Federal approval for a ConocoPhillips Alaska oil exploration will remain in effect after a federal judge ruled the US Bureau of Land Management conducted a reasonably thorough environmental study.

The US District Court for the District of Alaska denied the tribal and environmental groups’ bid for a preliminary injunction to stop the company from drilling four test oil and gas wells in the National Petroleum Reserve-Alaska, awarding the agency deference for mitigating impacts on the reserve.

BLM’s prohibitions on bulldozing tundra vegetation and limitations for off-road travel are sufficient under the Naval Petroleum Reserves Production Act, as the law doesn’t …