NOTICE: August 9 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 9, 2022, unless and until the State Water Board advises that this determination has been updated.  These curtailments reflect a minor increase in water supply since last week as a result of recent precipitation events:

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 Bear River subwatershed with a priority date of 1853 or later;
   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; and
   3. Post-1914 appropriative water rights and a pre-1914 appropriative water right claim in the Cache Creek subwatershed with a priority date of 1914.
2. Post-1914 appropriative water rights in the Sacramento River watershed outside of the Legal Delta with a priority date of 1920 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.
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 1888 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.  Curtailments in the Sacramento River watershed and possibly the Legal Delta are expected to further increase next week upon approval of the readopted emergency curtailment and reporting regulation, which allows for the protection of water foregone by the Sacramento River Settlement Contractors (SRSC) and the 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.

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 16, 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. Legal Delta.  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.
2. San Joaquin River Exchange Contractors.  Because the U.S. Bureau of Reclamation (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.
3. CVP and SWP 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.
4. 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.
5. 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.
6. Curtailments based on the subwatershed-scale analyses.  Curtailments account for both local water unavailability in headwater subwatersheds and watershed-wide conditions.
7. Modification of demands for water rights and claims associated with contractual agreements with Reclamation and the California Department of Water Resources.  SRSC and FRC demands were reduced compared to 2018 data, consistent with contractual deliveries planned this year.  As noted above, approval of the revised and readopted emergency regulation is anticipated to result in a change in these demands in mid-August.

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 9, 2022.  The 50% exceedance water supply forecast was selected to determine curtailments at this time.  Other than modifications identified above, demand data informing curtailments continue to be based on reported diversions from 2018, with quality control to eliminate duplicative demands under different water rights and claims.

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.