Lake Texoma is one of the largest reservoirs in the United States, the 12th-largest US Army Corps of Engineers' lake, and the largest in USACE Tulsa District. Lake Texoma is formed by Denison Dam on the Red River in Bryan County, Oklahoma, and Grayson County, Texas, about 726 miles upstream from the mouth of the river. It is located at the confluence o…Lake Texoma is one of the largest reservoirs in the United States, the 12th-largest US Army Corps of Engineers' lake, and the largest in USACE Tulsa District. Lake Texoma is formed by Denison Dam on the Red River in Bryan County, Oklahoma, and Grayson County, Texas, about 726 miles upstream from the mouth of the river. It is located at the confluence of the Red and Washita Rivers. The project was completed in 1944. The damsite is about 5 miles northwest of Denison, Texas, and 15 miles southwest of Durant, Oklahoma. Lake Texoma is the most developed and most popular lake within the USACE Tulsa District, attracting around 6 million visitors a year. Oklahoma has more of the lake within its boundaries than Texas.