Oil and gas leasing is being proposed near Great Sand Dunes National Park and Preserve in Colorado. The proposed lease parcels are outlined in red. The park is in purple to the left of the yellow line running atop the Sangre de Cristol Range/BLM

Oil and gas drilling sites less than a mile from Great Sand Dunes National Park and Preserve in Colorado are proposed to go up for auction later this year, raising concerns over light and air pollution, as well as ecosystem impacts, that energy exploration could generate for the park.

While the lease sites located on roughly 18,000 acres controlled by the U.S. Bureau of Land Management are east of the ridgeline of the Sangre de Cristo Mountains, the park's boundary goes to the top of that ridgeline, and so drilling could potentially be visible from the park.

"We have not had the opportunity to assess direct impacts to viewsheds, etc., but we are nonetheless concerned about increased industrial activity, impacts to wildlife and ecosystems," Vanessa Mazal, senior Colorado program manager for the National Parks Conservation Association, said Tuesday in an email.

In its formal scoping comments to the BLM, NPCA staff noted that "the National Park Service’s Air Resources Division air quality trends monitor for 2015 (the most recent year for which monitoring data is available) assigned Great Sand Dunes National Park the highest level of air quality concern for ozone as well as Sulphur and nitrogen indicators. It assigns a 'moderate concern' value for visibility and haze, also regulated values under the Clean Air Act."

And since storm winds tend to move east to west, according to the National Park Service, there is concern that air pollution from lease operations could be blown into the park.

This section of the official Great Sand Dunes National Park and Preserve map shows how storm winds (red arrows) sweep east-to-west over the Sangre de Cristol Range/NPS

“Drilling on these proposed parcels is likely to harm Great Sand Dunes Park and Preserve. Some of the lands targeted for leasing are less than a mile from the summit of the Sangre de Cristo range, which forms the park’s eastern boundary," Ted Zukoski, a staff attorney in Earthjustice's Rocky Mountain Office, said on Tuesday.

"Air pollution from drill rigs may enter the park. Those driving or hiking into or out of the park at Mosca and Medano Passes will confront the sight, lights and sounds of drilling and ongoing oil and gas operations. The park’s wildlife don’t recognize land management boundaries; they are likely to be impacted by drilling these lands too.”

NPCA staff also worried that drilling could diminish Great Sand Dunes' nearly pristine night skies, and generate industrial noise that would impact the natural soundscape.

"The NPS’ Natural Sounds Program has conducted acoustic monitoring in the park and found that Great Sand Dunes has one of the lowest levels of measurable ambient noise in the national park system," the group's scoping comments noted. "This natural quiet was partly the basis for a 2009 U.S. District Court decision preventing oil and gas drilling in the Baca Wildlife Preserve managed by U.S. Fish and Wildlife Service, which is adjacent to the park on the west side of the dune fields."

NPCA requested that if lease parcels aren't removed from the auction or deferred, that the BLM consult with various state and federal agencies on the potential for impacts, including how seismic activity could affect "dune formation within the park."

Public pushback has recently led the BLM to change its leasing plans. In Utah, for instance, the location of three parcels next to Zion National Park led the agency to remove them from auction.

The BLM is expected to release an environmental assessment analyzing the proposed lease, which is set for September 6, on March 22.