Background and Challenge

Below the surface of the earth—between rock fractures, sand, and soil—underground basins contain a large percentage of the water on which we depend. In dry years, these groundwater basins can contribute nearly half of California’s water supply. Some communities rely almost entirely on groundwater. But coordinating water management across basins can be complicated: in the Northern Sacramento Valley, groundwater subbasins are often hydrologically connected, which means that pumping in one basin could affect flows to other basins, all while water resources are confronted by, among other challenges, climate change. To implement California’s Sustainable Groundwater Management Act, then, local groundwater sustainability plans need to take into account the interconnective flow between basins, which requires sophisticated engagement and coordinated action across regions and agencies.

Our Approach

Faced with a challenge that requires collaboration from multiple regions, CBI organized Northern Sacramento Valley’s Interbasin Coordination effort in 2021. Participants included representatives of 13 different subbasins in the valley—from the Tehama County Flood Control and Water Conservation District to Glenn County Groundwater Authority, Colusa Groundwater Authority, Butte County Groundwater Sustainability Agency, and many more. CBI helped groundwater sustainability agencies identify and share technical and general information, directed participants to consider cross-boundary flows and stream interactions, and helped establish a framework for long-term regional coordination.


Participating representatives of groundwater sustainability agencies developed a shared framework to coordinate their long-term management of an interconnected water supply. Guidelines are being put in place for future dispute resolution among different regions, too, and the ongoing communication between regions sets up a possibility for much needed cooperation as environmental conditions shift in the years to come.