May 6 - McClatchy-Tribune Regional News - Bruce Henderson The Charlotte Observer, N.C.

Four environmental groups said today they will sue Duke Energy unless the company stops "illegal" construction at its Cliffside power plant.

The Southern Environmental Law Center said it will send Duke a notice that it will file suit in 60 days on behalf of the Natural Resources Defense Council, Southern Alliance for Clean Energy, National Parks Conservation Association and Sierra Club.

The groups base their case on a February federal appeals court ruling. The ruling said the Environmental Protection Agency was wrong to remove power plants from a list of 67 hazardous air pollutants, including toxic mercury, that are subject to the most stringent air pollution controls.

That means Duke hasn't done enough to control mercury or other toxic pollutants, the groups claim.

Duke calls its pollution controls state of the art. Both the utility and N.C. air-quality agency have said the February court ruling does not affect Cliffside.

Cliffside, which burns coal, now releases 157 pounds of mercury a year. A new permit allowing addition of a new 800-megawatt boiler -- which opponents want to stop -- caps the release at 99 pounds a year. Duke says actual emissions will range from 70 to 80 pounds.