State Water Board Issues Draft Delta Flow Criteria and Requests Comments for August 3 Approval Meeting

July 22, 2010

The State Water Resources Control Board (State Board) on July 21 issued a report recommending draft flow criteria for the Sacramento-San Joaquin Delta (Delta).

The draft criteria feature increased Delta outflow and increased inflow from the Sacramento and San Joaquin rivers, including their tributaries:

  • 75% of unimpaired Delta outflow from January through June;
  • 75% of unimpaired Sacramento River inflow from November through June; and
  • 60% of unimpaired San Joaquin River inflow from February through June

The State Board said it will decide whether to approve the draft criteria at its August 3, 2010, meeting. That decision will be informed by the report, oral comments presented at the August 3 meeting, and written public comments received by noon on July 29, 2010.

The Delta is the logistical delivery hub for the largest single source of fresh water supply in California. The State Water Project (SWP) and federal Central Valley Project (CVP) deliver fresh water through the Delta to irrigate millions of acres of farmland and for drinking by more than 25 million Californians living in two-thirds of the state’s households from the Bay Area, to the San Joaquin Valley and Central Coast, to as far south as San Diego. The Delta also supports water supplies for local in-Delta towns and farms, and major Delta tributaries are principle sources of public water supply. For example, the San Francisco Public Utility Commission’s Hetch Hetchy system on the Tuolumne River and the East Bay Municipal Utility District’s system on the Mokelumne River serve millions of Californians living in the San Francisco Bay Area.

The State Board’s report responds to SBX7-1 (SB 1), the Sacramento San Joaquin River Delta Reform Act that was passed in late 2009. With respect to Delta flow criteria, SB 1 provides:

"For the purpose of informing planning decisions for the Delta Plan and the Bay Delta Conservation Plan, the board shall, pursuant to its public trust obligations, develop new flow criteria for the Delta ecosystem necessary to protect public trust resources. In carrying out this section, the board shall review existing water quality objectives and use the best available scientific information. The flow criteria for the Delta ecosystem shall include the volume, quality, and timing of water necessary for the Delta ecosystem under different conditions."

(Water Code § 85086(c)(1).) Under SB 1, the State Board’s final flow criteria report must be submitted to the Delta Stewardship Council within 30 days of approval.

The State Board report comprises some 190 pages addressing a range of legal, factual and scientific issues involving water rights, administrative procedures, the current state of the Delta, and various anthropogenic and biological changes that have occurred in the Delta since California’s development following the gold rush. However, the report cautions that the flow criteria do not consider any balancing of resource protection with public interest needs for water supply. The report states that sufficient information was considered to support the need for increased flows to protect certain ecological public trust resources, but the report also describes significant uncertainty in establishing specific numeric Delta flow criteria.

The significance of the Delta flow criteria recommendations must be considered in light of how public trust considerations are actually applied in management of California’s water resources. According to the California Supreme Court, the Public Trust Doctrine does not elevate in-stream ecological use of water above the development and use of public water supplies for consumption and use away from their natural sources. (See National Audubon Society v. Superior Court of Alpine County, 33 Cal.3d 419, 445-446 (1983) [rejecting “unbalanced” interpretation of Public Trust Doctrine and acknowledging that “[t]he population and economy of this state depend upon the appropriation of vast quantities of water for uses unrelated to in-stream trust values”].) Rather, the Public Trust Doctrine requires consideration of ecological trust values in connection with the ongoing development and use of water supplies for human use. (Id. at 446.)

Accordingly, the State Board’s report cautions that the draft flow criteria do not reflect any balancing of ecological values with the public water supply values. Rather, the draft criteria address only the ecological side of the equation, based on information that could be obtained and considered during the eight-month period since enactment of SB 1.

With those limitations, the report states that recent Delta flows are insufficient to support native Delta fishes for today’s habitats. From there, the report states that flow modification is one of the immediate actions available, although the State Board acknowledges that the links between flows and fish response are often indirect and are not fully resolved. The draft report compared the State Board’s flow recommendations to historic Delta flows over the last 18 to 22 years, as follows:

  • Draft recommendation: 75% of unimpaired Delta outflow from January through June
    Historic: Approximately 30% in drier years to almost 100% of unimpaired flows in wetter years for Delta outflows
  • Draft recommendation: 75% of unimpaired Sacramento River inflow from November through June
    Historic: Approximately 50% on average from April through June for Sacramento River inflows
  • Draft recommendation: 60% of unimpaired San Joaquin River inflow from February through June
    Historic: Approximately 20% in drier years to almost 50% in wetter years for San Joaquin River inflows

The report provides the following flow recommendations to address Delta hydrodynamics:

  • San Joaquin River Flow to Export Ratio: Vernalis flows to exports greater than .33 during the 10-day San Joaquin River pulse flow in October
  • Old and Middle River Flows: greater than -1,500 cfs in March and June of Critical and Dry water years
  • Old and Middle River Flows: greater than 0 or -1,500 cfs in April and May of Critical and Dry water years, when the Fall Midwater Trawl Index for longfin smelt is less than 500, or greater than 500, respectively
  • Old and Middle River Flows: greater than -5,000 cfs from December through February in all water year types
  • Old and Middle River Flows: greater than -2,500 when salmon smolts are determined to be present in the Delta from November through June
  • San Joaquin River flow to export ratio: Vernalis flow to exports greater than 4.0 when juvenile San Joaquin River salmon are migrating in the mainstem San Joaquin River from March through June
  • San Joaquin River at Jersey Point Flows: positive flows when salmon are present in the Delta from November through June
  • 2006 Bay-Delta Plan E:I ratio limits for the entire year

The report also provides the following flow recommendation to address the San Joaquin River:

  • San Joaquin River at Vernalis: 60 percent of 14-day average unimpaired flow from February through June
  • San Joaquin River at Vernalis: 10-day minimum pulse flow of 3,600 cfs in late October
  • San Joaquin River at Vernalis: 2006 Bay-Delta Plan flow objective for October

The State Board cautions that it does not intend for the flow criteria to be interpreted as precise flow requirements for fish under current conditions, but rather that they reflect the general timing and magnitude of flows under the narrow circumstances analyzed in the report.

The report also reaches the following additional conclusions and makes further recommendations as follows:

  • The effects of non-flow changes in the Delta ecosystem, such as nutrient composition, channelization, habitat, invasive species, and water quality, need to be addressed and integrated with flow measures.
  • Inflows should generally be provided from tributaries to the Delta watershed in proportion to their contribution to unimpaired flow unless otherwise indicated.
  • Studies and demonstration projects for, and implementation of, floodplain restoration, improved connectivity and passage, and other habitat improvements should proceed to provide additional protection of public trust uses and potentially allow for the reduction of flows otherwise needed to protect public trust resources in the Delta.
  • The Central Valley and San Francisco Regional Water Quality Control Boards should continue developing Total Maximum Daily Loads (TMDLs) for all listed pollutants and adopting programs to implement control actions.
  • The Central Valley Regional Water Quality Control Board should require additional studies and incorporate discharge limits and other controls into permits, as appropriate, for the control of nutrients and ammonia.
  • Temperature and water supply modeling and analyses should be conducted to identify conflicting requirements to achieve both flow and cold water temperature goals.
  • A strong science program and a flexible management regime are critical to improving flow criteria. The State Board should work with the Council, the Delta Science Program, the Bay Delta Conservation Plan (BDCP), the Interagency Ecological Program, and others to develop the framework for adaptive management that could be relied upon for the management and regulation of Delta flows.
  • The numeric criteria recommended in this report are all recommendations that are only appropriate for the current physical system and climate; as other factors change, the flow needs advanced in this report will also change. As physical changes occur to the environment and our understanding of species needs improves, the long-term flow needs will also change. Actual flows should be informed by adaptive management.
  • Only the underlying principles for the numeric criteria and other measures are advanced as long-term recommendations.
  • Restoring environmental variability in the Delta is fundamentally inconsistent with continuing to move large volumes of water through the Delta for export. The drinking and agricultural water quality requirements of through-Delta exports, and perhaps even some current in-Delta uses, are at odds with the water quality and variability needs of desirable Delta species.
  • The Delta ecosystem is likely to dramatically shift within 50 years due to large scale levee collapse.
  • Positive changes in the Delta ecosystem resulting from improved flow or flow patterns will benefit humans as well as fish and wildlife.

The range of individual stakeholders will likely have a range of views on the significance of the State Board’s draft flow criteria for achieving water supply reliability and ecosystem sustainability. Perhaps anticipating stark differences between some stakeholders, the State Board’s report admonishes that the preceding objectives cannot be accomplished without a large-scale interdisciplinary approach focused at more than just in-stream flows. According to the State Board:

"The flow criteria identified in this report highlight the need for the BDCP to develop an integrated set of solutions, to address ecosystem flow needs, including flow and non-flow measures. . . . Although flow modification is an action that can be implemented in a relatively short time in order to improve the survival of desirable species and protect public trust resources, public trust resource protection cannot be achieved solely through flows – habitat restoration also is needed. One cannot substitute for the other; both flow improvements and habitat restoration are essential to protecting public trust resources."

The report is available at the State Board’s website:

If you have any questions or concerns, please contact the following from our office, or the attorney with whom you normally consult.

Eric Robinson or Hanspeter Walter | 916.321.4500