NOTICE: May 10 Weekly Update on Curtailment Status of Water Rights and Claims in the Delta Watershed

From the State Water Resources Control Board:

This post 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 May 11, 2022, unless and until the State Water Board advises that this determination has been updated:

  1. Post-1914 appropriative water rights in the San Joaquin River watershed outside of the Legal Delta with a priority date of 1957 or later.

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, and the next curtailment status update will be provided by email and web posting no later than May 17, 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 Water Unavailability Methodology for the Delta Watershed continues to indicate that local water supplies may be insufficient to satisfy all water rights in multiple headwater subwatersheds. However, curtailments based on the subwatershed-scale analysis could affect several rim reservoirs that generally have more junior storage rights in the subwatersheds.  Curtailing those users would not make water available to senior upstream diverters and could result in the requirement to bypass needed storage as the limited snowpack continues to melt.  Accordingly, consistent with the Board’s direction to consider opportunities and needs to replenish stored water supplies, the Deputy Director for Water Rights has determined in the exercise of his discretion under Section 876.1 subdivision (d) of the Drought Emergency Regulation that today’s curtailments will continue to be based only on watershed-wide conditions, not the analysis of water unavailability at the subwatershed scale. Regardless of curtailments, all right holders are reminded that they must abide by the terms of their water right and ensure that downstream senior water right holders are not harmed by their diversions. If water right holders or claimants believe their water rights are being impacted by the suspension of curtailments, they may notify the State Water Board by emailing with specific details regarding their concern, or they may file a formal complaint with the Division of Water Rights Enforcement Program.

The above curtailments factor in reduced demands associated with Central Valley Project and State Water Project exports from the Delta under the State Water Board’s April 4, 2022 Order Approving Temporary Urgency Changes to Water Right License and Permit Terms Relating to Delta Water Quality. The water unavailability analysis supporting current curtailments also accounts for demands of the San Joaquin River Exchange Contractors from the Upper San Joaquin River subwatershed in May, as well as estimated agricultural and municipal return flows based on CalSim 3 results for 1976.  Today’s curtailment status update is based on the output of the Water Unavailability Methodology for the Delta Watershed for the calendar month of May. As such, today’s update considers observed water supply data and forecasts from the California Nevada River Forecast Center (CNRFC) that were updated on May 10, 2022.  The 50% exceedance water supply forecast was selected to determine curtailments at this time.  Curtailment statuses will be reassessed next week (or earlier if appropriate) based on daily water supply observations and updated forecasts.  Demand data informing curtailments continue to be based on reported diversions from 2018.

Notice of Expected Wide-Scale Curtailments in the Near Future

Water right holders and claimants are advised that, based on current hydrologic forecasts, curtailments are expected to increase progressively through the spring and summer and continue through the early fall until significant precipitation occurs. Accordingly, water right holders and claimants should plan for reduced supplies even if your water right or claim is not currently curtailed.

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.

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 to obtain login credentials.

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 or call the Delta Drought phone line at (916) 319-0960.

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