California diverting river flows for groundwater recharge, reducing flood impacts

May 10, 2023
The state’s Department of Water Resources is implementing an emergency program to provide temporary pumps and siphons, diverting high river flows from flood-prone communities for groundwater recharge.

The California Department of Water Resources (DWR) announced that it is implementing an emergency program to divert high river flows away from flood-prone Central Valley communities and into groundwater recharge basins.

DWR says that it is working with local agencies and equipment vendors to provide funding and secure much-needed temporary diversion equipment, including pumps and siphons, and will support their deployment by local agencies.

The first set of temporary pumps and siphons were deployed by Fresno Irrigation District on April 25. The district is reducing downstream flood impacts in the Tulare Lake Region and expanding groundwater recharge efforts by diverting water from Kings River reaches to existing recharge facilities or working agricultural lands.

The pumps being deployed are equipped with flow meters and range in diversion capacity from 5 to 50 cubic-feet per second (cfs) of water from high-flow rivers. A single pump operating at 5 cfs for 24 hours moves approximately 10 acre-feet of water per day. Most crops require roughly three acre-feet of water per year for every acre, and one acre-foot can supply nearly three households for an entire year.

There are 15 temporary pumps currently in the planning and deployment phase in and around the Central Valley.

Operating these pumps to divert water for the next four months could capture upwards of 55,000 acre-feet in spring runoff, alleviating flood impacts to communities and bolstering the amount of water stored underground.

“In times of emergency, it’s critically important that state and local agencies roll up our sleeves to coordinate and communicate what is needed,” said Paul Gosselin, DWR Deputy Director of Groundwater Management. “Based on feedback from local agencies, DWR acted quickly to secure this needed equipment so agencies could expand their capacity to divert high river flows and increase groundwater recharge.”

Expediting groundwater recharge is a key water resilience strategy of the state’s Water Supply Strategy: Adapting to a Hotter, Drier Future and is helping local agencies bring historically depleted aquifers into balance.