It was created by the Clarence Cannon Dam ( formerly called Joanna Dam ) impounding the Salt River and is located about 20 miles ( 32 km ) southwest of Hannibal .
Mark Twain Lake is located in Ralls County , Missouri and Monroe County , Missouri .
Mark Twain Lake was created by the Clarence Cannon Dam ( formerly called Joanna Dam ) impounding the Salt River and is located about 20 miles ( 32 km ) southwest of Hannibal .
Mark Twain Lake is located in Ralls County , Missouri and Monroe County , Missouri .