Overall Health Index

The Western Lake Erie report card compares 11 lake indicators (total phosphorus, dissolved phosphorus, nitrate-nitrate, chlorophyll a, walleye, yellow perch, emerald shiner, bloom index, source water toxin, and recreational toxin) and 10 watershed indicators (total phosphorus, dissolved phosphorus, total nitrogen, nitrate-nitrite, source water toxin, total suspended solids, fish, macroinvertebrates, habitat quality, and fish consumption) to scientifically derived thresholds or goals. The lake indicators were combined into an overall lake health index, which is presented as a subregion percent score. The watershed indicators were combined into an overall watershed healh index, which is presented as a subregion percent score. Both scores were calculated as an average of the subregions weighted by geographic area.

The Detroit, Michigan skyline. Photo by Michael Kumm via Flickr, CC BY.