Eagle Lake near Willmar on verge of being added to impaired waters list
A lack of habitat variety and other stressers have adversely affected desireable fish species
WILLMAR — Eagle Lake is on the verge of being added to the list of impaired waters by the Minnesota Pollution Control Agency.
The listing is expected due to the decline in the mix of fish species in the lake, according to Margaret Johnson, manager, Kandiyohi County Soil and Water Conservation District.
More pollutant-tolerant species of fish are increasing in number while the numbers of desirable fish are in decline.
A 2020 fisheries study by the Minnesota Department of Natural Resources documented the impairment. The lake has experienced a decline in the numbers of sunfish, crappie and largemouth bass. Fish tolerant of pollution, such as carp, represent a greater share of the total fish mass in the lake.
Walleye numbers remain good, but that is attributed largely to the ongoing stocking of the lake and not natural reproduction, although some occurs.
Conditions in the lake do not favor reproduction for desirable species and they are not thriving.
What is termed “anthropogenic stress” in the roughly 850-acre lake is attributed largely to a lack of habitat variety in the lake, according to the analysis of the lake, Johnson explained.
The challenge will be to restore habitat needed by desirable species. Shoreline development — there are 271 homes and/or cabins lining the lake — plays an important role. The lake averages one dock per 100 feet.
There is nothing wrong with docks, but practices to remove aquatic vegetation and materials from the shallow waters ringing the lake deprive many species of habitat for both spawning and feeding, she explained.
Rock riprap placed along portions of the shoreline is another example of the changes that adversely affect habitat in the lake. The riprap warms up and does not provide the spawning habitat needed by species such as sunfish.
Working with shoreline owners on ways they can help improve and increase habitat variety in the lake will be the focus of efforts to improve the lake, according to the SWCD manager.