A proposal by NOAA Fisheries to ask federal agencies to augment flows from Grand Coulee and Chief Joseph dams to aid migrating juvenile salmon turned into a marathon discussion at the Fish Passage Advisory Committee meeting on April 21 and 22.
In the end, the committee decided against recommending an increase in flows—at least for now—deciding instead to wait for natural spring runoff to force higher spill levels at the hydroelectric projects to help push young fish down the Columbia River and into the estuary.
To some, the debate highlights a potential shift in priorities for managing water through the federal projects on the lower Snake and Columbia rivers. Instead of augmenting flows in the spring to help juvenile salmon migration, salmon managers are now focused on reducing the number of juvenile salmon that pass a dam through a powerhouse route, including fish bypass systems.
This year's cool spring is resulting in a late spring runoff, with relatively low flows in April. It's also the first year that eight federal dams on the Snake and Columbia rivers are targeting higher flows that would result in 125 percent total dissolved gas in tailraces of seven of the eight dams this spring, under the flexible spill agreement.
But since spring spill season began in early April, flows have been too low to achieve the 125 percent TDG. Most dams have been operating at minimum generation and spilling the remaining flows, resulting in average TDGs between 113 and 122 percent.
Paul Wagner, who represents NOAA Fisheries on the Columbia River Technical Management Team, laid out a proposal at FPAC's April 21 meeting to increase outflows at Grand Coulee Dam to maintain flows at Chief Joseph Dam at 95,000 cubic-feet-per-second from April 24-29, and to 110,000 cubic-feet-per-second from April 30 to May 8 in an effort to aid juvenile fish migration. Without releasing more water from Grand Coulee, average flows at McNary Dam are projected to be about 185,000 cubic-feet-per-second.
Wagner noted juvenile fish are in the river now, ready to migrate downstream. He said those that pass Bonneville Dam at this time of year tend to have higher smolt-to-adult returns. Increasing flow helps decrease travel time, allowing an earlier arrival in the estuary.
Wagner also noted other environmental benefits from augmenting flows during juvenile migration, including higher turbidity in the water that makes it harder for predators to find young salmon, and increasing near-shore connectivity. "We can wait. We can think about it. We can wait until natural flows come up—which are regulated flows—and defer. But I see no reason to," he said.
Jay Hesse, who represents the Nez Perce Tribe on both FPAC and TMT, noted that at some point, increasing flows would increase powerhouse passage, or PITPH, which is the number of powerhouse passages detected by PIT tags in a fish's downstream migration.
In the Fish Passage Center's Cumulative Survival Studies, PITPH is one variable shown to impact salmon and steelhead return rates. A study by NOAA's Northwest Fisheries Science Center last year found larger juveniles are more likely to survive to adulthood, and that larger juveniles were less likely to use a bypass system at six of seven dams compared to other methods, so use of a bypass had little to do with whether they survived to return as adults.
Wagner told the committee he's "on the fence" about the importance of PITPH, while other members said they believe it's an important factor in juvenile survival.
After much discussion and an afternoon meeting, the committee came back April 22 with some details. Hesse told the committee that it's counterintuitive, but low flows bring lower powerhouse passages, and increasing flows from current levels would increase powerhouse passages.
Dave Swank, FPAC chair and U.S. Fish and Wildlife Service representative on TMT, told the committee the Bonneville Power Administration could not commit to a daily flow rate at Bonneville Dam because of the uncertainties in Snake River flows during spring runoff. FPAC had asked BPA if it could achieve a daily flow average of 205,000 cubic-feet-per-second at Bonneville Dam from April 25 until natural flows pick up beyond that level. He said BPA offered to manage the lower dams on a weekly average, within a range of 10,000 to 15,000 cubic-feet-per-second.
Tom Iverson, who represents the Yakama Nation on FPAC, told the committee he was torn by the options. "The logic would say to put a little more water in the river. Move these fish out. But the fact is that we've built an entire spill program on the assumption of latent mortality and PITPH," he said, noting that the Columbia River System Operations draft EIS and current biological opinion rely on it. "NOAA's own models don't support it, but we've agreed on this adaptive management approach of focusing on PITPH and powerhouse passage and latent mortality," he said.
Iverson noted the proposal is for a small amount of flow that would provide moderate benefits to some early run fish for a couple of weeks.
"At this point, I'm not sure the juice is worth the squeeze on this one," he said. "If our analysis is showing that PITPH is better at these flows, then let's ride this out and test this hypothesis. That's the bottom line of what we're doing over these years is testing this hypothesis. So let's do it."
Other FPAC members expressed concern BPA was unable to manage their request for a daily average flow at Bonneville Dam.
In an email to NW Fishletter, BPA analyst and TMT member Tony Norris explained, "It is not possible to manage the flow at Bonneville Dam to a specific daily flow objective during the spring without significant allowance for uncertainties. During the spring, rises in streamflow are very temperature sensitive and streamflow forecasts can vary widely from day to day. Consider that Bonneville Dam is approximately 350 river miles downstream of the release point of flow augmentation from Grand Coulee Dam."
Despite initial support for Wagner's suggestion to increase flows, no FPAC member spoke up to offer support during its April 22 meeting. Swank said he had mixed feelings, and views PITPH as very important to survival, but agreed it's not the only consideration. He said if there were a vote, he would not oppose the proposal.
Wagner suggested FPAC has fought for years to get spring flows closer to the natural river flows. Now, he said, it all seems to be based on reducing the number of times that juveniles will pass through the powerhouses. "It's just such a disparity from what we've always wanted in the past," he said. "It's the functional river, which is something that I have fought for and continue to believe in, versus the absolute control . . . that powerhouse passage is the worst thing we could do, and need to avoid it at the cost of environmental benefit," he said at FPAC.
At the subsequent TMT meeting, Wagner told the group that he put forward a proposal to increase flow, but it was not supported by other fish managers. "The current operation, where spill is a very high priority, was preferred as the current operation because powerhouse passage under these low flow conditions is decreased, and spill passage is optimized," he said.
Charles Morrill, TMT member representing the Washington Department of Fish and Wildlife, added, "These are not new goal posts. These are a reflection of the flexible spill goals, and a desire at this point in time to keep the current operation, with the intent of minimizing powerhouse passage."
Additional water releases from Grand Coulee, Chief Joseph and Dworshak dams had been approved and implemented earlier in April to help juvenile fish migrate downstream and to protect emerging chum salmon from increasing total dissolved gas below Bonneville Dam, due to higher spill from the 2020 flexible spill agreement.
Jon Roberts, representing the U.S. Army Corps of Engineers, told the TMT on April 8 it received a request for additional flow from Dworshak Dam from April 7-20 due to hatchery releases in the Clearwater River. He said the agency analyzed the impacts to refill behind the dam, and determined an additional 7,000 cubic-feet-per-second will have no impact on refill by June 1.
Roberts said the reservoir wouldn’t fill as quickly in April, but it will still reach the desired elevation by June 1.
Shari Sears, fish and wildlife policy analyst for the Confederated Tribes of the Colville Reservation, requested increased flows below Chief Joseph Dam targeting a weekly average of at least 80,000 cubic-feet-per-second from April 14-30 to help both hatchery and wild spring Chinook and steelhead in the upper Columbia River. Her request was approved.
Salmon managers asked to increase the minimum tailwater below Bonneville Dam to an elevation of 12.5 feet from April 10-20 to protect incubating and emerging Columbia River chum from high TDG levels. Deeper water reduces the impacts of TDG on fish. The 11.3-foot tailwater elevation was deemed inadequate for protecting emerging chum. The action was also expected to benefit other species, including fall Chinook that spawned in the area.
The system operational request notes that the change could cause Lake Roosevelt to drop by as much as 5 feet, or not at all, depending on when the weather warms and spring runoff begins.
"As long as basically we're staying above 1,240 [feet in elevation], we're fine with the operation," said the Bureau of Reclamation's TMT member Joel Fenolio.