| Searsville Dam | |
|---|---|
Searsville Lake and dam, heavy reservoir siltation visible |
|
| Location | Northwestern Santa Clara and San Mateo County, California, USA |
| Construction began | 1890 |
| Opening date | 1892 |
| Owner(s) | Stanford University |
| Dam and spillways | |
| Type of dam | Masonry |
| Height | 65 ft (20 m) |
| Base width | 275 ft (84 m) |
| Impounds | Corte Madera Creek in the San Francisquito Creek watershed |
| Type of spillway | Service, stepped |
| Reservoir | |
| Creates | Searsville Lake |
Searsville Dam is a masonry dam that was completed in 1892, one year after the founding of Stanford University, and impounds Corte Madera Creek (in the San Francisquito Creek watershed) to form a reservoir known as Searsville Lake.[1] Searsville Dam is located in the Jasper Ridge Biological Preserve and is owned and operated by Stanford University. Neighboring cities include Woodside and Portola Valley, California.
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The dam caused the partial inundation of the small and declining town of Searsville and the Searsville Hotel, which was founded by John H. Sears in 1854 to support the local logging industry. It was owned by the Spring Valley Water Company.[2] In the 1906 San Francisco earthquake the dam suffered a "fingers-width" crack in the cement at the east end, however this was patched.[3]
The 65-foot-tall (20 m) and 275-foot-wide (84 m) Searsville Dam consists of a series of interlocking concrete boulders that resemble a massively steep staircase. After leasing the lake for recreational use for 50 years, the Stanford Board of Trustees closed public access to Searsville Lake in 1975 in forming the Jasper Ridge Biological Preserve. The reservoir has lost over 90% of its original water storage capacity as roughly 1.5 million cubic yards of sediment has filled it in. Searsville Dam does not provide potable water, flood control, or hydropower.[4]
The dam poses an impassable barrier to migrating salmonids which is significant because the San Francisquito Creek watershed hosts the most viable remaining native Steelhead trout (Oncorhynchus mykiss) population in the South San Francisco Bay.[5] A May 2002 steelhead trout migration study reported Searsville Dam as the only complete barrier to migration on mainstem San Francisquito Creek (construction of a fishway in 1976 resolved passage at the Lake Lagunita diversion dam 2.5 miles below Searsville Dam), and that elimination of the Searsville dam could restore ten miles of anadromous steelhead habitat.[6] A genetics study of San Francisquito Creek steelhead in 1996 found that the fish are native and not of hatchery stock.[6]
Several lines of evidence support the historical presence of Coho salmon (Oncorhyncus kisutch) in San Francisquito Creek. Archaeological remains of unspecified salmonids ("possibly Coho") were reported by Gobalet in the creek.[7] Leidy concluded that coho salmon were likely present and cited that the most suitable habitat for coho salmon was in perennial, well shaded reaches of mainstem San Francisquito Creek, and several small, perennial tributaries including Los Trancos, Corte Madera, Bear, and West Union creeks.[8] In addition, three independent oral history sources indicate that coho salmon were abundant in the creek through the first half of the twentieth century.[9][10] According to local historian Dorothy Regnery's notes from her 1966 interview with Edgar H. Batchelder, who was 2 years old when his father became caretaker of Searsville dam in 1897, "When the dam was "wasting", or overflowing, in the winter salmon would swim upstream as far as the base of the dam. Using a pitchfork Mr. Batchelder could spear them to supplement the family's menu." His "favorite place to fish for trout was in the Dennis Martin Creek".[3] A second source described catching "steelhead and silver (coho) salmon in San Francisquito Creek and the Guadalupe River System in the 30’s and 40’s. He said that the Guadalupe River also had runs of Chinook salmon (Oncorhyncus tshawytscha) that were very large in wet years."[10] Thirdly, Dennis L. Bark, a senior fellow at the Hoover Institution, recalls playing on San Francisquito Creek around 1947: "Salmon swam up it, and in winter it was a dangerous place."[11] The historical range of Coho salmon overlapped geographically with San Francisquito Creek. It is definitely established that Coho salmon were historically present in other San Francisco Bay streams such as San Mateo Creek and Alameda Creek.[12] Also, the southern limit of Coho salmon in coastal California streams was recently confirmed to extend through Santa Cruz County based on both archaeological evidence and historically collected specimens.[13]
The future of the dam and reservoir is in question and has become politically heated. A 2007 study by the Jasper Ridge Advisory Committee describes five main options
The Center for Ecosystem Management and Restoration (CEMAR) has issued comments on Stanford University's April 2010 document, "Draft Environmental Impact Statement for Authorization for Incidental Take and Implementation of the Stanford University Habitat Conservation Plan" (HCP DEIS), finding that because the Searsville Dam project involves water diversion, bypass flows, and potentially major and ongoing dredging for 50 years, that the impacts of operating the diversion dam must be analyzed in the HCP EIS. CEMAR Certified Fisheries Professional, Gordon Becker, has requested that the impacts that the EIS should address include "blocking steelhead and other Covered Species access to habitat, altering downstream hydrology and water quality in San Francisquito Creek, introduction, perpetuation, and dispersal of exotic species, degrading downstream habitat, dewatering, and other direct and indirect take of Covered Species".[15]
A vocal group argues that the dam should be removed. In addition to concerns about access to upstream salmonid spawning grounds, Searsville Dam inundated former wetlands formed by the confluence of Corte Madera Creek, Sausal Creek, Dennis Martin Creek and Alambique Creek. These wetlands likely served a valuable historical function by removing sediment and pollutants from the San Francisquito Creek mainstem. Anti-dam proponents point to a growing trend in habitat restoration nationally with over 500 dams removed in recent years.[16]
The Jasper Ridge Advisory Committee feels that the dam removal does have many drawbacks. There is no guarantee that removing the dam would restore steelhead habitat and it would destroy habitat used by many birds and bats. In addition the removal of the dam and accumulated alluvial sediment would be complex especially given the downstream communities and environment.[14] Stanford University uses water from the lake to irrigate its golf course and other athletic facilities on its campus.[17]