EAST PALO ALTO, CALIF. — On New Year’s Eve, four inches of rain devastated East Palo Alto when San Francisquito Creek spilled over and flooded a neighborhood of mostly low-income households seated between the creek and Highway 101.
Marisela Ramos, president of the East Palo Alto West Side Neighborhood Committee, told KQED that most of the city’s residents do not have flood insurance and are struggling to receive aid for the damages.
This is not the first time East Palo Alto has faced these muddied waters.
In 1998, a similar flood struck the same neighborhood, as well as Palo Alto and Menlo Park. In the early morning hours of February 3, the creek overflowed its banks and swamped houses, streets, and vehicles. Firefighters were relegated to rescue residents by boat. The Palo Alto Daily Post estimated total repairs of damaged property during the 1998 flood at $28 million, and later revised the figure to a heaping $40 million.
As the affected residents of East Palo Alto grapple with the damages of this winter’s flood, a horrifying reality looms: these floods will become more commonplace in the future.
A recent study from the Pacific Northwest National Laboratory found that with warming global temperatures, the total precipitation area covered by future winter storms could increase by 22 percent in the Western United States. The PNNL also predicted a 10 percent increase in the “sharpness” of these storms—the degree to which precipitation is concentrated within the storm area. California already hosts particularly sharp winter storms, putting the state at a higher risk of flash floods compared to other Western states.
But in the years leading up to this most recent flooding event, California was plagued by one of the worst droughts the state has ever seen.
The fractured San Francisquito Creek Watershed and the ecological succession of its affiliated ecosystems tell a focused story of the impacts of drought, flooding, and human impacts on the natural world.
In 1892, Searsville Dam was built, impounding the San Francisquito Watershed to form Searsville Reservoir. The dam is located in Jasper Ridge Biological Preserve and is owned and operated by Stanford University. Since the reservoir was closed to the public in the 1970s, it has lost 90 percent of its original water storage capacity and has largely been filled in by sediment. This dramatic reduction in storage capacity is among the largest contributors to flooding events along the San Francisquito Creek.
Since its closure, researchers at Jasper Ridge Biological Preserve have documented drastic ecological succession in both the preserve at large and around Searsville Reservoir over these recent years of extreme drought.
Jasper Ridge has documented much of this ecological succession on their Twitter account over the last few years. In 2020, they documented the increased persistence of drought-adapted flora, like toyon—a variety of coastal sage scrub. In 2021, they observed other indigenous flora suffering, like the large groves of dying Manzanita trees found across the Preserve.
Around Searsville Dam, entirely new ecosystems have formed. On March 25, 2021, the Preserve Tweeted: “the willows in this picture did not exist many years ago. As ecological succession occurs in the upstream area of Searsville reservoir, a marsh is now developing with[in] these willows.”
Jasper Ridge has also witnessed dramatic changes in the Preserve’s fauna over recent years. Native species like the western pond turtle and the yellow-legged frog are now classified as threatened and near-vulnerable, respectively, by the International Union for Conservation of Nature. The red-legged frog, classified as threatened by the U.S. Fish and Wildlife Service, has not been logged in the Preserve’s species sighting list since 2007.
Perhaps even more concerning is the status of the steelhead trout, whose populations are threatened across Central and Northern California. The trout have historically lived in the waters below Searsville Dam, a structure which has already impacted their livelihood, but have been spotted by the Preserve more infrequently in recent years as the lake began to dry up from the drought.
The threats to both the ecosystems and the human neighbors of the San Francisquito Watershed are urgent. In the Preserve’s blog, they express concerns that without intervention, “sediment eroding from the Santa Cruz Mountains will completely fill the reservoir and overflow the dam—influencing downstream hydrologic behavior and potentially altering flooding dynamics.”
Restorations to various parts of the San Francisquito Creek watershed are currently underway, in large part from the San Francisquito Creek Joint Powers Authority, an agency that formed in response to the 1998 flood.
Their multi-stage restoration project first launched in 2019, when the agency completed the first reach. In this segment of the plan, the JPA widened the downstream creek channel and built larger levees in the region spanning from the San Francisco Bay to Highway 101. The agency claims that this work will provide an additional 10 feet of protection from rising tides compared to today’s high tide levels.
The second reach, which would restore the recently flooded upstream region spanning Highway 101 to the Pop-Chaucer Bridge, is currently in its planning stages. The agency proposes widening the channel, increasing the volume of water allowed to flow under the bridge, and ultimately protecting the surrounding community from a potential 100-year flood event. The proposed third reach would involve the creation of additional holding reservoirs upstream of Searsville Dam.
The JPA’s main concern at this time is funding for the second and eventual third reach of the restoration project. During the agency’s Board of Directors meeting on January 26, 2023, the JPA announced they were still short on funds for the second reach, which is slated for completion between 2024 and 2026. The JPA’s executive director Margaret Bruce recently told NPR that it would cost “at least $50 million to restore about a mile of the creek.”
Amidst debate regarding the dam’s existence and how to restore the creek to its natural flow, the Searsville Reservoir has gained national attention.
An ongoing exhibit at Berlin’s Haus der Kulturen der Welt features Searsville Reservoir as one of twelve—now honed down to nine—global sites currently up for consideration for a reference site to define a new geological epoch: the Anthropocene.
The candidates for this global reference site are all considered “golden spikes” or “GSSPs” for this human-defined geological epoch. GSSPs—Global Boundary Stratotype Section and Points—are geologic reference points that indicate the beginning of a new stage in our planet’s history.
The evidence from each site will be assessed by the Anthropocene Working Group, an international body of scholars working to formally determine whether or not the “Anthropocene” fits the criteria for a new geologic epoch distinct from the Holocene. After selecting a site, the AWG will submit their recommendation to the International Commission on Stratigraphy for approval.
Searsville Reservoir is of particular interest because of its unique sediment cores from the lakebed. The Jasper Ridge Biological Preserve's blog asserts that these sediment cores are so important because they “tell a story that is echoed in most other kinds of geological deposits that have been studied, revealing global, regional, and local signals of how the planet changed in the mid-20th century—exactly the time that the Anthropocene has been proposed to begin.”
The AWG will be assessing signposts including the first appearance of the human-made element plutonium, evidence of the increased burning of fossil fuels, and other geochemical signs that point to human-induced changes to the climate. Jasper Ridge notes that the most compelling evidence found at Searsville are found in the changes to subfossil pollen and aquatic microbiota.
Searsville also sets itself apart from other candidates due to its rapid deposition rate over the past few decades. The relatively quick accumulation of sediment in the lakebed allows records to be read and compared in much more minute detail than that of typical sedimentary deposits.
The AWG is yet to make their final selection. Final deliberations began late in 2022, and it is likely they will announce the proposed GSSP site sometime in 2023.
The devastation wreaked on those living around Searsville Reservoir and the affected San Francisquito Creek Watershed is immense. If the creek and reservoir restoration goals—and funding—of the JPA can be met, however, there is hope for the safety of both the local residents and for the threatened species that inhabit the region.
And if Searsville Reservoir is selected as the GSSP for the Anthropocene, there is much reckoning to be done. One lakebed can hold so much: a history of floods, drought, and species endangerment, and the very place where our human touch jettisoned the earth into a new form of existence.
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