A Harmful Algal Bloom (HABs) was observed and reported by SLPOA member Doug Smith in the Silver Beach area Thursday 10/16/2025. The report and pictures were passed along to Bob Steed at the Idaho DEQ and he responded:
“You're not alone in seeing this minor fall bloom. I just responded to similar reports from Lower Twin Lake and Hayden Lake. From your photo, it looks like a typical seasonal bloom. In late summer and fall, most of the available nitrogen in the water column has been consumed by aquatic plants and other algae. This creates an opportunity for cyanobacteria, which can fix atmospheric nitrogen, to thrive. In my view, these fall blooms aren’t necessarily driven by pollution or excess phosphorus—they tend to occur naturally when the growing season is extended.
Last year, by October 15, we had experienced two solid weeks of rain, and Panhandle Health District and I lifted all Public Health Advisories due to the end of the recreational season. Based on your image, it doesn’t appear that people are likely to come into close contact with the bloom, so human health concerns are minimal. However, the water may still pose a risk to pets and wildlife.
The current weather forecast suggests that lake mixing from wind and rain could occur in the next few days, which may help disperse the bloom. Please keep me posted if you notice any changes or progression.”