Prospect Lake reopens after the elevated blue-green algae bloom

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Lake had been closed since August due to elevated levels of microcystin toxin

COLORADO SPRINGS — Prospect Lake in Memorial Park is back open for recreational use following a 12-week closure due to blue-green algae.

Since closing on August 9, the parks, recreation and cultural services department has worked closely with the Colorado Department of Public Health and Environment (CDPHE) to conduct weekly water tests to make sure there weren’t elevated levels of microcystin toxin, which is produced by cyanobacteria (blue-green algae).

All results from the weekly water tests.

“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. “Safety is our priority, and we are continuing to actively research ways to address the long-term health of Prospect Lake.”

Tests returned in late October were well below the acceptable recreational level for the toxin, which is 4 micrograms per liter.

Picture of blue-green algae

Toxic blue-green algae has been found in three Colorado Springs-area bodies of water: Prospect LakePikeview Reservoir, and the pond at Homestead Ranch Regional Park.

As a precaution, the county parks department tested seven bodies of water at six county parks, including Bear Creek. Only one, Homestead Ranch, was found to contain the algae

When conditions are right, blue-green algae multiplies quickly. Those conditions include sustained hot weather, stagnant water, and polluted stormwater runoff.

These conditions result in too much nitrogen, potassium and phosphorus in the water. This causes the harmful bacteria to grow faster than the ecosystem can handle. The increased bacteria harm water quality, decrease the amount of oxygen available to animals living in the water, and can produce a toxin that is harmful to humans and pets. 

Blue-green algae are self-limiting, naturally-occurring bacteria, which means it eventually phases itself out of bodies of water.

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