Nancy Holt bulldozed trees and blocked the path to the creek behind her house after her grandson and his friend went wading in the water and got staph infections.

Myra Dotson developed red bumps on her knees and forearms after gardening. When they became infected, a doctor diagnosed her with MRSA, the antibiotic-resistant “super bug.”

Both women blame the infections on sewage sludge applied on nearby fields. Now an advisory board’s concerns are raising questions the county had hoped to begin answering two years ago.

In 2006, Orange County agreed to pay the UNC School of Public Health $10,000 to test air and water quality where sludge, also known as biosolids, was being spread.

“Since Orange County is one of the counties with the largest number of application sites, a … study would help establish the relative risks associated with biosolid application sites and afford better information with which to inform county communities, policymakers and partners,” according to a county memo.

The study never happened.

“We had several obstacles along the way,” said Tom Konsler, the county’s environmental health services director.

They included the loss of one of the researchers and the reluctance of local farmers to provide land for testing. Farmers take sewage sludge, rich in nitrogen and phosphorus, as free fertilizer.

“The first farmer who agreed to it got to talking with his family and said he couldn’t put the family farm at risk if a group got hold of the information and decided to do something about it,” Konsler said.

Sludge, the byproduct of the sewage treatment process, has come back up for two reasons.

First, the Orange County Commission for the Environment, a citizens advisory board, wants the county to establish a task force to study biosolids.

Second, the county’s search for a solid waste transfer station site has narrowed to two top contenders. One is privately owned. The other belongs to the Orange Water and Sewer Authority, which refuses to sell or even let the county on its land for testing because it disposes of sludge there.

Orange County ranks fifth among the state’s 100 counties in permitted biosolids application sites, according to the county. In addition to OWASA, land owners in the county accept sludge from Durham, Burlington, Mebane and Hillsborough.