Algae Blooms On Boulder Lakes, Ponds Could Be Harmful, City Warns

BOULDER, CO — Boulder officials are warning of potentially harmful algae blooms at local ponds and lakes.

The blooms may contain cyanobacteria — often referred to as blue-green algae, which can produce toxins that are harmful to dogs and people, the city said.

If you see any algae on local waterways, keep children and pets away, even if warning signs aren't posted, officials said.

Swimming, wading and boating are prohibited at Wonderland Lake, Sawhill Ponds and the Cottonwood /Goose Creek Pond near 55th Street and Pearl Parkway, the city said.

Harmful algae blooms that contain cyanobacteria often look like thick pea soup, according to the Colorado Department of Public Health and Environment. The harmful blooms can also resemble spilled paint on the water's surface and shoreline, or a thick mat of foam along the shoreline.

Don't miss the latest news updates in Boulder: Free Boulder Patch Newsletters and Email Alerts | Facebook | Twitter

"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," the city of Boulder said in a news release.

"The city does not test for cyanobacteria at lakes and ponds because the production of cyanotoxins is highly variable. Cyanobacteria doesn’t always produce toxins – which may be detectable at one time but dissipate within hours."