Fish and water managers agreed to several actions designed to extend salmon-friendly cooling flows from Dworshak Reservoir on Wednesday, but clashed on one that would have made navigation more difficult on the lower Snake River.
Officials from the Army Corps of Engineers and Bonneville Power Administration rejected a request from some fish managers including Washington, Oregon and the Nez Perce Tribe to reduce the level of Lower Granite Pool by a few feet, saying it would lead to unsafe conditions for tug and barge operators and port workers.
“The lower Snake reservoirs are held as low as possible while maintaining navigation safety,” said Doug Baus, of the Corps.
River managers and fisheries officials struggle nearly every summer to keep the lower Snake River below temperatures harmful for salmon and steelhead listed as threatened and endangered under the Endangered Species Act. But this year, the work is more difficult. River flows are well below average for this time of year and temperatures have been well above average.
Each summer, cold water is released from Dworshak Reservoir on the North Fork of the Clearwater River with the aim of mitigating high water temperatures in the Snake River at Lower Granite Dam, about 70 miles downstream. Those flows generally start shortly after the Fourth of July holiday and continue into the middle of September. During that time, Dworshak Reservoir is lowered from its full pool elevation of 1,600 feet to 1,520 feet.
However, because of the punishing heat wave that began late last month, the cold water releases started more than two weeks early this year and before the reservoir had completely refilled. That means the cold water flows that are critical for returning adult fall chinook and steelhead will run out in mid-to-late August. State, federal and tribal fisheries managers are working with federal officials from the Corps and BPA to figure out ways to save as much of the cool water as possible. Each week they meet in a forum known as the Technical Management Team to discuss river and fish passage issues. Members of the forum can request changes in river operations. The Corps and BPA serve as final decision-makers.
The two agencies previously agreed to reduce spill at some Snake River dams. On Tuesday, the Corps and BPA said they would further adjust spill on the Snake River; continue emergency trapping and transport of juvenile fall chinook and adult sockeye; and allow the river to temporarily exceed the target of 68 degrees at Lower Granite Dam during a narrow window in late July when the return of adult sockeye is tailing off but before the return of fall chinook ramps up. They also agreed to work on a plan allowing Dworshak Reservoir to be lowered as much as an additional 10 feet.
Baus said he felt the agreed-upon actions would be enough to keep the river at target temperatures and extend the cool water from Dworshak later into August.
“I’m really excited about all the time, thought and energy salmon managers have put into this,” he said.
But Jay Hesse, director of biological services at Nez Perce Tribal Fisheries, pressed for the Corps to also reduce the elevation of Lower Granite Reservoir. The Snake River between Lewiston and Lower Granite Dam has been held about 3 feet higher than normal this summer because sediment has reduced the depth of the navigation channel in many places. In a discussion about the request, Aaron Marshall of the Corps said Lower Granite Reservoir can’t be lowered further without affecting safety and the economics of barge transportation. He said shippers are already being impacted by low river flows. For example, barges can only be partially loaded with wheat at the Port of Clarkston because of shallow water there and must be taken to the Port of Lewiston to be topped off. He said lower water could cause cables holding barges in port to snap during loading and expose unknown hazards in the navigation channel.
Hesse pressed for lower reservoir levels and for the navigation community to do more to help fish. He asked that the navigation channel be shifted to deeper areas of the river and for some Port of Clarkston functions to be shifted to the Port of Wilma.
Hesse noted fish managers have agreed to reduce spill at the Snake River dams, to use more Dworshak water at the risk of not refilling the reservoir next year and to allow water temperatures to exceed temperature targets in late July. All of those actions are designed to help mitigate temperatures but each comes with a downside. For example, higher temperatures even in a narrow window could harm adult sockeye or fall chinook, reduced spill will mean more juvenile fish will pass the dams via routes shown to reduce survival, and using more Dworshak water means the reservoir will be at risk of not refilling next year.
“All of these actions we are putting on the table for fish, the reduced spill, the increased tailrace temperatures, the increased drawdown of Dworshak Reservoir, have consequences to other fish species or other life stages of the fish,” he said after the meeting. “We are not seeing others bear that burden in trying to keep things viable for fish.”
Erick Van Dyke, of the Oregon Department of Fish and Wildlife, expressed frustration that the Corps hasn’t moved quicker to dredge the navigation channel.
“Nothing has been done to get us over the hump,” he said. “Meanwhile fish are taking all of the weight from our lack of action.”
Hesse asked for the Corps’ rejection of the request to reduce the elevation of Lower Granite Pool to be appealed at another forum.
Barker may be contacted at firstname.lastname@example.org or at (208) 848-2273. Follow him on Twitter @ezebarker.