When he visited the Grand Canyon 100 years ago this month, President Theodore Roosevelt admonished Americans to “leave it as it is. You can not improve on it. The ages have been at work on it, and man can only mar it. What you can do is to keep it for your children, your children’s children, and for all who come after you.”

Unfortunately, the multihued geologic wonder that Roosevelt witnessed in May 1903 has been dulled by decades of pollution from massive antiquated coal-fired power plants in the Four Corners region — reducing 170-mile views to less than 70 miles on high-pollution days.

David Williams in his May 7 Roll Call Guest Observer, “Congress Must Rein In Expensive ‘Sue and Settle’ Tactics by EPA,” admonished not the polluters of the Grand Canyon but the EPA and conservation groups for taking action to protect it. But by singling out the EPA’s plan for cleaning up New Mexico coal plants marring the Grand Canyon and other parks, Williams has unknowingly stumbled on a textbook example of why the Clean Air Act works, not why it’s broken.

Williams insinuates that the EPA colluded with environmentalists to concoct a lawsuit, circumvent normal procedures and impose hastily considered rules on New Mexico’s power plants, all to advance its “not-so-ulterior agenda of killing the coal industry.” Though that sounds like a good plot for a political potboiler, it’s far from reality.

The mandate to eliminate pollution blight in large national parks and wilderness areas was established by Congress in 1977. Congress recognized that, like Roosevelt in 1903, all Americans deserve the chance to experience the nation’s majestic natural wonders — places like the Great Smoky Mountains, Everglades, Yellowstone, Yosemite and the Grand Canyon — free of industrial air pollution that was rapidly advancing from cities to parks. The EPA was charged with developing rules to achieve this goal.

Unfortunately, it took the EPA more than 20 years to finally adopt rules for gradually reducing regional haze pollution fouling the parks, rules that gave the states an astonishing 65 years to get the job done. To make matters worse, the EPA failed to enforce its own rules. Thirty-seven states did not submit the haze pollution cleanup plans that were due in 2007, and the agency took no action to force compliance. The National Parks Conservation Association and other groups sued the EPA, resulting in court-sanctioned settlement agreements that do no more than require the EPA to act within a reasonable time frame. (The agreements do not impose new “unilateral” rules as Williams suggests.)

New Mexico is one of the 37 states that failed to meet the 2007 regulatory deadline. Of particular concern was the state’s failure to require cleanup of the San Juan Generating Station, a coal-fired power plant built in 1976 that is linked to hazy air in Grand Canyon, Mesa Verde, Petrified Forest and other national parks. When New Mexico finally did submit a plan, it did not meet minimum standards for improving air quality at Mesa Verde and other parks. The EPA was therefore legally obligated under the Clean Air Act to write a federal haze cleanup plan in New Mexico.

In spite of this sordid history, the process of holding the EPA and New Mexico accountable to the law forced a dialog that produced a unique cleanup blueprint for the facility. This February, the EPA, New Mexico and PNM, which owns the San Juan Generating Station, hammered out a preliminary agreement. Republican Gov. Susana Martinez calls the plan “a reasonable solution that would improve air quality, conserve New Mexico’s precious water resources, avoid an extremely burdensome rate hike on consumers, protect jobs in northwestern New Mexico, transition away from coal and toward New Mexico natural gas.”

Martinez is right to focus on the economic and environmental benefits of cleaning up antiquated coal plants, rather than to invoke divisive rhetoric about “killing the coal industry” as Williams did. New Mexico receives $3.8 billion in revenue — from residents and visitors — from recreational activities such as hiking, biking and camping. Good air quality is essential to sustaining and growing this vital industry. The national parks affected by San Juan’s pollution annually generate a combined total of $922 million in spending.

Beyond the economics, cleaning up coal plants is the right thing for our national parks. Roosevelt, standing on the south rim of the Grand Canyon 100 years ago, appealed to his audience: “I want to ask you to do one thing in connection with it in your own interest and in the interest of the country — to keep this great wonder of nature as it now is.” He would be proud today of steadfast efforts to enforce the Clean Air Act and restore the wonder that he beheld.

Mark Wenzler is the vice president of Clean Air and Climate Programs for the National Parks Conservation Association.