Forecast Informed Reservoir Operations: Yuba & Feather Watersheds

FIRO is a reservoir-operations strategy that better informs decisions to retain or release water by integrating additional flexibility in operation policies and rules with enhanced monitoring and improved weather and water forecasts (American Meteorological Society; 2020). Since 2014, CW3E and federal, state, and local partners have developed, tested, and implemented FIRO at reservoirs across the Western United States. FIRO is now being assessed nationwide.

Lake Mendocino in the Russian River watershed

Map of the Yuba & Feather River watersheds

PROJECT STATUS

Permanent FIRO Implementation

Water Control Manual Update In Progress

OVERVIEW

The Yuba-Feather FIRO project includes two reservoirs in Northern California’s Sierra Nevada Mountains: New Bullards Bar Reservoir on the North Yuba River, operated by Yuba Water Agency, and Lake Oroville on the Feather River, operated by the California Department of Water Resources (DWR). The project builds on the Forecast Coordinated Operation (FCO) Program and serves communities throughout the Yuba-Feather system, with a focus on reducing downstream flood risk for residents in Yuba and Sutter Counties and along the lower Feather River.

The motivation for implementing FIRO in the Yuba-Feather Watershed is to further reduce flood risk and enhance water supply reliability in a region subject to highly variable precipitation driven by atmospheric rivers. Improved forecast-informed operations at New Bullards Bar and Lake Oroville offer the opportunity to retain more water for dry-season use while maintaining or improving flood protection and aquatic habitat.

The FIRO Final Viability Assessment published in March 2025 found that FIRO could enable management of up to 117,000 acre-feet of additional reservoir space at New Bullards Bar with planned spillway improvements, while reducing water levels on levees near Marysville by roughly 2 to 3 feet during major flood events. A Water Control Manual update is planned for mid-2027.

FIRO PROGRESS

Timeline of FIRO in the Yuba and Feather River watersheds

Forecast Informed Reservoir Operations implementation progress at New Bullards Bar Reservoir and Lake Oroville. Green circles with checkmarks indicate completed milestones, blue and gold circles without checkmarks indicate upcoming milestones.

KEY ACHIEVEMENTS

117,000 ac-ft

additional flood storage space to be enabled at New Bullards Bar through FIRO with the planned ARC Spillway

160,000+

residents along the Yuba and Feather Rivers with reduced flood risk

Cross-sector partner organizations working collaboratively to implement FIRO

Atmospheric River Control (ARC) Spillway

The ARC Spillway is a proposed second spillway at New Bullards Bar Dam, designed by Yuba Water to maximize FIRO. With the existing spillway, Yuba Water can’t make large pre-storm releases until the reservoir is already high in the flood pool, making it difficult to create significant storage space ahead of an incoming storm. The ARC Spillway fixes this by setting gates 31.5 feet lower, giving operators a way to release water earlier when forecasts first warn of an atmospheric river. Construction is expected to begin in 2030.