The U.S. Supreme Court won't review an Obama-era action that put land around the Grand Canyon off-limits to new mining claims, ending the legal battle as environmentalists keep a close eye on actions by the Trump administration that they fear could lead to more access for the mining industry.

The Obama administration put about 1,562 square miles (4,045 square kilometers) outside the boundaries of the national park off-limits to new hard rock mining claims until 2032. The 20-year ban was meant to slow a flurry of mining claims over concern that the Colorado River — a major water source serving 30 million people — could become contaminated and to allow for scientific studies.

The mining industry asked the Supreme Court in March to review the ban, saying it was based on an unconstitutional provision of federal law. The high court on Monday declined the request, leaving the ban in place.

"Clearly, we're disappointed," said Ashley Burke, a spokeswoman for the National Mining Association. "There continues to be great risk to our domestic supply chain thanks to unwarranted withdrawals like this." Burke said the association will continue advocating for land access. The American Exploration and Mining Association also challenged the ban. Environmentalists hailed the court's decision but are worried the ban could be undone administratively.