The biggest costs for snowmakers are energy, labor and equipment. "In the early months, October to January, 67 percent of all the energy going to a ski area is consumed by the snowmaking," said Robin Smith, president of MYNEIGE, Inc., a snow gun manufacturing and consulting company. The big energy consumers in the operation are water pumps and air compressors. Water pumps push water from rivers or holding ponds up the mountain to the guns, and air compressors pressurize air, which is mixed with water and ejected onto the slopes.

Automation can greatly reduce energy and labor costs. "Because modern automated equipment immediately adjusts for temperatures, humidity and in some cases wind, the performance is much more efficient than a manually operated system," Bob Magrino, director of mountain operations for Colorado's Loveland Ski Area, wrote in an e-mail. "Manpower, exposure to injury and power consumption are greatly reduced with automation and we can use our water more efficiently."

Some snowmakers prefer manual systems. "I like to be able to touch and feel it to make sure it's the highest quality," said Brent Larson, vice president of mountain operations at Sunday River, Maine. The tradeoff for manual control is higher operating costs: Sunday River spends $500,000 a year in labor, twice as much as many highly automated operations.

Water is a critical resource for snowmaking. Ski areas pump 50 to 400 million gallons of water in a year and they need it when river levels are lowest. To maintain minimum stream flows required by law, many ski areas pump water into holding ponds during high flows in spring and then balance their increased demand in winter by using water stored in their reservoirs. Not all the water withdrawn returns to the river during snowmelt -- an estimated five to 30 percent is lost to evaporation and absorption.

Efficiency is increasingly important for ski areas as it can reduce both expenditures and their environmental footprint. Replacing old guns with newer, more energy-efficient snowgun technology and automating them bring the most immediate benefits and can pay themselves off in two to seven years, according to Robin Smith. Organizations like Efficiency Maine, an independent trust that promotes energy efficiency, help ski areas with capital improvements. Efficiency Maine recently contributed $300,000 to a large snowgun purchase by Sunday River Resort.

"We needed to figure out a way to reduce our costs because the cost of electricity was increasing and we weren't able to use all the water we had available to pump," said Sunday River's Larson. "That drove us as a company to invest in low-energy equipment and now we're able to take advantage of the smaller windows of opportunity."