STEVENSON — A retention pond at a Tennessee Valley Authority coal-burning power plant leaked waste into a northeast Alabama creek Friday, putting more pressure on utility officials who are already trying to clean up a major coal ash spill from last month in Tennessee.

Workers at the Widows Creek Fossil Plant discovered the leak at the 147-acre retaining pond at about 6 a.m., officials said. By the time the discharge was stopped a few hours later, the spill had run into an adjacent pond and then overflowed into Widows Creek. A leaky pipe was likely to blame, the TVA said.

“Some did get into the creek. How much I don’t know,” TVA spokesman Gil Francis said. Most of the waste ended up in the second pond, he said.

Alabama emergency management officials were trying to determine if any drinking water systems were affected by the spill into the creek, which flows into the Tennessee River, said Scott Hughes, a spokesman for Alabama Department of Environmental Management.

The spill, about 30 miles southwest of Chattanooga, Tenn., comes after a dike burst at a plant near Kingston, Tenn., on Dec. 22, releasing more than 1 billion gallons of toxic-laden coal ash into a neighborhood. The spill has renewed a debate about whether states or federal regulators should oversee the materials, and at a hearing in Washington this week, Senate Democrats said they want stricter rules for toxic ash from coal-fired power plants.

The TVA, which is the nation’s largest public utility and serves 9 million customers in seven states, has similar ponds in several locations. An Associated Press analysis of Energy Department data found that nationwide, 156 coal-fired power plants store ash in surface ponds similar to one that ruptured last month in Tennessee.

Environmentalists reacted strongly to Friday’s accident, saying it was more evidence reforms are necessary.

“Just one day after U.S. Senate hearings on coal waste and three weeks after the massive rupture at the Kingston plant in Tennessee, a second spill makes clear the urgent need for regulation of coal waste to protect both human health and the environment,” Chandra Taylor, staff attorney for the Southern Environmental Law Center, said in a statement.

Adam Snyder, executive director of Conservation Alabama, called for an investigation by Congress, TVA and the federal Environmental Protection Agency into the operation of the ponds and whether enough is being done to keep residents safe.

“For the second time in less than one month, the citizens served by the Tennessee Valley Authority have been unnecessarily exposed to a multitude of health risks due to a failure of a coal ash pond,” Snyder said.

The federal utility said the pond that leaked Friday contained gypsum, a material that is captured in air pollution control devices at the plant. Gypsum is a naturally occurring mineral that contains calcium sulfate, which is used to make drywall, cement and fertilizer.

“It’s in wallboard, like in your house,” Francis said.

The spill occurred near the part of the Tennessee River that provides drinking water for the city of Stevenson.

Brent Blackmon, manager of Stevenson Utilities, which provides water to about 1,600 customers, said water samples were being taken from the river Friday afternoon and sent to a private laboratory in Tuscaloosa for testing.

“It’s just a standard test to determine if there’s anything that would contaminate our drinking water,” Blackmon said. He said he’s optimistic from the information he’s received that the substances that went into the creek were not toxic. He said results from the lab are expected Monday afternoon.

Francis said a pipe near the surface of the pond that draws off water and diverts into another pond had sprung a leak. TVA is still trying to determine when the leak began, but Francis said it couldn’t have been going on for long.

“All these ponds are looked at daily,” Francis said.

TVA inspected all its retaining ponds, including the ones at the Widows Creek Fossil Plant, after the rupture in Tennessee and said on Dec. 31 that the ponds were “all in good shape.”

The Alabama pond held a different kind of waste than what was contained in the Tennessee pond. The Kingston plant spill was wet fly ash, which contain heavy materials, including arsenic.

In 2005, the utility reported depositing 445,200 tons of gypsum in ponds at the Widows Creek plant. The Widows Creek plant also has fly ash ponds that are the largest in Alabama, according to EPA data.

– Associated Press Writer Bob Johnson in Montgomery and Dina Cappiello in Washington contributed to this story.