Tons of information out there on water temperatures in the Columbia river. There’s a 1941/42 study done showing average water temperature in Vancouver, Wa averaged 72 degrees in August so I’m not sure if global warming is the main cause. There’s a long list of causes given if you want to go into several studies done. Temperatures are a huge part of fish survivals in creeks, rivers, lakes and the oceans. I’ve fished often at Panguitch Lake at 8200 ft elevation in Utah. It’s frozen solid in the winter months but in the summer months, the waters warms dramatically. This results in almost all the trout to head to the deeper water. I prefer fishing there in early spring and late fall just before and after the Lake freezing over. I’d like to deviate and go to the morning after Mt. St. Helens eruption in 1980. At 8 am the morning after the eruption, the temperate of the Cowlitz River in Longview, Washington just as it was emptying into the Columbia was a staggering 90 degrees ! Needless to say, fish died ! Shortly after the Cowlitz emptied its flow of volcanic ash and logs into the Columbia River, the main shipping channel became blocked and even stranded a large freighter in the channel at the confluence of the COWLITZ into the Columbia River at Longview.