The city of Edina and the Nine Mile Creek Watershed District have detected high microcystin toxin levels in Lake Cornelia and are urging residents to stay away from the water due to public health concerns.

High blue-green algae levels were measured in recent samples by the Nine Mile Creek Watershed District.

High microcystin levels are typical with excess growth of blue-green algae. Follow-up toxicity monitoring was done to evaluate public health risk. The latest data indicates microcystin levels are at a level that presents a public health risk.

Exposure to Microcystins may harm the liver and be harmful to kidneys and, in extreme cases, death.

Symptoms of poisoning include jaundice, shock, abdominal pain/distention, weakness, nausea and vomiting, severe thirst and rapid or weak pulse. If you begin to notice symptoms, contact your health care provider; in animals, contact your vet. People and pets should not come into contact with the water until they are notified that it is safe.

Blue-green algae are a type of cyanobacteria present at low levels in many Minnesota lakes and ponds. When water is stagnant, warm and rich in nutrients — especially phosphorus — cyanobacteria can grow quickly, forming “blooms.” These blooms typically look like pea soup or bright green paint. They can produce a strong, swampy odor as the cyanobacteria break down.

“The city is working with Nine Mile Creek Watershed District and an engineering consultant to strategize solutions for the problem,” said Edina water resources coordinator Jessica Vanderwerff Wilson.

According to the district's education and outreach program manager Erica Sniegowski, this is a common urban water quality problem.

“Our infrastructure was designed to collect runoff from streets. This runoff flows untreated to local bodies of water. Pollutants gather in these areas and often create high levels of phosphorus, which can lead to harmful algal blooms,” she said.

Efforts to control the algae include weekly monitoring at the lake’s north and south basins until the levels drop. The watershed district and the city will work together closely to develop solutions for controlling the harmful algae. The Nine Mile Creek Watershed District Board will meet to discuss next steps.

Lake Cornelia is treated twice per year by lake restoration companies.

A meeting with residents will be held sometime in November.