Environmental groups are challenging proposed oil and gas lease sales on more than 100,000 acres near the Green River and San Rafael River, on the San Rafael desert of southern Utah, and near Dinosaur National Monument in the state's northeast.

The leases are among those the Bureau of Land Management conditionally expects to offer on Feb. 21. However, about a week prior to the sale, agency experts will winnow their prospective list and may delete some of the areas.

Altogether, BLM is considering offering leases on 172,095 acres on 109 parcels statewide, with the majority in the areas covered by the agency's Vernal and Price field offices, in a regular quarterly lease offering. The oil and gas industry had requested leases on another 188,689 acres on 127 parcels, but the BLM is deferring leases on those areas.

The deferred areas could be offered in future sales, said Adrienne Babbitt, spokeswoman for the BLM. Some might be withheld at this time because of considerations such as new land-use plans not yet completed, she said.

But many of the parcels not taken out of the lease sale, at least for now, are questioned by the conservationists.

"This sale, like several that we've seen under the Bush administration, includes some of Utah's most spectacular scenic lands," said Steve Bloch, attorney for the Southern Utah Wilderness Alliance.

According to SUWA, other groups formally protesting the leases are the Natural Resources Defense Council and Grand Canyon Trust.

Most of the challenged parcels are in the area between the San Rafael Reef and the Green River.

This region, in the San Rafael Desert, was supported for wilderness protection by a coalition of wilderness groups. But Congress did not enact protection for it.

SUWA placed two pieces of correspondence on the Internet concerning the Dinosaur controversy at suwa.org/library/Correspondence_btwn_Dino_NM_and_BLM.pdf.

The first is from Dinosaur's superintendent, Mary Risser, expressing concern with the possible lease of a parcel south of the national monument, which she wrote is within view of the monument's "primary visitor use areas."

The second is a reply from William Stringer, BLM Vernal Field Office manager. He wrote that portions of the parcel are private and the landowner has no objection to leasing underground reserves, so a portion of the parcel will be offered in the sale.

That is a prime example "of the rush to drill," Bloch said.

He also said some areas in the overall lease sale have known archaeological resources.

Babbitt said BLM regulations require that cultural resources may not be disturbed. Even if a lease is issued, the company must obey stipulations to protect ancient remains. A cultural properties clearance may be required, and if the development would damage archaeological resources, the project's plans would be changed. For example, a drill right might be relocated from a proposed site with cultural resources.