Wyoming committee urges Congress to ban unauthorized geoengineering after amendment fight over cloud seeding

The Agriculture, State & Public Lands & Water Resources Committee on Friday approved a joint resolution asking Congress to prohibit unauthorized atmospheric geoengineering and weather modification over Wyoming, following hours of public testimony and several amendments.

Committee members moved the resolution, 26LSO0208, through a multi‑part amendment process that added staff wording emphasizing state duties under the Tenth Amendment and directed the governor to coordinate with neighboring states and the Western Governors' Association on atmospheric policy. Lawmakers also debated whether to explicitly reference federal airspace law (49 U.S.C. 40103) and whether to exempt cloud seeding operations used for water augmentation. The committee ultimately adopted an explicit exemption for cloud seeding language and then removed direct textual references to “cloud seeding” from the resolution before the final roll call.

The measure asks Congress to prohibit unauthorized geoengineering and weather modification in the state and directs the secretary of state to transmit copies of the resolution to the president, congressional leaders and the state’s congressional delegation. Committee members said the resolution is intended to put federal and state actors on notice about Wyoming’s concerns while stopping short of creating an enforceable state statute.

Supporters of the resolution argued during committee debate that broad, federally coordinated programs of solar radiation management and other large‑scale geoengineering projects could pose risks to public health, water resources and agricultural productivity. Opponents and several testifiers urged the panel to avoid banning locally authorized cloud‑seeding programs used to augment snowpack and water supply; those speakers said cloud seeding is a distinct, small‑scale technology used by municipalities, ranchers and utilities to boost precipitation.

Public comment before the vote illustrated the split. Brad Brooks of the City of Cheyenne Board of Public Utilities and the Colorado River Working Group urged lawmakers not to conflate cloud seeding with the broader geoengineering allegations and asked that cloud seeding be excluded from any prohibition, citing local water needs on the Colorado River system. Industry representatives, including Augustus DeRico of Rainmaker, said cloud seeding uses silver iodide and other approved agents at concentrations they described as far below environmental thresholds and that regulators should study and, if appropriate, regulate the technology, not ban it. Several county conservation district representatives and the Wyoming Association of Conservation Districts also urged that cloud seeding be considered separately and that the state not forfeit operational tools for water augmentation.

By contrast, other witnesses pressed for the resolution, testifying that they had identified nanoparticles and other substances in precipitation samples and raised concerns about potential ecological and human‑health effects. Several medical and citizen witnesses urged a federal pause on unauthorized programs and more disclosure of federal agency involvement.

The committee adopted multiple amendments during floor debate before the final vote. The roll call on the amended resolution produced a committee tally announced in the record; the resolution passed and will be transmitted as directed.

Committee staff flagged the legal interplay with federal airspace authority during debate; an earlier staff note included suggested wording referencing 49 U.S.C. 40103 and clarified the limits of state authority to regulate national airspace. The committee ultimately kept language that underscores Wyoming’s interest in protecting air and water quality while acknowledging federal authorities.

The committee will circulate the adopted resolution to the governor’s office and to the state’s congressional delegation in Washington, D.C., per the adopted draft. The committee moved next to consider a separate draft that would impose a state moratorium and study requirement for cloud seeding; discussion of that bill continued before the panel recessed.

Ending note: The resolution is a formal state expression of concern and a request to federal lawmakers and does not itself alter state permitting statutes. The committee’s amendments reflect an effort to balance concerns about large‑scale geoengineering with local water‑management needs.