Current weather forecasts call for some precipitation and runoff in the Delta watershed. Today’s curtailment status update suspends some existing curtailments based on the updated output of the Water Unavailability Methodology for the calendar month of September. The State Water Board will continue to closely monitor forecasted precipitation and hydrologic conditions in order to issue updates to the curtailment status of water rights and claims in the Delta watershed.
The following water rights remain curtailed, effective September 17, 2022, unless and until the State Water Board advises that this determination has been updated:
1. Water rights and claims on the following Sacramento Rivertributary:
a. Post-1914 appropriative water rights in the Putah Creek subwatershed outside of the Legal Delta with a priority date of 1924 or later.
2. Post-1914 appropriative water rights in the Sacramento River watershed outside of the Legal Delta with a priority date of 1961or later.
3. Water rights and claims on the following San Joaquin River tributaries:
a. All post-1914 appropriative water rights, pre-1914 appropriative water right claims, and riparian water right claims in the Chowchilla River subwatershed,
b. Post-1914 appropriative water rights and pre-1914 appropriative water right claims in the Calaveras River subwatershed outside of the Legal Delta with a priority date of 1800 or later, and
c. 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 1852 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 1853 or later.
5. Post-1914 appropriative water rights in the Legal Delta with a priority date of 1961 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. The next curtailment status update will be provided by email and web posting no later than September 20, 2022. Please check the Delta Watershed Curtailment Status List for the current curtailment status of each water right and claim in the Delta watershed.
Today’s update considers observed water supply data and forecasts from the California Nevada River Forecast Center (CNRFC) that were updated on September 16, 2022. The 50 percent exceedance water supply forecast was selected to determine curtailments at this time. Demand data informing curtailments are based on reported diversions from 2018 as adjusted through an ongoing QA/QC process.
Due to drought conditions, there has been a significant reduction in rice production in the Sacramento Valley. As a result, historic return flow factors associated with draining rice fields for harvest in prior years are not appropriate for September 2022. Therefore, the methodology was adjusted to retain return flows estimated for August in the Sacramento River watershed, which are more consistent with current reductions in rice production.
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.