The mammoth engines of the West Desert Pumping Projects will be shut off in two weeks, unless the Air Force changes its mind and lets the state's project continue.

The lake is dropping rapidly. Since it reached its historic high point in 1986 and last year, it has gone down more than five feet.U.S. Geological Survey experts measured the level Monday at 4206.7 feet above sea level. That is exactly the level below which the state promised the Air Force it would not continue to pump.

The project lowers the lake level by pumping water into two huge artificial reservoirs in the western desert. One of these overlaps the Air Force's bombing range west of the Newfoundland Mountains.

Air Force officers don't want any more water flooding onto the range because pilots' depth perceptions could be distorted by waves during high-speed training flights. Because of this problem, the Air Force had reservations about creating the ponds in the first place.

State officials agreed to discontinue pumping once the lake dropped below 4206.9, said Alton Frazier, spokesman for the Utah Division of Wildlife Resources.

But now the lake is that low, they want to continue.

William J. Alder, meteorologist in charge of the U.S. Weather Service's Salt Lake headquarters, said the Great Salt Lake is dropping as quickly as it went up during its unprecedented rise of the past few years. In fact, March 1, 1984 was the last time it was this low.

"Normally the drop in the whole month of October is only half an inch, and we've dropped three inches" in the first half of the month, he said.

Temperatures at Salt Lake International Airport averaged 6.5 degrees above normal for the past two weeks. Only trace precipitation was recorded for most of northern Utah during the same period.

Lake experts predict that evaporation will force the inland sea down to a low of about 4206.5 feet above sea level this fall. "If we maintain this dry regime, it could go a little lower than that," Alder said.

Utah officials want to go on with the project because of environmental advantages, a greater margin of safety, the possibility of rehabilitating the Antelope Island causeway at a lower wave level, and because pumping benefits the AMAX Co.'s extraction efforts.

AMAX uses brines pumped in the flood-control project. It spent more than $500,000 this summer to extend an inlet canal so water could flow to the pumps.

When the lake began dropping fast, state experts asked the Air Force for permission to continue pumping until the 4205-foot level.

So far, the Pentagon has not replied.

"We talked to the Air Force this morning," Frazier said Monday. No answer has come from the higher brass.

So the state is continuing to pump, arguing that it didn't agree to stop at 4206.7 feet, it agreed to stop when the lake fell below 4206.7.

Alton said the lake level will be read again Nov. 1.