Restoring the Sonoma Creek Marsh

Audubon California is nearing the end of a massive restoration of wetland habitat in San Francisco Bay.

Fat hawks perch on every second power pole on highway 37 between Marin and Vallejo, scanning the farmland on the north side of San Pablo Bay and the marshland on the south. Before hydrolic mining during the Gold Rush created manmade mudflats at the mouth of the river, these were once all wetlands. The farmland was created around 1900 when levees were constructed along the Napa River and maintained by the property owners.

In the 1960s and early 1970s, the US Army Corps of Engineers kept the levees in repair, but during the late 1970s, the levee to the Napa River failed and breaches were not repaired. During the floods of the early 1980s, tidal action reclaimed some of the area, creating the wetlands that exist today. The remaining agricultural land has now become too salty for most agriculture, and has been sold or abandoned.

Audubon California is working with the Marin-Sonoma Mosquito and Vector Control District and the San Pablo Bay National Wildlife Refuge to restore the ecological function of 400 acres the Sonoma Creek Marsh. Lead by Restoration Ecologist Rachel Spadafore, the project will rely on our network partnerships and provide hands-on educational opportunities for volunteers and students.

The construction of tidal channels will drastically improve the flow of the tides, cycle nutrients and provide habitat to marsh-dependent wildlife species, including federally endangered species like the California Ridgway’s Rail (formerly known as the California Clapper Rail), and the salt marsh harvest mouse.

Designated as an Important Bird area, San Pablo Bay and its surrounding wetlands provide critical habitat for the birds of the Pacific Flyway. Birders visiting the refuge can see Brown Pelicans, White-tailed Kites, Golden Eagles, Peregrine Falcons, Common Yellowthroats, and migratory shorebirds including Whimbrels and Willets.

The channels will also provide spawning and feeding grounds for endangered and commercial fish, improve water quality and reduce the amount of pesticides applied to pooled water to control mosquito populations.

Refuge from high tides becomes critical as extreme storm events and rising tides resulting from climate change become more frequent and more intense. The construction of a gently-graded high marsh transition zone will reduce flooding of adjacent private lands and provide crucial high tide refuges for rails and small mammals.

Finally, the project, as part of a larger conservation vision, has the potential to set precedence for other large-scale tidal marsh enhancement projects in the Bay Area.

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