table." He suggested ramping flows down beginning May 19 to 12 kcfs, to 10 kcfs on May 20 and to 8 kcfs on May 21, before deciding when to hit minimum.
Fisheries managers will meet Tuesday, May 20, to discuss ramping flows down, and TMT will make the decision at its May 21 meeting.
TMT also decided to continue for at least two more weeks flows from Grand Coulee Dam that ensures flows at Grant County Public Utility District's Priest Rapids Dam of 135 kcfs, as long as refill by the July 4 weekend of Lake Roosevelt is assured. Again, refill of the reservoir is a higher priority in the BiOp than is the 135 kcfs flow at Priest Rapids.
"The rationale to continue this operation is that the fish out of the Snake River are late. The freshet is taking its time," said Paul Wagner of NOAA Fisheries. "When they do come out of the river, we want to make sure they are coming out in higher flows."
Wagner added that the spring freshet is on a similar track as that experienced in 1999 when flows were also fairly low through this period. However, while the timing is similar, 1999 was a high flow year and this year is not predicted to be as high, Turner said.
The fisheries managers also asked river operating agencies to try to keep the flow at Priest Rapids Dam more consistent. Flows have often been higher.
Shane Scott of the Washington Department of Fish and Wildlife said biologists are predicting the end of chum emergence to fall on May 15, based on the accumulation of temperature units. That would end protection flows for chum this year.
Wellschlager said that would remove the tailwater restrictions at the dam and allow for more consistent flows at Priest Rapids Dam. Turner said it would also reduce the total dissolved gas levels at Bonneville Dam.
Technical Management Team: www.nwd-wc.usace.army.mil/TMT/index.html
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