DWP Hopes to Deepen Snowpack in Sierra

A laggard beginning to the Sierra Nevada snow season has prompted the Los Angeles Department of Water and Power to give nature a nudge, embarking for the first time in a decade on a program to increase precipitation by seeding clouds as they pass over the mountains.

A Fresno contractor flew the first cloud-seeding sortie on Tuesday night, and if forecasts for another front hold true, was to send a twin-engine plane aloft again today to drop more rain-making silver iodide pellets through the cloud deck.

Most Los Angeles drinking water comes from melted snow that runs off the eastern slope of the Sierra. Despite two storms this week, the snowpack is only about a quarter of what it was last year at this time, authorities said.

“We’ve gotten off to a pretty slow start,” said Doug Gillingham, DWP project engineer for the cloud-seeding effort. “Normally by this date we have received 50% of the snowpack.”

Water officials said there is no immediate danger of short water supplies; the system’s reservoirs hold roughly two years of water. “We’re not in a panic situation yet,” Gillingham said, “but we’re attempting to do whatever we can.”

An initial three-week seeding campaign was commenced in what the DWP called a “stopgap measure.” The operation will cost $10,000, officials said. A three-month, $40,000 effort already had been planned to begin later this month, pending approval by the Los Angeles Board of Water and Power Commissioners. Approval of the longer-term project hinges on a determination that the seeding operation will not harm the environment.

A Fresno-based firm called Atmospherics Inc., one of only about five in the nation that do cloud seeding, is conducting the DWP project.

Cloud seeding has been carried out in Central and Northern California for three decades. Interpretations of its success vary, but most studies have found that seeding can enhance rainfall from storm clouds by about 5%. The DWP has not attempted cloud seeding since 1977.

In 1978, lethal mud slides occurred in Southern California shortly after seeding had been conducted by the Los Angeles County Flood Control District, prompting lawsuits and calls for tighter state regulation of so-called weather modification experts.

This season’s snow shortage gained wide public attention in late December, when operators of ski resorts lamented that the lack of snow deprived them of profitable Christmastime openings. The last week’s storms cured that problem for now, as ski slopes throughout the state reported they were open Wednesday, many with fresh coverings of snow.

State water officials said ski operators have been spoiled in the last decade by a spate of unusually early starts to the snow season, and indicated that the late beginning of the snow season this year is not far off the norm. The crucial measurement of snowpack comes in early April, when the pack historically reaches maximum density.

While the snowfall might not have been abundant so far, state experts said, the season really is only beginning and long-range predictions vary as to whether it will be a wet or dry year.

“I think anybody who is running a water project and has customers is concerned,” said Dave Hart, an official with the state Department of Water Resources. “But no one is willing to say yet that we are in the middle of a drought.”