Toxic blue-green algae found in DeWeese Reservoir


WESTCLIFFE, Colorado – A growing bloom of toxic blue-green algae at DeWeese Reservoir State Wildlife Area has prompted Colorado Parks and Wildlife to warn the public to avoid contact with the water.

“Algae have become a seasonal problem at DeWeese and in recent summers have forced CPW to close the water for all activities except fishing to avoid the risk of exposure to humans and their pets,” said CPW District Wildlife Manager Justin claw. “The algae can be harmful to humans and pets if touched. Sensitive people can get a bad rash, for example. And it’s potentially fatal if ingested.”

CPW will put up signs at the reservoir warning visitors to avoid the water and explaining the danger of algal blooms:

  • Don’t drink the water
  • Do not replicate in water (including swimming, skiing, paddle boarding and wading)

If anyone or their pet comes into contact with the algae, signs are urging them to shower with fresh, clean water immediately.

The alert was raised after tests found dangerous levels of toxicity in the water and elevated levels of algae were observed in a turquoise film on the reservoir.

“You can still fish during an algal bloom,” Krall said. “But there shouldn’t be any skin-to-water contact.

“It’s also important to exercise care when handling and cleaning fish caught in DeWeese. Toxins accumulate in the liver and intestines of fish. It is therefore important that any fish removed is properly cleaned and thoroughly cooked before consumption.”

Algal blooms are common when temperatures rise, usually in late summer, he said. CPW has been closely monitoring the reservoir and taking water samples weekly to check for elevated toxicity.

Other forms of recreation still permitted at SWA include: picnicking, hiking, wildlife viewing, and camping.

Algae are an important part of aquatic food webs, but some types of blue-green algae can produce toxins that, at elevated levels, can have adverse health effects on humans and pets. There is currently no method to remove toxins from lakes.

For more information on blue-green algae, visit the CDPHE website.

The public can help reduce the occurrence of blue-green algae blooms by preventing nutrients (nitrogen and phosphorus) from entering water bodies, by using lawn fertilizers responsibly, picking up animal waste and avoiding the use of deicers containing urea.


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