The Northwest region of Lake Erie's western basin is at the mouth of the Detroit River, where water from Lake St. Clair and Lake Huron enters Lake Erie. On the Canadian side of the lake is the Essex watershed region, which is relatively rural and primarily agricultural. The U.S. side of the lake is somewhat more developed, but most of this region's watershed inputs come from the Detroit River and the city of Detroit, Michigan, which was a population of nearly 700,000 people.

The Northwest region score is made up of ten indicators that had adequate data. The highest-scoring indicator was recreational toxin. The lowest-scoring indicator was emerald shiner. Read more about the specific indicator scores here.