City Council splits on preferred aeration designs for Prospect Lake in Colorado Springs

Mar. 27—Members of the Colorado Springs City Council on Monday were generally split on two options for proposed aeration designs at Prospect Lake that could prevent fish kills from harmful algae, with more councilmembers supporting a design that would permit motorized boats in the lake's waters over a second option that would ban boats.

After battling harmful blue-green algae in the lake for years, which has at times closed it to all recreation, parks department staff presented the City Council two aeration system design options on Monday that aim to kill and prevent toxic algae in the lake.

Both designs would scatter an enzyme-based product into the waters that helps combat blue-green algae blooms, but only one would allow motorized boats on the lake. Local boaters have urged the city not to ban boating at Prospect Lake, saying if it weren't permitted there would be no alternative options in El Paso County.

The design that would permit boat usage proposes to aerate the lake through weighted lines. It would not have any fountains boats could harm, said Erik Rodriguez, an environmental health and safety specialist for the city parks department.

The alternative option would deploy devices from LGSonic that are powered by solar panels and emit ultrasonic wavelengths that prevent algae growth, Rodriguez said. The ultrasonic wavelengths kill the algae without releasing other harmful toxins into the water, he said.

The devices would monitor Prospect Lake for data such as temperature, Rodriguez said. High temperatures combined with low oxygen levels can contribute to toxic algae blooms that have recently become more common in Colorado.

Councilman Randy Helms said Monday he preferred the design permitting boat usage because it accommodates residents who want the option to boat locally.

"It takes into account the health of the lake and the constituents who want to continue in the future with waterskiing with motorized boating," Helms said.

The design that would allow boats is also significantly less costly than the alternative design, according to a staff presentation. The estimated cost of materials for the design allowing boats is $23,000 while the estimated cost of the system that would ban boats is $153,500.

Those estimates do not include the anticipated cost of labor and other improvements the city may have to make to implement the systems, Rodriguez said.

Either option would be financed through about $459,000 in American Rescue Plan Act funding the city set aside to aerate Prospect Lake, he said. To stay within federal guidelines, the city must be under contract for construction by 2024 and must finish the project by 2026, city staff previously said.

Rodriguez told councilmembers the design that would allow boats could make it more difficult for the city to meet new, stricter state standards governing the levels of chlorophyll a, a molecule used in photosynthesis. The ultrasonic devices proposed for use in the second design option better control algae growth, he said.

In 2027, the new rules will apply to all bodies of water larger than 25 acres.

If Colorado Springs feels it won't be able to meet the new standards, parks staff might request a variance from the state in 2026, Rodriguez said.

Councilman Bill Murray said the city must also be aware of other pollutants that need to be removed from the water, like oil that could leak into Prospect Lake from motorized boats. He supported the design that would use ultrasonic devices but would ban boats.

"I would think, clearly, (design No.) 2 would be the best to handle things as far as making sure the public is protected, the lake is protected and the environment is protected," Murray said.

Rodriguez said if the city chose the less costly aeration design that would allow boats, but found it didn't meet new state standards, officials could eventually upgrade their system to the proposed alternative.

Councilman Wayne Williams said he supported the option that would allow boats because it could be upgraded and is less costly.

"It sounds to me like we ought to try option one first," he said. "There's a pretty significant cost disparity between the two and a pretty significant use ability between the two as well."

While the council gave its feedback on both options Monday, the city administration overseen by the mayor's office will make the decision sometime next week, said Kim King, assistant director of the Parks, Recreation and Cultural Services Department.

Residents can also give their feedback on both designs through an online survey available through Friday, King said. The survey is available at coloradosprings.gov/prospectlakeaeration.