A recreation closure has been issued for Cherry Creek Reservoir in Cherry Creek State Park due to the presence of blue-green algae in the water.

According to Colorado Parks and Wildlife (CPW), samples from the reservoir tested positive for microcystin, an algal toxin.

Algae are naturally occurring in many lakes across Colorado, especially as temps warm up. However, they can become dangerous to humans and pets when they multiply rapidly, or “bloom”.

“The threshold for water recreational closure set by CDPHE is 8 micrograms per liter (ug/L) of microcystin and above. This is considered a “red” level”,” the release said.

The samples from Cherry Creek Reservoir reportedly showed concentrations of 10 ug/L.

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 swimming, paddleboarding, or wading, is prohibited. No closures have been announced for boating and fishing at this time.

“All skin-to-water contact should be avoided for humans and pets,” Cherry Creek Operations Manager Larry Butterfield said. “Contact with the water could cause minor skin rashes and make pets ill. Dogs need to be on-leash to keep them from drinking or playing in the bloom.”

Checkout the Cherry Creek State Park website for update on the closure.

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