Citing dangerous levels of toxic algae, officials have issued a health warning for Lake Cornelia in Edina, saying people and animals should not come into contact with the lake’s water.

High levels of blue-green algae, known as microcystins, were measured in recent samples collected by the Nine Mile Creek Watershed District, city officials said.

“The latest data indicates current microcystin levels present a public health risk,” read a statement last week from the city, which made a similar declaration last September. “Exposure to microcystins may harm the liver and be harmful to kidneys and, in extreme cases, [cause] death.”

Symptoms of poisoning for humans and pets alike include jaundice, shock, abdominal pain, weakness, nausea and vomiting, severe thirst and rapid or weak pulse. Medical attention should be sought if any of these symptoms arise after contact with the water.

The Watershed District will continue monitoring the lake until toxin levels drop and the health risk subsides.

Lake Cornelia, just off Crosstown Hwy. 62 and west of Southdale Center, is technically a wetland and only 7 feet at its deepest. Its north basin is on the federal Environmental Protection Agency’s “impaired waters” list for failing to meet water quality standards.

Jessica Wilson, Edina’s water resources coordinator, said most of the initial algae bloom can be traced to a high concentration of phosphorus. Add a little sunlight, and the blue-green algae grows and expands.

The major source of the phosphorus is runoff from the greater watershed emptying into the lake’s south basin, Wilson said. But other sources — shifting sediment, past agricultural activity, even goose droppings — also contribute.

Lake Cornelia also was the site of a curly leaf pondweed invasion in 2015 and 2016. The plant unleashes significant amounts of phosphorus when it dies off in the summer, Wilson said.