DEQ Issues Watch Advisories for Two Twin Falls County Reservoirs
The Idaho Department of Environmental Quality has issued watch advisories for Little Wood Reservoir and Salmon Falls Creek Reservoir as summer temperatures create conditions favorable for harmful algal bloom development, state officials said.
Agency staff detected algae presence near Twin Falls Dam in July after residents reported suspicious growth to the DEQ. Microscopy and toxin test strip testing conducted multiple times throughout the month in areas near the dam have not identified toxin levels in the water samples collected, according to the agency.
Despite the negative toxin results so far, the DEQ is recommending that residents and visitors avoid contact with any visible algae blooms out of an abundance of caution. “When in doubt, stay out of the water, and always use caution when recreating in or around a water body,” said Dr. Tasha Owen, senior water quality scientist with the DEQ.
Rising Temperatures Fuel Bloom Risk
Harmful algal blooms develop under specific environmental conditions—warm water temperatures, stagnant water bodies, and excess nutrient levels—that are becoming increasingly common in Idaho reservoirs as summer progresses. The combination of heat and minimal water movement creates an ideal breeding ground for problematic algae growth.
While the testing near Twin Falls Dam has not shown toxin presence, the algae itself poses health risks. Human exposure to contaminated water can cause skin irritation, nausea, and vomiting. Pets face even greater danger, as they are more vulnerable to illness from direct contact with or ingestion of contaminated algae.
“There is the presence of a bloom. But we’re not, our investigations have not reported toxin levels,” Owen explained, underscoring the ongoing monitoring effort despite the current test results.
Public Urged to Report Suspected Blooms
The DEQ is asking Twin Falls County residents to remain vigilant and report any suspected harmful algal blooms through the agency’s website. The public can submit photos and location details to help the agency track bloom activity throughout the summer season.
The watch advisories will remain in effect as water quality specialists continue sampling and monitoring throughout the region. The agency intends to maintain its testing protocol as long as conditions remain favorable for algal growth.
Boaters, swimmers, and other water recreationists in the Twin Falls area should stay informed about current water quality conditions and exercise caution when visiting Magic Valley reservoirs. More information about harmful algal blooms and reporting procedures is available on the DEQ website.
The advisories come as Twin Falls County faces multiple environmental challenges this summer. West Nile Virus was found in mosquito samples east of Twin Falls, and a red flag warning was issued for southern Idaho highlands, reflecting the broader array of seasonal health and safety concerns facing the region.