Wyoming committee hears detailed scientific briefing on cloud seeding, operations and costs

CHEYENNE — Scientists and program managers told the Wyoming Legislature’s Agriculture, State & Public Lands & Water Resources Committee that cloud seeding can increase precipitation under certain conditions but that precise seasonal benefits remain uncertain, and that the state’s program faces funding constraints.

In a presentation spanning the program’s science, operations and environmental monitoring, Barry Lawrence, deputy director at the Wyoming Water Development Office, introduced speakers from the University of Wyoming, Heritage Environmental, the University of Wisconsin and the Utah Division of Water Resources. Dr. Jeff French of the University of Wyoming summarized the meteorological basis for winter “glaciogenic” cloud seeding and cautioned: “Cloud seeding does not create clouds out of clear sky.”

The presenters described how seeding agents such as silver iodide are intended to encourage ice formation in supercooled liquid clouds (clouds below freezing but composed largely of liquid droplets). French said research groups have moved beyond simple statistical comparisons to experiments that combine targeted observations and numerical modeling to link seeding inputs to physical changes in clouds. He cited the SNOWIE experiment (2017) and related modeling and publication efforts that identified measurable ice‑formation signatures in some cases and produced estimates of seasonal impacts when models are validated against those observations.

Wyoming’s program history and operations were reviewed by Lawrence. He said airborne funding and operations were cut in the most recent legislative session and that the ground‑based component would operate only if 100% of its funding were provided by Colorado River water users or other partners. Lawrence described Wyoming’s ground network as 13 generators (10 in the Wind River Range, 3 in the Sierra Madres) with remote monitoring, 24/7 seasonal operations and periodic site visits for maintenance. He told the committee generator run‑hours for the 2024–25 season and noted the Sierra Madre targets received a large share of seeding hours this winter.

On cost and yield, presenters gave ranges rather than single values. Lawrence and the Water Development Office cited prior Wyoming studies and a hydrologic evaluation that produced ensemble mean cost estimates in a range roughly between about $35 and $125 per additional acre‑foot depending on method and target (airborne vs. streamflow estimates), with several study designs and years producing different results. Jonathan Jennings of Utah said Utah’s program estimates have been materially lower in some years (he cited figures around $27 per acre‑foot in a higher‑capacity program) but emphasized that cost per acre‑foot depends heavily on program scale, generator density, instrumentation and whether airborne or drone methods are used.

Environmental monitoring and toxicity were addressed by Patrick Golden (Heritage Environmental) and Dr. Ross Edwards (University of Wisconsin). They summarized trace‑chemistry studies done around cloud seeding projects: silver is detectable in snow and stream samples at parts‑per‑trillion levels in many baseline measurements, and silver iodide is far less soluble than silver nitrate. Edwards said regulatory water‑quality thresholds for dissolved silver are orders of magnitude higher than typical trace detections from seeding operations and that most silver in natural soils and sediments is present at levels far above the tiny additions expected from seeding. Golden said environmental assessments for prior Wyoming projects resulted in findings of no significant impact and noted that permitting processes (NEPA for federal lands; temporary use permits on state lands) had been completed for earlier operational phases.

Committee members pressed presenters on the limits of certainty. One legislator said he remained skeptical about role of state funding and value for taxpayers; presenters replied that the scientific understanding has advanced substantially in the last two decades but that exact seasonal gains and downstream effects remain topics for continued research and calibrated modeling.

The committee also heard operational context: Wyoming participates in a multistate program to augment Colorado River streamflow; the 2018 basin agreement and subsequent cost‑sharing from lower‑basin agencies have previously supported research and operations. Lawrence and others emphasized that program design, generator density, and instrumentation (radars, radiometers, aircraft or drones) materially affect evaluations and costs.

The session concluded with committee members and presenters agreeing the science has advanced but also identifying clear remaining research needs — especially calibrated seasonal modeling, denser observation networks and third‑party evaluations to reduce uncertainty about magnitude and distribution of any benefits.

Ending: Committee members asked staff to draft follow‑up materials and indicated interest in more detailed hydrologic and cost analyses before making new funding decisions.