Snake River Sunset

Snake River.

In a pair of marathon meetings, members of the Columbia River Technical Management Team considered a series of operational changes at Snake River dams and fish plans to help salmon and steelhead through August, during which water temperatures in the lower Snake River are expected to continue to reach lethal levels for fish.

Meetings on July 9 and July 14 each lasted 3 1/2 hours as fish managers and dam operators discussed possible "triage" to help current adult runs of endangered Snake River sockeye and juvenile fall Chinook migrating downstream, while saving enough cold water in the Clearwater River behind Dworshak Dam for the rest of the summer's fish runs.

The goal, salmon managers said, is to keep the Snake River at 68 F at Lower Granite Dam while preserving enough Dworshak Dam water to last through Aug. 31.

The endangered Snake River sockeye—which suffered a mass die-off in 2015 due to drought and extreme heat—appear to be suffering from heat stress after making it past eight dams to reach Lower Granite Dam, said Claire McGrath, representing NOAA Fisheries on TMT. However, she added, compared to the 10-year average, more sockeye have made it that far and the fish are making the journey much faster than in 2015.

The measures being taken by TMT are considered a temporary fix for this year's extreme conditions and not permanent changes.

Many of the proposals put forth were expected to have only incremental impacts on the Snake River's water temperatures, which hit 81 F near the surface of Lower Granite Dam's forebay on July 6, and on July 10 came close to 70 F at 15 meters deep—where water is drawn for fish ladders to inspire salmon to continue their journey over the last of eight federal dams.

Salmon and steelhead begin to experience difficulties and sometimes stall their journey upriver when river temperatures reach 68 F.

"We're making some tough choices," Jay Hesse, TMT member representing the Nez Perce Tribe said. "We're making a bad situation a little less bad."

"This has been a very lethal and difficult river condition for aquatic life this year," Erick Van Dyke, TMT's Oregon representative, added. He said that even cooling the water by one-quarter to one-half of a degree Fahrenheit is important right now to fish in the Snake River.

Some of the measures that are already being taken allow Snake River water temperatures to increase by reducing water releases from Dworshak Dam for a few weeks sometime between July 23 to Aug. 17, when fewer fish are migrating in the Snake River, and changing the spill priority on the federal system so that two of the Snake's dams are near the bottom of the list when there's a lack of load and BPA needs to spill water over dams.

Managers will also consider drawing more water from the reservoir behind Dworshak Dam and letting it drop by 10 extra feet this summer.

The U.S. Army Corps of Engineers rejected a proposal to restore minimum operating pools at each of the four lower Snake River dams, prompting the Nez Perce Tribe to object and elevate the issue to the Regional Implementation Oversight Group—a step rarely taken by TMT.

"We have been discussing and sharing at length the accommodations—the triage—we're doing for fish," the Nez Perce Tribe's Hesse said, adding that he doesn't see the same accommodations being made by the navigation sector.

On July 9, Hesse suggested the Corps and barge operators could be looking into alternatives for barging this summer. On July 14—noting that he's not an expert in navigation—he asked whether the Corps has investigated moving navigation to areas of the river with sufficient depth, or whether barging companies could use ports farther downriver that have better depth.

The issue of sediment accumulating in the lower Snake River is not new. Last summer, TMT twice denied a request by the Port of Clarkston to raise the pool at Lower Granite Dam so barges could continue to ship wheat. This spring—despite objections by fish managers—the Corps announced that the minimum pool levels would be raised by up to 3 feet for the next two summers to prevent barges and other boats from hitting the bottom of the river due to sediment from high runoff in 2018 and 2020. The Corps is working on obtaining environmental clearances needed to dredge the area.

Representing the Corps at TMT, Doug Baus said that restoring the minimum operating pools at each of the four lower Snake River dams could not be reasonably considered due to safety issues for navigation.

Aaron Marshall, also representing the Corps, explained that the variable MOP operation provides the minimum level needed for navigation, and said that barge operators and ports have already adjusted to "less than optimum conditions." He said this year's conditions have had economic impacts and the Corps has to consider the potential safety issues with lowering the pool. When a barge gets stuck, he said, it puts the cable control lines at risk of snapping under the load which could injure or kill workers. Several cables broke last year under low pool conditions, he said.

NOAA's McGrath said she recognizes the small benefit to juvenile fish and travel time within the forebays of each dam that would come with lower pools, but has concerns that there may not be a temperature benefit, and that the change could have negative consequences for water temperatures at Lower Granite's fish ladder intake and the adult fish trap.

Corps representative Jon Roberts said his agency does not have the computer models to look at how adjusting the MOP would impact water temperatures. Conceptually, he said, lowering the pools reduces the surface area of the reservoirs and reduces solar radiation from air temperatures. But he also noted that a lower pool could increase the temperature at the ladder intake and trap.

The Corps did agree to prepare to implement the five other measures in Oregon's System Operation Request 2021-4 throughout the summer, as conditions warrant or as authorization is given—including one that was immediately implemented after TMT's July 9 meeting. The measure implemented is a short-term prioritization of spillways, returning to summer spill volumes and closing spillway weirs at Little Goose, Lower Monumental and Ice Harbor dams.

"Prioritizing spill through the traditional spill routes may provide cooler water at lower depths in the forebays. However it is unlikely to overcome the broader issue of current climate abnormalities and is part of the current toolbox that is available to address the warm water crisis the current heatwave has exacerbated," the request states.

Baus said another measure—to seek efficiencies for the Lower Granite Doble test to minimize the risk of losing more water from behind Dworshak Dam—had been resolved at a July 8 Fish Passage Operations and Maintenance Team meeting.

Another measure included going back to the 2021 Fish Operations Plan spill while continuing to truck juvenile fish from Lower Granite Dam if conditions warrant.

A proposal to modify the summer flow augmentation limit from Dworshak Dam to draft the reservoir an additional 10 feet will require approval of another Dworshak Dam board, but if approved, the Corps agreed to draw water to a 1,525-foot elevation instead of a 1,535-foot elevation by the end of August, and starting 200,000 acre-feet releases on Sept. 1 operating to a 1,510-foot elevation rather than a 1,520-foot elevation by the end of September.

The Corps will also coordinate a potential alternative to stretch out cool water augmentation measures that do not require a change in state or federal water quality standards. The action is dependent on weather conditions and is associated with the prior proposal not to fully refill the pool behind Dworshak Dam before drafting for temperature control.

On July 14, members also discussed and changed the priority for which dams spill when there's a lack of load, pushing two Snake River dams to the bottom of BPA's priority list for spill—just above Dworshak Dam—to preserve the cooler Dworshak Dam water in Snake River pools.

On July 21, they moved ahead with another systems operational request—this one sought by the Idaho Department of Fish and Game—for a temporary change to water temperature criteria to conserve water in the Dworshak Reservoir. The measure increases criterion for the Lower Granite tailrace from the current 68 F to 69.5 F beginning July 23 and extending to Aug. 17.

Idaho's TMT representative Jonathan Ebel said there's a relatively short window in the Snake River between when adult sockeye returns taper off, and fall Chinook and steelhead begin to return. He asked to use that window to conserve Dworshak's cool water for later in August and allow the temperatures at Lower Granite Dam to get warmer, instead of releasing it when fewer fish are migrating. TMT members concurred.

The suite of actions follows TMT's prior measures to manage water temperature, including a July 2 operations change to reduce summer spill at Lower Granite and Little Goose dams from July 3 to July 31 to increase the proportion of water in the tailraces drawn from deeper and cooler levels of the dams' forebays.

The Corps' Baus noted that in less than two weeks, the Corps received three SORs that included 10 significant changes that needed to be analyzed.

"We acknowledge and appreciate there's been a lot of time and energy put into this," he said, and later added, "I just want to highlight we're doing the best we can to disseminate information and be clear in what we're doing and what we're not doing." He expressed confidence that the measures would help reduce Snake River temperatures for fish, and reserve enough Dworshak water for later in the summer.

Hesse said he wishes he were as confident as Baus. He noted that the Nez Perce Tribe is the only TMT entity to support all of the proposed actions to help fish. "I appreciate the collaboration and discussion that has gone into all of these actions" and hope many of the actions will be implemented to benefit fish, he said.

In explaining his reasons for objecting to the Corps' response to the issue over pool elevations, Hesse added, he's still not confident that TMT has done everything it can to lower water temperatures and help fish in the lower Snake River.

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K.C. Mehaffey covers fish issues for Clearing Up, and is editor of the NW Fishletter. She joined the NewsData writing team in February 2018. From lawsuits to scientific studies, she is enjoying the deep dive into the Columbia Basin's many fish topics.