Notice of Intention for the Santa Ana River Watershed Weather Modification (Cloud Seeding) Pilot Program

NOTICE IS HEREBY GIVEN that the Santa Ana Watershed Project Authority (SAWPA) will begin cloud seeding through the Santa Ana River Watershed Weather Modification Pilot Program in November 2023. All inquiries should be directed to the contact listed below.

Project Description: In 2020, SAWPA completed a study on the economic and technical feasibility of implementing weather modification, also known as cloud seeding, in the Santa Ana River Watershed to increase water supply in the region. Based on the results of the feasibility study, SAWPA will now conduct a 4-year weather modification pilot program to gather the necessary data to validate the effectiveness of the program and determine if a full-scale project can be implemented in the watershed. The 4-year pilot program anticipates increasing precipitation in the Santa Ana River watershed during certain storm and rain events by 3 to5 percent, which is expected to correspond to a 6 to 15 percent increase in stream flow. The cloud seeding program in the Santa Ana River Watershed would use a combination of two specific ground-based seeding methods, Cloud Nuclei Generators (CNGs) and Automated High Output Ground Seeding units (AHOGS), for the release of silver iodide to enhance precipitation during storm events.

Project Location: The pilot program is targeting high elevation areas in the Santa Ana River Watershed through 15 ground-based seeding units in various locations in Orange, Riverside, and San Bernardino Counties.

Environmental Review Information: SAWPA completed environmental review of the Project in accordance with the California Environmental Quality Act with the adopted of an Initial Study/Mitigated Negative Declaration on June 23, 2022 (State Clearinghouse number 2022040174). The adopted Initial Study/Mitigated Negative Declaration and associated Mitigation Monitoring and Reporting Program can be accessed on SAWPA’s website.

Project Information: Related project documents can be accessed on SAWPA’s website at:

All inquiries concerning this project and any communication required by this notice should be directed to Melissa Bustamonte, SAWPA Communications Specialist at

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