PAUL FOYSALT LAKE CITY (AP) â¿¿ The federal government is closing a public comment period on plans for oil shale development that have sharply cut public lands available for research and development projects. The Bureau of Land Management has tentatively decided to lease about 460,000 acres of oil shale deposits for research and demonstration projects, down from 2 million acres the Bush administration planned to offer across Colorado, Utah and Wyoming. Oil-friendly interests are complaining that the BLM is making little land available with too many regulations. The new plans calls for opening another 91,000 acres for tar sands development, down from 431,000 acres the Bush administration planned to offer. The government will make its final leasing decisions by Oct. 18, said Mitchell Leverette, division chief of solid minerals at the U.S. Bureau of Land Management's Washington office. First, the BLM will sift through what the National Parks Conservation Association says is more than 100,000 public comments. BLM officials said they haven't counted them. The comment period will close Friday. Environmental groups say a century's worth of trying to wring oil from rock has never proved economical, and new efforts will only ruin public lands. The National Parks Conservation Association said the "vast majority" of comments support BLM's more cautious approach. "It doesn't make sense to develop on a large scale and put our national parks and recreation economy at risk when oil shale and tar sands development have yet to be proven economically viable," said David Nimkin, the Southwest regional director for the National Parks Conservation Association. Several oil companies took out 160-acre government research plots years ago, but only one is actively working a demonstration project. Shell Exploration & Production Co. is experimenting with an effort to bake oil shale in the ground and suck out oil with pumps. Shell holds three federal research and development leases in Colorado but is running the demonstration on its own land.