Beyond Searsville Dam Coalition, spearheaded by Portola Valley native Matt Stoecker, talked to a crowd that packed the outdoor-gear store Patagonia on Alma Street in Palo Alto, which hosted the event.
The dam, built by the Crystal Springs Water Company in the foothills and completed in 1892, is the biggest limiting factor to steelhead trout spawning in San Francisquito Creek and its tributaries. It blocks 10 miles of habitat, he said.
Stoecker has been waging a lonely campaign for 10 years, ever since he saw a steelhead vainly try to breach the 60-plus-foot-high dam.
Stanford is currently seeking approval for a 50-year Habitat Conservation Plan from federal and state officials that would be the guiding principle of conservation, restoration and areas of potential development.
Stoecker and his supporters want Stanford to put dismantling the dam into the Habitat Conservation Plan, he said.
Stanford, however, favors keeping the dam, a position favored by scientists at Jasper Ridge Biological Preserve, where Searsville Dam is located, just south of the Stanford Linear Accelerator Center.
Stanford favors removing the sediment that has built up in the past 118 years. About 90 percent of the dam's water-holding capacity is blocked with sediment. The dam is expected to top off with sediment in 15 to 40 years, according to scientific reports.
Jean McCown, a Stanford spokeswoman, said the Habitat Conservation Plan commits the university to a study of the dam in 10 years.
The university has been considering what to do with the dam since at least the late 1990s. A position paper by the Stanford's Jasper Ridge Advisory Committee called removing the dam "a highly experimental project" that would be "complex and challenging."
Philippe Cohen, administrative director of Jasper Ridge Biological Preserve, said that conditions have changed since the dam was built. The area downstream from the dam has grown much more populated and residential.
The main problem with removing the dam today is that sediment currently being held back behind the dam would flow further downstream, through creeks in Woodside, Portola Valley and Palo Alto, then further through the San Francisquito Creek to East Palo Alto and the San Francisco Bay. No one knows exactly what that would mean for residents, Cohen said.
"With the change in the amount of sediment, how it's going to change flooding is a really tricky question," he said.
But Steve Rothert, California regional director of American Rivers, which has helped get numerous dams removed, said Tuesday night there are ways to prevent downstream problems after the dam is removed.
Computer modeling for other projects proved to be accurate in predicting where problems could occur, he said.
Taking steps to ease sediment and flooding problems for the similarly sized San Clemente Dam in the Carmel area costs an estimated $70 to $80 million. Much of the costs are paid for by funding from federal, state and private sources, he said.
Stanford hasn't been passive when it comes to the dam, however. Its Department of Civil and Environmental Engineering has been working on studies in the last four years related to the accumulation and management of sediments and how water flows through the system.
Researchers hope their work will help make management decisions about the dam.
Stoecker and Rothert said their groups will try to pressure Stanford, holding informational meetings, engaging residents in letter-writing campaigns, adding a legal and outreach component and forming student-based groups.
"We have an amazing opportunity to improve the watershed health," he said.
Other longtime watershed supporters are not yet committing to a position on the dam. The nonprofit Committee for Green Foothills was considering taking a position a few months ago but decided not to until the factors related to downstream flooding are known, said Lennie Roberts, San Mateo County advocate for the committee.
There needs to be much more study of the potential impacts, she said.
"There are a lot of countervailing concerns," she added.
A longer version of this article is posted on Palo Alto Online.