Mill Creek’s two branches begin in the glacial Sharon Short Hills in Sharon Township (South Branch), and in the sandy hills of the Waterloo Recreation area (North Fork). The streams then flow through a large glacial till plain, where they once meandered through swaths of oak savannah, oak forest, and tamarack swamps. The rich soils attracted farmers, who eventually channelized most of the streams and drained most of the swamps. Today, the creekshed remains the most agricultural in the Huron watershed, but suburban homes are encroaching on the farm fields. While there are many beautiful places on Mill Creek, some portions fail to meet minimum water quality standards. The Michigan DEQ has listed the creek as “impaired” due to excess phosphorus and poor fish and aquatic insect populations.
The Mill creekshed is the largest in the Huron watershed, covering 143 square miles. The entire stream network runs 226 miles and empties into the Huron River just north of the Village of Dexter. The average gradient for the stream system is about 8 feet per mile, which is one of the flattest in the watershed. There are 40 lakes (open water >5 acres) and 18 ponds (open water < 5 acres). The 3 biggest lakes are Four Mile Lake (256 acres), Cavanaugh Lake (197 acres), and Pleasant Lake (195 acres). The creekshed comprises all or portions of the villages of Chelsea and Dexter, and the townships of Dexter, Freedom, Lima, Lodi, Lyndon, Scio, Sharon, Sylvan, and Webster; which are all in Washtenaw County. A tiny sliver of the creekshed’s headwaters arise from Jackson County.