Efforts by the National Park Service to better manage air tours over Grand Canyon National Park could go by the wayside if an amendment pending in the U.S. House of Representatives is allowed to stand, according to other members of Congress and the National Parks Conservation Association.

The amendment, offered by U.S. Reps. Trent Franks, R-Arizona, Paul Gosar, R-Arizona, and Joe Heck, R-Nevada, would prohibit the Park Service would spending any more money to implement a new air management plan.

Earlier this year the park released its draft environmental impact statement on an air-tour management plan  that officials believe will restore natural quiet over much of the iconic canyon. The plan states that it would boost the level of "natural quiet" in the park -- quiet that allows you to hear the murmuring of creeks, the roar of rapids on the Colorado River, the melodies of canyon wrens -- from 75-100 percent of the day across 50 percent of the park as is currently the case, to across 67 percent of the park within 10 years of the plan's implementation.

The amendment offered by Reps. Franks, Gosar and Heck, though, would bring work on the plan to a halt. The move has been harshly criticized by U.S. Rep Raul Grijalva, D-Arizona, and others who have circulated a release to their colleagues in the House stating that "(T)he Grand Canyon is being attacked with a misguided amendment that would harm one of America’s most iconic natural wonders."

The statement, cosigned by Reps. James Moran (D-Virginia), Norm Dicks (D-Washington) Edward Markey (D-Massachusetts.), and Ed Pastor (D-Arizona), pointed out that none of the alternatives in the DEIS "would ban overflights or put the air tour industry out of business."

"Instead, they offer different configurations for managing tours that balance the noise produced from air tour traffic with the enjoyment of the more than 4 million land based visitors," the statement adds. "In fact, the NPS’s preferred alternative would actually allow for 8,000 more air tours per year while at the same time reducing overall noise in the park."

At NPCA, Bryan Faehner, the national park advocacy group's associate director for park use, said Thursday that the amendment "would pull the plug on two decades of work by the agencies as well as hard work on the part of stakeholders."

Meanwhile, a handful of congressional representatives from both the Senate and the House have gone directly to Dave Uberuaga, the new superintendent of Grand Canyon National Park, to oppose the DEIS's preferred alternative.

In a letter (attached) sent June 20, two weeks after the public comment period closed, the politicians said the proposed air management plan would be detrimental to tourism as it might "discourage tourists from visiting the Grand Canyon, eliminating tourism jobs and dollars at a time that our states desperately need this economic activity."

And although the preferred alternative would allow upwards of 8,000 more flights over the canyon than have been flown in recent years, the senators contend that it "may cripple an industry, which provides more than 700,000 park visitors a year with a chance to view the dramatic vistas of the park from the air."

The letter was signed by Sens. John McCain (R-Arizona), Harry Reid (D-Nevada), and Dean Heller (R-Nevada) and Reps. Shelley Berkley (D-Nevada),  David Schweikert (R-Arizona), Heck, Gosar and Franks.