Commission backs recommendation for mayor to seek state, federal funding after presentation on California Aqueduct subsidence
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Summary
Staff told the Water Commission that subsidence has already reduced roughly 44% of capacity in affected reaches of the California Aqueduct and that DWR estimates capacity loss could reach 87% in 10 years without repairs; commissioners voted to recommend the mayor seek state and federal funding for repairs estimated at about $3.9 billion over 10 years.
Staff presented background and implications of subsidence affecting the California Aqueduct and the State Water Project, emphasizing the coastal branch that delivers water to Santa Barbara County.
An unnamed staff presenter explained that the aqueduct serves roughly 27 million people statewide and described how subsidence — primarily caused by decades of groundwater pumping in the Central Valley — compresses soils, lowers canal profiles and creates choke points that reduce flow capacity and operational flexibility.
“Already, as a result of subsidence, about 44% of aqueduct capacity has been lost,” the presenter said, and staff cited an estimate from Department of Water Resources planning that without near-term repairs capacity loss in affected reaches could reach as much as 87% within the next decade.
Staff described interim corrective actions being planned under the California Aqueduct Subsidence Program (CASP), such as raising canal liners in specified pools and removing certain check gates to restore freeboard and flow capacity. Staff said these interim measures and planning are costly; they cited a CASP estimate of repairs in the range of $3.9 billion over the next 10 years and said the state share is roughly three-quarters of that amount.
Commissioners asked about cost allocation and whether parties causing the subsidence should carry the cost. Staff noted the Sustainable Groundwater Management Act (SGMA) was intended to reduce overpumping in groundwater basins and to promote long-term sustainability, but they said precise user apportionment for aqueduct repairs has not been developed and that legal and cost-allocation disputes could take decades to resolve. In the interim, staff emphasized continuing to press state and federal partners for funding because local beneficiaries alone would face a substantial share of any repairs given where the coastal branch is located.
The commission moved and seconded staff's recommendation that council be asked to direct the mayor to send letters to state and federal legislative representatives to request funding for subsidence-related infrastructure repairs in the FY 26–27 budget. No public speakers addressed the item. Roll-call votes recorded Commissioner Young, Vice Chair Davis and Chair Keller voting yes; the motion carried.
Staff said DWR is also pursuing interim mitigations and that the city and Central Coast Water Authority will continue coordination at regional and state levels. When asked whether CASP estimates covered only interim work, staff said the $3.9 billion figure pertained to near-term/interim actions; long-term solutions remain under development.
