Swim beach temporarily closed and visitors asked to keep dogs out of water out of abundance of caution.

This morning, city staff observed what may be a harmful algae bloom in areas throughout the Boulder Reservoir. Samples have been collected for testing. Out of an abundance of caution, the swim beach is temporarily closed, and visitors are asked to keep dogs out of the water.

City staff will continue to monitor algae bloom tests overnight and operational updates will be available tomorrow. Community members are encouraged to check the webpage BoulderRez.org or text the keyword “BPRReservoir” to 888-777 for operational updates.

The reservoir remains open for watercraft use via entry through the main gate. Watercraft users should avoid contact with the water in areas that look inhabited with potential harmful algae and be cautious throughout the Reservoir until the bloom subsides. Harmful algae blooms can look like:

  • Thick pea soup
  • Spilled bluish-green paint on the water’s surface
  • A thick mat of foam along the shoreline
  • Short grass clippings

Boulder Reservoir is not currently being used by the city as a drinking water supply. Boulder Reservoir is only periodically used as a water source for the city and is not needed for drinking water at this time. The city is coordinating with Northern Water given the importance of the reservoir for water supply, irrigation and recreation throughout the region.

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