A new aeration system at Prospect Lake will kill and prevent harmful blue-green algae while also preserving the operation of motorized watercraft, including boats, within its waters.

Colorado Springs spokeswoman Cassie Melvin said in an email Thursday the city is finalizing a contract and scope of work with Colorado Springs-based Timberline Building Systems to install the new permanent, continuous aeration system that will combat blue-green algae blooms and prevent fish kills.

The algae harms water quality, decreases the amount of oxygen available to animals living in the water, and can be toxic to humans and pets.

Melvin said the city expects to begin installing the new aeration system this fall.

The city has battled the noxious algae in Prospect Lake for years, which has, at times, closed it to all recreation.

Parks staff announced Wednesday they again presume the presence of blue-green algae inside the lake at Memorial Park. It is indefinitely closed to swimmers, paddle boarders, non-motorized boaters, and others who could come into contact with the water. Fishing piers are still open, but anglers are encouraged to clean their fish well.

The parks department began searching for a long-term solution in 2022 and held communitywide meetings in March 2023 to help narrow down options for two aeration system designs.

One design would have closed the lake to motorized watercraft, or any watercraft with a motor on it, because it could have damaged the system. However, residents pointed out if boating was banned at Prospect Lake there would be no alternative options in El Paso County.

Officials chose a design that would preserve motorized watercraft activity on Prospect Lake.

It will target the deepest parts of the lake, aerating the water through weighted lines. The aeration lines will force air bubbles through lake water, a project webpage states. Oxygen in the air bubbles then diffuses into the lake, reducing levels of pollutants in the water and increasing the amount of beneficial bacteria in the lake, among other improvements.

As needed, the system will also scatter an enzyme-based product into the waters that helps combat blue-green algae blooms.

The system will turn over the lake completely about every two days, reducing “excess nutrient content” in the lake, according to the project webpage.

It was unclear Thursday how much the project will cost.

Parks officials previously said the city is using about $450,000 in American Rescue Plan Act funds to design and install the permanent system at Prospect Lake. To stay within federal guidelines, the city had to be under contract for construction by this year and must finish the project by 2026, officials previously said.