Refuge Units


The Detroit River International Wildlife Refuge is the only International Wildlife Refuge in North America.  The refuge includes islands, coastal wetlands, marshes, shoals, and waterfront lands along 48 miles of Detroit River and Western Lake Erie shorelines.  

  • Mud Island


    The 22-acre Mud Island and surrounding shoals is the northernmost unit in the Refuge.  The constructed island is made of dredge material contained by a surrounding dike.  A forest has naturally developed and includes red maple, silver maple, green ash, cottonwood and willow, creating stopover habitat for neotropical migrant birds during spring and fall. Warbling vireos are continually heard in the breeding season from the tops of the cottonwoods.   

    The 71.5 acres of shallow shoals surrounding the island are, on average, 2 feet in depth and important to spawning fish.  Between the mainland (City of Ecorse) and the island is the Ecorse Channel  – a popular fishing location for local residents. The aquatic plants there are diverse, and dabbling ducks and swans are commonly seen in abundance feeding on them. A shipping channel exists east of the island with an expansive wild celery bed mid-stream that connects to Grassy Island. These wild celery beds are full of fish and animal life.

    Mud Island is closed to the public.

  • Grassy Island

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    The 72-acre Grassy Island is constructed of contaminated dredge material surrounded by dikes. The Refuge also manages 232 acres of shallow shoals including the former Mamajuda Island. At least 30 species of fish are found around the Grassy Island shoals, including rock bass, yellow perch, and emerald shiner – many of which also spawn there.  Numerous aquatic plants such as muskgrass, pondweeds, and especially wild celery are abundant and provide food for waterfowl. Rocky shallows and fast current create good fish spawning and nursery habitat for species like walleye, which require habitats that keep their eggs well oxygenated. 

    The island has naturally become forest and is dominated by cottonwood, box elder, staghorn sumac, and willows with a significant area covered by Phragmites stands. The island has demonstrated high use by neotropical migrant birds during spring and fall. Mamajuda Island became submerged by the 1960s during higher water levels after having housed a lighthouse and residents from 1849 until 1910 and later a flashing light tower until about the 1950s. 

    Grassy Island is closed to the public.

    View additional information about Grassy Island.

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  • Calf Island


    A naturally formed island in the lower Trenton Channel of the Detroit River, the 11-acre Calf Island provides important stopover habitat for migratory songbirds. Each end of the island is flanked by high quality wild celery beds important for fish and waterfowl. A forest has naturally developed after an interesting past including use by farmers for keeping their calves and a home-site. Today the ruins of old structures are still visible and old lilac bushes used to landscape the property still waft their scent on spring breezes. On the north side of the island, an emergent wetland is present, surrounded by willows.  A number of mature red and swamp white oaks also exist on the island. The trees and shrubs on the island are often “dripping” with warblers, tanagers, vireos, flycatchers, and many others in both spring and fall.

    With the exception of hunting, public use activity on the island is prohibited at this time.

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  • Gibraltar Bay Unit


    Much of the upland of Gibraltar Bay Unit was once used as a former D-51 Nike Missile site.  The site was home to 30 anti-aircraft Nike Ajax missiles, 12 launchers, and two radar towers between 1955 and 1963. The embankment to Gibraltar Bay continues to protect the former launcher area from the water. After the site clean-up was complete in 1998, the launcher area was seeded with native grasses and wildflowers to benefit pollinating insects. A shoreline habitat project was completed in the mid-2000s, introducing a number of native plants. 

    Water flows through the embayment from the east side of Grosse Ile and its aquatic plant community is diverse. Emergent species are threesquare, arrowhead, pickerelweed, flowering rush, and American lotus and submergent species include pondweeds, wildcelery, muskgrass, and many others. This bay is important for bass, pike, and long-nose gar and is well-known for its ice-fishing.

    The Gibraltar Bay Unit is the first unit of the Detroit River IWR to open to the public daily from dawn to dusk. Location is at 28820 East River Rd, Grosse Ile, Mi.


  • Sugar Island


    Situated on the southeast end of Grosse Ile, just one mile from Bob-lo Island and 1.5 miles from Amherstburg, Ontario, the 30-acre Sugar Island is fascinating from a fish and wildlife perspective, although its recent cultural history is no less interesting. 

    The state-endangered channel darter is found around the island’s quick currents and rocky substrate.

    Migratory songbirds use the forest, but the fall hawk migration is most significant, with large flights of hawks and vultures often moving east from directly overhead. The only two significant sand beaches on the Michigan side exist on the east and west sides of the island during years of lower “average” water levels. These beaches are locally unique with threesquare and rufous bulrush at the ever-changing water’s edge. Willows, silverweed, milkweeds, and others can be found in the island’s sandy environment. The forest is particularly diverse and includes a stand of young sugar maples.

    Sugar Island was the site of a major amusement park in the late 1800s which included a dancing pavilion, restaurants, boat rental, and even a roller-coaster. 

    With the exception of hunting, public use activity is only allowed Memorial Day through Labor Day and is limited to the beach on the western side of the island. 

    Learn more about Sugar Island


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  • Refuge Gateway Property


    The Refuge Gateway property is adjacent to the Refuge's Humbug Marsh Unit in Trenton, Michigan and is the location of the Refuge’s Visitor Center.  This 44-acre industrial brownfield was the home of a Chrysler automotive plant until 1990; today, all of the land surrounding the Visitor Center is owned by Wayne County and cooperatively managed with the Refuge.  The site has been cleaned-up and converted to wetland and upland habitats and will includes a world-class boat dock and fishing pier, greenway trails, and a kayak and canoe launch. Completion of these projects is anticipated in 2017.

    Learn more about the Refuge Gateway property. 

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  • Humbug Marsh Unit


    The Humbug Marsh Unit is a major part of the “Conservation Crescent” of the lower Detroit River (including Humbug mainland, Calf Island, Gibraltar Bay, and Sugar Island) and a hotspot of biodiversity in this urban landscape. Adjacent to the future Refuge Gateway to the north, Humbug is mostly forested with some habitats kept relatively open through regular cutting. Humbug Marsh was designated as Michigan's first "Wetland of International Importance" by the Ramsar Convention on Wetlands in 2010. 

    Most of the habitat is influenced by prolonged flooding during wet seasons due to poorly drained soils. There are a few distinctive and naturally formed higher elevation ridges along the shoreline that create a truly unique landscape.  Full-grown oaks exceeding 150 years old are scattered about, while shagbark hickory, ash and elm dominate in a mosaicked fashion across the unit. Early successional habitats kept open by cutting exhibit lots of wildflowers for pollinators such as bee balm, mountain mint, ironweed, goldenrods, milkweed and many others that host butterflies, bees, and moths to name a few. The coastal wetlands are dominated by bulrushes, grasses, cattail, Phragmites, and sedges. An ever-changing habitat based on Great Lake water levels, the coastal wetlands are high quality habitat for interesting fish and wildlife. 

    Learn more about the Humbug Marsh Unit of the Detroit River International Wildlife Refuge. 

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  • Gibraltar Wetlands Unit

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    This 360-acre unit is only one half-mile from the 410-acre Humbug Marsh Unit and 1,607-acre Lake Erie Metropark – a significant amount of natural area in an urban landscape. Brownstown Creek flows through the unit fringed by a zone of cattail and Phragmites, and by river bulrush and blue-joint grass closer to shore. A small stand of wild rice grows along the shoreline. Stands of mature black walnut and pin oak are present along with large swaths of dogwood and buckthorn shrub creating valuable migratory bird habitat. The large wetland mitigation on the south half of the unit contains emergent wetland, reed-canary grass and hardwood swamp (mainly green ash, silver maple, cottonwood, and willow). Black-crowned night herons, marshbirds, pied-billed grebes, and many other species are found here. 

    The Gibraltar Wetlands Unit is situated adjacent to the Gibraltar Carlson High School and is frequently used by the school's Wetlands Science classes.

    This unit is closed to the public.  

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  • Lake Erie Metropark


    Lake Erie Metropark is managed in cooperation with the Huron-Clinton Metropolitan Authority.  The habitats of the Metropark are a mix of coastal wetlands and early-successional forest. The coastal wetland area is one of the largest in western Lake Erie and are relatively unobstructed by dikes (levees), so that habitats naturally take form based on Lake Erie’s short term and long-term water levels. Many different wetland habitat zones can be viewed exhibiting different types of vegetation based on elevation. This creates lots of different types of habitat for a wide range of fish and wildlife.

    Learn more about Lake Erie Metropark.


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  • Strong Unit


    Another unit highly influenced by Lake Erie water levels, the 204-acre Strong Unit contains emergent wetland, a former shoreline ridge of swamp white oak trees, and wet prairie. The size of the wet prairie is significant with blue-joint and reed canary grass, sedge, rose mallow, boneset, swamp milkweed, and other wildflowers. The southern 36 acres is a mix of hardwood swamp and a 17-acre “old field”, or wet prairie that produced soybeans until 2014 and is now fallow after having been seeded with native wildflowers and grasses to benefit pollinating insects and other wildlife.  

    The Strong Unit is open to self guided exploration.  

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  • Brancheau Unit


    The Brancheau Unit includes a high quality coastal wetland as well as a 67-acre marsh created by two artificial impoundments that were completed in 2010. A high abundance of soras (a marshbird), marsh wrens, moorhens, coots and pied-billed grebes use the unit for nesting when habitat conditions are suitable. Least bitterns can be heard calling some years and are periodically seen when they rise above the cattails. Migrating Wilson’s snipes are particularly abundant in September on the mudflat areas, along with numerous other shorebird species. Fall at the Brancheau Unit can be successful for hunters taking teal, gadwall, wood duck, and mallard. There are another 50 acres of recently fallowed old field that were augmented with native wildflowers and grasses in 2014.

    With the exception of hunting, public use activity on the Brancheau Unit is prohibited at this time. 

    Learn more about the Brancheau Unit of the Detroit River International Wildlife Refuge. 

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  • Fix Unit


    The Fix Unit is mostly former agricultural land that is now fallowed and will be made more consistently wet by a series of water control structures and a pump to be installed in 2016. The eastern section has an interesting wet prairie community of blue-joint and reed canary grass, Phragmites, and characteristic wildflowers in these types of habitats including boneset, grass-leaved goldenrod, swamp milkweed, spotted joe-pye weed, and others.  This unit is adjacent to the Michigan Nature Association’s Swan Creek Plant Preserve which has abundant American lotus. 

    The Fix Unit is open to self guided exploration.  

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  • Lagoona Beach Unit


    The Lagoona Beach Unit is managed cooperatively by the Refuge in partnership with DTE Energy. The 656 acres of existing hardwood swamp and coastal wetland are a part of an embayed estuary (drowned river mouth) and is influenced by Lake Erie such as water level fluctuation, sediment accretion and accrual, as well as nutrient, seed, and animal exchange to name a few of the many processes.    

    The Lagoona Beach Unit is closed to the public.

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  • Ford Marsh Unit


    Ford Marsh is a contiguous 180 acres of wetland adjacent to the River Raisin, Lake Erie, and habitat at Sterling State Park – a significantly large wetland complex on the western Lake Erie landscape. Currently dominated by white water lily and approximately 3 feet of water, hundreds of waterfowl have been seen staging here during migration including shovelers, teal, American black ducks, and gadwall. 

    Refuge staff can adjust water levels to provide cyclical periods of low and high water levels, which provides optimum habitat diversity for a wide range of wildlife.

    The Ford Marsh Unit is closed to the public.

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  • Plum Creek Bay Unit


    The Plum Creek Bay Unit is influenced by wind events that dictate the amount of water in the bay. Strong west winds blow water out, while east winds flood the bay. Plum Creek flows into this bay at the northwest corner and contains a number of springs on the south side. 

    Sora and Virginia rail are particularly abundant during nesting and migration. Shorebirds like least and semipalmated sandpipers, yellowlegs, killdeer, and herons and egrets are frequently seen in the mudflats and shallows of this unit.

    With the exception of hunting, public use activity on the Plum Creek Bay Unit is prohibited at this time

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  • Lady of the Lake Unit


    This unit is cooperatively managed with Consumers Energy and is 49 acres on 680 meters of western Lake Erie shore frontage situated next to the J.R. Whiting Power Plant. This unit is connected to additional wetlands owned by Consumers Energy. The cooperatively managed wetland is connected to Lake Erie via a 12-inch overflow pipe discharging into the LaPointe Drain Channel and subsequently, Lake Erie with a flap gate to prevent water Lake Erie from entering the wetland. The Lake Erie side of the wetland is a bermed trail with a sand beach worked by wave action on the east side. Unhardened sand beaches are rare along the western Lake Erie basin. The scarcity of the water/beach interface in this region makes this unit important conservation land.

    The Lady of the Lake Unit is closed to the public.

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  • Holloway Unit


    The Holloway Unit is a slice (in terms of the surrounding landscape) of the Erie Marsh and Erie State Game Area. Much of it is covered in American lotus with recent water levels. The uplands contain a mix of shrub and grassland habitat.

    The Holloway Unit is closed to the public.

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  • Erie Marsh Preserve

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    A cooperative unit with The Nature Conservancy, the preserve and adjacent Erie State Game Area is one of the largest contiguous coastal marshes along the western basin, and very significant in preserving a vast array of the region’s flora and fauna.

    The Erie Marsh Preserve is closed to the public.

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  • Gard Island


    Gard Island is managed cooperatively with the University of Toledo.  The 19-acre island is located within North Maumee Bay.

    Gard Island is closed to the public.

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