Sinking Land Threatens Water Infrastructure in San Joaquin Valley
The Department of Water Resources (DWR) has unveiled a detailed evaluation of water conveyance in the San Joaquin Valley, a critical agricultural hub for the nation and home to over 4 million residents. The San Joaquin Valley Conveyance Study highlights the impact of subsidence on regional water systems and proposes necessary infrastructure improvements for sustained water reliability.
This study, stemming from Governor Newsom’s 2020 Water Resilience Portfolio, identifies halting subsidence near key water facilities as a top priority. Achieving this goal involves elevating groundwater levels above critical points. The findings emphasize that repairing existing infrastructure is more crucial than creating new facilities, given the limited surface water resources.
“This study makes the picture unmistakably clear: the most effective path forward is stabilizing groundwater levels and repairing the major canals that bring surface water to the San Joaquin Valley,” said Joel Metzger, Deputy Director of Statewide Water Resources Planning and Enterprise Project Management. “Taking action to support these goals is essential if we want to protect the Valley’s communities, support its agricultural economy, and maintain a functioning water system in a hotter, more extreme future.”
Consequences of Land Subsidence
The San Joaquin Valley is one of the most severely affected areas by land subsidence in the United States, largely due to unsustainable groundwater extraction. This has led to permanent land sinking, diminishing the efficiency of California’s water conveyance infrastructure. Key systems such as the San Luis Canal and the California Aqueduct have suffered capacity reductions, with parts of the San Luis Canal sinking over eight feet since the 1960s. The 2023 subsidence levels have caused a 44% capacity reduction in the California Aqueduct, while 2017 saw a 10-foot subsidence in areas, cutting Friant-Kern Canal deliveries by approximately 300,000 acre-feet.
This subsidence limits California’s capacity to capture and transport floodwaters during wet years, increasing reliance on already strained groundwater resources and posing risks to the state’s economy, health, and safety if the trend continues.
Challenges of Limited Surface Water
The assessment points out that several water conveyance structures in the San Joaquin Valley rarely reach maximum capacity, indicating that water scarcity, rather than conveyance limitations, is the primary constraint. With surface water in short supply, expanding conveyance facilities would offer limited advantages.
The San Joaquin Valley Conveyance Study is part of a series by DWR, including the State Water Project Adaptation Strategy, that examines future water management challenges and solutions in the region. The upcoming San Joaquin Basin Flood-MAR Watershed Studies, expected in December 2025, will explore climate change impacts and potential groundwater recharge actions across the San Joaquin Basin’s tributaries to meet various water management needs.
Contact:
Marina Gelpi Clay, Public Affairs, Department of Water Resources
media@water.ca.gov
Original Story at water.ca.gov