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Utah's scenic Pilot Valley, crossed by one of the last pristine sections of the national historic trail known as the Hastings Cutoff, could be the scene of intensive potash mining under a proposal being developed by a Canadian mining firm.

Mesa Exploration Co., a publicly traded Vancouver-based company, is seeking Bureau of Land Management permission to prospect this stretch of salt flats where about 160 years ago California-bound immigrants struggled to reach the life-saving waters at Donner Springs. In statements to investors, the company said its proposed Bounty Potash Project will yield on par with the Intrepid potash operation to the south and east of Wendover, which generates up to $65 million annually.

BLM officials say approval is a long way off, even as the company says it's ready to drill. Historic preservationists, meanwhile, argue these lands should be off-limits.

Extraction of potash — which provides a key nutrient in agricultural fertilizers — on salt playas requires a network of ditches that use solar evaporation to precipitate potassium-rich salts from brine.

"There will be very little visual impact caused by the Bounty Potash operation as the area is out of sight of all but the few people who might visit this remote area," wrote geologist Dana Durgin in a Mesa Exploration technical report. "The people living nearby are also quite familiar with such a project and no significant local antipathy toward the project is expected."

But leaders of the Oregon-California Trails Association, a nonprofit devoted to preserving and promoting historic pioneer routes, say this kind of industrial development can only come at the cost of destroying the Hastings Cutoff.

"We can't have a wonderful wilderness environment with a section of pristine trail out there and still have a potash mine in the same area," said Salt Lake City historian T. Michael Smith, the group's Utah chapter president. "It is beautiful enough and historic enough in terms of the trail and the prehistoric uses that it should be preserved and used as it has for several decades."

The project area covers 125 square miles of playa exposed when Lake Bonneville dried up thousands of years ago, concentrating minerals into the ancient lakebed. Pilot Peak and the Silver Island Mountains frame this valley that posed the final 10 miles of the arduous, dangerous salt flat crossing for the ill-fated 1846 Donner party and the gold seekers who followed. Wagon wheel ruts remain visible in many places, even though the route was abandoned by the early 1850s.

A 54-mile national scenic byway encircling Silver Island skirts the southeast edge of the project area.

BLM owns most of the project area, which features a checkerboard of private and Utah state lands. Mesa leased 14 square miles of state land, is negotiating to acquire mineral rights on an additional 22 square miles of private land and has applied for prospecting permits on the remaining 89 square miles of federal land.

The technical report Mesa commissioned in early 2012 found a "substantial potash resource," citing a 1966 exploratory project that detected the presence of 5.1 million tons of potash. The report says Bounty is analogous to a nearby salt flat operation in size and grade.

For 75 years, Intrepid Potash's Wendover operation has produced up to 95,000 tons of potash and 200,000 tons of magnesium chloride a year. It has also carved 100 miles of bermed ditches into the lakebed.

When Bounty starts producing potash, Mesa has projected operating costs of $180 a ton for a commodity that sells for $500 to $650.

Mesa officials could not be reached Monday, but their public statements over the past several months give the impression Bounty prospecting is already under way and actual development will not face serious regulatory hurdles.

"Because the area is a lifeless, barren salt flat there are no anticipated environmental or permitting issues," the company reported in a July 31 news release. The company also announced its contractor Cross Marine Projects Co. would begin exploratory drilling by summer 2012.

However, the BLM has yet to complete its own minerals report, which will determine whether prospecting is necessary and appropriate, according to agency spokeswoman Megan Crandall, who stressed Monday that no drilling has been authorized. If that permission is given, the National Environmental Policy Act will require further reviews before mining can commence.

"There are a lot of moving parts," Crandall said. "We are absolutely taking our time to make sure we are doing all our due diligence to make the right decision."

Mesa has also filed exploration-permit applications on 116 square miles on BLM land in Grand County, covering three locations south of Green River where Intrepid has an active potash operation nearby, according to company press releases.

bmaffly@sltrib.com Bounty Potash Project

Mesa Exploration Co. is exploring the potash potential of the Pilot Valley, 120 miles west of Salt Lake City. The historic Hastings Cutoff of the California Trail runs across the proposed project area.