At least 55 square miles and as much as 145 square miles — that's a ballpark estimate of how much public land Dugway Proving Ground may be interested in acquiring in a base expansion.

This week, officials of the huge western Utah military base refused to disclose details of the size of the area they may want or why they would like to acquire it. But they did confirm they had sent paperwork about it to superiors at the Army Development and Test Command, Aberdeen Proving Ground, Md.

Dugway asked permission to study expanding the training and test ranges, a statement from the base said, and so far no answer has arrived from Maryland.

Although details of the size aren't known, what is known is that an acquisition apparently would involve the Yellow Jacket and Southern Triangle regions, both on Bureau of Land Management land. Dugway sought unsuccessfully to obtain these segments in 1988.

Back then, documents obtained by Deseret Morning News reporter Lee Davidson indicated some of the region was probably contaminated with unexploded arms carrying chemicals or high explosives from tests that occurred decades ago at Dugway.

The proving ground no longer tests offensive chemical weapons. Now it concentrates on defenses to biological or chemical attacks and hosts conventional military training.

The region in the new possible acquisition would extend Dugway's southeast boundary, involving a large stretch of BLM land north of the Tooele-Juab county line and west of the historic Pony Express Trail.

The land acquisition looks "pretty sizeable," said Steve Erickson, director of the military watchdog group Citizens Education Project, Salt Lake City.

In 1988, when the BLM objected to an attempted land withdrawal in some of the same areas, he said, "the Army was unable to really identify much in the way of unexploded ordnance," he said.

Other conflicts with the proposal included gold claims that could not be worked if Dugway acquired the region, he recalled.

"We generally don't like to see land grabs by the military," Erickson said. He also worried that the base's restricted air space would expand if the land area does.

The Pony Express Trail, while a dirt road, at times has a steady stream of traffic, while hikers and all-terrain-vehicle users sometimes go onto the adjacent BLM land that Dugway is thinking about.

"The area under discussion has not been clearly defined," said Glenn Carpenter, manager of the BLM's Salt Lake Field Office, which administers that area.

"The amount of public land managed by my office, within Tooele County, west of our Simpson Springs Campground and north of the Pony Express Trail includes about 145 square miles, or almost 93,000 acres," he said.

"It is unclear whether there may be an interest in that total or whether it is closer to 55 square miles, or about 35,000 acres, which was discussed almost 20 years ago."

Carpenter said he didn't know if Dugway was thinking about trying to obtain part of the Dugway Mountains in Juab County that extend south of the county line. If that is also under consideration, the size would grow by another 25 square miles.

The paper asked what impacts a military acquisition could have on public use. "There's a great deal of recreational activity that occurs in that area," Carpenter replied.

"There's rockhounding, there's a little bit of hiking, a lot of hunting." In addition, he said, a wild horse herd roams there, and a closure could affect its management.

"If they fence the area and fence those horses out, then that would eliminate those horses from areas they have used for generations," he said.

An active group of all-terrain-vehicle users likes to go four-wheeling there. Members of the public enjoy visiting sand dunes in the area, he said.

The Simpson Springs Campground, near the northeastern corner of the area the base could acquire, is going through renovations. "We're going to be adding some restrooms" and make other improvements, he said.

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