Cloud-Seeding to Hike Island Rain Planned

Cloud-seeding to increase rainfall on Santa Catalina Island will begin this month, with airplanes sprinkling dry ice into the clouds over the island, Southern California Edison Co. officials said.

The program will begin around Dec. 15, when Fresno-based Atmospherics Inc. will start monitoring Catalina’s weather to determine optimum times for sending up a plane to induce or increase rainfall, said Keith LeFever, Edison’s district manager for the island.

The program is intended to increase the amount of water in the Middle Ranch Reservoir, the island’s major water source, which has been significantly lowered after four straight years of less-than-average rainfall, plus an increase in water use during the last two years, LeFever said.

From 1984 to 1987, rainfall on the island averaged just over 7 inches a year, LeFever said. More importantly, the island had no rainstorms that lasted more than a day, which would have allowed runoff to accumulate in the reservoir, he said. Average annual rainfall since 1970 has been about 12 inches.

Third Time

This will be the third cloud-seeding program on Catalina. Previous programs were conducted during the 1977-78 rainy season, when an average of 26 inches of rain fell in a 12-month period, and in 1982-83, when rainfall was just over 25 inches, he said.

“Both times, it increased significant enough to warrant spending the money” on a third program, LeFever said. The previous programs cost about $50,000 each, but the bill for the latest program will depend on how many times the clouds are seeded, he said.

“In the last two years we’ve had less than average rainfall, and at the same time, we’ve had the highest-recorded consumption on record as far as water sales are concerned,” LeFever said.

Consumption has averaged about 380 acre-feet over the last 10 years, but in 1987 the figure reached 460 acre-feet, and the same is expected for this year. An acre-foot of water is 326,000 gallons.

Cloud-seeding typically takes place on inclement days when larger clouds are likely to form. During seeding, a pilot drops pellets of silver iodide, or dry ice, into a cloud, forming ice crystals that turn into rain as they grow heavier and fall to the warmer atmosphere. In the Catalina cloud-seeding program, Atmospherics will use dry ice.