The City of Boulder is reminding the community to use caution around lakes and ponds where toxic algae blooms may be present, even during the winter months.
Potentially dangerous blooms have recently been observed at Wonderland Lake in North Boulder.
According to city officials, nitrogen and phosphorus running-off into bodies of water from fertilized lawns and other sources can facilitate the growth of these blooms.
Signage notifying visitors of the harmful blooms at Wonderland Lake were to be posted in the area on Friday afternoon. Swimming, wading, and boating are prohibited in the lake. Dogs should also be kept out of the water.
Blue-green algal blooms are often described as thick pea soup or spilled bluish-green paint on the water's surface. Blooms, which thrive in shallow, warm, and still bodies of water, can contain toxin-producing cyanobacteria. If ingested, these toxins can be deadly to dogs.
However, city officials say, "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."
Several dogs died last summer after swimming in waters infested with blue-green algae. While most deaths have occurred in southern states, Colorado remains on alert for these potentially dangerous blooms.