SOUTHERN CALIFORNIA – The Santa Ana Watershed Project Authority (SAWPA), a joint power authority spanning portions of Riverside, San Bernardino, and Orange Counties, announced January 9 that they had conducted its first cloud seeding event.
The agency says that the 4-year Weather Modification Pilot Program, which launched in November 2023, intends to evaluate the effectiveness of enhancing local water supplies through cloud seeding in the region.
“If shown to be effective, cloud seeding can enhance the watershed resilience of the Santa Ana River Watershed by increasing snow and rainfall from storms by 5-15 percent in targeted areas,” said the SAWPA press release.
Cloud seeding during storms
Cloud seeding involves infusing silver iodide mixed with acetone particles into clouds during a storm causing ice crystals to form and water to condense into rain or snow.
SAWPA cloud seeded during three storms in the last week of December and first week of January.
SAWPA general manager Jeff Mosher said the program underscores the commitment of SAWPA to evaluate new local water supplies.
“If proven viable through this pilot study, cloud seeding could help support a more sustainable future for the environment and communities in the Santa Ana River Watershed,” said Mosher.
Effectiveness and health concerns
Northeastern University Assistant Professor of Public Policy and Urban Affairs and International Affairs Laura Kuhl says that while cloud seeding is not a new technology—the first experiments took place in the 1940s— it fell out of favor in the 1980s for being an “unacceptable ethical and environmental hazard.”
However, she says California, Idaho, Utah, Colorado, and Wyoming have all expanded their cloud seeding operations in response to the worsening drought.
Kuhl cites a 2003 National Academy of Sciences study that reports a high degree of uncertainty regarding the efficacy of cloud seeding.
Kulh says that while cloud seeding is often described as “creating” rain, it can be more accurately described as moving rain from one location to another.
“Despite claims of only local impacts, cloud seeding is already being coordinated at a regional scale across the Colorado River Basin. If adopted widely, cloud seeding could be used politically to deprive certain regions of rainfall (for example as a weapon of war), or to claim water that would otherwise be more widely distributed,” said Kuhl.
Kuhl notes several unintended consequences from cloud seeding – a study in the United Arab Emirates demonstrated that cloud seeding operations led to an increase in urban flooding. A blizzard in China that killed over 40 people and severe flooding in the United Kingdom have also been linked to cloud seeding.
Kuhl goes on to say that silver iodide is known to be toxic and is regulated under the Clean Water Act as a hazardous substance. Studies have documented the potential harms from bioaccumulation, particularly for aquatic life.
“While there are no simple solutions to water policy in the American West, significant policy changes are needed and current discussions about where and how to seed clouds don’t tackle these complex challenges,” said Kuhl.
SAWPA will continue its Weather Modification Pilot Program through April 2027.