Mark Twain Lake is a reservoir located in Ralls and Monroe Counties in the U.S. state of Missouri. It was created by the Clarence Cannon Dam (formerly called Joanna Dam) impounding the Salt River and is located about southwest of Hannibal. The lake was named for Missouri author Mark Twain and part of the area around it is Mark Twain State Park. The village of Florida, the birthplace of Mark Twain, is mostly surrounded by the lake. Authorization and purpose In 1937 the Joanna Dam project was first proposed as an answer to many years of flooding by the Salt River. With support and expertise of many, including Representative Clarence Cannon, the multi-purpose project was authorized by Congress in the Flood Control Act of October 1962. The dam and the lake offer multiple benefits to Northeast Missouri including: hydroelectricity, flood Control, recreation, fish and wildlife conservation, water supply (shortage of existing ground water), navigation. The dam was dedicated in 1984. Johnny Cash played at the dedication ceremony. Clarence Cannon Dam and power house Clarence Cannon Dam is a high and long combination concrete gravity embankment dam. The dam contains of concrete and of earth-fill. The dam contains a hydroelectric power plant, with two generators, capable of producing up to of power, or enough to supply a town of 20,000 people. When both units are operating at capacity, as much as of water pass through the turbines each minute. A regulation dam, located downstream from the main dam, creates a storage pool that can be used for pumped-storage hydroelectricity. When demand for electricity is low, power from other sources can be used to pump water back from the tailwater to the lake. This water can then be re-cycled through the turbines when energy is in high demand. Namesakes Clarence Cannon was one of the prime influences in the realization of the Cannon Dam Project during his 42 years serving in the U.S. House of Representatives. He was actively engaged in farming in Lincoln County throughout his life and the author of several publications on parliamentary law. Following his death in 1964, the Joanna Dam was officially renamed to honor the man who was a longtime supporter of the project. The lake is named for author Mark Twain, (pen name of Samuel Clemens) who was born in Florida, Missouri. At the time of his birth, Florida sat on the bank of the