Boulder County Warns Of Harmful Algae In Lakes, Ponds

BOULDER COUNTY, CO — Boulder County officials are urging people to keep their children and pets away from algae blooms at local lakes and ponds.

Some algal blooms can contain cyanobacteria, often referred to as blue-green algae. While most of the algae seen in ponds and lakes during summer months are not toxic, cyanobacteria can produce toxins, which can be harmful to dogs and humans at elevated levels, officials said.

Warmer temperatures, stagnant water, and nitrogen and phosphorus (nutrient) loading from fertilized lawns and other sources can facilitate algae and cyanobacteria growth.

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Cyanobacteria blooms may look like thick pea soup or spilled bluish-green paint on the water's surface and can also create a thick mat of foam along the shoreline, according to the Colorado Department of Public Health and Environment. In general, the long, stringy, bright green strands that appear either slimy or cottony, or are mustard yellow in color, are not the harmful type of algae, health officials said.

Anglers should also exercise caution and follow state recommendations to clean any caught fish thoroughly and to discard guts appropriately.

The City of Boulder and Boulder County do not test for cyanobacteria at lakes and ponds because the production of cyanotoxins can be highly variable, with harmful toxins detectable at one time but not detectable hours later, officials said.