Rochester, Minn. — In examining recent water samples from Beaver Lake in Steele County, the Minnesota Pollution Control Agency (MPCA) found toxins that indicate harmful algal blooms that can pose health risks to people and animals. The agency advises lakeshore owners and others who recreate in the lake to educate themselves about harmful algal blooms and take precautions.
The MPCA examined water samples as part of a response to a suspected recent severe algal bloom on the 98-acre lake near Ellendale that was first reported as a sewage spill.
The toxin detected in the recent Beaver Lake water samples must be swallowed to be harmful. In extreme cases, dogs and other animals have died after drinking lake water containing these toxins. If noticing a severe algal bloom in the water or scum on shore, people should avoid contact with the water and prevent their pets from swimming in or drinking the water.
While recent rain may have dispersed the bloom in Beaver Lake, people should still look for sludge or other matter on the water surface and shoreland. Scientists do not yet know what causes some blooms to produce toxins while others do not, so the safest course of action is to avoid contact with all severe blooms.
Harmful algae can be hard to distinguish from other types of algae. While it's often described as looking like pea soup or spilled green paint, it can take other forms as well.
There are currently no short-term solutions to fix a blue-green algal bloom. Once a bloom occurs, the only option is to wait for the weather to change — significant rainfall, wind shifts, or cooler temperatures — to disrupt the algae’s growth.
The key to solving algae problems long-term is to improve water quality by decreasing the amount of nutrients that runoff carries into lakes.
This bloom is unusual for Beaver Lake, popular for recreation because of its depth — 27 feet at the deepest — and high water quality. It’s part of the Cannon River watershed, where the MPCA, Cannon River Watershed Partnership, and other local partners recently completed a study of the river, its tributaries and surrounding drainage area. The study looked at 45 lakes in the watershed, and Beaver Lake was one of five lakes that fully met the water quality standards for being fishable and swimmable. (The other four were Dudley, Fish, Kelly and Roemhildts lakes.)
To protect the water quality of Beaver Lake, strategies in the watershed, which is mainly used for farming, include buffers along ditches and shoreland (including cabins on lakes), manure management, fertilizer management on crops and lawns, controlled cropland drainage, planting cover crops and sewer system upgrades and maintenance.
For more information, visit the Cannon River Watershed webpage. For more information about algal blooms, visit the blue-green algae webpage.