This site encompasses Big Muskego Lake, a large, shallow, muck-bottomed lake located in the City of Muskego, only a few miles from downtown Milwaukee. The lake contains islands of emergent vegetation and is fringed with cattail-dominated wetlands; sedge meadow and shrub wetlands also are found around the edges. The surrounding uplands have areas of woodland, agriculture, and residential development.
Its proximity to the state’s largest urban center notwithstanding, this IBA contains significant habitats for wetland birds. It hosts breeding populations of both Forster’s and black terns as well as marsh wrens, yellow-headed blackbirds, bitterns, rails, and waterfowl. Big Muskego Lake was one of the first places in southeast Wisconsin to which nesting ospreys and bald eagles returned. Great egrets, American white pelicans, and Caspian terns use the lake for foraging, and it also gets significant use as a stopover site by migrating waterfowl and shorebirds.