Three Valleys MWD adopts 2025 regional water plan, targets stranded assets and golden mussel delays

Three Valleys MWD adopts 2025 regional water plan, targets stranded assets and golden mussel delaysThe Southern California wholesaler has approved a long-term roadmap that projects 100% supply reliability through 2050, driven by major investments in wellhead treatment and recycled water injection to combat strict new conservation and contaminant regulations.

The 2025 Regional Urban Water Management Plan projects regional water demands will decline through 2050 due to the state's 'Making Conservation a California Way of Life' mandate.

Planned capital projects include the GRIP+ initiative to restore 9,200 acre-feet per year of stranded groundwater assets and a 3,500 AF recycled water storage project in the Spadra Basin.

General Manager Matthew Litchfield identified golden mussel mitigation as the district's most pressing challenge, temporarily delaying 22,000 acre-feet of required groundwater recharge.

The Three Valleys Municipal Water District (TVMWD) Board of Directors unanimously adopted the 2025 Regional Urban Water Management Plan (RUWMP) and Water Shortage Contingency Plan during its June 3, 2026, meeting. The comprehensive long-term planning document, developed in coordination with six participating member agencies, outlines a strategic framework to maintain 100% water supply reliability through 2050 despite climate volatility and tightening regulations. A central finding of the 2025 RUWMP is that regional water demands are expected to decline over the next 25 years, despite modest projected population growth. This downward trajectory is driven by compliance with California's new "Making Conservation a California Way of Life" regulations. According to the plan, participating retail agencies anticipate demand reductions ranging from 9% to 37% relative to 2017-2021 baselines. The region currently relies on a supply portfolio consisting of approximately 50% imported water from the Metropolitan Water District of Southern California (MWD) and 44% local groundwater. However, the RUWMP identifies "stranded assets" as a major threat to local supply reliability. Decades of historical land-use practices have introduced volatile organic compounds (VOCs) and nitrates into underlying aquifers, while strict new Maximum Contaminant Levels (MCLs) for per- and polyfluoroalkyl substances (PFAS) are forcing agencies to take existing extraction wells offline. To restore these stranded assets and reduce reliance on imported water, the RUWMP outlines a suite of collaborative capital projects. Key initiatives include the Groundwater Reliability Improvement Program (GRIP+), a partnership between TVMWD, the City of Glendora, and the City of Pomona. The project involves installing new extraction wells and advanced wellhead treatment systems to restore 9,200 acre-feet per year (AFY) of highly reliable local supply from the Main San Gabriel Basin. Additionally, the region is advancing the Spadra Basin Optimization project, a collaborative effort spearheaded by the Walnut Valley Water District, the City of Pomona, and Cal Poly Pomona. The project proposes injecting advanced treated recycled water into the Spadra Basin to create a drought-resilient local storage asset with a capacity of up to 3,500 AF. While the 2025 RUWMP projects long-term supply resilience, TVMWD faces immediate operational hurdles. During his work plan report, General Manager Matthew Litchfield identified invasive species mitigation as the district's most significant current challenge. Mitigation efforts for the golden mussel have prompted Los Angeles County to temporarily halt recharge operations in the Main San Gabriel Basin. "We do have an outstanding 10-year commitment to recharge 30,000 acre-feet in the Main San Gabriel Basin with Metropolitan," Litchfield told the board. "We still have about 22,000 acre-feet of water that we need to put into the ground that's still outstanding." Litchfield noted that with the State Water Project allocation currently at a favorable 45%, he is hopeful that mitigation efforts will progress enough to resume groundwater recharge operations by the fall. In other business, the board held a preliminary public meeting to review the proposed fiscal year 2026-2027 water standby charge, which is estimated to remain at $29.41 per equivalent dwelling unit. A formal public hearing and adoption vote for the charge is scheduled for June 17.