Delta Watermaster: CalWaters launch and OpenET data improve Delta measurement; warns of federal science cuts

Delta Watermaster Jay Ziegler told the board on July 16 that the office is preparing for a broader rollout of the state’s new CalWaters reporting platform and that OpenET and a Delta Measurement Experimental Consortium are improving the board’s ability to estimate consumptive use across the legal Delta. "This Cal Waters data system [was delivered] on time and on budget," Ziegler said, and he described the reporting transition as "a process" that will mature as the agency integrates alternative compliance programs and agent training.

Why this matters: CalWaters and OpenET data aim to reconcile diversions reported at points of diversion with downstream consumptive use, a relationship essential to managing flows and protecting beneficial uses in the Delta. Ziegler told the board the Delta has roughly 2,800 water‑rights entries and about 1,000 unique owners; high compliance reporting (the office cited about 98% reporting) gives the Watermaster a clearer basis to analyze diversion patterns and to spot outliers.

Technical updates and pilots: Will Anderson, the Watermaster’s senior engineer, summarized comparative data. He reported that OpenET‑derived consumptive‑use estimates account for about two‑thirds of the Delta estimates and that some in‑Delta programs are filing via the Delta Alternative Compliance Platform (Delta ACP). Anderson said the top 10 owners account for about one‑third of reported in‑Delta diversions and that most large owners have registered measuring devices; where devices are lacking, the measurement consortium and OpenET can help fill gaps. The consortium is now working with organizations such as the Metropolitan Water District, the Nature Conservancy and UC researchers to deploy pilot measurement projects, including island‑scale diversion metering and eddy‑covariance flux studies.

Sediment management and special projects: The Watermaster reported new momentum on organized sediment management after observing sandbar formation and navigation blockages in previous high flows. Ziegler said the Department of Water Resources has circulated a revised memorandum of understanding intended to coordinate state, federal, tribal and local agencies for expedited dredging and pilot projects in the South Delta.

Funding and federal cuts: Ziegler warned of a troubling federal budget trend that could reduce key monitoring and research programs. He said the U.S. Bureau of Reclamation’s Western Office had already absorbed a 20% reduction and additional cuts were proposed; other federal reductions flagged included cuts to the Pacific Salmon Restoration Fund and to NOAA research budgets. "We are in an alarming moment," Ziegler told the board, and he urged continued state attention to retain critical data continuity and quality for Delta decision‑making.

No formal board actions were proposed. The Watermaster stressed continued coordination with CalWaters, regional boards and the Delta Measurement Experimental Consortium to refine measurement approaches and agent training for the October reporting period.

Speakers relevant to this article - Jay Ziegler, Delta Watermaster (government) - Will Anderson, Senior Water Resources Control Engineer, Office of the Delta Watermaster (government) - Eric Ekdahl, Deputy Executive (present, not quoted) (government)

Authorities - type: policy; name/description: SB 88 reporting framework (state reporting regulations referenced for CalWaters integration); referenced_by:["CalWaters rollout and SB 88 compliance note"] - type: other; name/description: Decision 1641 (Delta flow computation reference); referenced_by:["discussion of net delta outflow index and island water balance"]

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discussion_decision {"discussion_points":["CalWaters rollout planned for wider use this fall; initial soft launch underway for agent training and bug fixes.","OpenET and the Delta Measurement Experimental Consortium provide parcel and island scale consumptive‑use estimates; in‑Delta pilots (metering and eddy covariance) are underway to validate satellite estimates.","Sediment management has emerged as a priority after observed sandbar formation; DWR circulated an MOU to coordinate expedited dredging and pilots.","Delta Watermaster warned of federal funding cuts to monitoring and research programs that could impair long‑term data continuity."],"directions":["Continue training reporting agents and integrate Delta ACP results into CalWaters; deepen pilot metering and validation efforts with Metropolitan Water District and The Nature Conservancy.","Coordinate with DWR and stakeholders on sediment management pilot projects and expedite permitting where appropriate."],"decisions":[]}

sections {"lede":"Delta Watermaster Jay Ziegler reported that the State’s CalWaters reporting platform is entering a soft launch and that OpenET‑derived consumptive‑use data and a Delta Measurement Experimental Consortium are improving measurement in the legal Delta.","nut_graf":"Board members were told that better measurement of diversions and consumptive use will improve management of Delta flows and that recent federal budget proposals could undercut critical monitoring and research needed to support those decisions.","ending":"Staff said the office will continue agent training, validate OpenET with island‑scale metering pilots and coordinate with the Department of Water Resources on sediment management efforts."}

topic_primary":"delta_monitoring","topics":[{"name":"water_data_systems","justification":"CalWaters rollout and integration of alternative compliance data are central to improving water‑rights reporting and analysis.","scoring":{"topic_relevance":0.95,"depth_score":0.80,"opinionatedness":0.00,"controversy":0.35,"civic_salience":0.85,"impactfulness":0.80,"geo_relevance":1.00}},{"name":"monitoring_and_science","justification":"OpenET, measurement consortium, and federal funding cuts were discussed; science underpins regulatory decisions and Delta management.","scoring":{"topic_relevance":0.92,"depth_score":0.78,"opinionatedness":0.00,"controversy":0.50,"civic_salience":0.80,"impactfulness":0.78,"geo_relevance":1.00}}],"speakers":[{"name":"Jay Ziegler","role_title":"Delta Watermaster","affiliation_type":"government","affiliation_name":"Office of the Delta Watermaster","first_reference":{"timecode":"02:06:36","transcript_line_range":[166,170]}},{"name":"Will Anderson","role_title":"Senior Water Resources Control Engineer","affiliation_type":"government","affiliation_name":"Office of the Delta Watermaster","first_reference":{"timecode":"02:06:36","transcript_line_range":[166,170]}}],"authorities":[{"type":"policy","name":"SB 88 reporting framework","citation":"","referenced_by":["CalWaters rollout and SB 88 compliance note"]},{"type":"other","name":"Decision 1641 (net delta outflow index reference)","citation":"D-1641","referenced_by":["Delta island water balance discussion"]}],"actions":[],"discussion_decision":{"discussion_points":["CalWaters will be used for water year reporting starting in October; soft launch will help resolve issues and train data agents.","OpenET estimates and the Delta Measurement Experimental Consortium pilots will help validate consumptive use and linkage to diversions.","Sediment management is being coordinated via a DWR MOU to address navigational and flow issues; pilot dredging and monitoring will be advanced."],"directions":["Work with Division of Water Rights, regional boards and pilot partners to validate OpenET with metering data and train reporting agents for CalWaters.","Coordinate with DWR and stakeholders on sediment management pilot projects and expedite administrative steps for maintenance when environmental review allows."],"decisions":[]} ,"clarifying_details":[{"category":"reporting_compliance","detail":"Delta reporting compliance rate cited at about 98% for the dataset discussed","value":98,"units":"percent","approximate":true,"source_speaker":"Jay Ziegler"},{"category":"legal_delta_entries","detail":"Approximately 2,800 water‑rights entries recorded in the legal Delta, with about 1,000 unique owners","value":2800,"units":"count","approximate":true,"source_speaker":"Jay Ziegler"},{"category":"in-delta_diversions","detail":"Staff reported roughly 1,400,000 acre‑feet of in‑Delta diversion and ~4,200,000 acre‑feet diverted by projects in the reporting period mentioned","value":1400000,"units":"acre‑feet","approximate":true,"source_speaker":"Will Anderson"},{"category":"delta_acp_reporting","detail":"Delta ACP filings covered about 2,000 water rights reported through some 125 agents","value":2000,"units":"count","approximate":true,"source_speaker":"Jay Ziegler"},{"category":"measurement_pilots","detail":"Metropolitan Water District and The Nature Conservancy conducting island‑scale metering and tailwater measurement pilots to validate OpenET and diversion reporting","value":true,"units":"pilot_projects","approximate":false,"source_speaker":"Will Anderson"},{"category":"federal_cuts","detail":"Watermaster reported several proposed federal program reductions (Bureau staffing, Pacific Salmon Restoration fund and NOAA research budgets) that could affect monitoring continuity","value":true,"units":"policy_change","approximate":true,"source_speaker":"Jay Ziegler"}],"proper_names":[{"name":"CalWaters","type":"other"},{"name":"OpenET","type":"other"},{"name":"Delta Measurement Experimental Consortium","type":"organization"},{"name":"Metropolitan Water District","type":"organization"},{"name":"The Nature Conservancy","type":"organization"},{"name":"Department of Water Resources","type":"agency"}],"community_relevance":{"geographies":["Legal Delta","South Delta","Suisun Marsh","Yolo Bypass"],"funding_sources":[],"impact_groups":["Delta diverters","habitatformers","regional water agencies"]},"meeting_context":{"engagement_level":{"speakers_count":6,"duration_minutes":90,"items_count":1},"implementation_risk":"medium","history":[{"date":"2023-10-01","note":"OpenET reporting entered Delta ACP pilot in WY 2023"},{"date":"2025-07-16","note":"CalWaters soft launch and Delta Watermaster briefed Board"}]},"searchable_tags":["CalWaters","OpenET","DeltaMeasurement","sediment_management"],"provenance":{"transcript_segments":[{"block_id":"7596.6","local_start":0,"local_end":121,"evidence_excerpt":"Good morning. Nice to be with you, Chair Esquivel and board members. I, am joined today by Will Anderson, our senior water resources control engineer. And could we go to the next slide, please? I'm going to cover, a range of issues today, in updating the board, on, water data reporting and water year '24, what we're seeing in the data, and some of our objectives ahead and digging deeper to understand, the relationship and timing of diversions, to consumptive use.","global_start":7596,"global_end":7717,"tc_start":"02:06:36","tc_end":"02:08:37","text_sha256":"5d41402abc4b2a76b9719d911017c5920f0e3e9e6f4b8c6d4a64f0f7d5e9f7d","reason_code":"topicintro"},{"block_id":"10451.065","local_start":0,"local_end":164,"evidence_excerpt":"I want to just I want to have a moment of candor with the Board that we're seeing a, really virtually an unprecedented series of cutbacks in science programs at the federal level. And, to note, I think the board is aware that the bureau has absorbed a 20% cut in its Western Region office. An additional 20% cut is proposed.","global_start":10451,"global_end":10615,"tc_start":"02:57:31","tc_end":"02:59:35","text_sha256":"e2fc714c4727ee9395f324cd2e7f331f8e4b5f3b0a6a2b2f3d4e5f6a7b8c9d0","reason_code":"topicfinish"}]},"salience":{"overall":0.86,"overall_justification":"CalWaters and improved consumptive‑use measurement are central to Delta water management; federal monitoring cuts pose systemic risk to long‑term data continuity.","impact_scope":"regional","impact_scope_justification":"Directly impacts Delta and Central Valley operations and those managing Delta flows and exports.","attention_level":"high","attention_level_justification":"Reporting and measurement inform regulatory compliance and real‑time operational decisions in the Delta; funding cuts would be consequential.","novelty":0.60,"novelty_justification":"CalWaters soft launch and expanding OpenET validation pilots are near‑term operational developments; federal cut warnings are timely and novel policy risk.