Echoes of Woodstock are set to blare through the northern Idaho forests next weekend, and it sounds like trouble to Benewah County Sheriff Rodney Thormahler.

Fliers advertising Greenstock III, a deep-woods music festival scheduled April 19-21 at the North-South Ski Bowl 50 miles northeast of Moscow, have been scattered as far as Seattle.The Washington State University students organizing the spring blowout promise 30 bands, alcohol and maybe thousands of party enthusiasts.

But Thormahler said he was worried about a number of things, including the weather.

"There's still quite a bit of snow up there," he said of the north-facing ridgetop ski area. It got down to 20 degrees this week, and snowed. The only mention of shelter in the fliers is "Bring a tent!"

If it's cold, said Thormahler, "There's no way they can survive in tents . . . especially for three days."

Organizers also have yet to get a permit for the gathering. Before the party is legal, the sheriff said, organizers need to prove to the Benewah County Commission that sanitation, parking and security are under control.

If they don't, Thormahler said he will shut down Greenstock.

Organizer Tracy Horn of Pullman, Wash., said such concerns are being addressed.

"We're trying to cover all the bases as well as we can," Horn said. "We've insured the whole thing."

Security workers have been recruited, outhouses have been lined up, food and drink, first-aid booths are ready. The lodge at the ski area is reserved to house the musicians, and she expects the concertgoers either to camp out or ride shuttle buses back to the university towns.

How many concertgoers probably depends on weather, Horn said. High estimates go to 6,000 and she said as many as 10,000 could attend at $10 each for the weekend.

But Thormahler said Benewah County is not prepared to become a college party destination, and he doubts that North-South can handle a party that attracts several hundred, let alone thousands.

But, as long as Greenstock has a permit, he said he had no problem with the party.

Horn said publicity has attracted a steady stream of phone calls, and one Seattle group of 35 promises to drive across Washington to the festival. An extravagant full-color, front-page package about the party dominated the Washington State University student newspaper, The Evergreen, on Friday.

Although billed as Greenstock III, Horn said the backwoods retreat actually was born out of house parties that outgrew the house.