Pulse Flows Component of the Water Storage Investment Program (WSIP) Groundwater Projects

The WSIP Groundwater Projects aim to improve local water supply in the San Joaquin Valley and southern California by developing groundwater storage through enhanced operations and new facilities. The Pulse Flows Component will provide ecosystem benefits, as required by WSIP, through the release of pulse flows from Lake Oroville into the Low Flow Channel of the Feather River. Pulse flows, a controlled release of water from a reservoir, mimic natural flow variations and enhance the quality of habitats and migratory corridors for native fish species.

The WSIP Groundwater Projects include the Chino Basin Program, the Kern Fan Groundwater Storage Project (Kern Fan), and the Willow Springs Water Bank Project (Willow Springs).  The WSIP Groundwater Projects were evaluated in previously certified EIRs, prepared by three separate lead agencies under CEQA: the Inland Empire Utilities Agency, the Groundwater Banking Joint Powers Authority, and the Rosamond Community Services District. These EIRs did not evaluate DWR’s actions necessary to implement the Pulse Flows Component; therefore DWR, as a responsible agency, prepared a Supplemental EIR (SEIR) to provide CEQA coverage for their actions.

ESA led the development of the SEIR for DWR, assessing a 575-mile-long region, including Lake Oroville, the Feather and Sacramento Rivers, and SWP infrastructure. The Draft SEIR was released for public review on February 16, 2024, with the Final SEIR anticipated in summer 2024.

As implementation of the project may require substantial variation in pulse flow magnitude and frequency, ESA coordinated closely with DWR and the California Department of Fish and Wildlife to formulate a “conservative pulse flow scenario” that was modeled by a team of hydrologists to evaluate whether the pulse flows would remain with the typical range of natural and operational variability experienced in the existing system, based on hydraulic conditions (water levels, velocity, inundation extent) and geomorphic processes (sediment transport, bank erosion).

Top image: Water from the upper Feather River watershed drains to Lake Oroville, the largest water storage facility in the State Water Project (SWP). Release of the pulse flows from Lake Oroville into the Low Flow Channel of the Feather River defines one of DWR’s three actions under the Pulse Flows Component. Photo by California Department of Water Resources.