Lake Texoma is one of the largest reservoirs in the United States, the 12th largest US Army Corps of Engineers' (USACE) 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 upstream from the mouth of the river. It is located at the confluence of the Red River and Washita Rivers. The damsite is approximately northwest of Denison, Texas, and southwest of Durant, Oklahoma. Lake Texoma is the most developed and most popular lake within the USACE Tulsa District, attracting approximately 6 million visitors a year.