The Minutemen civilian border-patrol group has hired a contractor to finish building 10 miles of fence along the Mexican border.
Construction on the fence began May 27, when about 150 supporters turned out for the groundbreaking, but the number of volunteers then dwindled.
"We don't want to put up something that will just be a symbol," said Al Garza, the group's executive director. "We want to make sure it's permanent, properly structured and done right."
As few as four people were observed working on the fence recently, said Cecile Lumer of the humanitarian aid group Citizens for Border Solutions.
"From the beginning, the numbers they have projected have always fallen very short of the reality," Lumer said.
One of the ranch owners, Jack Ladd, said he hoped the fence would keep Mexican livestock off his property, but he doubted it would keep people out.
"We want to make it clear that while we oppose illegal immigration, we weren't necessarily trying to keep Mexicans off the land," he said.