Heavy rains from Tropical Storm Florence have caused a slope to collapse at a coal ash landfill at a closed power station outside Wilmington, North Carolina, Duke Energy officials confirmed.

Duke spokeswoman Paige Sheehan said Saturday evening that about 2,000 cubic yards (1,530 cubic meters) of ash, enough to fill roughly 180 dump trucks, have been displaced at the Sutton Plant and that contaminated storm water likely flowed into Sutton Lake, the plant's cooling pond. The company hasn't yet determined if the weir that drains the cooling pond was open or whether any contamination may have flowed into the swollen Cape Fear River.

The gray ash left behind when coal is burned contains toxic heavy metals, including lead and arsenic. Sheehan says the company had reported the incident to state and federal regulators.

Spokeswoman Megan S. Thorpe at the state's Department of Environmental Quality said state regulators will conduct a thorough inspection of the site as soon as safely possible.

"DEQ has been closely monitoring all coal ash impoundments that could be vulnerable in this record breaking rain event," Thorpe said. She added that the department, after assessing the damage, will "hold the utility accountable for implementing the solution that ensures the protection of public health and the environment."

The coal-fired Sutton plant was retired in 2013 and the company has been excavating millions of tons of ash from old waste pits and removing it to safer lined landfills constructed on the property.

Florence slammed into the North Carolina coast as a large hurricane Friday, dumping nearly three feet (1 meter) of rain and swelling the region's rivers. The resulting flooding forced swift-water rescues and left several people dead.

As Florence spins inland, environmental regulators are monitoring more than three dozen toxic waste sites in the storm's path, as well as scores of low-lying water- and sewage-treatment plants at risk of flooding.

The Environmental Protection Agency has identified 41 Superfund sites in threatened parts of the Carolinas, Virginia, Maryland and Georgia, including polluted industrial sites, chemical plants, coastal shipyards and military bases.

EPA spokesman John Konkus said the agency is listening for any word of oil or hazardous substance spills from first responders, media reports and state and local emergency command posts. He said federal on-scene coordinators and equipment stand ready to deploy if needed.

There are at least two other coal-fired Duke plants in North Carolina that are likely to be affected by the storm.

The H.F. Lee Power Station near Goldsboro has three inactive ash basins that flooded during Hurricane Matthew in 2016, exposing a small amount of coal ash that may have flowed into the nearby Neuse River. The old waste pits are capped with soil and vegetation intended to help prevent erosion of the toxic ash beneath.

The Neuse is expected to crest at more than nine feet (3 meters) above flood stage Monday and Sheehan said the company expects the same ash basins are likely to be inundated again.

At the W. H. Weatherspoon Power Station near Lumberton, Sheehan said it had already rained more than 30 inches (75 centimeters) by Saturday evening, causing a nearby swamp to overflow into the plants cooling pond. The Lumber River is expected to crest at more than 11 feet (3.3 meters) above flood stage Sunday, which would put the floodwaters near the top of the earthen dike containing the plant's coal ash dump.

Environmentalists have been warning for decades that Duke's coal ash ponds were vulnerable to severe storms and pose a threat to drinking water supplies and public safety.

"Unfortunately, Duke Energy has spent years lobbying and litigating and still has not removed the coal ash from its dangerous riverfront pits in the coastal area, some of which are in the floodplain," said Frank Holleman, a senior attorney at the Southern Environmental Law Center who has battled the company in court. "When a hurricane like Florence hits, we have to hope and pray that our communities do not suffer the consequences of years of irresponsible coal ash practices by the coal ash utilities."

Superfund sites are among the nation's most highly polluted places. They often contain contaminated soil and toxic waste at risk of spreading if covered by floodwaters. More than a dozen Superfund sites in the Houston metro area were flooded last year during Hurricane Harvey, with breaches of potentially harmful materials reported at two.

The worst natural disaster in North Carolina history was Hurricane Floyd in 1999, which dumped nearly 2 feet (60 centimeters) of rain and flooded a broad swath of the coastal plain, swamping whole towns and dozens of hog farm lagoons containing millions of gallons (liters) of untreated urine and feces.

Environmental groups said Friday that they were worried that scores of hog lagoons will burst again or be overtopped by flooding, spilling their contents into rivers used as sources of drinking water. Also of concern were more than three dozen coal ash dumps at power plants in the region.

Among the Superfund sites most at risk from Florence is Horton Iron and Metal, a former shipbreaking operation and fertilizer manufacturing site in a low-lying floodplain along the Cape Fear River outside Wilmington. The 7.4-acre (3-hectare) site is heavily contaminated with pesticides, asbestos, toxic metals and cancer-causing PCBs.

Upriver along the Cape Fear is Carolina Transformer Co., a 5-acre (2-hectare) Superfund site in Fayetteville that also contains contaminated soil and groundwater contaminated with PCBs.

Forecasts call for the river to crest Monday at Fayetteville at more than 62 feet (19 meters) — nearly 30 feet (9 meters) above flood stage.

In Elizabeth City, the Triangle Pacific Corp. site includes a World War II-era Navy blimp base along the Pasquotank River that was later purchased by a company that manufactured wooden cabinetry. The site is contaminated with toluene, acetone, cadmium and arsenic.

Also of concern is the sprawling Norfolk Naval Shipyard in Virginia and Marine Corps bases at Camp Lejeune and Cherry Point in North Carolina and at Parris Island in South Carolina.

The shipyard near the mouth of the Chesapeake Bay dates to 1767 and contains contaminated soil and groundwater from more than two centuries' worth of dumped hazardous chemicals. Hazards at the Marine bases include ground saturated with toxic chemicals, old paint, ash from old trash burn pits and unexploded ordnance.

Nationwide, there are 327 Superfund sites in areas prone to flooding or vulnerable to sea-level rise caused by climate change, according to an Associated Press analysis of flood-zone maps, census data and EPA records. Nearly 2 million Americans live within a mile of the most at-risk sites.

Duke has been under intense scrutiny for the handling of its coal ash since a drainage pipe collapsed under a waste pit at an old plant in Eden in 2014, triggering a massive spill that coated 70 miles (110 kilometers) of the Dan River in gray sludge.

In a subsequent settlement with federal regulators, Duke agreed to plead guilty to nine Clean Water Act violations and pay $102 million in fines and restitution for illegally discharging pollution from coal-ash dumps at five North Carolina power plants. The company is in the process of closing all of its coal ash dumps by 2029.