Environmental groups are renewing efforts to stop exploratory drilling by a Canadian mining company hoping to build a gold mine in Idaho west of Yellowstone National Park.

The Idaho Conservation League and Greater Yellowstone Coalition, in documents filed in federal court last month against the U.S. Forest Service, ask that the case involving Excellon Idaho Gold’s Kilgore Gold Exploration Project in the Caribou-Targhee National Forest in Clark County be reopened.

Excellon Idaho Gold is a subsidiary of Toronto, Ontario-based Excellon Resources Inc.

The company says the area contains at least 825,000 ounces (23.4 million grams) of gold near the surface, and potentially more deeper. The company said it is looking at possibly building an open-pit mine if exploration finds that the gold is mostly near the surface, or an underground mine if the gold is deeper.

Those types of mines would require additional approval from the Forest Service.

The exploratory project was halted following federal court rulings in 2019 and 2020 concerning potential harm to Yellowstone cutthroat trout.

The Forest Service late last year approved a new plan put forward by the company involving road building and 130 drill stations.