Prospect Lake tests positive for Blue-green algae, second year in a row

COLORADO SPRINGS, Colo. (KRDO) -- The City of Colorado Springs says Prospect Lake will remain closed after test results for blue-green algae come back positive.

The test, which drew a water sample on June 16th, returned a microcystin level of 22 micrograms per liter. The acceptable recreational level for microcystin should be 4 micrograms per liter.

“We are going to continue to keep it closed and going to continue to test the lake until we do have two consecutive weeks with a level that is acceptable," said Erik Rodriguez, an environmental health and safety specialist.

Prospect Lake was closed for 12 weeks in the late summer and early fall of 2019 due to blue-green algae. Since that time, city's Parks and Recreation staff have taken proactive measures to keep it from happening again. Those new measures included the application of an enzyme-based, non-pesticide treatment that consumes the biomass at the bottom of the lake and helps oxygenate the water.

“It’s environmentally friendly," Rodriguez said. "What we are trying to do is keep the ecosystem of the lake healthy during our treatment and not use hazardous products so that’s why we chose something that was enzyme based.”

On Tuesday morning, crews returned to the lake to issue their 4th treatment this month.

"We’ve had a really hot and dry start to our May, and now June which has put us months behind where we were last year with the wetter and cooler weather in these months," Rodriguez said. "It wasn’t something that we anticipated and we thought we would have more operations and maintenance time to try and treat this and get it under control."

So even with the treatment and the blue-green algae still returning, is it time for a different strategy?

Rodriguez said not quite, “Most the other products that we could use and treat this would actually be detrimental to the lake health and the eco-system. So, that’s why we’ve gone where we are going and it’s going to take some time to actually build up and work.”

During the closure, the following activities are prohibited: swimming, bathing, paddle boarding, tubing, water skiing, and non-motorized boating of any kind. Also, make sure your pets stay away from the water at all times.

Fishing areas will remain open, though anglers are urged to clean extremely well.