California IN BRIEF : YOSEMITE NATIONAL PARK : Official Urges Halt to Cloud Seeding

A cloud-seeding flight over Yosemite National Park has upset officials and environmentalists who say it threatens the natural ecosystem and climate of the area. Last Sunday’s flight by Fresno-based Atmospherics Inc. was performed under a contract with the Turlock and Modesto irrigation districts. District officials said they are attempting to increase runoff by 2% to 7%. However, Yosemite Supt. Michael Finley said the cloud seeding must be stopped because it dispenses certain chemicals, including silver iodide. The chemicals are supposed to collect moisture to form snow or larger drops of moisture. Finley said the chemicals could accumulate in the park and damage the ecosystem. “The National Park Service has a policy opposing attempts at weather alteration systemwide,” Finley said. Before the program began, water officials hired a San Francisco firm to conduct an environmental review of cloud seeding in the area. Finley said the report failed to address the effect the weather modification system may have on the ecosystem. Experts disagree on the impact of silver iodide. One Park Service researcher said silver iodide may not have any measurable impact, but was still an intrusion of unknown dimensions into a natural ecosystem.