 I knew it could work,” Yeaman has said.Yeaman founded the conservancy in 1994 at the age of 70.Since that time, the conservancy has worked with private landowners using a tool called a conservation easement to protect more than 14,000 acres along the Upper Delaware River, which in 2010 was named Most Endangered River in the United States by American Rivers, a national conservation organization based in Washington, DC.