Searsville Dam

New Climate Change & Safety Concerns

Harmful algae production & methane emissions at Searsville Reservoir.
August 2010.

High Recorded Methane Emissions from Searsville Reservoir- Study Shows
Citing USGS studies of methane emissions from Searsville Reservoir, this report lists Searsville as having the highest recorded methane emissions of all 14+ international reservoirs studied (pg. 16 Table 3).
New Studies Show Methane Emissions from “Reservoirs are

a Globally Significant Source of Methane”.
Several new studies from leading researchers are finding that dams and reservoirs are a main source of methane emissions worldwide and that temperate reservoirs can emit as much harmful greenhouse gases as tropical reservoirs. Searsville Reservoir is particularly susceptible to elevated methane emissions due to high erosion rates upstream and nutrient input from adjacent horse facilities and upstream agricultural lands leased from Stanford.
1) This article and referenced reports describe how "reservoirs globally could emit up to 104 teragrams of methane annually. By comparison, NASA estimates that global methane emissions associated with burning fossil fuels totals between 80 and 120 teragrams annually."
2) Another 2013 study finds that "Sediment Trapped by Dams Creates Methane Emission Hot Spots"- Environmental Science and Technology
 3) This 2014 study finds that midlatitude dams and “reservoirs are a globally significant source of methane.” The study notes that the highest rates of methane emissions occur at in shallow reservoir areas and where sediment deltas are created at reservoir tributaries. The report notes that earlier studies have not always factored in this emissions hot spot are are likely under reporting emissions. Agricultural nutrient input and high sediment loads are identified as major contributors to high methane production in reservoirs. Searsville Reservoir is well-documented to have exceptionally high input of both sediment and nutrients as well as being a shallow reservoir with multiple, large sediment deltas at tributary streams.

4) New Global Warming Culprit: Methane Emissions Jump Dramatically During Dam Drawdowns  - ScienceDaily. This report finds that altering a reservoir's surface elevation and exposing submerged sediments leads to greater methane emissions. Searsville Reservoir's surface elevation has been documented to fluctuate up to 12 feet and some alternatives being considered would continue or expand methane emitting drawdowns.

Multiple methane emission pathways from a reservoir and dam. From Nature.


New 2014 UN Climate Change Report Identifies

Negative Impacts from Dams & Mitigation Needs

This seminal UN report identifies the “habitat impact” from dams and reservoirs as an environmental “concern” needing climate change mitigation actions. The report states with "high confidence" that species "extinctions will be driven by several climate-associated drivers" including "reduced river flows" and interaction with "eutrophication and invasive species". Searsville operations currently result in reducing, and often eliminating, downstream flows. The reservoir enables ongoing eutrophication and proliferation of invasive species that spread downstream. 

The UN report cites needed "management actions" to reduce risks to "terrestrial and aquatic ecosystem", which are relevant to considering the future of Searsville Dam, including "species migration and dispersal". The report cites a biodiversity adaptation objective to include “enhance capacity for natural adaptation and migration to changing climatic conditions” by providing “migration corridors”. Finally, the report identifies "reforestation" and "sequestration" of greenhouse gases as needed actions to protect ecosystems and reduce total emissions. 

Full report here.

These recommendations are critical for protection of San Francisquito Creek wildlife and deciding what to do with Searsville. For example, building fish passage around  a dam may provide only limited, single species migration while dam removal would create an unimpaired migration corridor for all aquatic and terrestrial species. Dam removal has been shown to both eliminate greenhouse gas emissions from the reservoir (and ongoing dredging) and to facilitate reforestation and carbon sequestration within the former reservoir area. At Searsville, dam removal and revegetation of the submerged reservoir area would add dozens of acres of carbon-capturing vegetation and natural habitat. With dam removal, Jasper Ridge Biological Preserve can reduce it's greenhouse gas footprint by eliminating a significant and ongoing methane source while increasing carbon sequestration.

Stanford / Carnegie Researcher Cites Need for Greater Methane

Emissions Data and Describes How Methane Emissions are Likely Higher than

Previously Thought
This report describes how methane emissions are drastically higher than previously thought. “The broad implication of the study is that we had shown very strongly that total emissions from the U.S. and total emissions from certain regions of the U.S. are potentially higher than what leading inventories would suggest,” said study co-author Anna Michalak, a researcher at the Carnegie Institution for Science in Stanford, Calif. “Something is missing from those inventories. We’re currently working with a faulty picture of what methane emissions in the U.S. look like.
National Science Foundation Reports Cite Negative Impact of Dams

and Significance of "Trout Streams" as an Ecosystem Indicator

1) National Academy of Sciences report uses “trout” as ecosystem service indicator.
"The group selected the indicator “trout stream miles” as a known forest indicator that could be applied in ecosystems that are relevant as trout habitat. Trout habitat requirements could become a proxy for other ecosystem services. Trout depend on the temperature regulation afforded by forest cover over streams; they depend on aquatic invertebrates, which are intolerant of polluted water and they depend on clear water that is not contaminated with sediment from runoff. If you buy the ecosystem service indicator of trout stream miles, you get at least three or four more indicators free." 

Native rainbow trout (and sea-run steelhead trout descendent) in Corte Madera Creek, isolated upstream of Searsville Dam. Photo- M. Stoecker

 “As the world scrambles to meet ever-growing water demands, the likelihood is that ecosystems will suffer untold damages. More than 50% of the world's wetlands have been lost since 1900, and as many as 80 fish species have become extinct. Sixty percent of the world's 227 largest rivers are subject to serious flow disruption from dams, diversions, and canals, leading to degradation of downstream ecosystems.

USGS Studies Describe How "earthquakes can be induced by impoundment of water in reservoirs"
These and other studies show that there is a significant safety "hazard", and liability risk, associated with maintaining a full reservoir or periodic filling and dewatering of a flood control reservoir. Studies show this to be a particularly relevant hazard at dams and reservoir adjacent to active earthquake faults such as the San Andreas Fault, which runs under part of Searsville Reservoir.

1) USGS- Man-Made Earthquakes

This USGS report states: "It has long been understood that earthquakes can be induced by impoundment of water in reservoirs"

2) USGS Reservoir-Induced Seismicity Study
This report states: "The probability of the occurrence of earthquakes at and in the region around a reservoir may be increased by impoundment."

"In some cases reservoir induced seismicity has been observed shortly after the initiation of filling."
In describing a proposed new dam project the USGS report states: "There is a need to pursue development of approaches to calculate how reservoir impoundment may affect earthquake probabilities at the (dam) site and its environs."

For years now, we have requested that Stanford conduct a study on the reservoir-induced seismicity potential of current Searsville Dam operations and alternatives being considered. We have previously shared the San Mateo County Dam Failure Inundation Area map, which shows widespread flooding of Stanford Campus, Menlo Park, Palo Alto, and East Palo Alto with a Searsville Dam failure. Searsville Dam is also identified by the U.S. Army Corps of Engineers as a "High Hazard" dam, whose failure would result in "probably loss of lives and significant property damage" (pg.5). Many of the 1000+ dam removal projects that have occurred around the country are due to dam owners wanting to eliminate the ongoing and elevating safety liability.


Other News



New Stanford Alumni Group Posts Online Open Letter Calling for Searsville Dam Removal


1,600+ Sign New Petition Asking Stanford to Remove Searsville Dam


The Usual Interview- BSD Director Takes on Searsville Dam

Take Action! Tell Stanford It's Time to Remove Searsville Dam

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Beyond Searsville Dam
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