Tidal Wetland Restoration at Cullinan Ranch and Sears Point - San Pablo Bay National Wildlife Refuge

Restoration at Sears Point near Petaluma, California

Tidal wetlands are a hot topic in restoration ecology. Since it was related to my work in 2015, I attended a field training in August to two exemplary sites in the North Bay region of the San Francisco Bay Area. These two sites, Cullinan Ranch and Sears Point, were at various stages of restoration. They are located on California Highway 37, a scenic route through protected bay and marsh lands that connects the City of Vallejo in Solano County with the City of Novato in Marin County. Both sites are within the San Pablo Bay National Wildlife Refuge, a huge federally protected complex that spans most of the northern shore of San Pablo Bay and its estuaries.

Tidal wetland restoration occurs where previously diked, bermed, or leveed tidal flows are brought back to their natural state. Generally, these tidal flows were blocked to protect agricultural lands, ranches, or other property from flooding. With such practice, valuable habitat for many fish and wildlife species is lost. When the berms, levees, or dikes are breached, natural tidal flow returns between the ocean, bay, sloughs, and rivers. Aquatic, mudflat, marsh, and upland habitats gradually return to the birds, fish, plants, and other life that once depended on them. With some additional help from restoration professionals and volunteers planting marsh and upland vegetation, biodiversity (different kinds of living organisms in an area) is restored, and natural ecosystem processes return. The effort is not always successful. Often, expected outcomes are not realized, and different approaches are needed. It can take many decades and many millions of dollars before the natural wetland ecosystem is fully restored.

Cullinan Ranch

Cullinan Ranch is just west of the Napa River and north of Highway 37. At Cullinan Ranch, restoration started in 2011 with a phased schedule through 2019. In 2015, we walked over land that would become inundated from breaching of levees, connecting the Napa River estuary with the bay. By 2019, the end goal was to finish breaching the levees so the tidal flows would create marsh and aquatic habitats for fish and wildlife. When I went back out there in 2019 and took a look, I saw a lot of water. The levees may have already been breached.

August 2015: Looking towards Highway 37 from a northern levee

March 2019: Looking from Highway 37 to the north 

One phase of the project included developing a parking lot with safe access from the highway, interpretive signage, and a levee trail dividing the national wildlife refuge and the State of California's Napa-Sonoma Marshes Wildlife Area Pond 1 unit. Public access at Pond 1 is available for people to enjoy walking through the tidal wetlands to view a variety of birds and other wildlife and for hunting and fishing. It includes a kayak launching dock and a viewing platform. In March 2019, tidal water inundated both sides of the trail. These tidal wetlands support many species of native fish and wildlife, including three-spined stickleback, tule perch, steelhead trout, California roach, Pacific herring, coast range sculpin, Pacific lamprey, and canvasback. They also provide habitat for threatened and endangered species such as Chinook salmon, Sacramento splittail, longfin smelt, salt marsh harvest mouse, and Ridgway's rail.

Cullinan Ranch trail, facing east, August 2015, during restoration

Same view from Cullinan Ranch trail in March 2019. Gulls are on the island and enjoy better fishing.

Sears Point

About four or five miles west of Cullinan Ranch is Sears Point, which starts at the intersection of State highways 37 and 121 and extends a good distance to the west. When people think of Sears Point, they probably think of the famous Sonoma Raceway where NASCAR and other competitions are held. What is less known is that Sears Point also has public access to the San Pablo Bay National Wildlife Refuge just opposite the Lakeville Highway.

Restoration of the Sonoma Baylands started as far back as 1995 to reconnect diked farmlands to the San Pablo Bay, and restored wetlands were incorporated into the national wildlife refuge. Partners included the Sonoma Land Trust, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, Ducks Unlimited, and others. In 2015, we saw Sears Point under construction, where the ground was was being contoured and filled with dredge to design and shape the landscape for marsh, slough, and upland habitats. The dredged material, essentially recycled from dredging projects in the San Francisco Bay, also raised the elevation in areas that had become subsided, meaning land that had sunk below sea level. Wetland vegetation was planted, and a levee was carefully built and sloped to protect the railroad and the highway while also providing upland habitat for marsh species. Today, the result is a naturally developing wetland ecosystem containing deep water, shallow water, mudflats, low marsh, high marsh, and higher elevation grasslands. Sears Point now has public trails, including the Sears Point trail, which is a portion of the San Francisco Bay Trail; a cellphone audio tour; and kayaking for outdoor enthusiasts.

Construction August 2015

Restored! March 2019

Cullinan Ranch is only accessible on the west-bound side of the highway. Sears Point is accessible when traveling from either direction. Driving both directions on Highway 37 is a worthy day trip if you're in the Bay Area. There are other access points for outdoor recreation, such as Skaggs Island and the Sonoma Creek Unit of the Napa-Sonoma Marshes Wildlife Area. Skaggs Island even holds raptor tours in the winter. A couple notes of caution: Avoid commute hours during the week, as this highway can be very slow and crowded. In very wet winters, check for flooding, as the highway is sinking below sea level.

Boat ramp and viewing platform - Cullinan Ranch 

Agriculture and nature may continue to be in conflict for years to come, but at least this restoration story is a successful one. San Francisco has no shortage of food supply, and the northern San Pablo Bay has no shortage of beautiful tidal wetlands, fish, and wildlife for generations to enjoy.