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Intertidal Habitats Being Restored At Cullinan Ranch

The scenery along Highway 37 is alluring in a desolate, understated way, with a view of both Mt. Diablo and Mt. Tam on clear days. A quick drive-by may reveal the occasional heron or bird of prey in the interlacing marshes and waterways, but without a closer look, the environment appears rather sparse. Appearance—in this case—is very deceiving.

These marshlands are home to numerous ducks, shorebirds—including the endangered California Clapper Rail—raptors, shrews and mice, and several species unique to the area. This sensitive eco-system also acts as an important filter for dirt and pollution, maintaining water quality in our bays.

Cullinan Ranch is the first vegetated tidal marsh adjacent to the San Pablo Bay. It comprises 1,500 acres and is bound by Highway 37 on the south and Duchman’s Slough on the north. The ranch has been slated for restoration since 1991, when it was purchased by the U.S. Fish and Wildlife Service. To understand the necessity for restoration, a snapshot of local history provides context.

The marshes and estuaries connecting to the San Pablo and San Francisco Bays are part of a 3,000-year-old network that once comprised over 200,000 acres. In the early days of the Spanish occupation, cattle were set out to graze on this land for most of the year, which is subject to seasonal water inundation due to high tide. Ranchers and farmers leveed and pumped the marsh in the 1850’s to allow year-round grazing and crop production.

After the land was blocked from seasonal water flow and subject to compaction by grazing cattle, it began to subside and is currently sunk 6-9 feet below sea level. Part of the goal in restoration is to raise the elevation.

Cullinan Ranch was primarily used for oat hay farming into the 1980’s, when it almost became a housing development called Egret Bay. Shifting public attitudes and awareness in the last fifty years began creating pressure for marshland development projects. After denial of the Egret Bay project the land was purchased by the USFWS.

Restoration funding is an entirely different animal, and it took about twenty years to acquire enough resources to start the project. Highway 37 also adds a difficult twist to this particular project. If the levee were breached without prior preparation, the road would flood. So, phase one includes a setback levee along 2.6 miles of the highway, with additional construction of acceleration and deceleration lanes.

The largess of the Cullinan Ranch project begins to hit home with a breakdown of its short and long-term goals. 26,000 feet of the northern levee will be lowered to allow for immediate creation of forty acres of intertidal habitat. In addition, breach locations have been selected along historic slough channels that will restore connection to adjacent waterways, but it’s projected to take at least sixty years for this aspect to reach its full effect. The projected breach date is January 2013. This should be an exciting event, as avian life will flock to feast on the influx of tidal invertebrates. This will jumpstart the return to a balanced ecosystem and create an inviting environment for the California clapper rail and dozens of other sensitive and endangered species, like the salt marsh harvest mouse, San Pablo song sparrow and Suisun shrew, and eleven species of fish that travel through San Pablo Bay to reach their spawning grounds. Other aspects—such as the complete regeneration of natural vegetation—will take some time.

Although ninety-two percent of the area’s marshes were destroyed between 1850 and 1930, some of the land surrounding Cullinan has already been restored, including adjacent salt ponds formerly owned by Cargill Salt Company.

Benicia is flanked by wetlands on three sides. Restoration to Martinez wetlands was started in 1992 after a 1988 oil spill. In 2006 a levee was breached at Little Honker Bay, creating seventy acres of wetlands in the Suisun Marsh. Benicia’s location amongst the Bay Area’s complex system of waterways affords it beautiful views and peaceful charm. If my great-grandparents had travelled here, they might have seen our marshlands in their pristine natural state, and if my grandchildren stay here, they may live to see it fully restored.

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