CVWD ties Mission Creek groundwater resilience to recycled water and SWP projects
Coachella Valley Water District, California · Meeting date: November 4, 2026 · Published: November 5, 2026
Coachella Valley Water District’s modelling finds that planned recycled-water recharge and imported-supply projects can keep all nine Mission Creek key wells above their minimum thresholds through 2050. But a severe climate scenario still produces a long-term decline in basin storage, underlining the importance of further supply development.
Key points
- Under both climate cases, the Near-Term and Future Projects scenarios keep all nine Mission Creek key wells above minimum thresholds through 2050.
- The near-term package assumes a pipeline will return treated water from Mission Springs Water District’s Nancy Wright Regional Water Reclamation Facility to Mission Creek for recharge from 2035.
- Future Projects add assumed supply benefits from Sites Reservoir and the Delta Conveyance Project, lifting average State Water Project deliveries for Mission Creek replenishment.
- Under the severe MIROC5 RCP 8.5 scenario, Mission Creek storage is modelled to decline through 2050 even with future projects, although the projects reduce the loss.
- CVWD expects to hold a public hearing on the alternative-plan updates on December 8 before submitting them to the Department of Water Resources by December 28.
Full report
Coachella Valley Water District is positioning recycled-water recharge and new State Water Project reliability schemes as central to sustaining the Mission Creek Subbasin, after modelling showed that climate-driven reductions in recharge and imported supply would erode groundwater storage without further intervention.
At a November 4 study session, staff presented the draft 2027 Sustainable Groundwater Management Act alternative-plan update for Mission Creek. The plan evaluates a baseline case, a near-term project package and a future-project package under moderate and severe climate assumptions.
The near-term package assumes Mission Springs Water District will convey treated water from the Nancy Wright Regional Water Reclamation Facility back from the Garnet Hill Subarea to Mission Creek for recharge from 2035. It also includes tertiary-treatment expansion at the Horton wastewater treatment plant. The future-project case adds imported-water reliability components associated with Sites Reservoir and the Delta Conveyance Project.
The Mission Creek model indicates that both the near-term and future-project packages can maintain groundwater levels above measurable objectives and minimum thresholds at all nine designated key wells through 2050 under both climate cases. The finding is significant because the broader planning area’s total demand is projected to rise from 14,369 acre-feet a year in 2025 to 17,925 acre-feet a year in 2050, a 25% increase.
However, the storage outlook is less favourable under the severe MIROC5 RCP 8.5 climate case. The draft plan projects lower mountain-front recharge and reduced imported-water replenishment under that scenario. By 2050, cumulative Mission Creek storage relative to 2009 is negative in the severe-climate cases. Future Projects reduce, but do not eliminate, the loss.
The longer-term model results sharpen the distinction between the two project packages. Under severe conditions, the near-term scenario shows one key well, 17J01, falling below its minimum threshold near the end of the extended 2074 modelling horizon. The future-project scenario keeps all nine wells above their measurable objectives and thresholds through that horizon, though cumulative storage remains negative.
Staff said the Mission Creek portfolio is less diverse than that of the Indio Subbasin, making it more exposed to changes in watershed runoff and imported-water availability. Existing recharge at the Mission Creek Groundwater Replenishment Facility remains the principal supply-management programme. No recharge occurred there in water year 2021-22, followed by 5,275 acre-feet in 2022-23 and 5,432 acre-feet in 2023-24.
The board was asked for feedback ahead of a planned December 8 public hearing on the alternative plans. Submission to the California Department of Water Resources is scheduled for December 28.
This summary was generated by AI based on the source document and may contain errors.
Source: Board of Directors Study Session, Coachella Valley Water District