More than a third of the public land in one of Colorado’s top ranching and tourism counties could receive increased protections if a bill introduced by the state’s U.S. senators Thursday becomes law.

The Gunnison Outdoor Resources Protection Act would place more than 730,000 acres of federal public land in Gunnison County and surrounding areas under stricter management and protection. County leaders, ranchers and outdoor recreators have worked with Sen. Michael Bennet for over a decade to craft the legislation.

Supporters say the additional protections are needed as the county manages an explosion in visitation and development, along with the effects of climate change and drought.

“These lands are the treasure of our country,” Gunnison County commissioner Jonathan Houck said during a news conference Thursday. “This isn’t just an issue for Gunnison County, this is an issue for the country.”

The would-be-protected lands are not contiguous and would fall under a variety of classifications, with different levels and goals for preservation. If passed, the bill would expand the Raggeds, Maroon Bells-Snowmass and Fossil Ridge wilderness areas. It would also designate large swaths of land north and south of Blue Mesa Reservoir as wildlife conservation areas.

No new oil and gas leases or mining claims would be allowed within the land that would be protected. The legislation would not affect existing leases or claims.

The proposed new designations would not impact existing water rights, private property rights or existing livestock grazing, according to Bennet’s staff.

The bill, co-sponsored by Sen. John Hickenlooper, would implement these protections affecting more than 600,000 of the 1.7 million acres of public land in Gunnison County:

• 214,650 acres would become special management areas.

• 223,868 acres would become wildlife conservation areas.

• 122,902 acres would become wilderness areas.

• 20,542 acres would become protection areas.

• 18,247 acres would become recreation management areas.

• 12,250 acres would become Rocky Mountain scientific research and education areas.

The bill would also withdraw 74,271 acres of public land in Delta County from oil and gas development, and it would block surface occupancy for oil and gas projects on 49,422 acres of public land in the county.

The bill, also referred to as the GORP Act using its acronym, has support from a wide range of public land users and local governments in and near Gunnison County, according to Bennet’s office. Commissioners from Gunnison, Delta, Saguache, Pitkin, Hinsdale and Ouray counties support the bill, as well as the Ute Mount Ute Tribe.

Members of the Gunnison Public Lands Initiative started discussion on future protection of the county’s lands in 2012. The coalition includes hunters, anglers, ranchers, mountain bikers and conservationists — interests that are sometimes pitted against each other in discussions about how Western land and water should be used.