Calleguas moves to shortlist brackish desalter concepts
Calleguas Municipal Water District, California · Meeting date: November 4, 2026 · Published: November 6, 2026
Calleguas will ask study partners to score 13 brackish-water desalination concepts at a workshop later this month, aiming to identify three to five options for detailed evaluation. The work is intended to refine potential facilities, water production and costs before recommendations reach the board next summer.
Key points
- Study partners have received fact sheets for 13 concepts, covering preliminary layouts, facilities, rough costs, water-production estimates and agreed evaluation criteria.
- A workshop scheduled for two weeks after the November 4 meeting is intended to narrow the field to three to five concepts.
- The subsequent analysis will include groundwater modelling, refined facility sizing and more detailed cost estimates.
- The studies will use existing basin models, with work in Las Posas Basin to be undertaken by Interra and a simpler Simi Basin model to be used by the consultant team.
- Recommendations are expected to go to the board and the Desalter Study Ambassador Council next summer.
Full report
Calleguas Municipal Water District is preparing to cut its brackish-water desalination study from 13 concepts to a shortlist of three to five alternatives, marking the next stage in its search for a project configuration to advance.
All study partners have received detailed fact sheets on the 13 concepts. Each contains a preliminary layout, the facilities involved, rough cost and water-production estimates, and information against criteria previously agreed by the partners. At a workshop scheduled for two weeks after the board’s November 4 meeting, participants will score the concepts, with the objective of leaving with a three-to-five-project shortlist.
The shortlisted concepts will then receive a more granular evaluation over the following months. Staff said this will include groundwater modelling, more detailed cost estimates and refinement of facility sizing based on hydrogeological analysis. The next workshop is planned for the spring, while recommendations are expected to be presented to both the Calleguas board and the Desalter Study Ambassador Council next summer.
The modelling approach will vary by basin. In Las Posas Basin, Interra would undertake the work because it has been conducting the basin modelling. The Simi Basin has a simpler existing model that the consultant team would use. Staff said the models have already been identified; the detailed project parameters to be entered into them depend on which concepts proceed.
The study has broader implications for Calleguas’ supply planning. Staff said some concepts under consideration include potable-reuse elements using effluent from Simi Valley’s wastewater treatment plant. That possibility could intersect with Calleguas’ existing Simi Valley recycled-water arrangement, which currently supplies recycled water to the Simi Valley landfill through a small wholesale system.
The district recently extended that recycled-water agreement through 2029. Staff said the additional time will allow Calleguas to assess how the desalter study, potential potable-reuse concepts and Simi Valley’s wastewater compliance planning could fit together. Simi Valley has received a time schedule order requiring compliance with more stringent salt-discharge requirements for its wastewater effluent, with several potential response paths still under evaluation.
This summary was generated by AI based on the source document and may contain errors.
Source: Board Meeting, Calleguas Municipal Water District