The polygons within this shapefile are the boundaries of potential Ecological Reference Areas (ERAs) as proposed by DNR staff. ERAs are areas that serve as models of ecological reference within the state. They are high quality examples of functioning ecosystems that are primarily influenced by natural ecological processes. ERAs are based on the Michigan Natural Heritage Database of documented natural community sites (Element Occurrences). A subset of these shapefiles were approved as ERAs by the Michigan DNR Director in October 2014, following a public review. The remainder of the polygons were not included in the public review either because approval had not yet been received from the landowner or because at the time the ownership was unknown. The polygons that were not approved as ERAs will be considered during the next review of ERAs. The polygons were developed by starting with selected natural community element occurrence polygons (as created by Michigan Natural Features Inventory) and then clipping by ownership boundaries and management/protection zones.