NOTICE: August 23 Weekly Update on Curtailment Status of Water Rights and Claims in the Delta Watershed

From the State Water Resources Control Board:

This update contains important information about the curtailment status of water rights and claims of right within the Sacramento-San Joaquin Delta (Delta) watershed pursuant to Initial Orders Imposing Water Right Curtailment and Reporting Requirements in the Delta Watershed (Order for water rights/claims under 5,000 acre-feet and Order for water rights/claims over 5,000 acre-feet)

The following water rights are curtailed, effective August 24, 2022, unless and until the State Water Board advises that this determination has been updated:

1. Water rights and claims on the following Sacramento River tributaries:
   1. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Cache Creek subwatershed with a priority date of 1861 or later; and
   2. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Yuba River subwatershed with a priority date of 1875 or later.
2. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Sacramento River watershed outside of the Legal Delta with a priority date of 1904 or later.
3. Water rights and claims on the following San Joaquin River tributaries:
   1. Post-1914 appropriative water rights, pre-1914 appropriative water right claims, and riparian water right claims in the Calaveras River subwatershed outside of the Legal Delta;
   2. Post-1914 appropriative water rights, pre-1914 appropriative water right claims, and riparian water right claims in the Chowchilla River subwatershed;
   3. Post-1914 appropriative water rights, pre-1914 appropriative water right claims, and riparian water right claims in the Fresno River subwatershed;
   4. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Merced River subwatershed with a priority date of 1859 or later; and
   5. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Mokelumne River subwatershed outside of the Legal Delta with a priority date of 1890 or later.
4. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the San Joaquin River watershed outside of the Legal Delta with a priority date of 1900 or later.
5. Post-1914 appropriative water rights in the Legal Delta with a priority date of 1920 or later.

Curtailments are expected to continue through the summer and early fall until significant precipitation occurs.  Based on current water supply forecasts and water right demand projections, beginning in September curtailments are tentatively expected to increase in the San Joaquin River watershed and decrease in the Sacramento River watershed. Curtailments to priority dates in the early 1800s are expected in the San Joaquin River watershed, and curtailments to priority dates in the 1930s are expected in the Sacramento River watershed and the Legal Delta.

Water supply forecasts will continue to be evaluated regularly to determine if, when, and to what extent the further re-imposition or suspension of curtailments may be appropriate.  The next curtailment status update will be provided by email and web posting no later than August 30, 2022.  Please check the Delta Watershed Curtailment Status List for the current curtailment status of each water right and claim in the Delta watershed.

The above curtailments consider the following technical and policy inputs to the Water Unavailability Methodology for the Delta Watershed (methodology):

1. Implementation of new emergency regulation provision regarding demands under water rights and claims associated with contractual agreements with the U.S. Bureau of Reclamation (Reclamation) and the California Department of Water Resources. (Cal. Code Regs., tit. 23, § 876.1, subd. (d)(8).)  Following approval of the revised and renewed emergency regulation, which allows for the protection of water foregone by the Sacramento River Settlement Contractors (SRSC) and Feather River Contractors (FRC) in accordance with an operations plan for the Central Valley Project (CVP) or State Water Project (SWP) that meets certain criteria, demands for the rights and claims held by the SRSC and FRC reflect 2018 reported water diversion data, and have not been reduced to reflect projected reductions in diversions in accordance with this year’s operations plans for the CVP and SWP.
2. Removed duplicative demands in the Legal Delta.  Following additional quality control of demand data, the methodology’s demand dataset has been adjusted to remove duplicative diversions reported under both post-1914 appropriative water rights and riparian water right claims associated with the same place of use within the Legal Delta.
3. Concurrence of the Delta Watermaster.  After consultation with and the concurrence of the Delta Watermaster, and consistent with the technical assumptions regarding water unavailability in the Legal Delta outlined in methodology documents released on June 27, 2022, curtailments remain in place for certain rights within the Legal Delta.  Although the methodology indicates that water is unavailable for appropriative water right holders in the Legal Delta with a priority date of 1908 or later, curtailments in the Legal Delta will remain unchanged pending further discussion between the Division of Water Rights and the Office of the Delta Watermaster.
4. Quality control of demand data for water rights and claims 1,000 acre-feet or greater. The methodology’s demand dataset has been updated to correct reporting inaccuracies and eliminate duplicative demands under multiple water rights and claims encompassing annual diversions of 1,000 acre-feet or greater.
5. San Joaquin River Exchange Contractors.  Because Reclamation has resumed deliveries to the San Joaquin River Exchange Contractors (SJREC) of previously stored water from the Delta via the Delta-Mendota Canal, curtailments assume zero demands under the SJREC’s underlying claims of right from the San Joaquin River.
6. CVP and SWP (collectively, Projects) rights in the Sacramento River watershed and in the Legal Delta.  Current analyses indicate that water is unavailable to all Project water rights in the Sacramento River watershed and the Legal Delta.  Accordingly, those Project rights are curtailed.
7. Return flows.  The above curtailments factor in estimated agricultural and municipal return flows based on CalSim 3 results for 1976, which have been applied to all headwater and valley floor subwatersheds.
8. Term 91.  Irrespective of the above curtailments, Term 91 curtailments continue to apply to all rights within and outside the Legal Delta containing Term 91.
9. Curtailments based on the subwatershed-scale analyses.  Curtailments account for both local water unavailability in headwater subwatersheds and watershed-wide conditions.

Today’s curtailment status update is based on the output of the methodology for the calendar month of August.  As such, today’s update considers observed water supply data and forecasts from the California Nevada River Forecast Center (CNRFC) that were updated on August 23, 2022.  The 50 percent exceedance water supply forecast was selected to determine curtailments at this time.  Other than modifications identified above, demand data informing curtailments are based on reported diversions from 2018.

The determination of water unavailability used to inform curtailments is based on the Water Unavailability Methodology for the Delta Watershed.  The data used to support curtailments and other relevant information is available on the State Water Board’s FTP site.  To access the documents posted on the FTP site, please email Bay-Delta@waterboards.ca.gov to obtain login credentials.

Water right holders and claimants are responsible for monitoring their curtailment status online on the Delta Watershed Curtailment Status List.  Notice of changes to curtailment status will not be mailed.  For those with limited internet access, a pre-recorded curtailment summary can be heard on the Delta Curtailment Status phone line at (916) 323-4643.

For more information about drought in the Delta watershed, please visit the Delta Drought webpage.  For more information about curtailment compliance and responses to the Initial Orders Imposing Water Right Curtailment and Reporting Requirements in the Sacramento-San Joaquin Delta Watershed, please visit the Curtailment Compliance and Responses webpage.  The Curtailment Compliance and Responses tracker is updated regularly and can be filtered to see the latest changes.  If you have any questions, you may send an email to Bay-Delta@waterboards.ca.gov or call the Delta Drought phone line at (916) 319-0960.