The 2025 water year brought solid rainfall and strong reservoir performance. Thanks to coordinated management and advances in forecast-informed reservoir operations, Sonoma Water and its partners are well positioned for the year ahead. Thank you to everyone who joined us for a discussion of reservoir conditions, lessons from last year and what forecasts suggest for this winter.
Speakers
Jeanine Jones – Interim deputy director of interstate resources management, California Department of Water Resources
Jeanine Jones oversees interstate, drought and climate activities for DWR. She has decades of experience in water management and policy with a focus on statewide planning, drought preparedness and climate change adaptation.
Nick Malasavage – Chief, operations and readiness division, U.S. Army Corps of Engineers San Francisco District
Nick Malasavage manages flood risk management and reservoir operations throughout the Bay Area and North Coast. He has led Army Corps efforts to test and advance Forecast-Informed Reservoir Operations at Lake Mendocino and Lake Sonoma.
Donald Seymour – Deputy director of engineering, Sonoma Water
Donald Seymour directs water supply planning and reservoir operations for Sonoma Water. He works closely with state and federal partners to implement forecast-informed reservoir operations, oversee Russian River system modeling and ensure reliable water deliveries to contractors.
Supervisor Lynda Hopkins – Chair, Sonoma County Board of Supervisors and Sonoma Water Board of Directors
Lynda Hopkins represents Sonoma County’s 5th District and chairs the Sonoma Water board. She is active in regional water policy and works to balance water supply reliability, environmental stewardship and community needs across the Russian River watershed.
Questions & Answers
Question: With cutbacks at the National Oceanic and Atmospheric Administration, how accurate will forecasts be?
Answer: Cutbacks could reduce the quality of forecasts from the California-Nevada River Forecast Center, which tracks Russian River inflows and reservoir conditions. That would be concerning, since reliable forecasts are what allow the U.S. Army Corps of Engineers to decide whether to hold water or release it ahead of storms.
Question: Does Ukiah have a claim on Lake Mendocino water? Where does Ukiah’s water come from?
Answer: Ukiah does not have rights to redivert water released from storage in Lake Mendocino. The city’s water supply comes from natural flows in the Russian River, water imported from the Eel River through the Potter Valley Project and groundwater wells.
Question - Does the Sonoma Water Urban Water Management Plan show there is enough water to support projected population growth? Until what year? Some water alarmists say there is not enough water to support needed housing.
Answer - Yes, based on the population growth and water demands projected by Sonoma Water's customers there is adequate water supply for the planning horizon out to 2045.
Question: How are we collaborating with fish and wildlife agencies?
Answer: The Forecast-Informed Reservoir Operations program has involved close coordination with the California Department of Fish and Wildlife and the National Marine Fisheries Service since it began as a pilot at Lake Mendocino in 2014. Both agencies have provided significant input as the program expands to Lake Sonoma and prepares for a formal flood control manual update. In addition, the National Marine Fisheries Service issued biological opinions in 2008 and again in 2025 that guide how Sonoma Water and the U.S. Army Corps of Engineers manage reservoir operations on the Russian River. Developing those documents required extensive collaboration among all agencies involved.
Question: Has a sounding been done in Lake Sonoma to check storage capacity since recent major storms that may have increased siltation and reduced capacity?
Answer: The U.S. Army Corps is currently scoping how best to conduct that work. Some preliminary soundings near the outlet show no major changes, but challenges remain in other areas of the reservoir, such as tree cover in certain arms that makes surveys difficult. U.S. army Corps is exploring new technologies and methods to get a clearer picture of sedimentation so it can better understand storage conditions more than 40 years into operating the reservoir.
Question: Were there any river flooding consequences from applying the forecast-informed reservoir operations curve? What determines how much or how quickly you draw down the reservoir before a storm?
Answer: The U.S. Army Corps of Engineers has not seen any flooding consequences from applying the FIRO curve. The program shifts the timing of releases, with smaller pre-releases before storms and low flows maintained during storms. Additional water is released after river levels begin to fall. The amount and pace of releases depend on the storm forecast, expected inflows, and the safe release capacity of each reservoir.
Question: Does FEMA account for forecast-informed reservoir operations when developing flood insurance rate maps?
Answer: FEMA assumes the Army Corps operates reservoirs as designed—to prevent flooding. FIRO has not changed that obligation. The bottom line remains protecting flood-prone communities while also improving water supply.
Question: An S2S coalition of agencies and partners has formed to improve subseasonal-to-seasonal forecasting. How can people learn more about the coalition and its work?
Answer: The Department of Water Resources participates in the S2S Coalition, which shares updates and pilot projects on its website, s2sforecasting.org. The site includes a contact link for those interested in joining and the coalition welcomes new participants.