Analysis of sediment and possible effects on macroinvertebrate population on the Maple River and Lake Kathleen in Cheboygan, MI.

Abstract

The Maple River Dam in Cheboygan, MI, is scheduled for removal within the next few years. All studies on dam removal up to this point have begun after the dam has been removed. They usually use sediment samples and macroinvereibrate populations far upstream of the dam location as references to approximate the original conditions of the river downstream of the dam. We took sediment samples on the Maple River downstream of the dam as well as in Lake Kathleen, the reservoir above the dam. We found that sediment in Lake Kathleen is mostly fine­ grained organic material , while the dominant substrates in the Maple River are a combination of pebble and cobble. Additionally, there are significantly higher concentrations of P04 , C, and N in lake sediment than in the river. It is likely that once the dam is removed, the fine-grained sediment from the lake will wash downstream, carrying nutrients with it. Change in dominant substrate in the Maple River could directly affect macroinvertebrate populations by removing habitat and altering water flow and dissolved oxygen. The influx of nutrients could cause rapid growth of algae or aquatic plants, which would indirectly affect macroinvertebrate populations by altering food and habitat availability. Regardless of the final results, the completion of this study will provide a more accurate understanding of how sediment is transported and deposited after dam, and how this spread of sediment affects macroinvertebrate populations.