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Uploaded: Thursday, January 17, 2013, 7:00 PM
Stanford officials look to solve Searsville dilemma
120-year-old dam created lake that is nearly full with accumulated sediment
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by Sue Dremann
Palo Alto Weekly Staff
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| Stanford University officials are facing a mountain of decisions regarding what to do with Searsville Reservoir, which is slowly filling up with silt, in addition to dealing with a federal investigation for possible violations of the Endangered Species Act.
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 west of Interstate 280 is currently about 90 percent full of silt that has washed down from the creeks that feed into the reservoir. 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, he said.
The steering committee hopes to finish its studies by 2013, but realizes that it won't be making recommendations until 2014 -- 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 2014, 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.
LISTEN ONLINE: David Freyberg talks about the history and engineering of Searsville Dam and Reservoir and why it is 90 percent full of silt on Wednesday, Jan. 16 (6 minutes).
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Posted by Steve, a resident of the Menlo Park: Central Menlo Park neighborhood, on Jan 18, 2013 at 12:28 pm
Is there an opportunity here that, while not solving all the problems identified, goes a long way toward mitigating many of them?
Perhaps the silt should be seen as a resource to be recovered and utilized over the long term rather than as a problem to be gotten rid of all at once. Silt is the type of soil that ever gardener wants, especially in the towns along the bay where impervious clay is the more common soil type. If the silt were dredged and made available to private gardeners and both commercial & civic landscaping services, I expect that we would come to see it as a resource to be valued & utilized rather than the "millions of tons of silt" that need disposing.
Removing it at a rate of 5% to 10% per year would allow Searsville Lake to eventually return to health, providing increasing flood control for the communities below, water for Stanford's irrigation and, perhaps, recreational & educational opportunities for future generations.
Adding a fish ladder to the dam would be the crowning touch as steelhead could once again access the spawning beds upstream from the lake.
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Posted by Brent Britschgi, a resident of another community, on Jan 18, 2013 at 4:03 pm Any discussion of THE Lake brings back fond memories of our younger days swimming in the lake, diving off of the pontoons in the middle and taking in the rays on the beautiful beach. And of course our days extended into in the evening when we would have early super among the trees. Also, we became very resourceful in our ways of avoiding the toll booth at the gate.
What a shame we no longer have this recreation resource. I see nothing in the report that mentions recreation nor did I hear anything in the fascinating oral report about the dam.
Our conservation arm is lucky that I have no say over the future of the lake, because if it was up to me I would restore it to the recreation use it once was...
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Posted by Matt S., a resident of the Portola Valley: other neighborhood, on Jan 20, 2013 at 1:38 pm Hi Brent- I totally understand the desire to restore recreational activity at the reservoir. My dad went to Stanford and took my mom on dates there back in the day. My brothers and I fished it growing up. For better or worse, it will not be reopened for recreation as Stanford has more research studies going on there now than when they closed it to protect the studies.
Hi Steve- I agree with you that there are many uses for the sediment, including many more times the amount in Searsville that is desperately needed for SF Bay wetland restoration efforts and to help combat rising sea levels as this sediment is what builds up those wetlands during high tides.
While fish ladders and fishways are attractive options to consider, more and more studies are showing that these high tech options are not very effective and often cost millions of dollars to build and maintain. Here is a great recent article and study on this problem related to large dam on the east coast with sea-run fish:
Web Link
In addition to the issues described in the article and other west coast studies, fish ladders are challenging in flashy watersheds like San Francisquito and particularly Corte Madera Creek , where Searsville Dam sits, as relatively high surface flows are needed to properly operate such facilities. Additionally, adult steelhead that do make it above dams and reservoirs to spawn (as well as their numerous downstream migrating offspring) must be trapped as they migrate back downstream to avoid being eaten by the high density of non-native fish in the reservoir and in order for them to safety make it downstream of the dam. Then they need water to swim to the Bay and this is further depleted by the huge evaporation rates from the reservoir and Stanford's diversions at the dam itself. Fortunately, we expect a thorough investigation of these issues and options as Stanford's technical studies progress this year.
Previous Stanford studies have also determined that even if Searsville was dredged to it's original capacity, it's significance on flood protection downstream would be very minimal and potentially on parr with benefits gained by restoring natural wetlands and overflow floodplain areas currently submerged by the reservoir.
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