SOUTH LAKE TAHOE  (AP) — Major ski resorts in Lake Tahoe and the Sierra Nevada are using high-tech snow-making machines to weather a record drought that has left many Sierra Nevada mountainsides dry and bare.

The corporations that operate Heavenly, Northstar, Kirkwood, Squaw Valley, Alpine Meadows and Mammoth Mountain have made major investments in snow-making tools, the San Jose Mercury News reported Saturday. This month nearly all of their snow was made with machines.

The machines are expensive to run and require a lot of water and power. But they provide reliable snow at ski resorts where guests make reservations long in advance of weather reports.

“If it wasn’t for snow making, we probably wouldn’t be open,” said Barrett Burghard, head snow maker at Heavenly Ski Resort.

The machines can’t replicate natural snowflakes, but skiers and ski resort operators say the quality of machine-made snow has improved greatly in recent years. Some machines can produce an acre of thigh-deep snow in an hour. The equipment is more consistent and pellet size is more consistent, they say.

“In the past, you’d have big goobers that were wet and tiny floaters who’d drift off into the trees,” said Joe VanderKelen, president of manufacturer SMI Snowmakers.

But small, family-owned ski resorts that don’t have snow-making equipment are suffering. Many haven’t opened this season, costing jobs and hurting local businesses.

A record drought has left the Sierra snowpack at 17 percent of its normal water content. State records show that Heavenly only has 9 inches of natural snow at 8,800 feet, compared to 49 inches last year.

On Friday, Gov. Jerry Brown officially declared a drought state of emergency and called on all California residents to conserve water as much as possible.

The drought has prompted cities to ration water, ranchers to sell cattle and farmers to fallow fields.

The Marysville Appeal-Democrat (http://bit.ly/1kJTQRi ) reports that wildlife refuge managers in Northern California are preparing for water cutbacks that could jeopardize future waterfowl populations that sustain the duck-hunting business.