A draft environmental review released by the U.S. Forest Service is proposing a 20-year withdrawal of 30,000 acres of public lands near Yellowstone National Park which have been targeted for mining.

The environmental review, released on Thursday, evaluated a Forest Service proposal to prevent new mining on public lands in the Emigrant Gulch and Crevice regions near Yellowstone National Park for up to 20 years.

Sen. Jon Tester and Rep. Greg Gianforte have both advocated for the withdrawal by writing letters to congressional leadership. Sen. Steve Daines did not write a letter of support, but said Thursday he backs the decision.

“I'm glad that after an extensive process, driven by public input, the U.S. Forest Service is following the local community’s wishes to protect this area that is critical to Montana’s outdoor economy,” said Daines. “I will continue to explore opportunities to move forward with permanent protections.”

Opponents of mining north of Yellowstone National Park fear that large-scale gold mining on public lands in the area could pose threats to local communities, wildlife, recreation and waterways, including the Yellowstone River.

Two foreign-backed mining companies have revealed plans to develop gold mines in Park County, which serves as the year-round gateway to Yellowstone National Park.

As a result of the November 2016 proposal, the U.S. Department of Interior called for a two-year time-out on new mining activities to provide time to conduct a formal, public study of the lands and connected waterways.

Interior Secretary Ryan has also expressed support for the withdrawal.

Business and conservation advocates hailed the decision as a step in the right direction.

“These proposed mines would threaten Yellowstone wildlife, the visitor experience and adjacent communities,” said Stephanie Adams, Yellowstone program manager for the National Parks Conservation Association. “(Our organization) commends the Forest Service for its science-backed examination of the resources at stake on these lands and urges them to withdraw these public lands for the full 20 years.”