Tour outlines shared challenges to San Francisquito Creek watershed

Stanford faculty and staff recently participated in an educational tour of the San Francisquito Creek that emphasized the complexity of shared challenges created by human intervention in the historic waterway and suggested the need for coordinated solutions.

Kate Chesley Searsville Dam

Searsville Dam was the starting point for a recent tour of the San Francisquito Creek watershed for people interested in the future of the watershed.

The name San Francisquito Creek literally connotes "little" San Francisco in Spanish. But the creek's impact is anything but little for the humans, plants and animals dependent on its water for life.

Flood worries, sediment buildup, industrial runoff, protection of endangered species, proliferation of invasive species, drought and the impacts of climate change are among the challenges facing the many communities and organizations – including Stanford – working to create a sustainable future for the creek and its watershed.

Members of those organizations, as well as local residents, gathered recently for a watershed tour sponsored by the Committee for Green Foothills, a nonprofit organization that preserves open space and natural resources in San Mateo and Santa Clara counties. The tour started in Stanford's Jasper Ridge Biological Preserve, below where the watershed begins at the crest of the Santa Cruz Mountains, and ended where the creek empties into San Francisco Bay at Friendship Bridge between East Palo Alto and Palo Alto.

The tour took participants through areas both bucolic and urban. Each stop revealed the effects of human intervention on the creek, which marks the boundary between Santa Clara and San Mateo counties.

Highlighted were the efforts of groups such as Acterra, which is reintroducing native plant species along creek banks in Palo Alto; Beyond Searsville Dam, which works to remove barriers to steelhead migration; Citizens Committee to Complete the Refuge, which enhances the tidal marshes at the mouth of the waterway; and the San Francisquito Creek Joint Powers Authority, which addresses issues of flooding and environmental protection for communities located along the creek.

50 square miles, 20 creeks

The San Francisquito Creek watershed is about 50 square miles and encompasses more than 20 creeks. Many of the streams merge halfway between the mountains and the bay into San Francisquito Creek. Over thousands of years, the creek has carried sediment downstream to create the alluvial fan upon which Atherton, Menlo Park, Palo Alto, East Palo Alto and Stanford were developed.

The tour started at Searsville Dam, located in the Jasper Ridge Biological Preserve. Built by the for-profit Spring Valley Water Company in the late 1800s, the dam was designed to provide water to the newly created Stanford University and San Francisco. The dam created Searsville Lake, flooding the site of the town of Searsville, which served the sawmill industry. The dam and surrounding areas were purchased by Stanford in 1919.

Today, the area is part of Jasper Ridge, founded in 1973. Students and scholars use the wetlands created by the dam and lands near the reservoir to pursue field research into such areas as biodiversity, climate change, species extinction and ecosystems – all with the intent to bring greater understanding to natural systems.

Searsville Lake is also a source of non-potable irrigation and fire protection water for Stanford. However, the ongoing drought has interrupted Searsville water diversions since about a year ago.

Stanford speakers participating in the tour combined to tell the story of the dam, the 1,200-acre Jasper Ridge Biological Preserve, the environmental research that takes place there and the university's efforts to conserve water and create sustainable water management plans benefiting the watershed.

The university has launched a comprehensive study of the future of Searsville Dam that includes faculty members whose areas of expertise focus on environmental sustainability, water and land management, biology and engineering. Committee members have been weighing such issues as research and educational activities at Jasper Ridge, university water supply needs, the environmental effects of the dam on habitats and wetlands and flood risks. Of particular concern is the more than 125 years of sediment buildup, which has reduced the water capacity of Searsville Reservoir by more than 90 percent.

Sediment 'poster child'

The sediment is the result of the highly friable nature of rocks in the Santa Cruz Mountains. With each earthquake or heavy rain, sediment enters the creek in abundance. As a result, Searsville Dam has become a "poster child for sediment issues," according to dam expert David Freyberg, associate professor of civil and environmental engineering.

The faculty and staff committee studying the dam's future is expected to make recommendations about what the university should do by the end of the year. Possible changes include dredging the reservoir, bypassing the dam or altering or removing it.

"The issue has less to do with what we decide to do and more with how we go about doing it," according to Philippe Cohen, executive director of Jasper Ridge. He explained that the regulatory agencies that will review any university dam proposals expect precision. The complex environmental issues involved in the dam suggest a need for flexibility.

"If we do what we are going to do wrong – and we do it wrong in a big way – we do it wrong permanently," Cohen said, adding that some of the debates about the dam's future are over "competing ecological values."

Once the committee's recommendations are in place and the dam's future decided, Stanford will be able to create long-term water management plans for the campus, according to Tom Zigterman, Stanford's associate director of water services and civil infrastructure. Zigterman explained to tour participants that campus conservation efforts have already reduced Stanford's domestic water use by 21 percent. That number is expected to increase to 36 percent with the completion of the Stanford Energy System Innovations project in 2015. Like many Bay Area communities, Stanford gets its drinking water from the Hetch Hetchy Reservoir in the Sierra Nevada. Nonpotable water comes from groundwater and local surface water.

"The main thrust of everything we do with energy and water is sustainability," Zigterman said.

Zigterman said the university is keenly aware of water users and residents downstream on San Francisquito Creek and seeks to create a long-term solution for Searsville and a sustainable water management plan that represents a "comprehensive solution that is coordinated." As a result, modeling for Searsville Dam alternatives includes projected impacts all the way to the bay.