Over nearly 20 years, the couple has invested in the property, motivated by a commitment to land conservation and restoration of a historic home. The property has been placed in a conservation easement that protects it forever by allowing no additional building on the site. Going beyond restoring the house, which dates to the mid-1700s, they installed solar systems to generate more electricity than they use. If power lines are expanded, Mr. Bruer and Ms. Mathison could lose a pine woods that buffers the home from the transmission line corridor that is 400 feet away. Historic stone walls could be destroyed and the home’s value seriously deteriorated.