The Southwest region of Lake Erie's western basin spans the area just beyond the influx of the Maumee River to the near-center of the basin. In this region, large swathes of algal blooms grow and persist, fed by nutrient inputs from other parts of the lake that come together in the shallow center of the western basin. This region encompasses the open water near the center of the western basin as well as small portions of shoreline in Michigan and Ohio.

The Southwest region score is made up of eleven indicators that had adequate data. The highest-scoring indicator was recreational toxin. The lowest-scoring indicator was nitrate-nitrite. Read more about the specific indicator scores here.