Updated November 2025

November 2025 Sonoma Water Temporary Urgency Change

On October 15, 2025, Sonoma County Water Agency (Sonoma Water) filed temporary urgency change petitions with the State Water Resources Control Board (State Water Board), Division of Water Rights (Division) requesting approval of temporary changes to water right Permits in the Russian River watershed.  The petitions seek authorization to implement a hydrologic index based on Lake Mendocino storage values, rather than the current index based on cumulative inflow into Lake Pillsbury, starting December 24, 2025.
This temporary change is requested to ensure that the water supply condition for the Russian River is determined by an index that is reflective of watershed conditions. Sonoma Water states there is an urgent need to implement the proposed changes due to the significant reduction of potential Eel River water imports through PG&Es Potter Valley Project. 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.

For more information, visit the Sonoma Water Agency - TUCP Webpage

April 2025 Sonoma Water Temporary Urgency Change Petition

In April 2025, Sonoma Water Agency  submitted Petitions for Temporary Urgency Change (TUCP) to modify the criteria for establishing the water supply conditions and the minimum instream flow requirements for the Russian River watershed that were established by Decision 1610.

The necessity for these petitions is twofold.

Since 2010, Sonoma Water has submitted petitions in the spring to protect listed salmonids under the Endangered Species Act by implementing reduced minimum instream flow requirements that were required by the 2008 Russian River Biological Opinion issued by NOAA National Marine Fisheries Service. While the 2008 Biological Opinion had a 1S-year term that ended in 2023, Sonoma Water and the U.S. Army Corps of Engineers are in consultation and coordinating with other agencies to complete the successor Biological Opinion, which is expected for release by mid-year 2025.
Due to changes in the operation by PG&E of the Potter Valley Project, the hydrologic index that defines the water supply condition in the Russian River watershed is inadequate to determine actual conditions due to its reliance on Lake Pillsbury cumulative inflow and the assumption of Potter Valley Project historical transfers of Eel River water to the East Fork of the Russian River. The TUCP requests changes that are the same as approved most recently by the State Water Resources Control Board in an order issued on October 31 ,2024, which remains active through April 29, 2025. This request for an alternate 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.

The State Water Resources Control Board (SWRCB) approved Sonoma Water's Temporary Urgency Change Petition.

Read the TUCP for more information: