Published: January 22, 2009

A month of negative news for the Tennessee Valley Authority could lead to positive changes in national policy, including federal regulation of toxic coal wastes and new legal constraints on coal-fired power plants. More broadly, the authority’s recent travails may help persuade the public that coal is nowhere near as “clean” as a high-priced industry advertising campaign makes it out to be.

 In December, hundreds of acres of Roane County in eastern Tennessee were buried under a billion gallons of toxic coal sludge after the collapse of one of the T.V.A.’s containment ponds. It was an accident waiting to happen and an alarm bell for Congress and federal regulators.

Senator Barbara Boxer of California noted that coal combustion in this country produces 130 million tons of coal ash every year — enough to fill a train of boxcars stretching from Washington, D.C., to Australia. Amazingly, the task of regulating the more than 600 landfills and impoundments holding this ash is left to the states, which are more often lax than not. Ms. Boxer will press the Obama administration to devise rules for the disposal of coal ash as well as design and construction standards for the impoundments.

Just as the T.V.A. was dealing with this mess, Lacy Thornburg, a federal district judge in North Carolina, ordered the giant utility to reduce emissions from four coal-fired power plants that had been sending pollution into North Carolina.

The ruling validated an unusual legal strategy adopted by North Carolina’s attorney general, Roy Cooper, who sued the T.V.A. in 2006 on grounds that pollution from its power plants in Alabama, Tennessee and Kentucky constituted a “public nuisance” to the citizens of his state. Mr. Cooper chose this route because the Bush administration had systematically weakened regulations that had been used in the past to force power companies to clean up their emissions.

Taken together, the coal ash disaster and Judge Thornburg’s ruling did much to undercut the coal industry’s cheery “clean coal” campaign, whose ads would have us believe that low-polluting coal is here or just around the corner.

It is neither. Coal is certainly an important fuel, providing just over half of the nation’s electricity. And progress has been made: new coal-fired plants are cleaner than old ones, and older plants that have been required under the Clean Air Act to install pollution controls are cleaner than the many plants that have managed to escape the law’s reach.

But coal remains an inherently dirty fuel, and a huge contributor to not only ground-level pollution — including acid rain and smog — but also global warming. The sooner the country understands that, the closer it will be to mitigating the damage.

A version of this article appeared in print on January 23, 2009, on page A22 of the New York edition.

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