FAQs & Research

FAQs, Research & Important Links

Frequently Asked Questions


Portions of the western Delta where farming occurred on peat soils have been subject to oxidation and have subsided until they are today below sea level.  Levees in these areas are now engineered to rigorous standards to protect both people in the region and the variety of statewide infrastructure that crosses the area.  Most of the Delta is NOT subsided.

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The western edge of the Delta is 30 miles from the nearest active fault, the Hayward Fault.  Most Bay Area earthquake threat is associated with faults on the Peninsula or in the North Bay, which are even farther from the majority of Delta levees.  No Delta levee has ever failed in an earthquake, even before recent improvements that have brought levees to a high engineering standard.  The likelihood of earthquakes interrupting water deliveries is much greater along the California Aqueduct, which crosses blind thrust faults on the western side of the San Joaquin Valley, or in urban areas in the Bay Area and Southern California.  The best defense against interruptions in water deliveries is increased investment in local water systems.

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The likelihood of liquefaction is low and is confined mostly to levees that have been constructed on recent alluvial foundations.  Many Delta levees were constructed on peat soil, which is not subject to liquefaction.  Levees may move in response to seismic activity but do not collapse.  In addition, Delta levees are being engineered with wider bases to further lessen the chance of damage.  Urban areas in the Delta region rely on these kinds of robust levees for protection against flooding.


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The Delta smelt is a two- to three-inch fish native to the Sacramento-San Joaquin Estuary, where it lives in the freshwater-saltwater mixing zone except when it migrates upstream to freshwater to spawn.  It has a short (one-year) life cycle and is very sensitive to changes in flows and other habitat conditions.  Thus, adverse conditions that could later affect other aquatic species may affect Delta smelt first.  While the Delta smelt is not as well-known or useful to humans as the Chinook salmon that also depend on adequate Delta flows, the health of the smelt is an indicator of the health of the estuary as a whole.  It is somewhat like a caged bird in a coal mine that dies first if there are dangerous gases present that could kill miners.


Reductions in the numbers of Delta smelt have coincided with increases in water exports over the past 40 years that have dramatically altered freshwater flows.  Delta smelt have been listed as threatened under the Endangered Species Act since the 1990s, and exports have been reduced on numerous occasions in attempts to protect them.  No one disputes that millions of smelt have been killed at the export pumps in the south Delta, and other stressors such as predation and poor water quality have also contributed to their decline.


In an effort to maintain preferred levels of exports for the State and federal water projects, the Bay Delta Conservation Plan (BDCP) has focused on changing where or when freshwater is taken from the Delta and on creating habitat in hopes that it will compensate for changed environmental conditions that harm Delta smelt and other species.  However, no planning effort has seriously considered reduction of water exports to levels that can be sustained through both wet and dry years so that all fish have enough freshwater to recover and thrive.  Without that, no other efforts to protect the environment for fish and other species will be successful.

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The Delta is part of an estuary, so the mix of fresh water and salt water has always fluctuated with tides and seasonal flows.  During drier months, river flows lessen and the salinity of Delta waters increases. In the winter and early spring, river flows increase and push the salt water boundary further back toward the Bay. Overall, salt water levels vary throughout the Delta, with the greatest concentrations of salinity occurring on the west side of the Delta.

However, pumping increasing amounts of fresh water from the Delta for export has increased salinity in the South Delta, where powerful pumps sometimes actually reverse the flows of the San Joaquin River.  Troublesome non-native species have established themselves in this more saline environment, and native species often do not fare as well as they historically did.

Fisheries, agriculture, and people within the region and throughout the state are dependent on the Delta’s fresh water supply.  Many factors affect Delta water quality, including upstream urban and agricultural discharges, and legacy mercury from Gold Rush activities. But none is as important as the amount of fresh water flowing through the Delta.  For that reason, water management policies that help to maintain the Delta’s fresh water supply are of great environmental and economic importance.

Today, most of the fresh water in the Delta comes from the Sacramento River.  Efforts to divert the majority of flows from that river through giant tunnels under the Delta and to create compensating artificial habitat are a costly and problematic alternative to managing freshwater flows through the Delta for the benefit of the Delta region and the rest of the state.

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One of the arguments for building tunnels under the Delta to move Sacramento River water directly to the export pumps in the South Delta is that tunnels will protect export supplies from sea level rise.  Here are some things to bear in mind on this subject.


First, estimates of possible sea level rise in California vary tremendously.  There is little doubt that sea levels are rising, but the degree and rate of rise are somewhat speculative.  Delta engineers note that levees can be raised incrementally if necessary to keep up with gradually rising water levels.  This will have to be done anyway to protect people and property in the Delta, including infrastructure of statewide importance like highways, railroads, and water and gas pipelines.


Second, sea levels high enough to affect water transfers will likely also affect the proposed water intakes in the northern part of the Delta.  And long before this becomes an issue, large portions of the San Francisco Bay Area will be inundated.  The answer here is not to build expensive tunnels that we may not be able to use anyway (“stranded assets”) but to rethink how we manage water in California, focusing on ways to optimize regional self-sufficiency.


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ARkStorm means “Atmospheric River (AR) 1000 (k) (for precipitation levels expected to occur once every 1,000 years).  The U.S. Geological Survey (USGS) developed this hypothetical “superstorm” scenario that would be similar to storms that occurred in California in 1861 and 1862 and caused widespread flooding, property damage, and loss of life.   Under this scenario, rainfall would be so heavy that it would overwhelm the state’s normal flood management strategies and infrastructure.


Weather of this kind would cause flooding not just in the Central Valley, where the Delta is, but in Orange County, Los Angeles County, San Diego, and the San Francisco Bay area.  Interruptions to export water deliveries would represent a small part of the devastation and economic loss that such a storm would cause.  As is the case with earthquake threats, the best defense against interruptions in water deliveries under any disaster scenario is increased investment in local water systems.

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A number of sea water desalination projects are underway in California.  However, there are several problems with desalination.  First, facilities are expensive to build, and when water rates increase to pay for them, users tend to use less water, which in turn reduces revenues.  Second, the desalination process uses a lot of energy, which is costly and hard on the environment.  Third, the desalination process produces a lot of salt, which cannot be released back into the immediate environment without altering the ocean ecosystem.  Eventually, technology will develop solutions to all these problems, and the cost of desal will become competitive with the cost of water delivered by other means.  In the meantime, by far the least expensive way to get more water is through conservation.  Water recycling is also less expensive than desal.

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Most Delta farmers have what are called riparian water rights: rights to use water that is adjacent to their property as long as they use it for reasonable purposes.  By contrast, many users of export water receive it through infrastructure that has been built at public expense and for which they may not have paid the full cost; in that case, the water they use may reasonably be considered to be subsidized by taxpayers.


Where Delta farmers may be considered to benefit from some level of subsidy is in the maintenance of levees.  Delta landowners provide financial support for the local reclamation districts that maintain the levees they rely upon, but the State, through the Delta Levees Subventions Program, in some cases provides reclamation districts with matching funds for levee maintenance.  Voters, too, have approved investments in levees to protect both people and infrastructure in the Delta.  As a result of these investments over the last 30 years, the majority of Delta levees meet strict engineering standards, and the frequency of levee failures has decreased dramatically.

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While the Sacramento-San Joaquin Delta extends into five counties – Solano , Yolo, Contra Costa, Sacramento, and San Joaquin – the majority of its lands and waters fall within Sacramento and San Joaquin counties.  The Delta contains more than 738,000 acres of land, used primarily for farming. Within its primary zone, defined by the Delta Protection Act of 1992, more than 60 islands make up the 500,000 acres which cannot be developed.  Development is allowed in the Delta’s secondary zone and is occurring in a number of growing urban areas and communities such as Stockton, Lathrop, Tracy, Oakley, and West Sacramento.  In 2009, the Legislature passed the Delta Reform Act, which created a Delta Stewardship Council that will, among other activities, review future proposals for growth in the secondary zone.

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We should, and we do, share the state’s water resources.  The important question is how much we have to share.


California’s State and federal water storage and delivery systems were developed during a period in the 20th century that was, from a historical perspective, unusually wet, and they were developed at a time when the health of the environment was not a matter that most people gave any thought to.  Even then, though, planners knew that they would need additional projects to get all the water they wanted for their water redistribution system.  They planned to put dams on several rivers in Northern California in order to add 5 million acre feet (MAF) of water per year to the State Water Project’s supply.  That would have given them a total of 8 MAF.


However, in the early 1980s, those rivers were given Wild and Scenic Rivers status and became unavailable for development.  Water managers knew that without the extra 5 MAF, they would not be able to meet projected demands after the year 2000; they were getting only three-eighths – about 37% – of the water that they originally planned for.  Unfortunately, pressures for urban and agricultural development overwhelmed the regulatory system, which couldn’t seem to say “No” when users asked for more water.


There are various estimates of how much more water has been promised than can actually be relied upon.  In 2009, Phil Isenberg, who had chaired Governor Schwarzenegger’s Delta Vision Blue Ribbon Task Force, testified before the state’s Little Hoover Commission.   He said that the Task Force had learned that the total sum of 6,300 water rights in the Delta watershed exceeds the average annual flow of the watershed by 8.4 times.  The sum of the promised water is 3 times the highest recorded annual flow.


According to the California Water Atlas, California has 50,000 water rights holders.  These water rights holders claim that they divert about 250 million acre feet of water each year.  But California receives just 71 million acre feet of usable water from annual precipitation on average.  Even allowing for the fact that water can be used more than once, this is a significant disparity.


“Paper water” – paper promises of future water that may not actually be there – has supported urban growth is some parts of California where it might not otherwise have occurred.  Growers in the San Joaquin Valley have planted high value, thirsty permanent crops like almonds and pistachios in the expectation that they could somehow wring the water they needed every year, even in a drought, from the state’s over-subscribed system.  In addition, both urban and agricultural users have relied on groundwater to supplement surface water supplies.  The result is that in many parts of the state, and particularly in the San Joaquin Valley, groundwater has been dangerously depleted.


Even Bay Delta Conservation Plan (BDCP) planners recognize that water diversions from the Delta cannot continue at the volumes that exporters became accustomed to in the 1990s and 2000s, as fish populations plummeted. And drought conditions statewide make it clear that no amount of water transfers from north to south and west can compensate for California’s unrealistic ideas about how much water it has to work with.   Certainly, twin transfer tunnels will not provide any additional water in a drought, which California can expect to experience one-third of the time.

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The Bay-Delta is an estuary, which means that the whole system, from the High Sierras to the Golden Gate and beyond, needs water to be healthy.  Water that flows to the Pacific is not wasted.  It supports a complex food chain necessary for the health of multiple fish species and mammals, even Orca whales.  Flows through the Delta and the estuary support California’s iconic Chinook salmon, on which a multi-million dollar commercial and recreational salmon fishing industry stretching north to Alaska depends.  Dr. Jeffrey Michael of the University of the Pacific estimated that when California’s salmon fishery was closed in 2008 and 2009 due to collapsing fish populations, 1,823 jobs and over $118 million in income were lost.

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Here’s what the Bay Delta Conservation Plan, on its Your Questions Answered page, has to say about fracking:


“The California Department of Water Resources does not regulate the uses to which State Water Project supply is put.


“State constitutional restrictions require the reasonable and beneficial use of water, and state laws require that water pumped from the Delta be put to stipulated beneficial uses. Beneficial uses include agricultural, municipal, and industrial consumptive uses; power production; and in-stream uses including fish protection flows. Fracking presumably would be an ‘industrial’ use of water.”


So yes, water from the Delta could be used for fracking.

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Handouts and Research Documents


Restore the Delta: Save the SF Bay Delta & There’s a Better Solution

Restore the Delta: Earthquake Fact Sheet; Addressing myths

Restore the Delta Response to the BDCP Presentation by Paul Helliker (DWR Director)

Map and Table: Users of Delta Water Irrigating Selenium-Impaired Soils in the San Joaquin Valley

Map: Peripheral Tunnel Project Relative to Existing Delta Infrastructure

Pie Chart and Table: Where Does Delta Water Go? And What For?

Average Annual South of Delta Water Deliveries, 2000-2009

California Sportsfishing Protection Alliance (CSPA) Bill Jennings PowerPoint: San Joaquin Waters & BDCP


Restore the Delta Comment Letters on Legislation


Water Bond Information: Restore the Delta comments
Joint Comment Letter: SB848 to (Wolk) – Safe Drinking Water, Water Quality, and Water Supply Act of 2014

Joint Comment Letter: AB2554 (Rendon) – Clean, Safe, and Reliable Drinking Water Act of 2014″>Joint Comment Letter: AB2554 (Rendon) – Clean, Safe, and Reliable Drinking Water Act of 2014

Joint Comment Letter: AB1331 (Rendon) – Clean, Safe, and Reliable Drinking Water Act of 2014


Restore the Delta Comment Letters on BDCP


Restore the Delta Joint Letter with Environmental Justice Groups
Request for Restarting and Extending Bay Delta Conservation Plan Comment Period Due to Lack of Meaningful Access for Limited English Speakers

Environmental Water Caucus Comment (EWC) Letter on BDCP Plan and EIR/EIS
Comments on the Draft BDCP and Draft BDCP EIR/EIS

Restore the Delta Public Comment Letter on Draft BDCP and EIR/EIS Plan (added 7.17.14)
Comments on the BDCP and Associated Draft EIR/EIS


Restore the Delta Comment Letters on Drought Barriers

Letter to California Department of Water Resources, March 16, 2015
Letter to Army Corps of Engineers, March 30, 2015
Restore the Delta’s Annotated Guide to the Governor’s Drought Proclamation of April 1, 2015


Restore the Delta Protest-Petition on TUCP(temporary urgency change petition)

Restore the Delta’s Protest-Petition to SWRCB February 13, 2015
Restore the Delta’s Protest-Petition to SWRCB, DWR, and USBR May 5, 2015

Useful Links and Documents


Link to Delta Protections Commission’s Economic Sustainability Plan
Link to Environmental Water Caucus Responsible Exports Plan
Link to website for Delta Protection Commission