Officials took reporters on a tour of the dam and reservoir Wednesday afternoon, Jan. 16, to demonstrate the complexities they are up against, with probably 20 years left before the lake might dry up.
The lake is currently about 90 percent full of silt that has washed down from the creeks that feed into the reservoir west of Interstate 280. Roughly two-thirds of the lake area is now forested wetlands that have been reclaimed by trees and plants after 120 years' worth of silt has filled the valley.
Searsville is located in what is now Jasper Ridge Biological Preserve on Stanford land. The dam was built between 1888 and 1892 by the private Spring Valley Water Company, which was to supply water to San Francisco, Stanford professor David Freyberg said. Stanford acquired the reservoir and dam in 1919, but sediment problems were known even then, said Freyberg, a civil and environmental engineering professor.
In 2013, the university will decide what to do with Searsville — whether to restore the lake through dredging, allow the lake to fill in, partially excavate it, or divert the water to another area such as Felt Lake, officials said.
But aside from the expense involved in removing and disposing of the millions of tons of silt, what happens to Searsville could affect water flows downstream along San Francisquito Creek. Searsville was not built for or intended for flood control, Freyberg said, but it has been affecting the downstream environment for more than a century.
Palo Alto, Menlo Park and East Palo Alto are now all built up with homes and businesses abutting the creek. What effect removing the dam might have on downstream flooding has not yet been analyzed.
Stanford relies on the reservoir for 20 percent of its non-potable water for irrigation uses. Land-use issues, sensitive archaeological sites, and the effect on 130 migrating bird species, native plants and sensitive and endangered species such as the red-legged frog and steelhead trout, are among many issues related to Searsville, which sits in an environmentally sensitive area.
Because the dam does not allow the steelhead to swim upstream to spawning grounds, some environmental groups have demanded the university remove the dam. Beyond Searsville Dam and other organizations complained to the National Marine Fisheries Service, which has confirmed it is looking into investigating whether the impediment to the fish constitutes a "taking" of the species that would violate the Endangered Species Act.
Stanford spokeswoman Jean McCown, who is on the advisory task force looking into the many alternatives, said the federal investigation would not sway Stanford from taking a "responsible approach" to seeking a solution that would satisfy the many concerns the project poses. The university has been working regularly with the National Marine Fisheries Service on the project, but the investigation is coming out of a separate law-enforcement branch, she said.
The task force plans to have a list of options by the end of 2013, which would then be sent to university administrators for consideration. Many federal, state and local regulatory agencies will have to weigh in on and approve any plan.
Officials met with representatives of the San Francisquito Creek Joint Powers Authority on Tuesday to discuss flooding issues related to Palo Alto, Menlo Park and East Palo Alto, McCown said.
Staff Writer Sue Dremann can be emailed at email@example.com.
A six-minute explanation of the history and engineering of Searsville Dam and Reservoir by Stanford University professor David Freyberg has been posted on Palo Alto Online.