Counties: Oconto

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Oconto Marsh. South Marsh, 17 Aug. 2000. Sedge meadow. Photograph, E.J. Judziewicz.

Site Description

Oconto Marsh is one of the largest wetlands along the western shoreline of lower Green Bay, surrounding the Oconto River mouth and stretching several miles to the north and south. Most of the site is owned by the state (as part of the Green Bay Shores State Wildlife Area), but there are some private inholdings. Most of the wetland, particularly around the delta, is a complex of sedge meadow and emergent marsh, though shrub swamp is also present in association with these communities. Patches of swamp hardwood forest are also present further inland and on small islands in the river channel.

The main marsh area features low beach ridges and swales and abandoned oxbows and meanders of the Oconto River near the river's delta at Green Bay. Fluctuations in water levels caused by seiches and long term water level changes are large enough to have an impact on vegetation composition and extent and type of wildlife habitat

The marsh is an important breeding area for birds and receives significant use from migrating waterfowl and shore birds. It is important to many species that have been forced to abandon former habitat in the southern part of the bay because of high water levels, wetland filling and pollutants. A number of rare animals inhabit this site.

Water quality remains a problem in Green Bay. Point pollution and nonpoint discharges into the Oconto River may adversely affect the marsh. There is development pressure on the marsh's western edge and in the areas bordering the city. The primary use of the site is recreation.

Additional Comments

Significance of this site is high owing to the size of the marsh and its values to rare animals. Continued work is needed on water quality and invasive species control.