Lake Dennison Recreation Area is a 121-acre state park in Winchendon, Massachusetts, occupying a small section of the 4,221-acre Birch Hill Flood Control Project, a U.S. Army Corps of Engineers property managed here by the Massachusetts Department of Conservation and Recreation. Along with nearby lands that include Otter River State Forest, it serves both as part of a broader flood-control landscape and as a local recreation destination. The park offers a swimming beach, picnic areas, a pavilion, restrooms, fishing access, a boat ramp for non-motorized craft, 150 campsites, and trails used for hiking, horseback riding, cross-country skiing, and snowmobiling.