Russian River Weekly Update 6/1/26

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Lake Mendocino in April 2026, by E Salomone

Reservoir Storage & Operations:

Water supply information provided by Sonoma Water (find more water storage info here).

Water storage data for Lake Mendocino, Lake Pillsbury, and Lake Sonoma as of 6/1 and 5/30, showing current levels and changes.

The chart displays Lake Mendocino's water storage levels from 2019 to 2026, measured in acre-feet.

Graph showing Lake Pillsbury water storage levels from 2019 to 2026 with target scenarios for future storage.

Graph showing Lake Sonoma water storage levels from 2019 to projected 2026, highlighting a level of 260,368 acre-feet on June 1, 2026.

State Water Board Approves Russian River Temporary Urgency Change Petition

On March 20, the SWRCB issued an order approving the TUCP. Sonoma Water’s petition sought authorization to implement a hydrologic index based on Lake Mendocino storage values, rather than based on cumulative inflow into Lake Pillsbury. The petition requested the same temporary changes approved by the SWRCB in 2025. The request for an alternative hydrologic index based on Lake Mendocino storage levels originates during the drought of 2013-2015 and was used again during the drought of 2020-2022. The implementation of the alternate hydrologic index was one of several important interventions that prevented Lake Mendocino from going dry in 2021. This temporary change is to ensure that the water supply condition for the Russian River is determined by an index that is reflective of watershed conditions. The urgent need to implement the changes is due to the significant reduction of Eel River water imports through PG&Es Potter Valley Project as ordered by the Federal Energy Regulatory Commission (FERC), effective May 15, 2026 – much sooner than in 2025. The influence of Eel River imports on downstream hydrologic conditions in the Russian River has been, and will continue to be greatly diminished, and thus use of the Eel River hydrologic index is not a reliable metric for Russian River water supply conditions. More information on the District's website.

2026, 5-20 SWRCB notice of Temporary Urgency Change Order issuance.pdf

REMINDER: FERC Approves Potter Valley Project Flow Variance, Effective Friday, May 15th

Reminder, on May 14, 2026, FERC issued an order approving the 2026 temporary flow variance for the Potter Valley Project flows from the Eel to the Russian River. This means that starting May 15th, flows to the Russian River will remain at 25 cfs and will fluctuate between a range of 5-25 cfs based on Lake Pillsbury storage forecasts and water temperature data. Visit the RRFC Webpage for more information.

2026, 5-14 FERC approval of PG&E 2026 Flow variance.pdf

Future of the Eel River to Russian River Trans Basin Diversion (Potter Valley Project)

RRFC webpage on the Future of the Eel River to Russian River Diversion

SWRCB Potter Valley Hydroelectric Project webpage

REMINDER: FERC Notice of Scoping Document, Meetings, and Comments

The Federal Energy Regulatory Commission published a Notice of Scoping Meeting and Request for Comments on the Proposed Surrender, Decommissioning, and Non-Project use of Project Lands (NERF) dated May 22, 2026.

FERC will prepare a document discussing the environmental impacts of both the decommissioning and the building of the New Eel Russian Facility (NERF.) FERC will use this document in its decision-making process to identify potential adverse and beneficial impacts of the proposed project surrender and reasonable alternatives. The scoping process gathers input regarding the environmental impacts of the proposal. Specifically, FERC staff request comments on potential alternatives and impacts, as well as identification of any relevant information, studies, or analyses concerning effects on the quality of the human environment.

Comments are due Friday, July 24, 2026. Refer to the documents below for more information.

Two meetings will also be held in Ukiah. Refer to the documents below for more information.

2026, 5-22 FERC PVP NEPA Scoping Notice.pdf 2026, 5-22 FERC PVP NEPA Scoping Document.pdf 2026, 5-25 IWPC Press Release on FERC scoping doc.pdf

Recent comments and articles:

REMINDER: SWRCB Notice of Availability of the Scoping Report for the Potter Valley Hydroelectric Project Surrender and Decommissioning Project

On May 12, 2026, the State Water Resources Control Board (State Water Board or SWRCB) posted the Scoping Report for the Potter Valley Hydroelectric Project Surrender and Decommissioning Project (Scoping Report). The Scoping Report summarizes comments received during the State Water Board’s Notice of Preparation of an Environmental Impact Report for the Potter Valley Hydroelectric Project Surrender and Decommissioning Project public comment period, which closed on November 3, 2025.

Link to the Scoping Report on Maven's Notebook website

Additional information related to the Potter Valley Hydroelectric Project can be found on the State Water Board’s Potter Valley Hydroelectric Project webpage: SWRCB Potter Valley Hydroelectric Project webpage

Questions regarding the Scoping Report or Potter Valley Hydroelectric Project: please contact Wilhelmina Chon, Project Manager by email at: Wilhelmina.Chon@waterboards.ca.gov.

Mendocino County AG Department - 📢INVASIVE PEST ALERT!📢

The Mendocino County Ag Commissioner, Angela Godwin and officials at the California Department of Food and Agriculture (CDFA) have issued an alert regarding multiple detections of Glassy Wing Sharpshooters (GWSS) at Costco's around the state including neighboring counties. Through the work of CDFA, the nursery stock was tracked to have originated from one nursery. Multiple shipments went out between April 21 to May 26. All stages of life of the pest have been detected. Mendocino County Ag Dept, Ag Depts of other counties, and CDFA have rapidly responded, working with Costco to notify customers that purchased plants. Mendocino County Ag Dept has increased its trapping and monitoring. The GWSS is a serious pest that spreads Pierce's disease, a serious disease that can infect/affect grape vines.

WEBINAR: Inside California’s Open Data Ecosystem 6/4/26 12-1:30 PM by CA Water Data Consortium

This year marks 10 years since California passed the Open and Transparent Water Data Act (AB 1755, Dodd), a landmark commitment to making water and ecological data accessible, interoperable, and useful. A decade in, it's worth asking: What have we built? And what still needs to happen? A special panel edition of Data for Lunch brings together three practitioners who each sit at a different node of California's open data ecosystem. Together, these three efforts represent the full stack: how data gets published, how it gets discovered, and how it gets used in practice.
This is a conversation about what it takes to build California’s open data ecosystem, from AI readiness and federated platform architecture to governance frameworks and data model design. Panelists will get into the hard stuff: standardization problems that lack clear solutions, path-setting architectural decisions, and workforce and platform gaps that are slowing progress. They'll help us identify what needs to change and who can help make it happen. More information and registration.

WEBINAR: Voices from the Field – Policy and Partnership for a More Resilient CA

Join Sustainable Conservation on Wednesday, June 10 at 10 AM for the final webinar in the spring Voices from the Field series to explore what it takes to advance restoration in California today. Will discuss how the Cutting Green Tape Initiative and the state's 30x30 strategy are removing policy and permitting barriers. You’ll hear from leaders at the California Natural Resources Agency and California Trout on the cross-sector collaboration and on-the-ground strategies driving nature-based solutions forward, and what it will take to scale them statewide. Register now to join and learn how Policy & Partnership are the key to a more resilient California.

Recording of Proposition 4 Workshop Now Available

The April 30th joint webinar on the Proposition 4 Watershed Resilience and Sustainable Groundwater Management (SGM) Grant Programs is now available: April 30th Recording

As a reminder, these two programs are administered by the California Department of Water Resources (DWR) under Proposition 4, the Safe Drinking Water, Wildfire Prevention, Drought Preparedness, and Clean Air Bond Act of 2024. You can find more information on each program at their respective webpages: Watershed Resilience Grant Program and Sustainable Groundwater Management Grant Program

Upcoming DWR Proposition 4 workshop and comment periods.

The Dam Safety and Climate Resilience program is now accepting public comment on draft Guidelines until 5pm on June 11th. The program has two workshops available:
- May 27th, 10:00–11:00 AM — Program Overview. Register here: Registration Link
- June 2nd, 2:00–3:00 PM — Disadvantaged & Vulnerable Communities Tools. Register here: Registration Link
The California Irrigation Management Information System (CIMIS) draft Guidelines are now available. Workshops are tentatively planned for June 26th and 29th.
The public review period for the draft Guidelines of the Riverine Stewardship has ended. Final Guidelines will be released over summer.
The Urban Streams program will be releasing draft Guidelines in May. Information on workshops will be available soon.
The Water Desalination Grant Program will hold a pre-draft Guideline webinar on June 22nd from 1:00–2:00 PM. Register here.. You may register at this link.

Please check the program pages above frequently, as additional Proposition 4 guidelines and funding opportunities will be released as they become available. You may also contact: financialassistance@water.ca.gov.