NASHVILLE (AP) - A utility is cleaning up a drilling slurry spill at a state natural area where it is laying a gas pipeline in Nashville.

Piedmont Natural Gas spokesman David Trusty told The Tennessean (http://tnne.ws/12Aor6U) on Tuesday that the company regrets the spill and is working with state environmental officials to remove an estimated 300 gallons of a clay mixture from Otter Creek in the Radnor Lake Natural Area.

Radnor advocate Clark Tidwell, a longtime Nashville attorney, said the mishap is what environmentalists feared when Piedmont got permission to cross the preserve.

"It is tragic. It was something that was foreseeable and it was something the commissioner of environment and conservation could have prevented by just saying no," Tidwell said.

John McFadden, John McFadden, executive director of the Tennessee Environmental Council, also opposed the pipeline going through the area .

"Every time we create these corridors to run these utilities, especially through these natural areas, we create situations where polluting these resources is a high probability," McFadden said.

Piedmont reported the accident on Saturday to the Tennessee Department of Environment and Conservation. TDEC spokeswoman Meg Lockhart said the agency is overseeing the cleanup and investigating how it occurred.

An incident report from Piedmont stated the hydraulic pressure of boring was too great for soft soil conditions to withstand.

The bentonite clay occurs naturally and is not toxic. However, the substance turns the water cloudy - a condition known as turbidity.

Lockhart said the spill could harm or kill aquatic wildlife, including a species of crayfish.

Environmentalists, neighbors in the upscale southern Nashville neighborhood and the Friends of Radnor Lake group opposed running the pipeline through the property.

As part of its permit a pplication, Piedmont filed a response plan for dealing with spills and Trusty said the plan was followed. Still, he conceded the spill should not have occurred.

"I don't want to minimize our attitude on this," Trusty said. "It is something we regret."

The natural area, administered by the state park system, includes and surrounds an 85-acre lake for which it is named. The lake was created in 1914 to provide water to the Louisville and Nashville Railroad Company steam engines at nearby Radnor Yard.

The pipeline will not go under the lake itself.