CLEVELAND, Wis. - A Manitowoc County farmer is offering a $15,000 reward to nab vandals he says spread liquid manure over his property, the latest chapter in a saga that has pitted neighbors against the state's fifth-largest dairy farmer.

Tod Leiteritz, 55, says vandals opened a valve of a holding structure and sent thousands of gallons of liquid manure cascading over his property on Oct. 12.

Leiteritz's Maple Leaf Dairy, which has 3,500 cattle on almost 5,000 acres and employs 50 people, has been the target of criticism in the past.

Neighbors have blamed his farm for emitting sickening odors and damaging the local watershed, which feeds into Lake Michigan.

The neighbors group, called Centerville Cares, has recently filed suit in Manitowoc County contesting the operating permit of the farm, arguing that the Department of Natural Resources has never fully analyzed the farm's pollution impact.

His opponents have blamed the farm for a Sept. 9 fish kill that claimed about 2,000 forage fish and 100 game fish in Fischer Creek. They also suspect the farm was responsible for an Oct. 13 runoff of manure from a drain tile that runs through Maple Leaf Dairy and into the creek.

Leiteritz said his success has been tarnished by harassment from environmentalists and their lawyers.

"I think it's unjust, to say the least," Leiteritz said. "We're just like anyone else - we're trying to make a living."

Todd Palmer of Madison, the attorney for Leiteritz, has contacted the FBI office in Green Bay because he said the vandalism smacks of "ecoterrorism" and that federal laws may have been violated.

The farm has also complained of other acts of vandalism, but does not link it to opposition from Centerville Cares.

The lawyer for Centerville Cares, Andrew Hanson called the farm "the environmental equivalent of a neighborhood crack house."

"It's been a series of problems out there," Hanson said.

In Wisconsin, manure was responsible for 52 pollution cases between June 1, 2004, and July 1 of this year, according to the Department of Natural Resources. This included 17 fish kills and the contamination of 20 private water supplies.

At some of the wells, "liquid manure was coming right out of the tap," said Gordon Stevenson, chief of the runoff management section of the DNR and manure regulator for 21 years.

"This is the worst year I've seen."

Currently, there are a half-dozen enforcement cases against dairy farms over manure pollution, Stevenson said.

The DNR has never taken action against Leiteritz's farm for manure problems. Officials said they are still investigating these latest cases.

Russ Tooley, who lives along the lake and is president of Centerville Cares, said he has nothing against dairy farms.

"They can get as big and ugly as they want," said Tooley. "But you have to be able to breathe the air, and the water has to be able to support fish. As a neighbor, I can't stand (the smell), and he's killing all of the fish."