City Of Boulder Warns Of Harmful Algae Blooms

BOULDER, CO — The City of Boulder is urging people to keep their children and pets away from algae blooms at local lakes and ponds. Potentially harmful blue-green algae is growing in Wonderland Lake, city officials said. The algae has also been reported at Thunderbird Lake in southeast Boulder. Swimming and wading are not allowed in both lakes, officials warned.

The city is installing signs in the Wonderland Lake area that remind visitors to follow current regulations that prohibit swimming, wading and boating at the lake and to keep their dogs out of the water, city officials said.

While fishing is allowed at Wonderland Lake, any fish that are caught should be cleaned thoroughly and guts should be discarded appropriately, the city said.

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Blue-green algae, also known as cyanobacteria, can grow rapidly during the summer. The blooms thrive in slow-moving water bodies, such as lakes and ponds.

Some cyanobacteria species can produce cyanotoxins during algal blooms which can be harmful at elevated levels if ingested by dogs, wildlife and humans, or during wading and other recreational contact with water. The toxicity of a cyanobacteria bloom is difficult to predict because a single species can have toxic and non-toxic strains, and toxic strains do not always produce toxins.

The City of Boulder does not test for blue-green algae regularly because of the many lakes and ponds it manages, but officials may monitor the growth of algae bloom.

Because swimming, boating and wading are prohibited in the Wonderland Lake and Thunderbird Lake areas, the city does not anticipate conducting additional testing in those locations, officials said.

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 brown, purple or white.
• 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 probably is pollen).

The City of Boulder will continue to monitor reports of blue-green algae and will provide additional notices if it is found at city lakes and ponds, officials said.