Cowboys and environmentalists unite! The unlikely amigos are banding together to try to keep natural gas drillers away from ranches on public land in the San Juan Basin in northwestern New Mexico and southwestern Colorado. Yesterday morning, they blocked drilling crews from entering four ranches, arguing that drilling leads to erosion, water contamination, and livestock deaths, but the ranchers say they’ve been unsuccessful in their efforts to attract the attention of Congress and the U.S. Bureau of Land Management. “This is a David-and-Goliath issue, and as long as Washington is not behind getting the problem fixed, it will not be fixed,” said rancher Tweeti Blancett. Steve Henke, who heads a local BLM office, said the agency was not about to phase out drilling operations. The San Juan Basin produces 10 percent of the natural gas in the U.S., and the Bush administration has made clear that it wants only to increase the amount of drilling in the area.