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.