<< Back

Mendota Heights promises aid for aging lake

By Nathaniel Minor, for COJO 250 (Reporting for print media)

As a small, 100-acre lake with good water quality in the residential heart of Mendota Heights, Rogers Lake would seem to be a prime spot for summer fun.

Weeds, according to 10-year lakeside resident Pat Hickey, prevent most people from even dipping a paddle into the otherwise clear water.

“Potentially, you’d hang up your canoe in the weeds, and if you put a paddle in there, you’d get stuck,“ Hickey said. “Very hard to navigate in a canoe or paddle boat.”

In addition to more than a dozen lake homes, Rogers Lake boasts a city park on the north shore of the lake and St. Thomas Academy, an all-boy’s Catholic junior and senior high school, on the south shore. Along with the school, Dakota County is the other primary lakeshore owner.

That being the case, Hickey and other residents took their problem to the Mendota Heights city council, with hopes of financial means to their goal of making the lake suitable for recreational use. By a unanimous vote at its April 7 meeting, the city council promised $15,000 to go toward chemical treatment of the lake.

The ecosystem of the lake is fragile, according to Tim Olman, a Department of Natural Resources (DNR) aquatic plant management specialist, who said the city and the lake’s residents need to handle the situation carefully.

Chemicals, Olman said, are preferable to the other method: mechanically removing the weeds with a large harvester.

“I have a feeling...the harvester could stir up the bottom quite a bit,” Olman said.

According to Olman, the sediment on the bottom of the lake could contain phosphorous, which, if brought to the surface, could spur algae growth.

However, he said that a lake being algae-filled doesn’t necessarily mean it’s sicker than a lake with clear water. Algae are a different type of aquatic plant, which are necessary to keep the biological balance of the lake.

“Rogers [Lake] is in a clear water state, which means it’s going to have a ton of plants in it,” he said. “Back, 20-30 years I think, it was an algae dominated turbid water lake.”

Potential algae isn’t the only problem, said Garry Loufek, a science teacher at St. Thomas Academy who’s been testing the water quality for more than a dozen years. If many of the weeds were removed, Loufek said it would leave the bottom open for troubling wave action.

While phosphorous is natural to all Minnesota’s lakes, Olman is also worried about a non-native invasive species, Eurasian water milfoil.

“If they use mechanical removal, there’s a high likelihood species that are not native to the lake would enter the lake via the harvester,” he said.

Steve McComas, an aquatic scientist from Blue Water Science, a private, local company, disagreed with Olman’s assessment.

“Herbicides can be a little bit cheaper, but you’re taking a little bit more of a risk with the water quality,” he said.

McComas said herbicide will kill plants and leave them to decompose in the lake, but mechanically harvesting them includes physically removing them from the water as well. The harvester would make it easier to control the amount of plants being removed.

Still, Mendota Heights is committed to the chemical method. McComas had been contracted to conduct a needs assessment, but the city council opted to follow the advice from the DNR.

Loufek supports the city council’s decision to chemically treat the lake, and plans to monitor the effect the herbicide will have. He doesn’t see a need for the weeds to be removed, but understands the desires of the residents as well.

Hickey, the lakeside resident, said he only wants to make the lake viable for recreation, “by no means [wants to remove] all the weeds.”

“We’re doing everything possible to keep this lake in its most natural state, without having it overcome with weeds and cattails,” Hickey said.

Olman said the lake could be suitable for canoeing and paddling, but not much more. “I don’t know that it’s realistic to expect that you could sail a sailboat out there,” he said.

Olman and the DNR’s first choice would be to leave the lake alone, forgoing any human, chemical or mechanical intervention. Rogers Lake, Olman said, is toward the end of its life.

“I would say it’s an eutrophic lake, that means it’s a lake past retirement if we were talking in human years,” Olman said. “All lakes do this...in the cities, the aging process is probably accelerated.”

What’s different here, Olman said, is the lake is being prevented from the life course the majority of lakes follow. Similar lakes in the outer regions of the state are allowed to ebb and flow, from turbid to clear water states, and they eventually become less lake and more marsh.

“It’s going to be a shallow, weedy lake in our lifetimes, and I don’t think that it's right to try and change that,” Olman said.

The city council committed to only a year’s worth of treatment, and only time will tell for whom the project will be a success. In future years, the total bill will be split 50-50 by the city and the lake’s residents.

“The council is holding the responsibility,” Hickey said. “[They have the] support of all the residents and the community to keep this natural treasure alive and well in the city,” Hickey said.

<< Back