Six years after a catastrophic coal ash spill in Tennessee washed away homes and polluted rivers, the Environmental Protection Agency on Friday announced the first federal regulations for the toxic wastes created by coal burned to produce electricity.

But the regulations do not treat coal ash as hazardous waste, as environmental groups had demanded, and accepted rules favored by electric utilities.

The regulations do not cover all coal ash ponds at shuttered power plants or require that existing unlined coal ash impoundments be moved to lined, dry storage away from waterways.

For the first time, the EPA will regulate the storage and disposal of the estimated 140 million tons of coal produced by utilities every year. Currently, states regulate coal ash impoundments with standards that vary widely.

Known as "coal combustion residuals," coal ash typically is stored in unlined ponds or pits next to waterways. Coal ash slurry contains toxic arsenic, mercury and heavy metals that contaminate groundwater, streams and rivers while also polluting the air. The EPA said it has documented 160 cases of air and water contamination from coal ash ponds.

Among the EPA regulations, to be imposed over time, is a requirement that utilities close coal ash ponds that are found to be polluting groundwater or waterways, or are considered structurally unsound. The EPA will also increase monitoring of coal ash dust released into the air.

Under the regulations, new impoundments may not be built near wetlands or other sensitive areas, and regular coal pond inspections and monitoring of groundwater will be required.

Some environmental groups, while welcoming what the Sierra Club called "a modest first step," said the EPA did not go nearly far enough.

"The EPA is bowing to coal-fired utilities' interests and putting the public at great risk by treating toxic coal ash as simple garbage instead of the hazardous waste that it is," Scott Slesinger, legislative director at the National Resources Defense Council, said in a statement.