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Temporary Urgency Change Petitions
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Join the webinar to learn about the Temporary Urgency Change Petitions (TUCP) that address water supply conditions and fisheries requirements in the Russian River.

Wednesday, October 28, 2026 frm 5:30 – 6:30 pm.

Hear from:

  • Lynda Hopkins, Sonoma Water Board of Directors, Sonoma County Board of Supervisors
  • Jessica Martini-Lamb, Environmental Resources Division Manager, Sonoma Water
  • Donald Seymour, Deputy Director of Engineering, Sonoma Water

Register for the webinar: https://qrco.de/tucp2026

August 2026 Temporary Urgency Change Petitions

On August 28, 2026, Sonoma Water filed temporary urgency change petitions (TUCPs) with the State Water Resources Control Board Division of Water Rights. These petitions were submitted for Permits 12947A, 12949, 12950 and 16596 to temporarily modify the permit terms that: (1) set minimum instream flow requirements in the upper and lower reaches of the Russian River under a Normal water supply condition for a period from May 1, 2027 until October 15, 2027; and (2) replace the hydrologic index that establishes the watershed water supply condition for setting the minimum instream flow requirements. These petitioned requests are as specified in the 2025 Russian River Biological Opinion (RRBO).

The requested hydrologic index is based on storage thresholds in Lake Mendocino evaluated from October 1 through June 1 that establishes Normal, Dry or Critical water supply conditions. These designations set the minimum instream flow requirements specified in Decision 1610, except for the requested summertime reductions in minimum flows under a Normal water supply condition. To protect listed salmonids under the Endangered Species Act, the RRBO calls for the reduction in the minimum instream flow requirements over the summer. Due to recent operational changes of PG&E's Potter Valley Project, the proposed change in the hydrologic index ensures alignment of the hydrologic index designations with actual conditions in the Russian River watershed.

March 2026 Temporary Urgency Change Petitions

On March 19, 2026, Sonoma Water filed temporary urgency change petitions (TUCPs) with the State Water Resources Control Board Division of Water Rights. These petitions were submitted for Permits 12947A, 12949, 12950 and 16596 to temporarily modify the permit terms that: (1) set minimum instream flow requirements in the upper and lower reaches of the Russian River under a Normal water supply condition for a period from May 1, 2026 until October 15, 2026; and (2) replace the hydrologic index that establishes the watershed water supply condition for setting the minimum instream flow requirements. These petitioned requests are as specified in the 2025 Russian River Biological Opinion (RRBO). The requested hydrologic index is based on storage thresholds in Lake Mendocino evaluated from October 1 through June 1 that establishes Normal, Dry or Critical water supply conditions. These designations set the minimum instream flow requirements specified in Decision 1610, except for the requested summertime reductions in minimum flows under a Normal water supply condition. To protect listed salmonids under the Endangered Species Act, the RRBO calls for the reduction in the minimum instream flow requirements over the summer. Due to recent operational changes of PG&E's Potter Valley Project, the proposed change in the hydrologic index ensures alignment of the hydrologic index designations with actual conditions in the Russian River watershed.

The petitions were approved on May 21, 2026, implementing the requested changes for 180 days through November 16, 2026.

Weekly Hydrologic Reports 

Summary reports of recent historical hydrologic conditions and forecasted rainfall for the Russian River watershed.  

Minimum in-stream flow background

Sonoma Water controls and coordinates water supply releases from Lake Mendocino and Lake Sonoma to implement the minimum instream flow requirements in Water Rights Decision 1610, which the State Water Resources Control Board adopted in 1986. Decision 1610 specifies minimum flow requirements for the Upper Russian River, Dry Creek, and the Lower Russian River. These minimum flow requirements vary based on water supply conditions, as specified in Decision 1610. The Decision 1610 requirements for the Upper Russian River and Lower Russian River are contained in term 20 of the Water Agency’s water-right Permit 12947A (Application 12919A). The Decision 1610 requirements for the Lower Russian River are contained in term 17 of the Water Agency’s water-right Permit 12949 (Application 15736) and term 17 of the Water Agency’s water-right Permit 12950 (Application 15737). The Decision 1610 requirements for Dry Creek and the Lower Russian River are contained in term 13 of the Water Agency’s water-right Permit 16596 (Application 19351).

Sonoma Water’s operations are also subject to the Russian River Biological Opinion issued by the National Marine Fisheries Service on September 24, 2008.

Additional Reports

Fall 2026 Temporary Urgency Change Petition Frequently Asked Questions

1. What is a Temporary Urgency Change Petition (TUCP)?

A Temporary Urgency Change Petition (TUCP) is a request to the State Water Resources Control Board (State Water Board) to temporarily modify certain conditions of a water right permit. Sonoma Water uses this process to respond to changing water supply conditions in the Russian River watershed while maintaining reliable water supplies and protecting fish and other aquatic species. If approved, the State Water Board issues a Temporary Urgency Change (TUC) Order authorizing the changes for a maximum of 180 days.

2. Why does Sonoma Water file TUCPs?

Sonoma Water is responsible for maintaining a reliable water supply while protecting the Russian River and complying with state and federal regulations.
Sonoma Water’s water rights state that watershed hydrologic conditions (Normal, Dry or Critical) in the Russian River watershed are determined primarily by water storage conditions in Lake Pillsbury in the Eel River watershed. Lake Pillsbury is part of Pacific Gas & Electric’s Potter Valley Project, which transfers Eel River water into the Russian River watershed.

Sonoma Water files TUCPs to:

  • Request that water supply conditions in the Russian River watershed, which determines the minimum instream flow requirements in the Russian River and Dry Creek, be based on water storage thresholds in Lake Mendocino rather than Lake Pillsbury storage conditions in the Eel River watershed.
  • Comply with the 2008 and 2025 Russian River Biological Opinions.

3. Has Sonoma Water requested these changes before?

Yes. Sonoma Water has filed TUCPs with the State Water Board since 2009 to address water supply conditions and fisheries requirements in the Russian River. Minimum instream flow changes under normal water supply conditions have been made since 2009 as required by the 2008 and 2025 Russian River Biological Opinions. Biological Opinion changes to minimum instream flow requirements have been requested and approved in 2010, 2011, 2012, 2016, 2017, 2019, 2023, 2024 and 2025.
The Lake Mendocino storage thresholds used in the current request were developed in 2023 and have been requested in TUCPs filed twice a year in 2023, 2024, 2025, and 2026. The State Water Board has issued orders for each of these petitions approving this request.
The current petition requests continuation of these previously authorized changes rather than introducing a new method for determining water supply conditions.

4. What changes are Sonoma Water requesting?

Sonoma Water is requesting the continuation of two changes previously approved by the State Water Board:

  • Use Lake Mendocino storage levels to determine water supply conditions. Instead of relying on conditions in the Eel River watershed, Sonoma Water proposes using established water storage thresholds in Lake Mendocino to determine whether Russian River water supply conditions are Normal, Dry, or Critical.
  • Adjust minimum instream flow requirements during salmonid rearing season. During Normal water supply conditions from May 1 to Oct. 15, Sonoma Water is requesting a reduction in minimum instream flow requirements from 185 to 125 cubic feet per second (cfs) in the Upper Russian River and from 125 to 70 cfs in the Lower Russian River. These changes would apply during the May 1 to Oct. 15 juvenile salmonid rearing season.

These changes would allow water supply conditions to better reflect water availability in the Russian River watershed and improve habitat conditions for protected salmon and steelhead. The proposed minimum instream flow changes establish minimum requirements; actual river flows may be higher.

5. How does the TUCP affect salmon in the Russian River?

Biologists with the National Marine Fisheries Service (NMFS) determined that higher summer flows in portions of the Russian River and Dry Creek can negatively affect habitat conditions for young coho salmon and steelhead.
Under the federal Endangered Species Act, NMFS issued Biological Opinions in 2008 and 2025 addressing these impacts. Lower summer flows can reduce water velocities, creating more suitable habitat for young salmonids. Reducing minimum instream flow requirements also helps conserve cold water in Lake Mendocino, supporting cooler river temperatures during the summer and providing water for fish migration later in the year.
The requested changes are consistent with the 2025 Russian River Biological Opinion and are intended to improve habitat conditions for protected salmon and steelhead.

6. How long does a TUC Order remain in effect?

A TUC Order issued by the State Water Board provides temporary authorization to modify water right permit conditions, for up to 180 days.
Sonoma Water’s current TUC Order expires Nov. 15, 2026. The agency has requested that the State Water Board authorize the changes for another 180-day period, from Nov. 16, 2026, through May 14, 2027.
Because the underlying water right permit requirements have not been permanently changed, Sonoma Water must submit additional petitions when continued temporary changes are needed. Each petition is reviewed by the State Water Board.

7. How can I stay informed about the TUCP?

The State Water Board’s TUC Orders include requirements for monitoring and reporting on river conditions, fisheries and water quality.
Sonoma Water posts weekly hydrology and water quality monitoring results during an active TUC Order, along with information about the petition and related documents.
For updates and additional information, visit www.sonomawater.org/tucp.

More Information