Wild Salmon are in Hot Water
Every summer, wild salmon face a dangerous journey up the Columbia and Snake Rivers. As temperatures rise, so do the risks to wild salmon, and in 2025 things are heating up. Salmon and steelhead are cold-water species. Studies have shown that when water is heated to 68 degrees Fahrenheit, these fish begin to struggle. In these warm conditions, their migration slows down, their stress levels rise, and they become more vulnerable to predators and infections. In some cases, warm water can kill them before they ever reach their spawning grounds.The first issue of this year’s Hot Water Report noted that even in early July, reservoir water temperatures were already exceeding 68°F. For example, the Ice Harbor reservoir reached 68.79°F on July 4th, setting the tone for a dangerous season. Conditions have only worsened since. By early August, Ice Harbor Reservoir had been above 70°F for 24 consecutive days, peaking at 72.14°F on August 5-6. Across all four Lower Snake River reservoirs, temperatures have now exceeded 68°F for an average of 30 days, compared to 25 days this time last year. On July 16, 2025, water temperatures behind Lower Monumental and Little Goose dams reached 72.1°F, and on the Columbia, the Dalles Reservoir spiked even higher, hitting 72.86°F on July 30. Warm water contains less oxygen, and for salmon who are already expending massive amounts of energy to swim hundreds of miles upstream, these conditions can be devastating. When the water is both hot and low in oxygen, it becomes a serious threat to their health and their ability to spawn. This is not a new problem, and it is not just about the weather. The dams on the lower Snake and Columbia rivers have turned fast-moving rivers into slow, warm reservoirs. That creates long stretches of water that heat up quickly and stay hot for long periods of time. Hot, stagnant water can also lead to toxic algae outbreaks, which are harmful for humans, wildlife, and pets. Toxic algae has been present in the lower Snake River in 2023 and 2024, and was recently found in Brownlee and Hells Canyon just last week. Idaho’s salmon are born in some of the coldest, cleanest, and most protected headwater habitats in the lower 48. But to reach these habitats, salmon have to pass through more than 900 miles of rivers—including eight dams and reservoirs. The science is clear, the longer we wait, the greater the risk that we lose these iconic fish forever. Removing the four lower Snake River dams is our best shot at giving salmon a fighting chance. With leadership from Congress, everything the dams do can be replaced. But we cannot replace wild salmon once they are gone. Tell Congress: authorize and fund dam removal before it is too late.