Cloud-seeding the Wind River Range for more snow-pack?
Environmental, legal concerns may trump state
by Julia Stuble

A controversial application for cloudseeding over the Wind River Range is working its way across desks on the Shoshone and Bridger-Teton National Forest (BTNF) managers, with environmentalists’ concerns battling the state of Wyoming’s thirst for irrigation water.

The application was submitted by Weather Modification, Inc., a company which received funds from the state to pursue a five-year pilot cloud-seeding project. Wyoming appropriated $9 million to the project, one part of which has begun in the Medicine Bow Mountains and Sierra Madre range in the southeast corner of the state. The state government initiated the project to determine if cloud-seeding is a viable method for increasing snow-pack, and thus alleviate drought concerns on the parched agricultural lands across Wyoming. The state also wants to increase snow-pack to aid municipal water supplies, hydropower and fisheries. Cloud-seeding is a process in which silver iodide, a salt, is sprayed into the atmosphere, where it then encourages snowflakes to form. The salt is first dissolved in acetone, and then ignited using propane, which aerosolizes the chemical to distribute in the air.

Weather Modification’s application asks for about ten “generators” or aerosolizes, spread across lands in the Wind River Range. According to Greg Bevenger, a hydrologist with the Shoshone National Forest, only two generators will be on the BTNF, and one on the Shoshone. Another seven will be on private or state lands.

These generators have a small footprint, explained Bevenger, meaning this is not so much an environmental concern. “There is a potential for nitrate deposition in light of energy development in the Upper Green River Valley,” he said, adding the “fate of the silver iodide, that is, when it falls to the ground,” are concerns for the forest managers from an environmental perspective. Nitrate deposition leads to lake acidification, a problem that has been compounded by larger amounts of nitrates in the atmosphere from industrial sources. The BTNF is currently monitoring several lakes in the Wind Rivers for increasing nitrification of lakes.

There are fears that more precipitation over the Range will “scrub” out more pollutants from the air, leading to more deposition than is currently happening.

However, the environmental concerns are not the only headache for the forest managers when reviewing this application. They have legal issues to deal with as well. The Wilderness Act of 1964 prohibits weather modification over Wilderness Areas. The Forest Service also has manual directions which require that weather modification proposals be approved at the chief’s level, in Washington D.C., Bevenger said.

In the Forest Service’s Manual, regulation 2323.45 states “Do not permit long-term weather modification programs that produce, during any part of successive years, a repeated or prolonged change in the weather directly affecting wilderness areas.” Bevenger said the managers have directed regional offices “to look into that.” The application was submitted for a special-use permit. The forests will initiate a public scoping process fairly soon, said Bevenger, which will then determine the National Environmental Policy Act’s level of environmental analysis.

Depending on the scoping, the application could be given a categorical exclusion, or subjected to an Environmental Assessment (EA) or an Environmental Impact Statement (EIS). Categorical Exclusions are designed to address recurring, non-controversial projects while EA and EIS’s address more controversial, long-term, more impactive projects.

“The question is if weather modification is appropriate in wilderness areas, and that will be evaluated,” explained Bevenger. The state’s funds for this project were administered by the Water Development Commission, which awarded two contracts. One was given to Weather Modification for the actual cloud-seeding while another was given to the National Center for Atmospheric Research for monitoring of the project. The three mountain ranges which are seeing, or may see, the cloud-seeding project were selected by the state.