On August 16, seismic "thumper trucks" were poised to explore for oil and gas in the Canyons of the Ancients, a national monument in southwest Colorado, home to several rare lizards and more than 5,000 archeological sites. But four environmental groups sued to stop the 30-ton trucks from rolling across the landscape, and in late August, U.S. District Judge Lewis Babcock in Denver halted the exploration until Sept. 30.

Two years ago, when the Canyons of the Ancients became a national monument, 85 percent of the area was already leased to oil and gas interests. The remaining 2,000 acres of unleased land were off-limits to new exploration, in order to protect fragile wildlife habitat and the ancestral Puebloan ruins scattered across the area. But when British-based Western Geophysical announced plans to use thumper trucks in a seismic survey for more oil and gas, the Bureau of Land Management's environmental assessment predicted little lasting damage, effectively giving the company a green light.

A similar seismic project by Western Geophysical was halted last winter near Arches National Park in Utah because of environmental concerns (HCN, 5/13/02: Energy boom's forward guard stalls out in Utah ... for now).

Environmental groups say the company's plan violates the monument's proclamation, which permits new exploration only to prevent "drainage" of oil and gas resources in a common reservoir. "The decision showed a blatant disregard for the proclamation," says Mark Pearson, executive director of the San Juan Citizens Alliance, one of the groups that sued. "That does not bode well for the future management for the rest of this monument or any monument in the country."