Please be aware that blue-green algae, also known as cyanobacteria, can grow rapidly during the summer and may be harmful 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, the only body of water regularly tested for blue-green algae is Union Reservoir, because it is the only area where swimming and wading are allowed; however, the City may monitor bodies of water in response to reports of blue-green algae blooms. Visitors and residents should exercise caution and keep children and pets out of any areas where algae are observed.

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

• May look like thick pea soup or spilled paint on the water’s surface.
• Can create a thick mat of foam along the shoreline.
• Usually are green or blue-green, although they can be other colors including red or gold.
• Sometimes are made up of 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 (this is probably pollen).

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