The Colorado River is hundreds of miles from the San Joaquin Valley. Not a single drop of it flows to Valley farms or communities. So when federal negotiations over the river’s future make headlines, it’s easy to see it as someone else’s problem. But California’s water system doesn’t respect those boundaries — and decisions made in the Colorado River Basin can directly reshape what’s available here.
The upcoming federal decision on post-2026 operating rules for the Colorado River could have significant ripple effects across California, especially for the farms, communities, and ecosystems in the San Joaquin Valley.
The Colorado River supplies roughly one-third of Southern California’s water for more than 19 million people. If that supply is reduced — whether by drought, new federal rules, or litigation among Basin states — Southern California won’t simply go thirsty. It will turn to other sources to make up the difference. Chief among them: Northern California water delivered through the State Water Project and Central Valley Project.
In other words, there may be increased competition for conveyance capacity for water, potentially making it more difficult to secure adequate water supplies for the San Joaquin Valley during certain times of the year.
Research on statewide water operations shows that when Colorado River deliveries decline, Southern California agencies typically increase demand for State Water Project supplies, stored water, and transfers originating in the Central Valley. This substitution effect can intensify competition for limited Delta exports and south-of-Delta conveyance capacity — the very lifelines that sustain much of the Valley’s agriculture and communities.
Even without this additional pressure, the outlook is already sobering. The Public Policy Institute of California estimates that implementation of groundwater sustainability requirements alone could lead to the permanent fallowing of roughly 500,000 to 900,000 acres of farmland in the San Joaquin Valley in the coming decades. That represents not just lost crops, but lost jobs, shrinking rural economies, and generational impacts on families who have farmed here for decades.
Paul Peschel, P.E., formerly assistant general manager of water operations for Modesto Irrigation District, recently warned that the region cannot afford to view Colorado River negotiations as someone else’s problem. Decisions made there, he noted, will inevitably shape water availability here because California’s water system is interconnected — when one major source shrinks, pressure shifts to the others.
Although the San Joaquin Valley does not receive Colorado River water directly, statewide systems are deeply interconnected. Shared infrastructure, transfer markets, and operational decisions mean shortages in one region can cascade into another. Analysts describe this as “substitution pressure”: when one major supply tightens, demand shifts to the next available source, often the Delta-based projects that serve the Valley.
The Water Blueprint for the San Joaquin Valley (Blueprint) is actively working to reduce the risk of “north-to-south” water competition by building cooperative partnerships with Southern California agencies — most notably the Metropolitan Water District of Southern California (Metropolitan). In May 2024, the Blueprint and Metropolitan signed a historic memorandum of understanding (MOU) to collaborate on projects in the San Joaquin Valley that improve water management, storage, and recovery for both regions.
The agreement establishes a framework to identify groundwater banking sites, expand conveyance capacity, and develop programs that capture excess water in wet years and make it available during droughts. Under this model, Metropolitan could store surplus water in Valley aquifers when supplies are abundant and later exchange or recover that water when conditions turn dry, creating a two-way reliability benefit rather than a zero-sum transfer.
Meanwhile, the Colorado River system itself remains under extraordinary stress. Lake Mead and Lake Powell — the reservoirs that anchor supplies for the Southwest — sit at historically low levels after decades of drought and overuse. Failure to stabilize these reservoirs could trigger sweeping impacts across the Western economy, affecting more than 40 million people and major agricultural regions.
Negotiations among the seven Basin states have been contentious. Lower Basin states, including California, have already implemented substantial conservation efforts to stabilize the system, while debates continue over how much additional responsibility should fall upstream.
For the San Joaquin Valley, the lesson is clear: what happens on the Colorado River will not stay on the Colorado River.
That’s why the Blueprint’s focus is on developing new water supplies — required in California’s SB 72, which sets a target of identifying 9 million acre-feet of additional water supply by 2040 to offset the anticipated loss from warmer ambient temperatures. Without expanded capacity, California will be forced into an increasingly zero-sum game, shifting water from one region to another during shortages.
The most straightforward and cost-effective approach to increasing capacity is the recharge of currently depleted groundwater reserves. This method utilizes existing, unused storage within aquifers. Approximately 140 million acre-feet of usable aquifer storage is available south of the Delta, which could be replenished with dedicated excess water. This would add almost three times the amount of water storage to the existing reservoir capacity, which would benefit all water users. An additional benefit of accelerated aquifer recharge is the mitigation of ongoing expensive infrastructure damage associated with land subsidence caused by drained aquifers.
Ultimately, this issue is about people, not just policy. It’s about farmworkers wondering if there will be work next season, small towns struggling to keep businesses open, and families deciding whether the Valley still offers a future for the next generation.
The Colorado River may be far away, but its future is intertwined with our own. Protecting the San Joaquin Valley’s water security means paying close attention to decisions made across the entire Western water system and ensuring that California invests in solutions that expand supplies rather than redistribute scarcity.
