An Arizona U.S. senator has introduced a bill that permanently would ban new hard rock mining claims outside Grand Canyon National Park.
Environmentalists and Native American tribes applauded Democrat Kyrsten Sinema's introduction of the bill Thursday.
They say mining in the region could contaminate water that serves millions of people.
But the bill isn't expected to have an easy ride in the Senate, which is controlled by Republicans who have opposed the measure. The House approved a similar bill earlier this year.
The Obama administration banned new mining claims in the region until 2032.