Fixing the toxic algae problem at Prospect Lake in Colorado Springs means no more water skiing

Andrea Chalfin/KRCC News
Prospect Lake in what is now Memorial Park in Colorado Springs was filled in 1890 for overflow from the El Paso Canal. July 2021.

Motorized boating will no longer be allowed at Prospect Lake in Colorado Springs' Memorial Park, beginning May 1. The city plans to install a new aeration system aimed at preventing toxic algae blooms, which prompted extended lake closures in 2019 and 2020.

The algae, often referred to as blue-green algae, is naturally occurring, but when it grows rapidly or blooms, it can be harmful to people and fatal to pets. In the past, the city has treated the water with enzymes to deal with blooms as they've occurred.

Now, they're looking for a more proactive approach to addressing the algae, said Kim King, recreation and administration manager with the city's parks department.

"With additional aeration in the lake, having that oxygen allows the lake to stay in a healthier condition," said King. "Prospect Lake really has no flow," she added, which the Centers for Disease Control says can be a contributing factor to blooms.

King said they successfully proposed an aeration system as part of the city's funds from the American Rescue Plan Act, or ARPA, at an estimated initial cost of $400,000, to include tethered fountains. Enzyme treatments, she said, cost $100,000 per year.

The installation will include hoses throughout the lake. "When you have all of that infrastructure in place, we're very concerned about the ability of that infrastructure to stay in place if you have motorized activities occurring," King said.

The city expects to have the system in place sometime between May and July.

Prospect Lake is small, just 52 acres, and a paved path around it is 1.25 miles long. In the summer months, boaters have traditionally frequented the lake for water sports like skiing and tubing, as well as hand-powered uses like kayaking and standup paddleboarding.

And while the city recognizes it's disappointing for those who recreate on the lake with motorized craft, "we're really looking at that long-term health of the lake and an opportunity to really do something proactive," King said.

2021 data on annual permits for boating on Prospect Lake show interest in hand-powered craft outpacing motorized watercraft. Daily use permits, King said, showed nonmotorized use of the lake at more than 10.5 times than for motorized craft.

There’s currently a kayak and SUP rental concession at the park. King said that the city is looking into adding a second contract vendor to promote nonmotorized uses of the lake.