Valley Water expands desalination feasibility study, secures key regulatory exemption for Bay discharge

Valley Water expands desalination feasibility study, secures key regulatory exemption for Bay dischargeThe Santa Clara Valley Water District is adding $500,000 and 18 months to its desalination engineering feasibility study to conduct further modeling, keeping the estimated $1.7 billion backup supply option in play.

Staff are advancing a $500,000 contract amendment for consultant Black & Veatch, extending the study through the end of 2028.

The expanded scope includes hydrodynamic modeling for intake, outfall location modeling, and targeted water quality sampling.

The Regional Water Board ruled on July 3 that the California Ocean Plan does not apply to the project's San Francisco Bay discharges, easing state permitting requirements.

A recent cost comparison estimated a 24 million-gallon-per-day desalination facility at $1.7 billion, carrying higher operating costs than potable reuse.

The Santa Clara Valley Water District (Valley Water) is expanding its engineering feasibility study for a proposed desalination project after receiving a favorable regulatory clarification regarding brine discharge. During the July 29 meeting of the Recycled Water Committee, staff outlined a planned $500,000 amendment to the existing $1.7 million consultant contract with Black & Veatch. The amendment will extend the study's timeline by 18 months, allowing work to continue through the end of 2028. Henry Barrientos, a senior water resource specialist for the district, stated that the additional funds will cover critical technical gaps. The expanded scope of work includes hydrodynamic modeling for the intake alternative, modeling for two potential outfall locations, and specific water quality sampling to better characterize the intake site. The project also recently cleared a major regulatory hurdle. Barrientos told the committee that Valley Water received a letter from the Regional Water Board on July 3 confirming that the California Ocean Plan is not applicable to the project's potential discharges into the San Francisco Bay. This exemption provides crucial clarification and is expected to facilitate the state permitting process. The desalination project is currently being evaluated strictly as a backup water supply alternative under the district's 2050 Water Supply Master Plan. Earlier estimates presented to the committee priced a 24 million-gallon-per-day desalination facility at approximately $1.7 billion. While capital costs were compared against an equally sized potable reuse facility, Barrientos noted that the desalination option carries higher operational costs, primarily due to elevated energy consumption and frequent membrane replacement requirements. The initial phase of the feasibility study is currently 95% complete. Once the $500,000 contract amendment is formally approved by the Valley Water board, staff anticipate needing about a year to finalize the expanded technical modeling, which will culminate in a conclusive update report to guide the board's long-term supply decisions.