Grizzly Island Wildlife Area: Tule Elk and 100,000 Wintering Ducks in the Suisun Marsh

The Suisun Marsh in Solano County is easy to overlook from Interstate 680 or Highway 12. Wikipedia calls it the largest brackish-water marsh on the West Coast. It forms where the Sacramento and San Joaquin rivers flow into Suisun Bay, and it is named for the Suisunes, a Patwin group who lived there. Grizzly Island Wildlife Area, run by the California Department of Fish and Wildlife, protects about 12,900 acres of it.

What lives there

The wildlife area mixes natural tidal wetlands with diked marsh. CDFW staff run pumps and waterways to create more than 12,000 acres of seasonal ponds that feed and shelter more than 100,000 waterfowl each winter. Some animals, like the California clapper rail and the Suisun shrew, live only in these tidal marshes. Visitors also come to see the tule elk herd, and the property has about 75 miles of roads and trails.

A marsh shaped by people

According to Wikipedia, market hunters shot ducks here for San Francisco from the Gold Rush until about 1880. Farmers then built levees and farmed the marsh, but the soil grew too salty, and farming and grazing stopped. Public agencies and private interests bought most of the land to keep it as waterfowl habitat.

Check before you go

CDFW says the wildlife area is closed to all non-hunting uses from late July, for the tule elk hunt, through the end of waterfowl season in early February. It can also close in winter because of flooding, and its West Unit has been temporarily closed since Jan. 9, 2026. Visitors must sign in and out at the booth at the entry gate. Cell service is limited.

During the closure, CDFW suggests other spots in the marsh: Hill Slough Wildlife Area, off Highway 12 on Grizzly Island Road before the bridge; Peytonia Slough Ecological Reserve, at the foot of Kellogg Street in Suisun City; and Belden's Landing on Grizzly Island Road, for fishing and launching boats.

To get there, take Highway 12 east from I-80 toward Rio Vista and turn onto Grizzly Island Road at the light by Sunset Shopping Center. The headquarters is at 2548 Grizzly Island Road, about 9.5 miles past the first one-lane bridge.