Swimmers and pets, beware! You're at serious risk of a rash if either of you encounter water from parts of the Cherry Creek Reservoir.
Colorado Parks and Wildlife has shut down entire sections of the lake after the emergence of a toxic blue-green algae bloom.
Signs are posted where swimming, paddleboarding and wading are prohibited, including at the marina and West Shades area. Boating and fishing are still allowed everywhere they normally are permitted.
Updates to closures will be available on the park's website.
So what triggered the shutdown?
The park allows recreation when the algal toxin microcystin is under 8 micrograms per liter of water. Even then, swimmers should be cautious. The Colorado Department of Public Health and Environment found 10 micrograms per liter of water, which triggered the closures.
If Fido was looking forward to a frolic in the reservoir, tough luck.
"All skin-to-water contact should be avoided for humans and pets," Cherry Creek Operations Manager Larry Butterfield said in a statement. "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."
