The Office of the Delta Watermaster and members of the Delta Measurement Experimental Consortium on Tuesday demonstrated Cal Waters — the Division of Water Rights’ new water‑rights and reporting database — and outlined revised SB 88 measurement regulations that will take effect for water year 2027.

Cal Waters demonstration and migration context: Why it matters

Alex Burke of the Delta Watermaster office showed participants the Cal Waters test environment, navigating to the “My annual reports” page, explaining how OpenET‑derived monthly and annual evapotranspiration (ET) totals display, and how reporters may accept OpenET values or submit measured data. “This is the Cal Waters home page. This is what you see when you first sign in,” Burke said during the demo, adding that the test environment will not submit official data.

The Office stressed that the system moves from the legacy ERIMS database — now in read‑only mode — to a user‑based Cal Waters approach in which PINs and agent/owner linkages will determine access. The migration is intended to let organizations consolidate many rights under a single account and to provide clearer geospatial place‑of‑use mapping pulled from an ESRI backend.

SB 88 regulation changes and timelines

A Delta Watermaster staff member summarized regulatory changes adopted by the State Water Board in August and noted that the Office of Administrative Law reviewed minor edits before final codification. The revised rules reconfirm measurement requirements but adjust timelines: several provisions will apply beginning in water year 2027. The staff member described the revised definition of a “large diversion” as a point of diversion capable of diverting more than 30 cubic feet per second (cfs) or more than 10,000 acre‑feet per year, and said required measurement frequency for large diversions will be daily or more frequent (up to hourly for the largest facilities), with data submitted to the State Water Board via Cal Waters or an approved public site.

Why the changes matter: compliance and ACPs

Office staff said the new rules require updates to alternative compliance plans (ACPs) so they align with the regulation changes. Jay Ziegler, Delta Watermaster, asked the group to weigh in on approaches that are technically feasible and cost effective across the Delta’s varied diversion types: “We have begun conversations with a few of the large diverter entities around the Delta,” he said, and emphasized the need for site‑specific methods tied to the realities of conveyance and diversion systems.

What remains open

Participants raised operational questions about multifactor authentication, agent versus owner access, and how multiple water rights can be consolidated under organization accounts. The Office encouraged users to contact Cal Waters help resources and staff for account linkage issues. Officials said they will continue outreach as reporters begin using Cal Waters and will refine training and standard language to reduce transition challenges.

Next steps

Staff asked stakeholders to review the posted regulations and engage on ACP updates and implementation approaches; the group plans technical follow‑up and outreach workshops to support the migration and compliance work. The Office reiterated that ERIMS is in read‑only mode and that new reporting will occur in Cal Waters going forward.