San Dieguito Groundwater Study
About the Study
OMWD is studying the possibility of developing a local water supply through a groundwater desalination project in the San Dieguito Valley utilizing grant funding from California’s Department of Water Resources. View our initial Feasibility Study (28 MB) and Appendices (75 MB) completed in 2017.
The study will analyze:
- The amount of groundwater that could be extracted from the basin on a sustainable basis without impacting the environment or current water users
- Groundwater quality
- Methods of groundwater treatment
- Identification of adequate land for the wells, treatment facility, and brine disposal necessary to operate the potential project
- Costs associated with producing the new local water supply
- Whether the expense of producing the new water supply is cost-efficient when compared to the cost of developing other potable water supplies
Initial study yielded positive results, and on December 12, 2018, OMWD’s Board of Directors adopted a mitigated negative declaration as part of the environmental review process for this potential project. The project has recently completed its one-year pump test cycle producing data that has confirmed the results of the 2017 Feasibility Study and provided positive indications that the basin can support a potential potable water supply. The results of the pilot well pump test are available for review in the Design Pilot Report. Based on these results, OMWD’s Board of Directors has decided to approve further investigations intended to inform the ultimate decision to move forward with the project.
OMWD is heavily reliant on imported water, much of which comes from far-off places like the Sacramento-San Joaquin Bay-Delta and Colorado River. The development of a local, sustainable water source like this one is becoming increasingly important as imported water costs continue to rise and water availability becomes more uncertain. Local sources also provide water supply redundancy should imported supplies be cut off.
About the Potential Project
The potential project would extract groundwater from wells located in the San Dieguito Valley Groundwater Basin and deliver it to a nearby desalination facility. Treated through reverse osmosis, a filtration process that improves water quality by removing impurities such as salts, hardness, and other dissolved minerals, the water would be available for uses like drinking and fire protection.
The groundwater used to create this supply for OMWD customers would be above and beyond that already being used by existing groundwater users. In other words, customers already using groundwater through a private well would not be impacted.
Project costs will be calculated as part of the study. The project would be paid for through OMWD capital improvement funds and developer fees, as well as potential state and federal grants.
The water supply would need to be produced at a cost that is comparable to developing other local potable water supplies in order to be considered feasible. OMWD has anticipated this cost in its long-term financial planning.
OMWD continues to host public outreach meetings to discuss the project with local residents and area stakeholders. A PowerPoint presentation providing an update on the study was reviewed by stakeholders at the October 17, 2017, community meeting. OMWD held a community meeting to discuss a test well in San Dieguito Valley at Solana Santa Fe Elementary School on December 4, 2018.
OMWD hosted another community outreach meeting on April 27, 2021 to provide a detailed update on the project and to present initial findings from the recently completed one-year pump test. A recording of the meeting can be viewed on OMWD’s YouTube channel.
The results of the one-year pump test were favorable and further confirmed that this project is feasible and will have minimal impact on the greater basin. At its April 14, 2021 Board Meeting, OMWD’s Board approved further project studies through 2023 intended to inform the decision to potentially move forward with preliminary design and an environmental impact report.
For More Information
For more information about the study or the potential project, please contact Joey Randall, OMWD Assistant General Manager, at 760-753-6466.
To learn more about OMWD’s efforts to explore groundwater desalination as a potential local source of potable water, visit our San Elijo/San Dieguito Valley Groundwater Project page.