JACKSONVILLE (AP) - Neighbors opposed to a plan to restart operations at the historic Opp Mine spent three hours warning Jackson County commissioners about the potential for pollution and property destruction.

Dozens testified against a requested zoning change that would allow the property owners to initiate a large strip-mining operation near a residential neighborhood about a mile from Jacksonville.

Dr. Bob Nyamik of Medford told the commissioners Wednesday that environmental reports show mercury contamination at the Opp Mine is five times the acceptable level in some areas. He said digging for aggregate will release a “plume” of mercury that will end up in Jackson Creek.

“I think this is a very real threat to our environment,” Nyamik said.

Property owners Frank Hardin and Bob Robertson have threatened to pursue a $50 million lawsuit against Jackson County unless officials grant them a zoning change from woodland to aggregate resource. The change would allow them to mine between 1.4 million and 1.6 million cubic yards of aggregate - and possibly gold - from a 30-acre section of the 157-acre property.

The owners gave their side of the story to commissioners on Feb. 14, refuting community concerns in a hearing that stretched three hours and was continued on Wednesday.

That's when neighbors and their experts had their say, complaining that increased truck traffic would jeopardize Jacksonville's historic status and criticizing the owners for sending a letter a few years back that threatened residents with legal action if they testified against the mining project.

Besides the threat of mercury and arsenic, hydrologist Jonathan Williams warned that blasting and mining could cause a reduction in ground water and lower yield in wells. He said 59 residents depend on groundwater within 1,500 feet of the proposed mining site.

Mark Von Holle, who lives above the Opp Mine, said the property was originally purchased by the Hardins for $225,000. It was sold in 1996 for $950,000 to a partner company and currently is listed for $6 million.

Von Holle said the owners claim the property is worthless, and then use the threat of lawsuit to blackmail the county into complying with their request.

“What is wrong with this picture?” Von Holle asked. “Who is really trying to get something for nothing?”

Mining supporters will give rebuttal testimony in April, and commissioners likely won't make a decision until May.