The Impact of Small Dam Removal on Benthic Macroinvertebrate Communities of Mill Creek (Washtenaw Co., MI)

Abstract

Dams have been built around the world for various uses since the beginning of civilization. Lately, many more modern dams do not serve their original purpose and/or are in need of repair or removal. Due to the drastic altering of the river-scape that dams have created, removing dams is also a high disturbance event. Unfortunately there have been few studies documenting the impacts of dam removal. This study focuses on the removal of a low-head dam in Southeast Michigan and the impacts the removal has the macroinvertebrate communities at 3 sites upstream and 1 site downstream. Qualitative samples were collected, then using the Hilsenoff Biotic Index paired t-tests were conducted. The results show a significant, slight increase in HBI score occurred after the dam removal, as well as an increase in the average EPT Richness and % EPT Species Composition. These findings are similar to other studies in that macroinvertebrate communities improved quickly after dam removal, leading to the conclusion of increased water quality.