LONG LAKE — The Long Lake area is taking a serious look at water quality over the next two years.
A partnership between the Minnehaha Creek Watershed District (MCWD), the Long Lake Waters Association and the cities of Long Lake, Medina and Orono has started assessing several different water quality issues in five lakes that are part the Long Lake Creek Subwatershed, which flows into Lake Minnetonka.
Specifically, the partnership is looking at invasive carp and stormwater runoff thanks to a $112,00 grant from the Minnesota Board of Soil and Water Resources.
Previous studies done in the area have established there are carp in Long Lake, but the studies haven’t shown exactly how carp are impacting the system or how carp might best be managed. The grant money will allow the MWCD and its partners to begin studying these important factors this year.
These assessments will allow the MWCD to figure out the most cost-effective projects to implement in order to reduce the number of carp in the area, as well as what role each city will play in the projects.
History of water quality in Long Lake
In 2018, the Long Lake Waters Association conducted a study with the firm WSB to tag and count carp in Long Lake. The study found there are too many carp in the lake — between 11,000 and 24,000 common carp — and determined 21,000 carp would need to be removed to restore ecological balance to the lake.
“We’ve been collecting water quality data in that area for a while now,” Brian Beck, the research and monitoring program manager with MCWD, told Lakeshore Weekly News. “We know generally what the issues are. The idea with the grant is to move things forward so we know how to deal with the problem”
The carp problem
Common carp uproot the bottom of the lake when they search for food. Uprooting sediment can devastate habitats for certain lake dwellers and it can release nutrients that are buried under the sediment.
These nutrients can cause algal blooms, which is unhealthy for anything living in the lake and is why some lakes turn a green color during the summer.
The common carp is considered an invasive species by the Minnesota Department of Natural Resources as the fish are native to Europe and Asia and can easily spread to other bodies of water once they’re introduced to an area.
Carp were introduced to the Midwest in the 1880s as game fish. In 2019, common carp are established in 48 states, the DNR says.
How to manage
Once carp is discovered in a water system, there are three things that need to happen to manage the invasive fish, Beck explained.
If there are too many carp in a lake or water system, some of them need to be removed, Beck said. But that isn’t doing enough to stop the problem — it is also important to find out where the carp are coming from and block their route with special barriers. These barriers allow water to flow through, but prevent more carp from getting into a lake.
Another water quality issue is runoff from yards and gardens where fertilizer is used. High levels of fertilizers in lakes can also cause agal blooms.
According to Beck, the MCWD’s assessment will allow the cities involved to pinpoint where agricultural runoff is coming from. Cities can use the data to speak to residents about fertilizer usage or introduce mitigation techniques, such as rain gardens or sand filters, to help prevent the runoff from reaching the lake.
“When we work with our city partners — when we find an area is producing a lot of phosphorous — we can work with that city to install a treatment system,” Beck said.
From April to March 2020, the MWCD says it will work on characterizing the drivers of poor water quality through carp, watershed and wetland assessments, which will allow the partnership to determine the most cost-effective ways to improve water quality in the Long Lake Creek Subwatershed, the project website says.
The MWCD hopes to implement these projects in the first half of 2020.
The project website is www.minnehahacreek.org/project/long-lake-creek-subwatershed-assessment.