The Water Replenishment District of Southern California (WRD) and the City of Torrance have held a ceremonial groundbreaking for the Torrance Groundwater Desalter Expansion Project (TGDEP), marking a significant step forward in the region's long-term effort to reduce its dependence on imported water and unlock a brackish aquifer that has been unusable for decades.
A problem decades in the making
The project addresses a hydrogeological legacy stretching back to the early twentieth century. Over-pumping of groundwater along the Southern California coast caused water tables to drop below sea level, allowing seawater to intrude into freshwater aquifers. Los Angeles County responded in the 1960s by installing a network of seawater barrier injection wells that successfully halted further intrusion, but in doing so trapped a plume of salty groundwater inland from the barrier. That 14-square-mile brackish plume in the West Coast Groundwater Basin has made groundwater extraction economically unviable in parts of the region ever since.
WRD's first attempt to tackle the problem came with the Robert W. Goldsworthy Desalter, commissioned in Torrance in 2001 and expanded in 2018. The facility currently treats 3.6 million gallons per day of brackish groundwater using reverse osmosis and supplies roughly 25% of Torrance's water needs. The current expansion project aims to go significantly further.
Scale and technology
The construction funding approved by the WRD Board of Directors in November 2025 brought the total project value to $166.5 million, up from the approximately $160 million budgeted when contractor McCarthy-Jacobs was first selected in 2024. The scope covers four new groundwater extraction wells, feedwater pipelines, and substantial additional treatment capacity at the existing Goldsworthy facility. Upon completion, the expanded plant will deliver up to 7,100 acre-feet of drinking water per year.
The treatment train may be among the first of its kind in the United States to combine nanofiltration with reverse osmosis for a municipal brackish groundwater system.
Funding and outlook
WRD has secured more than $82 million in grants and low-interest loans from multiple sources, including the US Environmental Protection Agency's Clean Water State Revolving Fund, the US Bureau of Reclamation's WaterSMART Desalination programme, California's Proposition 1 Water Desalination Grant, and the Bonneville Environmental Foundation. The remainder of the budget is drawn from WRD's Capital Improvement Programme, with a bond issuance planned. WRD owns the facility; the City of Torrance operates it.
When the McCarthy-Jacobs joint venture was awarded the design-build contract in 2024, full-scale operational capacity was targeted for 2027. The commissioning date is now set for 2029. The TGDEP is the central pillar of WRD's broader Brackish Groundwater Reclamation Programme, which also envisions a potential second desalter in Manhattan Beach to treat the northern section of the brackish plume
