On May 1, the day Stanford University released its plans for Searsville Dam, an article titled "1000 dams down and counting" was published in the journal Science. This study showed that stream ecosystems are resilient and respond quickly and positively to dam removal. It also cautioned that current models are not very effective at predicting downstream effects. With that in mind, what should be the fate of Searsville Dam?
Santa Clara Valley Audubon Society and the Committee for Green Foothills started grappling with this question in 2011 when we were asked to support dam removal. Although removing a dam that no longer serves its original purpose of water storage is clearly an appealing idea, we were concerned about the many unknowns and decided not to take a position at that time.
We did not doubt that dam removal would facilitate passage of steelhead trout to their upstream historic spawning areas, but what were the likely impacts to other habitats and sensitive species that live in the watershed?
We were also concerned about increased flood risks to the 8,400 homes and businesses in the creek's historic floodplain in East Palo Alto, Palo Alto and Menlo Park. No dam-removal project located above a similar highly developed flood zone has ever been attempted. We asked ourselves, what are the risks to cities downstream? And what opportunities are associated with the dam that could be lost if it is removed?
Since we wanted more information before taking a position, we expressed an interest in comprehensive studies of options that included evaluation of all the risks and trade-offs. We were invited to join the 25-member Searsville Alternatives Study Advisory Group, which began meeting in early 2013. Other stakeholders included local elected officials, regulatory agencies, environmental and conservation interest groups, representatives of Jasper Ridge Biological Preserve, and residents concerned with upstream and downstream flooding risks.
For two years we heard presentations from many disciplines, asked questions, and reviewed studies, models and engineering and technological solutions. Our Advisory Group evaluated risks, discussed benefits and trade-offs, and considered alternatives, with each stakeholder contributing his or her own unique perspective.
As representatives of environmental organizations working in the communities of the San Francisquito watershed, we focused not only on fish passage but also on the larger suite of habitats and resources and the potential results of any action on the myriad species (and people) that share the watershed.
A particular concern was the potential loss of open water at Searsville reservoir (at a great cost to bat species); potential loss of up to 200 acres of wetlands and wetland/riparian forest (at a great cost to migratory bird species); and unavoidable sedimentation of the creek downstream and the Bay (with potential impacts to several endangered species and increased flood risks).
Stanford's Faculty and Staff Steering Committee also intensively studied Searsville's options on a separate, parallel track. Their recommended course of action: Create an opening at the bottom of the dam to drain the reservoir and flush out the fine sediment, with the intent that this will allow fish passage and provide attenuation of peak flood flows. Some habitats will be restored under this plan, while others will be reduced, relocated or lost. A major advantage of this option is that it is reversible; if models of sediment impacts and risks of downstream flooding prove inaccurate, and adverse impacts become evident in the watershed, the opening in the dam can be closed.
The Searsville Alternatives process now begins an intensive new phase of public and environmental-agency review. This process will be rigorous, particularly since many questions remain and details need to be fleshed out. There will be many opportunities for public engagement, and shovels in the ground will be several years away.
We thank Stanford University for inviting us to participate in the Searsville Alternatives Study Advisory Group and thank the other stakeholders who made it such an engaging educational experience. We are glad the collective wisdom of this process has chosen a cautious path forward.
Shani Kleinhaus, environmental advocate for the Santa Clara Valley Audubon Society, and Lennie Roberts, legislative advocate for the Committee for Green Foothills, can be reached at email@example.com and firstname.lastname@example.org respectively.