Onslow County is shown here, including the New River and the locations mentioned in this article.

The collapse of a dike on a rain-soaked industrial swine farm in Onslow County sent 25 million gallons of hog waste surging across roads and crops and into the headwaters of the New River.

The state's worst spill of agricultural waste began Wednesday afternoon, just as state legislators were debating whether to put new restrictions on the state's booming corporate swine industry. The proposal was rejected in favor of a study.

Adding further irony, the 1 ½-year-old farm involved in the accident was the first to be sanctioned under new regulations designed to protect the state's waters from livestock waste. Pork industry officials have maintained that farms built under the new guidelines are environmentally safe.

On Thursday, state investigators linked the accident to a fish kill in at least one tributary of the New River and were bracing for bigger problems today as the waste plume moves downstream.

The full impact of the spill may not be known for days or weeks. Widespread fish kills, for example, often occur hours or days after a spill of sewage or animal waste, when the oxygen level in the water has been depleted.

The risks to humans were believed to be minor.

"Right now, the biggest problem would be for people that had waste rush over their well head, especially if the well wasn't properly constructed," Onslow Health Department director Danny Jacob said. He encouraged residents to bring in water samples for testing if they are concerned about contamination.

Further downstream, the New River flows through Jacksonville and the Camp Lejeune Marine base, but a state official said the city and the Marine facility draw their water from wells deep enough to not be affected by the spill.

"This is the biggest spill we've seen from a livestock operation," said Debbie Crane, spokesman for the state Department of Environment, Health and Natural Resources. She said the fish kill alone could result in fines of up to $10,000 for the farm's owner, a Purina Inc.-backed venture called Oceanview Farms Ltd.

The spill tore a 25-foot-wide gash in the side of the farm's 8-acre waste lagoon, an above-ground earthen enclosure built to hold 30 million gallons of hog waste. A wall of wastewater washed out part of a driveway and cut large swaths across fields and woods.

More than a mile from the farm, tobacco and soy plants that had been covered with wastewater the day before remained coated with black sludge. Cars had to cross a river of hog waste that stood at least 8 inches deep on State Road 1235, neighbors said.

"Who's going to clean it up? That's what I want to know," fumed Sidney Whaley, a retired farmer who, two years earlier, had tried to prevent the hog farm from opening.

Blackish, foul-smelling water stood in pools in the fields surrounding his house, and the whole neighborhood had a dank, swamp-like odor.

The state's Division of Environmental Management dispatched teams of inspectors to the area to check bacteria levels in nearby streams and ditches. Jim Bushhardt, a DEM engineer, said officials also were trying to determine what caused the lagoon dike to rupture in the first place. Heavy rains, which neighbors say had dumped more than a foot of water on the area in the past two weeks, were believed to have contributed to a weakening of lagoon walls, he said.

He said it is possible that lagoons at other, similarly constructed hog farms may be experiencing problems as a result of the heavy rain. The part of northwestern Onslow County where the accident occurred is near the heart of North Carolina's hog belt, where millions of hogs are raised in large, factory-like farms.

Farm officials at the site and in Wilson declined to comment Thursday. Charles Carter Jr., part-owner of the construction company that built the lagoon, blamed the spill on the wet weather.

"Didn't nobody mean for it to happen. It just happened," said Carter, who was trying to repair the hole Thursday afternoon.

But Bill Holman, a Raleigh-based lobbyist for environmental groups, said he was disturbed that the accident occurred at a new, state-of-the-art farm that should be a showcase for the swine industry.

"It's troubling that this so-called up-to-date lagoon experienced this catastrophic failure," Holman said. "Environmentalists had been concerned, frankly, about the older facilities. It's troubling to learn that what we've been pushing for may not be adequate.

"Environmental organizations have said for some time that the state needs stricter regulations of large industrial hog farms," Holman said Thursday. "I think this unfortunate spill underscores that need."

Whaley, the neighbor, agreed.

"When they built this thing they assured us that it was state-of-the-art -- that it wouldn't even leak," he said. "Now the woods and fields around here are just coated with hog manure. What a mess."