Tomales Bay and its watershed are a resource-rich part of Marin County. Tomales Bay is included in the Gulf of the Faralones National Marine Sanctuary. It is also part of the Central California Coastal Biosphere Reserve and the Western Hemisphere Shorebird Reserve Network (TBWC 2003 1). In 2002, the U.S. Fish and Wildlife Service (USFWS) designated Tomales Bay as a Wetland of International Importance (TBWC 2003). The National Audubon Society has recognized the Bay as an “Important Bird Area.”
The Tomales Bay watershed has intertidal, subtidal, and benthic habitats as well as dunes, mud flats, salt marshes, and freshwater marshes (TBWC 2003). Large eelgrass beds grow in the northern half of the Bay with smaller ones lining the eastern shore. Small islands provide roosts for birds and haul out areas for marine mammals. Tomales Bay subwatersheds include Inverness, Lagunitas Creek, Walker Creek, and east shore drainages such as Millerton Gulch, Grand Canyon, and Tomasini Canyon.
The Inverness subwatershed is a collection of many small creeks draining into the west shore of Tomales Bay. These creeks include Haggerty Gulch, Fish Hatchery Creek, Redwood Creek, and First, Second, and Third Valley Creeks.
The Lagunitas Creek subwatershed is the largest drainage into Tomales Bay. Its major tributaries include San Geronimo Creek, Devils Gulch, Cheda Creek, Nicasio Creek, and Olema Creek. At the southwestern edge of the watershed, Olema Creek flows in nearly a straight line through a rift valley along the San Andreas Fault zone. The subwatershed includes the Kent, Alpine, Bon Tempe, Lagunitas, and Nicasio reservoirs. The San Geronimo Valley is the last un-dammed headwaters of Lagunitas Creek, and is considered critical Coho salmon spawning and juvenile rearing habitat. In response to concerns about the effects of further development in the watershed on Coho salmon populations, Marin County DPW has prepared a draft San Geronimo Valley Salmon Enhancement Plan.
Topography in the 76-square mile Walker Creek watershed ranges from 1,500 feet to sea level where the creek empties into Tomales Bay just south of its mouth. The northern tributaries, Keyes Creek and Chileno Creek, flow through wide valleys with gentle, grassy hills. The upper watershed is much more rugged with extensive areas of coast live oak forest. The watershed contains a 220-acre natural lake, Laguna Lake, at the top of Chileno Valley. Soulajule Reservoir, constructed in 1968 in Arroyo Sausal and enlarged in 1980, is managed by the Marin Municipal Water District (MMWD).
The small tributaries draining the east side of Tomales Bay include Millerton Gulch, Grand Canyon, Tomasini Canyon, and other unnamed tributaries. These small watersheds occur on both public and private lands.
1 Tomales Bay Watershed Stewardship Plan.
Learn more about the history and habitat of the Tomales Bay watershed.
Winter Weather Outlook
The National Weather Service's Climate Prediction Center anticipates that there will be a strong El Niño this upcoming winter and their latest precipitation outlook for December through March indicates that Marin is likely to receive higher than average amounts of