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River Operatort Hold Firm
on Filling Snake Reservoirs Sept. 1

by Mike O'Bryant
Columbia Basin Bulletin - August 27, 2004

Against some salmon managers' objections, the Bonneville Power Administration and Army Corps of Engineers this week held firm to their proposal to begin filling reservoirs behind Snake River dams Sept. 1.

During the migration of juvenile salmon and steelhead, the Corps limits reservoir elevations at the four lower Snake River dams to a minimum operating pool. Lower reservoirs result in increased water velocity through the pools and that helps to reduce the travel time for juveniles as they migrate through the river to the ocean.

This week, BPA's Nick Lane, along with the Corps, proposed during the Technical Management Team meeting to lift the MOP restriction Sept. 1 and to begin filling lower Snake River reservoirs, an operation that Lane said is usual this time of year.

"The operation is consistent with what we've been doing in the past," Lane said, "and we're not amenable in making significant changes."

Although some salmon managers opposed lifting the MOP operation Sept. 1, they did not propose to elevate the decision to the Implementation Team, the policy body that normally decides disputes at TMT. However, the Nez Perce Tribe, which also objected to the decision to lift the MOP restriction, asked that the Corps to begin consultation with the tribe immediately.

Typically, the MOP restriction, which is listed as an action in NOAA Fisheries 2000 Biological Opinion, is lifted Sept. 1 each year after most of the Snake River juvenile salmon have migrated down through the river and when the adults begin to show up at dams in large numbers. By raising the elevation of the reservoirs, each dam is able to produce more electricity and the higher pools help adult salmon migrating upstream to spawning grounds gain access to fish ladders at the dams.

However, this year and for the past two years, the Technical Management Team has reserved up to 200,000 acre feet of additional water from Dworshak Dam on the North Fork of the Clearwater River for release through mid-September. This year 174 kaf is available for use in September, according to Steve Haeseker of the U.S. Fish and Wildlife Service. Some salmon managers said that extending flow augmentation out to mid-September should also signal a change in when the MOP restrictions are lifted.

USFWS, Oregon Department of Fish and Wildlife and Idaho Department of Fish and Game officials said that the value of Dworshak water, both throughout the summer and the additional water held over to September, is to help cool the lower Snake River water temperature and for flow augmentation. They said the additional water should be used to help reduce travel time for the few remaining juvenile fall chinook salmon left in the river and should not be used to fill the reservoirs, which they said lifting the MOP restriction would do.

"Over the summer we've reserved water for good conditions for the Clearwater fish in September," Haeseker said. "We've argued a lot over that water and to lift MOP now doesn't make sense."

Dave Statler of the Nez Perce Tribe said that the additional Dworshak water is especially important to the tribe because only 9 percent of the Clearwater River migration of subyearling fall chinook salmon have migrated so far, leaving 91 percent still to pass through Snake River dams.

However, Paul Wagner of NOAA Fisheries said that new information is showing that the value of that water is to improve the river environment and that it is less important after Aug. 31 to help decrease travel time to the ocean.

He said that NOAA now thinks there are two operating seasons in the lower Snake River. The first includes flow augmentation and cooling from Dworshak Dam, along with MOP and spill at Snake River dams. "That season is coming to an end and MOP operations are coming to an end as well," Wagner said.

The second season modifies the Snake River operations to one that controls the river environment. While maintaining cool water is important during this time, he said, flow augmentation is less important. That season begins when fewer juveniles are passing dams and when adults are returning in large numbers, he said. "The value of speeding the fish through reservoirs during this time is very low," he said.

Also at TMT this week, salmon managers proposed in a Systems Operational Request to extend higher than minimum outflows at Dworshak Dam through mid-September. Flows of 45 degree Fahrenheit water are now at 10,600 cubic feet per second and the dam's elevation is at 1,533 feet. Outflows will drop Sept. 1 to about 7 kcfs, according to the Corps, and will drop again to minimum flow of about 1.4 kcfs on Sept. 15 or when the reservoir reaches an elevation of 1,520 feet. That SOR was accepted by both salmon managers and by river operating agencies.

Related Sites:

Mike O'Bryant
River Operatort Hold Firm on Filling Snake Reservoirs Sept. 1
Columbia Basin Bulletin, August 27, 2004

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