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Temporary Urgency Change Petitions

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.  

More Information

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