Five Island Lake Assoc.


As the days of winter continue, sometimes it is pleasant to think about all of the joy that spring promises – warmer temperatures, longer days, working to prepare and plant vegetable and flowers gardens and once again hearing the sounds of Five Island Lake.

While still indoors there are websites and magazines that shoreline property owners can learn about and plan for projects that control erosion, filter rain water and add natural buffers to the landscape. Professionals who study lake water quality will agree that maintaining a healthy lake is far less costly than trying to fix a degraded one.

In the 2018 Five Island Lake study completed by FYRA Engineering, urban areas were identified as making up 10% of the watershed and accounting for 14% of the watershed phosphorus load by source. According to the website,, “Too much phosphorus can cause increased growth of algae and large aquatic plants, which can result in decreased levels of dissolved oxygen– a process called eutrophication. High levels of phosphorus can also lead to algae blooms that produce algal toxins which can be harmful to human and animal health.”

The study identified urban land practices that would be beneficial to the lake’s water quality. Non-structural practices included no phosphorus lawn fertilizer, pet waste management, soil quality restoration. Structural suggestions were septic system inspections and repairs, rain gardens/bioretention and bioswales.

Five Island Lake benefitted greatly from the 1990 shoreline stabilization project described in Dr. James Coffey’s book, Saving the Glacier’s Creation. The Palo Alto County road maintenance crews offered their services to riprap the shoreline with field stones that the farmers wanted removed from their ground. This stabilized “all the major sites of shoreline caving.” Thirty-one years later, private property owners around the lake know how important that long-term stabilization has been.

Today the lake shore can also include practices such as establishing native plants and adding a rain garden to the landscape. Kentucky blue grass has about 5”inches of root depth. Native flowers and grasses have several feet of roots which filter pollutants from entering the water. These beneficial plants also attract birds and butterfly species.

According to Iowa State University Extension and Outreach, “A rain garden is a specially designed and slightly depressed site where rain water can be collected and allowed to slowly percolate through the spoil. Filtering the rain water through the soil and plant roots removes many of the lawn and roof chemical residues and soil particles.” More information can be found at ISU Extension and Outreach and Minnesota Extension and Outreach websites.

Check out the value of a rain garden and the hard work that native plants such as meadow rue, ironweed, cardinal flower, swamp milkweed, queen of the prairie, false aster, prairie blazing star and many others can do to improve water quality and add diversity to landscapes.


What is the average depth of Five Island Lake?

submitted by Diane Weiland


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