Because our analysis of the nation's most active power plant coal ash dumps revealed that the South is home to a disproportionate share of poorly regulated facilities like the one that failed catastrophically at TVA's Kingston plant in Eastern Tennessee, we wanted to take a closer look at the facilities across the region.

We used data from the Environmental Protection Agency's Toxics Release Inventory to compile the following chart, which shows total releases to on-site surface impoundments -- the technical name for coal combustion waste dumps -- at all electrical utilities in the South, which the Institute for Southern Studies defines as including 13 states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia and West Virginia.

The chart groups the facilities by state, listing the states in descending order by total volume of toxic chemicals released by electrical utilities to on-site surface impoundments. It includes the name of the power plant, the corporate owner (with South-based companies denoted by an asterisk), the community where the plant is located, and the total toxic releases to the surface impoundment. (Click on the chart for a larger version.)

Some observations:

* Every state in the South is home to at least one power plant with an active on-site surface impoundment. The greatest volume of toxic chemicals was released to surface impoundments in Alabama, with more than 13.3 million pounds dumped in 2006. The state with the greatest number of on-site surface impoundments is Florida with 17, though only a relatively small amount of waste was dumped into six of its impoundments. That was followed by Kentucky with 15 impoundments, North Carolina with 12, and Georgia with 10.

* By and large, the South's surface impoundments are located at plants owned by companies based in the region.  The states that are exceptions to this rule are West Virginia and Arkansas, where plants using surface impoundments are all based outside the region, and Texas, where all but one are outside companies.

* The company that relies most heavily on surface impoundments in the region is the Southern Co. The Atlanta-based firm reported toxic releases to 22 surface impoundments at power plants in the South in 2006. It was followed by Raleigh, N.C.-based Progress Energy with 12 surface impoundments, Ohio-based American Electric Power with 11 and Knoxville-based TVA with nine. Charlotte, N.C.-based Duke Energy and Louisville-based E.ON are tied with eight each.

* The companies using surface impoundments to store toxic coal ash have considerable political clout. In the 2008 election cycle, for example, the Southern Co.'s political action committee spent more than $540,000 on federal lobbying, according to the Center for Responsive Politics' OpenSecrets.org database. At the same time, Progress Energy's PAC spent more than $443,000, AEP's more than $1.3 million, Duke's more than $1.2 million, and the E.ON US PAC more than $32,000. TVA, meanwhile, is owned by the federal government.

(Photo of Tennessee coal ash disaster from the Tennessee Valley Authority's latest photo gallery)