Utah water year above average

For the second time running, Utah has ended the water year on a positive note. But that won't stop a Sandy company from working to increase winter precipitation in the state.

The 2006 water year ended midnight Saturday, when October began. By Monday, federal experts were able to calculate that the year's precipitation across Utah had totaled 103 percent of the 30-year average. While slightly better than typical, that wasn't as good as the previous year's precipitation.

"2005 was a little better," said Ray Wilson, hydrologist with the U.S. Natural Resources Conservation Service office in Salt Lake City. That year, he said, "we ended up with 125 percent."

The '05 water year marked the end of a six-year drought, and this immediately past water year confirmed that dry weather was over for most of the state. That was true "especially in the north," Wilson added.

"Down south ... most of the basins were a bit below average." But they did not drop to the parched conditions of recent years.

2006 water year precipitation ranged from 115 percent of normal on the Weber River drainage, to a low of 84 percent in southeastern Utah, he said.

Meanwhile, North American Weather Consultants, Sandy, is revving up for its annual cloud-seeding projects. Since the spring runoff — which results from the mountain snowmelt — provides most of the water for Utah reservoirs, cloud-seeding seeks to increase winter snowpack.

Projects in central and southern Utah will begin Nov. 15 and others in the state around Dec. 1, said Don A. Griffith, the company's president. Such projects have been going on in parts of Utah since 1974, he added.

A legal advertisement listed potential customers for the project, which is licensed by the Utah Division of Water Resources. They include several counties, water conservancy districts and ski resorts.

Griffith said the state may pay around 50 percent this year. He preferred not to discuss dollar amounts, however.

Storm systems often don't produce much precipitation, he added. Winter clouds may lack enough freezing nucleoli, which are usually composed of dust particles.

When clouds blow across mountaintops, ice accumulates around the particles. As these become heavier they fall out as snow.

Some sort of impurity, such as a bit of dust in the air, is needed to serve as a nucleus where the ice can accumulate. Or snow may fall from higher in a cloud, providing the nucleus. Cloud seeding, also called weather modification, releases a fog of extremely fine silver iodide crystals, around which ice can collect.

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.