October 24, 2019
Summer water temperatures in the Columbia River can rise high enough (above 20 degrees Centigrade, 68 degrees Fahrenheit) to have adverse impacts on salmon and steelhead migrating upstream. Such temperatures cause disease, stress, and lower spawning success and can kill the fish.
In their migration, salmon and steelhead will sometimes seek temporary refuge in areas of the river that provide cold water, which are mostly found where cooler tributaries join the mainstem Columbia River, according to a draft plan, “Columbia River Cold Water Refuges Plan,” completed by the federal Environmental Protection Agency this month and is now out for comment.
The plan says that today the water quality standard for temperature in the lower Columbia is 20 degrees C, but prior to 1940 the river was some 2 to 2.5 degrees C cooler. Today’s higher temperatures in the river are due to anthropogenic causes, such as dams and reservoirs and climate change.
And, the plan says, we can expect the river to continue warming with the average August temperature rising from today’s 20 degrees C to 23 degrees C by 2040 and to 24 degrees C by 2080, all bad news for salmon and steelhead, particularly those who pass through the lower river in August when temperatures are the highest.
In another river temperature-related development, 55 scientists on Tuesday sent a letter to policymakers in Washington state, Idaho and Oregon highlighting the need to address the harmful effects of hot water on salmon and steelhead in the Columbia-Snake River Basin due in large part to reservoirs behind federal dams.
The letter says that as federal agencies study alternatives to restore ESA-listed salmon populations, “strategies to reduce overall mainstem water temperatures do not appear to be sufficiently addressed.
“This serious flaw, if uncorrected, will mean that hot mainstem water will remain unmitigated and salmon and steelhead losses will continue and worsen over time, especially for Snake River stocks.
“The option of breaching lower Snake River dams, combined with existing or modified cold water releases, has enormous potential to alleviate the very serious problem of elevated summer temperatures in the lower Snake River, and increase the survival rate from out-migrating smolts to returning adults (smolt-to-adult return; SAR) for all salmon species.
“It would also significantly increase available spawning and rearing habitat for imperiled Snake River Fall Chinook.
“No other action or actions can significantly lower summer water temperatures in the lower Snake River on a long-term basis, while also providing additional cooling in the lower Columbia.”
Rick Williams, Ph.D., former chair of the Independent Scientific Advisory Board for the Northwest Power and Conservation Council, fisheries consultant, Boise, Idaho said, “As federal agencies announce their plans for Snake/Columbia salmon policy and actions in early 2020, they must do more than just tweak the system a bit to deal with temperature. We will fail to solve the hot water problem, and fail to restore salmon runs, if federal agencies select any long-term plan that does not include removal of lower Snake dams. That action appears to be the only one available that can significantly lower water temperatures and aid in recovering Idaho’s salmon and steelhead populations.”
The EPA had help as it developed the Cold Water Refuges Plan from federal, state and local agencies, tribes, watershed councils “and a variety of other parties involved in water quality and fish management in the Lower Columbia River,” said John Palmer, Senior Policy Advisor, Water Division, EPA Region 10. That list includes about 250 people.
Initially, he said, EPA had asked those that participated in the plan’s development to review the plan, but that the agency is not limiting the review of the draft plan and will provide access to anyone who would like to review it. “EPA is interested in getting their feedback, particularly on recommended actions in the draft plan that involve their organizations,” he said.
The EPA was directed to develop a Columbia River cold water refuge plan by a reasonable and prudent alternative included in NOAA Fisheries’ 2015 biological opinion for Columbia River temperature, the draft plan says.
Most cold water refuges in the Columbia River are created where colder tributary streams meet the warmer Columbia. This type of refuge is at the confluence as well as in the lower section of a river where salmon and steelhead can rest to minimize their heat exposure.
Cold water refuges can also be formed by inflowing groundwater in a river channel or in stratified reservoirs where deeper water is cooler. In addition, night time temperatures in rivers are cooler and provide some relief, but these types of refuges are minor and “there is no evidence that they serve a significant role for salmon and steelhead in the Lower Columbia River,” the draft plan says.
The draft plan says that the average August temperature at McNary Dam is 20.9 degrees Centigrade (69.2 degrees Fahrenheit) and that water warms in the 80 miles downstream to the John Day Dam pool by another 0.6 degrees C. At 21.5 degrees C, the highest average August temperatures are in the John Day pool, but those temperatures drop slightly at The Dalles and Bonneville dams. Peak temperatures can reach 22 degrees C or more.
Most, but not all of the Columbia River’s 191 tributaries in the lower river are cooler than the Columbia mainstem, some as much as 9 degrees C cooler and most of the cooler tributaries are located downstream of the Cascade mountains, the plan says. EPA filtered out tributaries where average August temperatures are less than 2 degrees C colder than the Columbia River or its mean August flow was less than 10 cubic feet per second, the minimum needed to form a cool water plume in the Columbia that could attract salmon and steelhead.
Among the 13 tributaries that made the cut and that are located downstream of Bonneville Dam, the largest are Skamokawa Creek (August mean temperature difference -5.1 degrees C), Cowlitz River (-5.4 degrees C), Kalama River (-5 degrees C), Lewis River (-4.1 degrees C), Sandy River (-2.5 degrees C), Washougal River (-2.1 degrees C), Oneonta Creek (-8.2 degrees C) and Tanner Creek (-9.6 degrees C).
The list shortens above the lower Columbia River dams. In the Bonneville pool are Eagle Creek (-6.1 degrees C), Rock Creek (-3.8 degrees C), Herman Creek (-9.2 degrees C), Wind River (-6.7 degrees C), Little White Salmon River (-7.9 degrees C), White Salmon River (-5.5 degrees C), Hood River (-5.9 degrees C) and the Klickitat River (-5 degrees C).
In The Dalles pool is the Deschutes River (-2.2 degrees C).
In the John Day pool is the Umatilla River (-0.1 degree C). Although the river’s temperature difference with the Columbia is less than 2 degrees C, EPA chose to include it because it is the only sanctuary in the John Day pool.
Some 12 of the tributaries are considered of primary importance and make up 97 percent of the total cold water refuge volume. They are easily accessible and deep enough to provide cover and have been documented as having been used by salmon and steelhead, the plan says.
They are the Cowlitz, Lewis, Sandy, Wind, Little White Salmon (empties into Drano Lake on the Columbia), White Salmon, Hood, Klickitat and Deschutes rivers, along with Tanner, Eagle and Herman creeks. Only one of these, the Deschutes River, is upstream of The Dalles Dam.
The bulk of summer steelhead migrate past Bonneville Dam during the two-month period when the river is at its warmest, with temperatures exceeding 20 degrees C. In addition, the first half of the fall chinook run will also migrate during these warm temperatures. Steelhead and fall chinook are the species that most often encounter warm lower Columbia River temperatures and are the species that use cold water refuges the most, the plan says.
Sockeye and summer chinook salmon pass Bonneville earlier and are less likely to use a cold water refuge. Even in cases such as the warm water they encountered in 2015, sockeye and summer chinook still use cold water refuges less. These fish will encounter even warmer temperatures in the mainstem if they were to delay their migration.
About 60 to 80 percent of steelhead use cold water refuges when the mainstem water temperature hits 20 degrees C. About 40 percent of fall chinook use cold water refuges when the water is slightly warmer, about 21-22 degrees C, but not for as long as steelhead which don’t spawn until late winter and spring, so they have more time to hang out to wait for better conditions.
Most of the steelhead that use the Deschutes River cold water refuge are ultimately migrating into the Snake River (61 percent of the fish that use the Deschutes cold water refuge) and others will head to the Middle Columbia (30 percent). Some 8 percent are heading to the upper Columbia River.
The EPA plan is to maintain at least the top 12 cold water refuges in the lower Columbia River, but also to enhance two: the Umatilla River, the only significant opportunity for increased cold water refuge in the warm 93 mile reach between the Deschutes River and McNary Dam, and 15 Mile Creek, because it has substantial cooling potential and has been prioritized for restoration of Endangered Species Act-listed steelhead recovery.
Plans to maintain the refuges in each of the 12 streams are described in detail in Chapter 7 of the plan. They include using existing regulations to protect streams, restore riparian shade, stream morphology and instream flow, time cool water releases at upstream dams to provide more cool water when most needed, manage sediment at the mouth of streams and limit harvest of steelhead and salmon within refuges.
Overall, EPA says, the number and timing of existing cold water refuges “appears to be sufficient under current and 20°C Columbia River temperatures but may not be in the future. Therefore, maintaining the current temperatures, flows, and volumes of the 12 primary CWR in the Lower Columbia River is important to limit significant adverse effects to migrating adult salmon and steelhead from higher water temperatures elsewhere in the water body.”
However, more cold water refuges may be needed in the future as the Columbia River warms, adding that the non-primary tributaries could provide that protection through restoration and enhancement.