Prospect Lake in Colorado Springs back open after elevated levels of toxic algae

Prospect Lake in Colorado Springs at Memorial Park on 8/9/19.
By  | 

COLORADO SPRINGS, Colo. (KKTV) - Prospect Lake at Memorial Park is back open for recreational use after the water tested positive for high levels of toxic bacteria known as "blue-green algae."

The announcement came on Wednesday following a 12-week closure.

"We are thankful to community members for their patience during the lake closure and particularly pleased that the public adhered to our warnings of avoiding water contact over the last three months,” said Erik Rodriguez the health, safety, and environmental specialist for the city. “Safety is our priority, and we are continuing to actively research ways to address the long-term health of Prospect Lake.”


The bacteria can be harmful to humans and especially to pets. 11 News partner WECT in North Carolina recently did a story on three dogs that died hours after playing in a pond that had blue-green algae. Click here for more on that story.

The water tested positive for high levels of blue-green algae back in August.

Rodriguez said the bacteria is more dangerous to dogs because it will concentrate on their fur.

The blue-green algae is common in Colorado, particularly when the temperatures are up. Experts say it thrives during summer months or when water temperatures are warmer than usual -- and loves slow-moving water.

“It’s the sun, the sun is going to allow that bacteria to basically take of and get growing. That is when we see the toxins released is during the daylight hours. That is when it is really concentrated in the water," Rodriguez said.

"For the bloom to die down, it's kind of weather-dependent and nutrient-dependent. It depends on what is going on weather-wise."

The City of Colorado Springs sent the following release to the public Aug. 9 when the levels were high:

A precautionary water sample taken from the lake Friday morning, Aug. 9, by the Colorado Department of Public Health and Environment (CDPHE) tested positive for mycrocystin toxin, which is produced by cyanobacteria, also known as blue-green algae.

Staff from the Parks, Recreation and Cultural Services Department have closed and roped off the swim beach and closure signs have been posted. The following activities are prohibited during this time: swimming, bathing, paddle boarding, annual permitted motorized and non-motorized boating of any kind, including water activities like tubing and water skiing. Rentals will not be available during this time, and no pets are allowed. Fishing areas will remain open, though anglers are urged to clean fish well and remove guts.

“Given today’s positive test for mycrocystin toxin, we have closed Prospect Lake for usage,” said Erik Rodriguez, health, safety and environmental specialist with the Parks, Recreation and Cultural Services Department. “CDPHE will continue to test weekly until the bacteria clears up.”

What is harmful algae?

Blue-green algae are a type of bacteria common in lakes throughout Colorado. The algae multiply rapidly to form blooms and scums and are impacted by a combination of sustained hot weather, stagnant water, and polluted stormwater runoff.

What contributes to blue-green algae growth?

Polluted stormwater runoff can have adverse effects on plants, fish, animals and people. Too much nitrogen, potassium and phosphorus in the water is known as nutrient pollution and can cause algae to grow faster than ecosystems can handle. Significant increases in algae harm water quality, food resources, and decrease the oxygen aquatic life. And sustained hot temperatures and conditions exist for this type of algae to thrive.