Complex sentence: Lookout Point Dam and Lake are located on 7,800 acres of land that make up the dam and surrounding areas are managed by the United States Army Corps of Engineers and the Willamette National Forest.
Split into simpler sentences: Lookout Point Dam and Lake are located on 7,800 acres of land that make up the dam and surrounding areas. All of this area is managed in conjunction by the United States Army Corps of Engineers and the Willamette National Forest.