|Source||Confluence of Arroyo Sausal and Salmon Creek|
|⁃ elevation||233 ft (71 m)|
|south of Preston Point|
|0 ft (0 m)|
|Length||18.5 mi (29.8 km)|
|⁃ left||Verde Canyon, Frink Canyon|
|⁃ right||Chileno Creek, Keys Creek|
Walker Creek is a northwest-flowing stream in western Marin County, California, United States. It originates at the confluence of Salmon Creek and Arroyo Sausal and empties into Tomales Bay south of Dillon Beach, California.
Keys Creek is named for Irish settler John Keyes, who settled on the creek in 1849 and used this once-important waterway to transport agricultural produce to San Francisco.
Watershed and course
The Walker Creek watershed drains 76 square miles (200 km2) and ranges from 1,500 feet (460 m) to sea level where the creek empties into Tomales Bay just south of its mouth. The Walker Creek mainstem is formed by the confluence of Arroyo Sausal and Salmon Creek.
Arroyo Sausal heads at about 789 feet (240 m) and flows northwest, crossing Point Reyes-Petaluma Road into Hicks Valley then west to Soulajule Reservoir. This reservoir was constructed in 1968 in Arroyo Sausal and is managed by the Marin Municipal Water District (MMWD).
The California Office of Environmental Health Hazard Assessment has issued a safe eating advisory for any fish caught in Soulajule Reservoir due to elevated levels of mercury and PCBs.
From here Arroyo Sausal joins Walker Creek at elevation 236 feet (72 m) at Marshall-Petaluma Road.
Salmon Creek heads at 800 feet (240 m) and flows west 4.5 miles (7.2 km) along Hicks Valley Road then Marshall-Petaluma Road to meet Arroyo Sausal and form Walker Creek. Salmon Creek was described historically as a salmon and steelhead trout (Oncorhynchus mykiss) spawning and nursery area, although it has been seriously damaged by poor farming practices, dairy pollution and soil erosion.
From the confluence of Arroyo Sausal and Salmon Creek, Walker Creek descends to the northwest, paralleling Marshall-Petaluma Road as it curves westward. At the mouth of Verde Canyon, the creek crosses under the road and turns northwest, passing the mouth of Frink Canyon to a confluence with Chileno Creek. At the top of the Chileno Valley, a 220-acre (89 ha) natural lake, Laguna Lake, which straddles the Sonoma County - Marin County border and is the source of Chileno Creek, which flows 6.25 miles (10.06 km) west along Bolinas Ridge to Walker Creek.
From the Chileno Creek confluence, Walker Creek meanders westward, passing south of the town of Tomales, California. It crosses under Highway 1 at milepost 44.45 and is immediately joined by Keys Creek, entering from the north.
Keys Creek heads at 290 feet (88 m) and flows 3.5 miles (5.6 km) west through the town of Tomales below which it joins Walker Creek.
Below Keys Creek, Walker Creek continues southward along the Highway 1 to enter Tomales Bay just east of Preston Point.
In the early 1900s, coho salmon (Oncorhynchus kisutch) were abundant in Walker Creek, but were nearly extirpated apparently due to severe erosion and siltation secondary to overgrazing and logging operations. In 1975 D. W. Kelley performed a comprehensive investigation of steelhead trout (Oncorhynchus mykiss) and coho salmon populations. He found small numbers of steelhead young-of-the-year in all viable habitat areas in the watershed, but only eight coho near the confluence of Chileno and Walker Creek. In addition, the Soulajule Reservoir dam blocked all anadromous salmonid fish migration to Arroyo Sausal. California Department of Fish and Game (CDFG) began planting coho salmon from Olema Creek into Walker Creek in 2003 with modest success. In 2008 and again in 2013 coho returned to Walker Creek, Salmon Creek and Frink Canyon. Fishing for steelhead is open only below Highway 1.
Portions of Keyes Creek immediately downstream of the present Highway One bridge were once navigable and used to ship locally-grown potatoes by barge to San Francisco. The current small size of the channel at this location, more suitable for a canoe than a barge, is dramatic evidence of siltation due to erosive agricultural practices in the Walker Creek watershed over the past 150 years.
Mercury was mined at several sites in the Walker Creek watershed through the 1960s and early 1970s including the Gambonini, Chileno Valley, Franciscan and Cycle mines. Soulajule Reservoir, built after a severe drought in 1976–1977 inundated the Franciscan and Cycle mines and a tailings pile. The largest mine, at the Gambonini Ranch near the confluence of Salmon Creek and mainstem Walker Creek, closed in 1970.
- U.S. Geological Survey Geographic Names Information System: Walker Creek
- David L. Durham (2001). Durham's Place Names of the San Francisco Bay Area: Includes Marin, San Francisco, San Mateo, Contra Costa, Alameda, Solano & Santa Clara Counties. Word Dancer Press. p. 190. ISBN 9781884995354.
- Jack Mason, Helen Van Cleaver Park (1976). Early Marin, 2nd Edition. North Shore Books. p. 153.CS1 maint: uses authors parameter (link)
- Erwin G. Gudde, William Bright (1998). 1500 California Place Names: Their Origin and Meaning. University of California Press. p. 193. ISBN 9780520920545.CS1 maint: uses authors parameter (link)
- U.S. Geological Survey Geographic Names Information System: Arroyo Sausal
- Admin, OEHHA (2009-03-18). "Soulajule Reservoir". oehha.ca.gov. Retrieved 2018-11-13.
- U.S. Geological Survey Geographic Names Information System: Salmon Creek
- J. T. Allen. Salmon Creek Survey (PDF) (Report). California Department of Fish and Game. Retrieved 2015-08-09.
- "Chileno Creek". Geographic Names Information System. United States Geological Survey.
- Lauren Hammack, Prunuske Chatham, Inc. (August 10, 2005). Geomorphology of the Walker Creek Watershed: Projects for Habitat Enhancement and Sediment Management (PDF) (Report). Marin Resource Conservation District. p. 16. Retrieved 2015-08-09.CS1 maint: multiple names: authors list (link)
- D. W. Kelley (April 1, 1976). The Possibility oRestoring Salmon and Steelhead Runs in Walker Creek, Marin County (PDF) (Report). Marin Municipal Water District. Retrieved December 26, 2017.
- Marin Municipal Water District (MMWD), Garcia and Associates (GANDA) (March 2010). Walker Creek Salmon Monitoring Program Final Compilation Report (Report). California Department of Fish and Game. Retrieved 2015-08-09.CS1 maint: uses authors parameter (link)
- Mark Prado (October 22, 2013). "Young, endangered coho salmon seen in Walker Creek for the first time in five years". Marin Independent Journal. Retrieved 2015-08-09.
- "Tomales Bay Watershed". Marin County Department of Public Works. Retrieved 2015-08-09.
- Mark Prado (May 28, 2006). "Tainted Reservoir: Fish contaminated with mercury in Marin's Soulajule". Marin Independent Journal. Retrieved 2015-08-09.