Welcome to the Lower Snake and Columbia River Hot Water Report, week six. This weekly report presents the conditions on the Lower Snake and Columbia Rivers via graphs, analyses, and stories. We have been tracking the rivers as they become too hot for migrating salmon, as well as the return of each individual salmon species.
In 2015, extreme water temperatures killed upwards of 300,000 salmon in the Columbia Basin. Extinction is looming for wild Snake River salmon and steelhead, with myriad threats facing these dwindling stocks. As each salmonid species journeys through the Columbia and Snake, we will highlight its unique attributes and discuss how different species respond to increasing river temperatures. We’ll also hear first-hand from scientists, tribal fishers, guides, and citizens on the Columbia and Snake rivers throughout the summer.
Will you be on the river this summer? Do you have a story or photo you would like to share? Please send them to Jacob Schmidt
If, in the course of your river trips this summer, you come across a dead sturgeon, remember to contact the Washington Department of Fish and Wildlife.
The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, Idaho Conservation League, Columbia Riverkeeper, Idaho Rivers United, Friends of the Clearwater, and Washington Sierra Club.
Check out previous Hot Water Reports
READING THE DATA
The daily mean temperature at the forebay (upstream reservoir) of each dam is represented in the solid lines, while the 10 year average (2008-2017) for each reservoir is represented by the dashed line of the same color. The dotted line across the top of the graph represents the 68° survival threshold for juvenile salmon. The longer temperatures remain above 68° and the farther the temperatures rise above 68°, the more severe the effects, including: increased metabolism, increased susceptibility to disease, reduced fecundity (reproductive potential), and/or death.
If you are unfamiliar with the location of the Lower Snake and Lower Columbia dams, you can find them on this map.
A brief respite to the recent heatwave can be seen in temperatures remaining consistent over the last few days. As the lines representing the temperatures at individual dams begin to part ways, note that the temperatures are positively correlated with the conversion rate of returning sockeye. The hotter the reservoir, the fewer salmon survive to be counted at the next site upstream.
Conditions at Lower Granite have briefly dropped back below the survival threshold just in time for the last batch of migrating sockeye. While the average temperature at the recording site on Lower Granite Dam, I received a report this week from a retired Fish and Game employee that their thermometer was reading a high water temperature of 75° near Lewiston, ID.
Windy conditions brought cooler temperatures to some parts of the basin, while fanning wildfire flames in others. The milepost 90 fire is currently burning over 10,000 acres along the north shore of the Columbia just upstream from John Day Dam, adding heat and removing shade from the riverbank. Several other fires are burning south of the river as well.
The Washington Department of Fish and Wildlife issued a new rule calling for all salmon caught between McNary Dam and Priest Rapids Dam to be returned to the river. Fisheries managers in the Yakima basin believe that the abnormally high temperatures of the Yakima have caused sockeye and summer chinook to wait longer in the mainstem of the Columbia, or even to have returned downstream to escape the heat. Overfishing this section of the Columbia at this time could have drastic consequences for Yakima Valley salmon. This rule will go into effect on August 6.
WEEKLY HIGH TEMPERATURES 7/27 - 8/2
Temperature data included in these reports come from the USGS Current Conditions for Washington State and the Fish Passage Center. Graphs and tables were assembled by SOS Staff on 13 July 2018 with the latest data.
2018 Columbia-Snake Basin Adult Salmon Returns – year-to-date
The first sockeye of the year returned to Redfish Lake Creek on July 26. Over the ensuing weeks, this intrepid traveler will be joined by others, but the 2018 return is not expected to be significantly improved over 2017’s at Idaho’s highest salmon spawning ground.
It is believed at this time that all sockeye have passed Lower Granite Dam, the last barrier on their journey to the Sawtooth Mountains. A total of 266 sockeye have been counted at Lower Granite, a mere 9.5% of the 2,800 that made it in 2014. While an improvement over the dismal returns of 2017, the events of this summer summon once again the specter of extinction for Snake River Sockeye. With nearly half of the salmon run dying off in the too-warm waters of Lake Sacajawea, calls to remove the Snake River dams are gaining strength. Fishery managers note that the cooler waters from Idaho’s Dworshak reservoir could reach farther downstream in the lower Snake, and even into the Columbia mainstem, if the four lower Snake dams were bypassed.