There is an algae bloom present at Cheesman Reservoir. While toxicity is unknown, Denver Water is following CDPHE precautions and is conducting periodic testing. Caution signs will be posted at the reservoir for recreational users to follow.

We are advising all users to take the following precautions:

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

Fishing is permitted — rinse fish with clean water and properly dispose guts.

If you or your animals have nausea, vomiting, diarrhea, rash, irritated eyes, seizures or breathing problems, call Poison Control: 1-800-222-1222.

There is no threat or concern for Denver Water’s drinking water. Denver Water vigilantly safeguards our mountain water supplies, and the water is carefully treated before it reaches your tap. In 2025, Denver Water collected more than 58,000 water samples and conducted 128,000 tests. With summer temperatures, Denver Water staff is trained to look for and respond to the presence of possible algae blooms. Guidance for response is in line with CDPHE.