Colorado Parks and Wildlife (CPW) is asking residents to not make contact with the water at DeWeese Reservoir after a growing bloom of blue-green algae was discovered in the lake. 

“Algae has become a seasonal problem at DeWeese, forcing CPW in recent summers to close the water to all activity except fishing to prevent the risk of exposure to humans and their pets,” said CPW District Wildlife Manager Justin Krall.

“The algae can be harmful to people and pets if touched. It can give sensitive people a bad rash, for example. And it’s possibly fatal if ingested.”

According to CPW, algae blooms are common in the summer as temperatures begin to rise. DeWeese Reservoir was tested after a turquoise film was observed on the surface of the water. 

Results found that there was “dangerous levels of toxicity” in the lake according to CPW.

Officials will be monitoring the toxicity level of the lake over the coming weeks. In the meantime, any recreation that includes contact with the water, like paddle boarding or wading, is prohibited. 

“You can still fish during an algae bloom. It’s also important to take care when handling and cleaning any fish caught in DeWeese. Toxins accumulate in the liver and guts of fish. So it’s important any fish taken is properly cleaned and thoroughly cooked before eating it,” Krall said. 

There are currently no known methods to remove algae toxins from lakes, CPW said. 

The Colorado Department of Public Health and Environment (CDPHE) makes the following recommendations for anyone near a lake that has blue-green algae: 

• Keep kids out
• No pets in water
• Do not drink water
• Avoid contact with algae
• If exposed, shower immediately

 “The public can help reduce the occurrence of blue-green algae blooms by preventing nutrients (nitrogen and phosphorus) from entering waterways through responsible use of lawn fertilizers, picking up pet waste, and avoiding using deicers that contain urea,” CPW said. 

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