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Five Island Lake Assoc.

Aging Lakes

By Staff | Feb 16, 2021

In the natural course of nature will a lake eventually die?

In the northern part of Iowa, three different glaciers impacted the landform and the formation of the lakes throughout the Dakotas, Minnesota, Wisconsin and Iowa. According to the research done by Dr. James Coffey and shared in his book, Saving the Glacier’s Creation, Five Island Lake was formed during a 3000-year period 12,000 to 15,000 years ago. The Wisconsin Glacier was a huge sheet of ice, 10,000 feet thick in places. “This massive mountain of ice moved vey slowly, grinding and crushing all that was beneath it – dragging soils, rocks, boulders under its huge weight. This material covered the previously existing landscape like a blanket, filling in the valleys and flattening out the terrain.”

It took centuries for Five Island Lake to form. Since then, it has entered into its natural three stages of life. A young lake is oligotrophic. Its features include steep shorelines, conifer trees, a rocky bottom, clear water, few aquatic weeds, high oxygen concentration and cold-water fish. A middle age lake is mesotrophic with less steep shorelines, conifer and deciduous trees such as oak, ash and maple and the bottom is mostly sand from the erosion and weathering of rocks. It is less deep and the water is clear with cold and warm water fish such as bass, perch and bluegills. Older lakes are eutrophic with mostly flat shorelines, deciduous trees and shoreline plants. They are shallower and hold little oxygen in waters deeper than 30 ft. The water is murky with heavy aquatic weed growth. There are fewer cold-water fish but bass, pike, panfish and carp thrive in old lakes.

These are general definitions of aging lakes over the course of time. While changes occur naturally, humans are also pressuring bodies of water by building houses, concrete driveways, septic systems, doing landscape plantings, agriculture soil erosion and chemical soil applications near the shoreline and within the watershed.

The first written recordings of the existence of Five Island Lake were in 1853. Since then, there have been a series of efforts to improve the lake. These ranged from building a damn in 1891, dredging from 1912-20, the south end of the lake was cleaned by men from the Civilian Conservation Corps in 1933, dredging from 1948-50 and the last dredging project that began in 2002. In the latest evaluation of the lake by the Iowa Department of Natural Resources there are concerns about the clarity and health of the lake. As you know from past articles there is now an overall management plan being written that will address the human pressure on the lake’s health. It will require money, commitment and adept leadership but all are possible.

Any of the above could have ended the life of Five Island Lake. To date, citizens have not let that happen even though change takes time. So, thanks to those people, this unusually shaped lake continues to provide recreation and contentment for the populace.

Question: Why was Five Island Lake named Medium Lake in the late 1800’s?

submitted by Diane Weiland