Colorado Parks and Wildlife is urging residents to stay away from the DeWeese Reservoir after a toxic algae bloom was discovered in the water Wednesday.

Signs have been erected around the reservoir in Custer County, warning of “risk of death” if people or animals make contact with or consume the water.

Wildlife Manager Mike Trujillo ordered the closure of all activity except fishing at the reservoir, including swimming, skiing, paddle-boarding and wading. Anyone who fishes in the water is urged to thoroughly clean and cook fish caught.

“This algae bloom poses an immediate health risk to people and pets,” Trujillo said. “You can still fish, but there should be no skin-to-water contact.”

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Trujillo said testing found dangerous levels of toxicity in the water and elevated levels of algae were observed in a turquoise-colored film on the reservoir.

Officials have been monitoring the reservoir closely since the toxic algae was first discovered in the water on June 30.

The blue-green algae bloom is actually bacteria, according to pollution control agencies. The blooms prosper in areas with warm water, an increasing issue with global climate change.

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There is no way to remove toxins from lakes, Trujillo said, but the public can help prevent the algae blooms by keeping nutrients from entering waterways through lawn fertilizers, pet waste and de-icers that contain urea.

If any person or animal is exposed to the water, the Colorado Department of Public Health and Environment recommends they shower immediately.

The DeWeese Reservoir State Wildlife Area is still open to nonwater recreation, including picnicking, hiking, wildlife viewing and camping.