The "very tiny particles of silver iodide" leads to artificially generated ice crystals, Griffith said. The droplets evaporate, depositing liquid on other ice and spurring the formation of snowflakes.

Artificially created ice crystals look and behave like natural ones, he said.

Contrary to what some may imagine, North American Weather Consultants doesn't use aircraft to seed clouds.

"We have ground-based equipment that disperses these silver iodide particles on the windward side of these mountain barriers," he said. Winds carry them to the right sections of clouds.

Griffith estimated that 150 or 160 generators will be used for the project in Utah.

The silver iodide does not present any environmental problems, he said. Studies carried out using federal funds showed "typically ... no significant environmental impacts whatsoever."

A company Web site states that the U.S. Public Health Service holds that concentrations of 50 micrograms of silver per liter of water is an acceptable level. With cloud seeding using silver iodide, the typical concentration of silver in rainwater or snow is less than 0.1 microgram per liter, it adds.

"As another example, the concentration of iodine in rainwater from seeded clouds is far below the concentration found in common iodized table salt," adds the Internet site, www.nawcinc.com/wmfaq.html.

Also, the company maintains that seeding is not "robbing Peter to pay Paul." That is, weather modification doesn't steal moisture from downwind areas. It contends that of the total atmospheric moisture passing over any point, the proportion falling naturally is small, typically less than 10 percent to 15 percent.

Cloud seeding may increase the precipitation to less than 20 percent of the total available moisture, the site says.

But does it result in significant water increases?

Yes, said Griffith. Scientists compared high-altitude areas in other states with places in Utah where there is a correlation in the normal, non-seeded precipitation. After seeding, they can check both the Utah targets and the control sites to see if the effort helped.

Griffith added, "It looks like we're seeing 10 to 15 percent increases in the seeded target areas that we're attributing to the cloud seeding."

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E-mail: bau@desnews.com