Here’s the release from the City of Colorado Springs:
The City of Colorado Springs has closed Prospect Lake, in Memorial Park, effective immediately, until further notice due to the presumed return of toxic algae. The closure follows a visual inspection Monday, June 15 by Parks, Recreation and Cultural Services staff. A precautionary water sample is scheduled to be taken from the lake by Colorado Springs Utilities on Tuesday, June 16. This test is to confirm the presence of mycrocystin toxin, which is produced by cyanobacteria, also known as blue-green algae.
“Our region has again been experiencing hot, dry weather, creating conditions similar to what we experienced prior to the 2019 algae bloom in Prospect Lake,” said Erik Rodriguez, health, safety and environmental specialist with the Parks, Recreation and Cultural Services Department. “Given today’s visual inspection, and the lake’s recent history with mycrocystin toxin, we have closed Prospect Lake for usage at this time. If Tuesday’s water sample returns positive, we will continue to test weekly until the bacteria clears up.”
Prospect Lake was closed for 12 weeks in the late summer and early fall of 2019 due to blue-green algae. Since that time, Parks’ staff has taken proactive measures, including the application of an enzyme-based, non-pesticide treatment that consumes the biomass at the bottom of the lake and helps oxygenate the water. The first two treatments were applied May 26 and June 11. The next scheduled treatment is Tuesday. Additionally, more water will be added to the lake, which will increase the oxygen level and help dilute the toxin.
During the closure, the following activities are prohibited: swimming, bathing, paddle boarding, tubing, water skiing and non-motorized boating of any kind. No pets are allowed. The use of permitted motorized boats is encouraged as this activity can help aerate the water. Fishing areas will remain open, though anglers are urged to clean fish well and remove guts.
BLUE-GREEN ALGAE BACKGROUND
What is harmful algae?
Blue-green algae are a type of bacteria common in lakes throughout Colorado. 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.
The Colorado Department of Public Health and Environment (CDPHE) offers additional information about blue-green algae on its website.