Writers on the Range Monument designations aren't land grabs. They're protection against theft.

Today, some Westerners might call the 1908 presidential proclamation of a Grand Canyon National Monument a "surreptitious land grab." But it all depends on who's doing the grabbing, and for what purpose.

Utah Republican Rep. Rob Bishop says that such proclamations allow presidents to "lock up" millions of acres of public land "like bandits in the night." I say the real thieves are those who would trash our national treasures. Congress enacted the 430-word Antiquities Act in 1906 to stop the looting of artifacts from archaeological sites on public lands. The law also gave the president discretionary authority to designate national monuments for the protection and proper care and management of "historic landmarks" and places of "historic or scientific interest."

Presidents have since used the Antiquities Act to protect far more than archaeological artifacts and natural antiquities across America. Theodore Roosevelt proclaimed the Grand Canyon a national monument in recognition of its great scientific and historic value, and to prevent mining and tourist development from threatening one of our nation's most treasured landscapes.

But proclamations don't guarantee protection. A now-abandoned uranium mine on the canyon's South Rim was allowed to operate long enough to cost taxpayers more than $15 million to remove toxic wastes from the surface. Despite visible reclamation, water flowing underground and through the mine's radioactive ore continues to poison a spring-fed creek, deep within the canyon.

We must be vigilant in preventing such permanent losses within protected areas. And we must set aside what is necessary to ensure that these treasures can be managed undiminished while being loved and leaned on by millions of visitors a year.

When Roosevelt proclaimed a Grand Canyon national monument 107 years ago, only a fraction of the canyon was included in that designation. His decision annoyed mining and tourist businesses in the booming Arizona territory, and local politicians fought the postage-stamp-sized monument's designation as a national park until 1919.

In 1975, though, Congress nearly doubled the park's acreage, declaring "that the entire Grand Canyon ... including tributary side canyons and surrounding plateaus, is a natural feature of national and international significance." Arizona Democratic Rep. Morris Udall and Arizona Republican Sen. Barry Goldwater joined bipartisan sponsors in passing the new law to further protect their state's defining landmark.

The Grand Canyon National Enlargement Act effectively prevented the U.S. Bureau of Reclamation from building two new dams in the canyon's upper and lower gorge. But it fell short in protecting "the Grand Canyon in its entirety," as Congress had intended.

Today, uranium mining is polluting springs used by human backpackers as well as bighorn sheep and other wild animals. Thousands of new claims threaten sites sacred to Native people along with the sole source of drinking water for Supai villagers. Deep wells in gateway communities are sucking dry the canyon's underground source of precious water. What's more, developers keep drilling deeper to promote more growth, which might include a 10,000-tourist-a-day tramway to the bottom of the canyon.

Now is clearly not the time to undermine existing laws for protecting our national patrimony. With Congress deadlocked, the president needs the flexibility to act when our nation's crown jewels need protection from previously unrecognized threats. Yet the opponents of the Antiquities Act continue to seek repeal of what they see as a harmful law that allowed Roosevelt to "lock up" the Grand Canyon with a single stroke of a pen. Rep. Bishop even calls it "the most evil Act ever written."

Meanwhile, Arizona Republican Rep. Paul Gosar is sponsoring a bill to block President Obama from using the Antiquities Act to prevent new uranium mines from further polluting the Grand Canyon. He said: "I will not sit idle while extremist environmental groups ... try to ruin the state I love."

But all of us are poorer when national treasures are lost, and we prosper when places like the Grand Canyon are protected in perpetuity. The entire Grand Canyon is sacred to all of our region's Native people, who are banding together to protect it. If ever a law existed to fight the thieves of time, the Antiquities Act is it. Choosing to rob our grandchildren of their heritage is assuredly a decision we'll all live to regret.

Roger Clark is a contributor to Writers on the Range, a column service of High Country News. He is a program director of the Grand Canyon Trust, based in Flagstaff, Arizona.