Environmental groups have argued for keeping public land on the top of the rim off limits to drilling because of the breathtaking scenic beauty of the area.

They have also campaigned to name the area a designated wilderness area, which would result in greater restrictions.

Colorado Environmental Coalition spokesman Peter Kolbenschlag said the Citizens' Campaign to Save Roan Plateau wanted the top of the rim permanently off limits to drilling. "This is not what the community wanted. They didn't say once the energy industry develops the bottom then they can do the top," he said.

"The area was set aside for energy back in 1912. Then got it converted by the environmental community into some sort of area that it isn't," Greg Schnacke, executive director of the Colorado Oil & Gas Association said, referring to the area formerly known as the Naval Oil Shale Reserve.

The draft management preferred plan is one of five alternatives the US agency was considering and falls in about the middle of possibilities for the plateau. A 90-day comment period on the draft plan will go into effect and public meetings will be held in western Colorado. The BLM will then create a final play that may include all or part of the five alternatives that were under consideration.

Jamie Connell, field manager for the BLM's Glenwood Springs, Colorado, office, said "tens of thousands of comments" had been received from the public. The BLM, an agency of the US Interior Department, has been working on the first ever plan for Roan Plateau for four years.

The preferred plan only affects publicly owned land. The US government owns large amounts of territory in the western United States, including about one-third of Colorado and about half of neighboring Wyoming.

In the preferred plan 35,000 acres -- all of the publicly owned land on the top of the rim -- would be off limits until 80 percent of the expected drills below the rim had been drilled and tested. But Connell said the wells below the rim would not have to be actually producing before permits would be allowed for the top of the rim. About 300 to 400 wells have been drilled in the area and the 80 percent estimate is around 2,400 wells, Connell said.

The BLM estimates the 80 percent would be arrived at in 16 years, but its window goes from 10 to 20 years. Energy companies prefer to move to adjacent areas when drilling wells and a delay of years would interrupt corporate plans.

Natural gas drilling is currently being conducted at the base of the plateau; the question was whether it should be expanded to the top.