Pinal County describes July–September cloud‑seeding pilot; lawmakers press for data and notice

The Pinal County Water Augmentation Authority described a July–September cloud‑seeding pilot in the Casa Grande area and defended its choice of hydroscopic (salt) flares and contractor selection, while lawmakers pressed for more data, better notification and independent verification of water‑production estimates.

Joe Singleton, the authority’s executive director, said the board authorized a one‑year proof‑of‑concept after a feasibility study recommended targeting the summer monsoon season. The authority obtained a permit from the Arizona Department of Water Resources, contracted Seeding Operations and Atmospheric Research (SOAR) to provide pilots and aircraft, and used hydroscopic flares (not silver iodide) to honor a stakeholder request not to overfly certain tribal airspace.

Singleton described flight logs and reporting tables in the authority’s final report, said some flight days used 500‑gram hydroscopic flares (about 1.1 pounds) and that monthly and final reports are posted on the authority’s website. He acknowledged one year of operations limits conclusions and described estimated average water gains in the seeded area as “a little under half an inch” using the project’s estimation methods; he also noted a range of estimates across sites and cautioned that large countywide numbers in the consultant’s tables are gross estimates and likely overstate yield.

Lawmakers asked when the authority would provide more detailed information. Singleton said the final report is complete and on the authority website and that he would ensure the report is submitted to ADWR; he also committed to providing a specific list of the flare chemical formulation to the committee. Several members said they had not received timely notice of the program and requested that affected legislators be directly notified of future meetings. Committee members asked ADEQ to review NOAA’s weather‑modification database and to pull comparative reports from other states.

Salt River Project meteorologist James Walter provided historical context, saying Arizona trials date to the 1940s and that SRP performed cloud‑seeding work through the early 1960s; he explained the physical mechanism by which hygroscopic (salt) and glaciogenic (silver iodide) seeding agents act as nuclei for droplet or ice formation. Members requested follow‑up technical briefings and a meteorologist return for more detailed questions; no formal action was taken at the hearing.