Shiawassee County is named for its principal river The Shiawassee. The river is about 110 miles long. It is one of the best examples of a warm-water river system in its eco-region. Its waters support over 61 species of fish and 14 species of freshwater mussel, including some rare and endangered species. We encourage you to spend a relaxed afternoon exploring the many features the Shiawassee River has to offer.