On May 22, 2025, the California State Water Resources Control Board (State Board) provided notice of an additional 15-day written comment period on its proposed revisions to the water measurement and reporting regulations (Proposed Revisions). The State Board updated the text of the Proposed Revisions to Title 23 of the California Code of Regulations, Chapters 2 (Appropriation of Water), 2.7 (Water Diversion and Use Reports), and 2.8 (Measuring and Monitoring) based on public comments received during the initial public comment period (February 28, 2025 through April 23, 2025). During this additional comment period, the State Board will only accept written comments that address the updated text to the Proposed Revisions. The State Board will not accept comments on the previous revisions released earlier this year. Written comments are due by 5:00 p.m. on June 6, 2025.
What Has Changed
Two key differences under the Proposed Revisions are that water users must submit a measurement methodology using a standardized form and the methodology must identify each point of diversion covered by the methodology in addition to each measurement location. The Proposed Revisions define a “measurement methodology” as “the combination of all measuring devices and any accompanying methodology … through which a diverter accounts for the volume and flow rate of water diverted under each claimed water right.” Additionally, the Proposed Revisions direct those diverters already measuring and reporting their rediversions to continue to do so. The revisions also allow the deputy director to request that a diverter measure rediversions that are currently unmeasured “if necessary to understand water availability.”
Many of the current submission requirements are similar. Water users who divert more than 10 acre-feet per year will need to report annual data, while water users who divert more than 10,000 acre-feet per year (Large Diversions) must submit weekly reports in addition to the annual report. Under the Proposed Revisions, annual reports must either be submitted electronically on a standardized form or directly to the State Board’s new online reporting platform, CalWATRS. Water users must have an email address in order to log onto the online reporting platform and submit the annual reports. Weekly reports for Large Diversions will need to either be submitted on a standardized form, submitted directly to CalWATRS, or posted to an otherwise approved publicly accessible website. Currently, the CalWATRS platform and all standardized forms are not yet available for public review.
Why the Change
According to the State Board, the Proposed Revisions are intended to improve clarity and compliance through the use of standardized forms and a new reporting platform.
Expected Deadlines for Compliance
If the Proposed Revisions are adopted as written, data that is used for an annual report and collected on or after October 1, 2025, will need to comply with the Proposed Revisions. Additionally, weekly data for Large Diversions will need to comply with the Proposed Revisions beginning on October 1, 2026.
Measurement methodologies first implemented on or after October 1, 2025, must be submitted to the State Board on or before January 31, 2027, or on or before the submission deadline of the annual report for which the measurement methodology first applies, whichever is later. Measurement methodologies first implemented before October 1, 2025, must be submitted on or before January 31, 2027.
Similarly, if a water user implements an alternative compliance plan in lieu of the requirements in proposed sections 933 through 935, then, alternative compliance plans first implemented on or after October 1, 2025, must be submitted to the State Board on or before January 31, 2027, or before its implementation, whichever is later. Alternative compliance plans implemented before October 1, 2025, must be submitted to the State Board on or before January 31, 2027.
State Board staff anticipates that the State Board will consider adoption of the Proposed Revisions at its August 2025 meeting. A link to the State Board water measurement and reporting rulemaking webpage can be found here.
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Somach Simmons & Dunn has submitted written comments addressing the Proposed Revisions on behalf of an interested party. This alert reflects the observations of the authors and is not intended to limit or otherwise describe the views of our clients.
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