Decades of heavy groundwater pumping have pushed the Salinas Valley aquifer to what Monterey County officials say looks a lot like a tipping point, with farms, city systems and thousands of private wells all on the line. Local water agencies are sprinting this summer to decide on projects that run from many hundreds of millions to roughly a billion dollars, aiming to halt seawater creeping inland and pull the underground basin back into balance.
According to CBS Bay Area, the immediate problem is seawater intrusion into coastal subbasins, combined with steady groundwater declines that could leave some wells too compromised to use. A separate analysis from the U.S. Geological Survey flags “undesirable effects,” including falling groundwater levels, loss of stored water and the inland advance of salty water beneath Castroville and Salinas, which helps explain the urgency coming from local boards.
What's at stake for farms and wells
Roughly 95 percent of the valley’s irrigation supply comes from groundwater, and hydrologists report that parts of the 180/400-foot subbasin already show signs of seawater edging in, a trend that could knock out key production wells if it keeps marching inland. Local coverage cited by Monterey County Now puts potential annual economic losses under steep groundwater pumping cuts in the range of $1.3 to $1.9 billion and notes that about 50,000 disadvantaged residents rely on the same basin for their drinking water.
Three big options on the table
After feasibility work and a flurry of staff briefings, agencies have narrowed their short list to portfolios that mix conservation with hefty infrastructure builds. Concepts include treating brackish groundwater and injecting it back underground, diverting Salinas River flows using canals or pipelines and upgrading the existing Castroville Seawater Intrusion Project. Cost estimates stretch from roughly $600 million to more than $1.3 billion, with one favored “injection only” brackish water project coming in near $950 million, according to the Salinas Valley Basin Groundwater Sustainability Agency and other local reporting.
Who pays and how much
The Monterey County Water Resources Agency is already talking dollars and cents, putting water delivery fees and related assessments on its board agenda as it plans for construction and future operations. County documents list a recommended Zone 2B water delivery charge of about $100.24 per acre-foot in FY 2026–27 and a service charge of about $113.57 per acre-foot for the Salinas River Diversion Facility, with public hearings scheduled so growers and residents can weigh in. Details are posted in the Monterey County Water Resources Agency materials.
What happens next
Board members and advisory committees are set to keep grinding through technical workshops over the summer as they sort through project portfolios, refine price tags and try to line up a recommended path forward for state review later this year. The Salinas Valley Basin GSA has released feasibility documents and hosted public workshops as it moves toward a formal board recommendation, according to SVBGSA.
Legal and regulatory risks
All of this is happening under the clock set by California’s Sustainable Groundwater Management Act, which requires critically overdrafted basins to reach sustainability or risk state intervention. That makes the Department of Water Resources a serious backstop for whatever local plan emerges. County and GSA leaders say the SGMA timeline, combined with the risk of mandated pumping cuts, is driving the push to choose projects that can both halt seawater intrusion and satisfy regulators, as laid out by the County of Monterey.
So expect a steady stream of public hearings, slide decks and funding battles in the coming weeks as officials try to match technical fixes with something communities and growers can actually pay for. For now, the tug of war between keeping saltwater at bay and keeping costs in check is set to shape Monterey County water policy for years.
