Researchers Confirm Minimal Environmental Impact of Cloud Seeding Silver Levels

The recent meeting of the Wyoming Legislature's Joint Agriculture, State and Public Lands & Water Resources Committee on August 28, 2025, highlighted significant discussions surrounding the environmental impacts of cloud seeding, particularly concerning silver concentrations in the environment.

Key Impact: The committee reviewed findings from various studies indicating that cloud seeding operations have negligible environmental impacts, particularly regarding silver levels in snow, water, and soil. Baseline samples taken from snowpack showed silver concentrations ranging from 4 to 6 parts per trillion, while stream baselines varied between 1 and 36 parts per trillion. These levels are significantly lower than natural occurrences of silver in the environment, which can reach up to 1.7 parts per million in undissolved particulate matter. The data suggests that the silver introduced through cloud seeding is minimal compared to naturally occurring silver from geological sources.

Secondary Topics: The meeting also addressed the forms of silver present in the environment and their toxicity. It was noted that silver iodide, commonly used in cloud seeding, is relatively insoluble and poses little risk to aquatic life. The World Health Organization and the Environmental Protection Agency set a water quality standard for silver at 100 parts per billion, while the concentrations from cloud seeding are significantly lower, often around 0.9 parts per billion. Additionally, the committee discussed the bioaccumulation of silver in the food chain, concluding that the stable compounds formed from cloud seeding do not lead to significant toxicity in aquatic organisms.

Conclusion: The findings presented at the meeting reinforce the safety of cloud seeding practices in Wyoming, alleviating concerns about environmental contamination. As the state continues to explore cloud seeding as a method to enhance water resources, these discussions will play a crucial role in shaping future policies and practices, ensuring that environmental integrity remains a priority for Wyoming's agricultural and natural resource management.