Reclaimed Water Used for Irrigation

Monterey County Water Recycling Projects, a combination of the Castroville Seawater Intrusion Project and the Salinas Valley Reclamation Project, began construction in 1995 and started delivering recycled water to fields near Castroville in 1998. By using recycled water pumped from the Monterey Regional Water Pollution Control Agency, farmers found they can safely irrigate their crops and reduce pumping of seawater-tainted groundwater. The unprecedented success of the Castroville Seawater Intrusion Project has led to the next step in fighting seawater intrusion – the Salinas Valley Water Project. Through the SVWP’s installation of a rubber dam on the Salinas River near Marina (Salinas River Diversion Facility), seasonally stored water can be blended with reclaimed water into the Castroville Seawater Intrusion Project’s pipelines for delivery as irrigation water.  CSIP currently serves 12,000 acres with irrigation water; there are plans to expand CSIP to another 10,000-12,000 acres as part of the implmentation of the SGMA groundwater sustainaiblity plan for the 180/400 (Pressure) sub-basin.

Seawater Intrusion in the Northern Salinas Valley

Seawater intrusion in the coastal areas of the northern Monterey County area was first detected as early as the 1930s and has continued since, now extending close to seven miles inland at the furthest extent of the intruded area. This has led to declining groundwater levels and salt intrusion, which are major concerns. In response, the Monterey County Water Resources Agency (MCWRA) constructed the Nacimiento Dam in 1957 and the San Antonio Dam in 1965 to control floods and enhance groundwater recharge, aiming to mitigate seawater intrusion.

Additionally, in 1998 MCWRA constructed the Monterey County Water Recycling Projects, which consist of the Salinas Valley Reclamation Project and the Castroville Seawater Intrusion Project (CSIP) to deliver recycled water for irrigation. The Salinas River Diversion Facility was brought online in 2010 to augment water supplies for CSIP. Monterey One Water operates these water supply projects; CSIP helps to reduce groundwater pumping and slow the rate of seawater intrusion.

The graphic below illustrates the mechanics of seawater intrusion in the Salinas Valley Groundwater Basin; the reversal of seawater intrusion is the most challenging project of the groundwater sustainability plan for the groundwater basin.  More information on a potential project, the brackish groundwater restoration feasibility study, can be found on the Salinas Valley Basin Groundwater Sustainability Agency’s webpage here.