June 9 would normally mark the start of open water swimming season at Lake Nokomis in Minneapolis. When bluegreen algae was found near the beach, however, the Minneapolis Park and Recreation Board encouraged people and pets to stay out of the water.
Bluegreen algae in lakes are fed by phosphorus and can sometimes grow out of control when the weather gets hot. Lakes with elevated levels of chloride (salt) are also more likely to experience algae blooms. During a bloom, a lake will usually smell bad and turn bright green like pea soup. On occasion, however, the water may be mostly clear, with floating brown blobs that look like poop. When this happens, it’s not safe for people or dogs to swim or wade in the water.
In 1992, Minnesota began monitoring the health of lakes, rivers, and streams around the state and developed an “impaired waters list” for the ones that aren’t able to fully support fishing, swimming, or recreation. Nokomis has been on the list since 2002 and is one of 740 lakes and rivers in Minnesota that is prone to frequent algae blooms due to excess nutrients.
Minnesota’s impaired waters list is updated every two years to reflect water monitoring data and long-term trends. Lakes, rivers, and streams are “listed” if they no longer meet state standards or “delisted” if they return to good health. Between 2020 and 2024, local communities in Chisago, Ramsey and Washington Counties successfully “delisted” 23 lakes and streams due to improved water quality. This year, Comfort Lake in southern Chisago County will be delisted as well, after more than 25 years of effort to restore the lake.
Unfortunately, the 2026 impaired waters list carries some bad news as well. Forty-six new impairments will be added statewide, including 14 east metro water bodies impacted by mercury and PFAS (Forever Chemicals). These chemicals bioaccumulate, and can cause health problems for anglers who frequently eat the fish they catch. Impaired lakes include DeMontreville, Elmo, Johanna and Owasso (PFAS), as well as Forest and Powers (mercury).
If you’re looking for a clear, clean lake with a swimming beach for the summer, Big Marine and Square Lakes in northern Washington County continue to achieve consistently high marks for clear and clean water. In addition, Forest, Tanners, and White Bear Lakes are good for swimming and rarely have algae blooms.
Beachgoers at Square Lake Park may also notice some changes this summer. Last fall, Washington County and the Carnelian-Marine-St. Croix Watershed District completed a stormwater reduction project, intended to treat water from the parking lot before it reaches the lake. There is also fresh sand on the beach and the fishing pier has been moved to connect with a paved pathway, allowing for better stroller and wheelchair accessibility.
If you love Square Lake and want to help keep it clean, we’re looking for volunteers to plant a new raingarden near the beach on Thursday, June 25 (6:30-8pm). Sign up at tinyurl.com/squarelake2026.
Want to learn more about the health of our local lakes, rivers, and streams? Join me at the Stillwater Library (Margaret Rivers Room) on Monday, June 15 (6:30-7:30pm) for a St. Croix – State of the Water presentation. We’ll talk about positive trends and success stories, as well as challenges on the horizon.
East Metro Water 