Idaho Fish and Game in the Magic Valley (Idaho) is getting reports of dogs that have died immediately after swimming in Salmon Falls Creek Reservoir. It is possible there is a bloom of Blue Green Algae developing. Blue Green Algae can be fatal to dogs that ingest it. This is unconfirmed at this time, but please be aware, pass the word, and take measures to keep your K9 buddy safe.
The photo shows what Blue Green Algae looks like from Lake Lowell a few years ago.