Cloud-seeding to increase rainfall on Santa Catalina Island will begin this month, as airplanes sprinkle dry ice into the clouds over the island, Southern California Edison Co. officials said.
The program will begin about Thursday, when the Fresno-based firm Atmospherics Inc. will start monitoring Catalina's weather to determine optimum times for sending up a pilot 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 and 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 important, the island had no rainstorms that lasted more than a day, which would have allowed runoff from the rain to accumulate in the reservoir, he said. Average annual rainfall since 1970 has been about 12 inches.
"We're not alarmed at all over the water levels," LeFever said. "We're concerned because impoundment is lower than it has been in the past 10 years."
This will be the third cloud-seeding program on Catalina, LeFever said. Previous programs were 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 significantly enough to warrant spending the money" on a third program, LeFever said. The previous programs cost around $50,000 each, but the bill for the latest program will depend on how many times the clouds are seeded, he said.
And as rain has decreased, water consumption has increased, 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.