In June, the House Natural Resources Committee invoked a rarely-used authority to force the Bush administration to make one million acres of public land adjacent to the park ineligible for exploration. Two months later, though, Interior Secretary Dirk Kempthorne allowed some 20 new claims in the area by deciding that the committee's move violated executive authority.
In the last decade, a pattern of contamination has also emerged in places where natural gas drilling has intensified. If drilling increases substantially across Colorado, Wyoming and Utah, it could also imperil the river.
Most wells rely on a process called hydraulic fracturing, which requires as much as two million gallons of water plus small amounts of often-toxic chemicals for a single well. The waste water then sits in open pits until it is treated, recycled or disposed of.
In February a waste pit high on a mesa overlooking the town of Parachute, Colo. sprang a leak, allowing some 1.6 million gallons of fluid to soak into the arid earth. According to state records, the spill migrated underground until it seeped from a cliff side and froze into a gray pillar of ice more than 200 feet tall. When it melted, the fluids dripped into the torrid currents of Parachute Creek and finally dumped into the Colorado River.
Although the number of gas drilling accidents in the upper Colorado River watershed is small relative to the amount of drilling, they have begun adding up. Colorado state records show that of some 1,500 spills in drilling areas since 2003, more than 300 have seeped into water. In one case last summer a truck carrying drilling fluids crashed into the Colorado, where it remained partially submerged for more than three weeks.
In neighboring Wyoming, the BLM found a 28-mile-long plume of benzene contamination in an aquifer beneath a gigantic gas field. The aquifer is near a tributary to the Green River, which in turn flows into the Colorado.
Doug Hock, a spokesman for the Canadian gas company Encana, which drills in Colorado and Wyoming, says that while there will always be spills, the fears of pollution are exaggerated. Encana uses steel and concrete casing around its drill pipes, lines its waste pits and, increasingly, cleans its waste water and re-uses it inside its wells.
"We have put in place safeguards to protect the water," Hock said. "There is always a balance -- this country has a great demand for energy."
But because the energy industry has been exempted from so many federal environmental regulations during the Bush administration, it's difficult to assess the industry's true impact on the river.
The mix of chemicals used in hydraulic fracturing is held as proprietary competitive information by the industry and kept secret from even the EPA. Scientists say that without knowing the specific ingredients in the mix, they don't know what compounds to test for after a spill and can't check to see if they've reached the river.
The 2005 Energy Policy Act exempted hydraulic fracturing from the Safe Drinking Water Act. Also exempted from federal control and water protection laws are the drilling industry's construction activities, including the sediments and dust produced from thousands of miles of road building, site grading and the drilling itself, even though that debris often ends up in waterways.
"We have seen an explosion in drilling, and at the same time we have seen a weakening of the federal standards under which drilling occurs," said Dusty Horwitt, an analyst with the Environmental Working Group.
Given the relaxation in regulatory authority, the development may be out-pacing scientists' ability to measure the implications.
In August drilling companies bid on 55,000 acres of federal parcels atop the Roan Plateau, a cherished wilderness area in central Colorado that drains into the Colorado River. A September report from the University of Colorado Denver predicted that in 15 years Garfield County, a western drilling area bisected by the river, will have 23,000 wells, six times what is has now, based on permit applications already filed with the state.