Avoid Contact With Blue-Green Algae Blooms - City of Longmont

Avoid Contact With Blue-Green Algae Blooms

a pond with a visible blue-green algae bloom, showing green-tinted water, swirling surface patterns, aquatic vegetation along the edges, and submerged plant stems.

Algae Blooms Could Have Harmful Effects on Humans and Pets

 

Warm water and summer sunshine can trigger blue-green algae blooms, also known as cyanobacteria. Blooms can appear in local lakes and ponds every summer, and some produce toxins that are dangerous to humans and pets.

 

Blooms thrive in slow-moving bodies of water, such as lakes and ponds. Some cyanobacteria species can produce cyanotoxins, which can be harmful at elevated levels if ingested by dogs, wildlife and humans, or during wading and other recreational contact with water.

 

In Longmont, Union Reservoir is the only body of water regularly tested for blue-green algae because it is the only area where swimming and wading are allowed. The City may also monitor other bodies of water in response to reports of blue-green algae blooms. Visitors and residents should exercise caution by keeping children and pets away from areas where they observe algae.

 

According to the Colorado Department of Public Health and Environment, harmful algae blooms often:

 

  • Look like thick pea soup or spilled paint on the water’s surface.
  • Create a thick mat of foam along the shoreline.
  • Appear green or blue-green, although they can be other colors including red or gold.
  • Show up as small specks or blobs floating just at or below the water’s surface.

 

Harmful algae blooms are NOT:

 

  • Long, stringy, bright green grass strands that feel either slimy or cottony.
  • Mustard yellow (that’s probably pollen).

 

Learn more about blue-green algae or call (303) 651-8416.

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