Have you ever noticed that the water in the Chetek Chain of Lakes starts out clear when the ice melts in the spring and gradually turns green by July each summer? This change is what the Wisconsin Department of Natural Resources (DNR) classifies as hypereutrophic based on algae, phosphorus and water clarity measurements.

A classification of “hypereutrophic” means that the lakes are extremely rich in nutrients, leading to thick algae blooms from July through September. The algae tends to accumulate in bays and other areas of stagnant water, creating unfavorable conditions and thick algae growth that turns the water green and limits sunlight penetration into the water. This limited light penetration in the summer causes aquatic plants to be confined to growing in shallow water. Deeper water and drop-off areas also become void of vegetation as plants don’t receive enough sunlight to grow causing a loss of essential fish habitat.  

Algae blooms in the Chetek Lakes are a result of too much phosphorus that has developed or entered the lakes through several sources. One source includes lake-bottom sediments that still contain phosphorus from when the lakes were wetlands before the dam was built. Phosphorus also enters the lakes through runoff from surrounding lands. This includes lake lots with lawns, farm fields, city storm drains, septic systems and natural sources such as wetlands, dead vegetation and leaves, and atmospheric particles and dust.

Health Impacts of Algae Blooms

Not only do algae blooms have adverse impacts on the lakes’ ecosystem, they can also cause illness in humans, pets and livestock. Algae blooms can produce several different toxins, including dermatoxins that affect the skin, gastrointestinal toxins that affect the stomach, hepatotoxins and cytotoxins that affect the liver, and neurotoxins that affect the central nervous system. People and pets may be exposed to algae toxins through direct skin contact with the algae, inhaling mist and airborne particles, and swallowing water and algae. The DNR does not recommend swimming when algae blooms are occurring. If a scum-layer or floating mat is present, do not recreate in or on that water.

Protecting and Improving Chetek Lakes Water Quality

Everyone has a role in reducing phosphorus pollution to protect and improve water quality in the Chetek Lakes. Implementing projects and land-use changes such as no-till farming, cover crops, grassed waterways, infiltrating rainwater, shoreline buffers and wetland restoration plans can positively impact water quality.

The DNR has several grant programs that fund projects designed to protect and improve water quality. For instance, the DNR has recently awarded a grant to the Chetek Lakes Protection Association for fish habitat installation projects, rain gardens and shoreline buffer plantings. Contact the Chetek Lakes Protection Association if interested in a similar project for your property.

To learn more about opportunities for your property, visit dnr.wisconsin.gov/aid/Grants.

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