"I know at the Dan River site there's a potential site already to, at least, move it away from the river, which could probably most logically be done in a short period of time, and we're looking at ways we can encourage the utility to do just that," McCrory told the paper.

Meanwhile, Duke Energy says it has permanently plugged the 36- and 48-in.-dia stormwater pipes at the Eden site with concrete and grout to prevent any further leakage.

Company spokesman Tom Williams says that, as the cleanup process continues, further protective measures will be guided by the regulatory agencies, particularly by the new U.S. Environmental Protection Agency rules—expected to be announced before year's end—on the handling of coal ash.

"We're looking at all options to address long-term issues not only at Eden but across our six-state system," Williams says. "It's a long process, but we're no different from other companies with coal-ash storage facilities."

Although gray ash coats portions of the river bottom more than 70 miles downstream, Duke Energy and the department insist the municipal water treatment systems are safeguarding drinking-water supplies.

Investigators with EPA and the department, as well as citizen environment groups such as the Dan River Basin Association, continue to conduct regular tests of the Dan River for nearly 30 types of metals and other contaminants.

On Feb. 21, the agency announced that levels of aluminum and iron still exceed state surface-water standards, although levels are declining. Readings for other materials have fallen within acceptable levels.