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Five Island Lake Assoc.

From Glacial Drift To Prairie Land

By Staff | Oct 27, 2020

It took millions of years for the forces of glaciers to form Iowa land and lakes. In the booklet, “The World Beneath Your Feet” by Mark Muller, it says that “Glacial drift is a deposit of sand, silt, clay and gravel left by glaciers or their meltaway streams many thousands of years ago.” Following this phenomenon, prairies began to grow throughout Iowa. Before statehood in 1846, 85% of Iowa was a complete eco system of tall grass prairie. Within a generation of non-native settlers, the Iowa prairie, except for .1%, disappeared under the plow. Settlers needed to make a living and the nutrient rich dark soil that was below the surface was found to be ideal, first for growing wheat and then discovering how well corn grew in the soil.

A prairie is a wide area of flat land covered in grasses. The most important part of the prairie is what is underneath the plant. The majority of its living mass is below the ground where the root system can range from 6 feet to 25 feet deep. Muller states that “The beauty of a perennial system like the tallgrass prairie is that it continually recycles nutrients and builds more soil every year instead of losing it. The prairie is a self-maintaining system.”

In 2018, the city of Emmetsburg hired FYRA Engineering to do a comprehensive Five Island Lake Water Quality Management Plan. They determined that the percent of land use within the lake’s watershed is made up of the following: Cropland 83%, Pasture 5%, Urban 10% and Forested 3%. One of the things affecting the lake’s clarity and health each year is the amount of phosphorus going into the lake. The total annual watershed phosphorus load by source is Cropland at 78%, Urban, 14%, Feedlots at 5%, Pastureland at 2%, Septic at 1% and Forestland at 0%.

Various agriculture conservation practices are in use to offset the phosphorus levels going into the lake such as No till, Terraces, Conservation Till and CRP. Increased perennial vegetation is the focus of the USDA Conservation Reserve Program (CRP) and the Wetland Reserve Program. These programs pay for taking agricultural land out of production to plant perennial vegetation such as prairies.

In a recent Iowa State University Prairie Project at the Neal Smith National Wildlife and Refuge Center prairie strips in cropland were studied. The research showed that “by converting 10% of a crop field to native perennial vegetation landowners can reduce sediment movement off their field by 95% and total phosphorus and nitrogen loss through runoff by 90% and 85% respectively.”

Through the CRP programs there are several prairies and set asides that have been established within Five Island Lake’s 7,657 acres of watershed. Warren Jennings, Watershed Coordinator estimates that between 200 and 300 acres of watershed are prairie acres. Plantings on these acres include Big Blue Stem and other native grasses and numerous forbs (commonly known as wild flowers). On the surface they add diversity to the landscape but below ground the plants’ root systems are doing their work to protect the health of the lake.

Submitted by Diane Weiland