California Department of Fish and Wildlife

Grizzly Island WA - General Information


Take 1-80 north from San Francisco, south from Sacramento. Take Highway 12 off-ramp east toward Rio Vista. Turn onto Grizzly Island Road, at the stoplight at Sunset Shopping Center. Hill Slough Wildlife Area is on both sides of Grizzly Island Road from Highway 12 to the first one-lane bridge. The Grizzly Island Complex Headquarters is 9.5 miles further on Grizzly Island Road.


Nature viewing, hiking, photography, dog training, fishing, and hunting of waterfowl, dove, pheasant, tule elk, and rabbit.


* Complete Area Regulations for hunting, fishing, and other uses can be found at


Access roads, parking areas, restrooms, public phone, maps and literature, disabled access for nature viewing, angling, and waterfowl hunting. No camping is allowed.

General Description

With 84,000 acres of land, bays and sloughs, the Suisun Marsh is significant: it is the largest contiguous estuarine marsh in the entire United States. The Grizzly Island Complex occupies about 15,300 acres of this prime wildlife habitat. The complex is a patchwork of 10 distinct land parcels, many of which are not connected and are surrounded by private land. They offer a variety of recreation opportunities and act as a vital buffer against further marsh development.

The Grizzly Island Complex combines natural tidal wetlands and artificially diked marshes. Each habitat attracts a special kind of wildlife. Pass some hours along the bay or on the graveled foot trails at Peytonia Slough... Experience the renewing rhythm of the tides, the changing complexion of marsh life. Some animals, like the California clapper rail and Suisun shrew, live exclusively in these tidal wetlands.

Fish and Gamers manage extensive waterways and pumps to create more than 8,500 acres of seasonal ponds. Plants like alkali bulrush and fat-hen are encouraged. This carefully managed combination of high nutrient food and resting ponds sustains more than 100,000 waterfowl that winter at Grizzly Island each year.

The remarkable mix of marsh scenery and wildlife has attracted nature lovers, hunters, anglers and others for decades. Boats and canoes drift easily on the tidal sloughs. There are 75 miles of roads and trails, and several self-guided hiking trails are being planned. Many dirt roads reveal otter crossings, but you'll also notice bicycle tracks and human footprints: there are lots of ways to experience Grizzly Island Wildlife Area.

You may also find tule elk tracks. A small group of this protected species was reintroduced to the Grizzly Island Unit in 1977 and they have prospered. In fact, several hundred of their offspring have been captured and relocated to start new herds in places these native elk once favored.

Rare, Threatened and Endangered Species

Salt marsh harvest mouse, peregrine falcon, California clapper rail, California black rail, bald eagle, Suisun aster, soft-haired birds beak.

Nearby Attractions

Brannan Island State Park, Rush Ranch, Jepson Prairie Preserve, Lagoon Valley Lake, Rockville Hills Park