Nothing in this chapter shall preclude a component of the state scenic rivers system from becoming a part of any national scenic rivers system. The commissioner of environment and conservation is directed to encourage and assist any federal studies for inclusion of Tennessee rivers in a national scenic rivers system. The commissioner may enter into written cooperative agreements for joint federal-state administration of a Tennessee component of any national scenic rivers system; provided, that such agreements for the administration of water and land uses are not less restrictive than those set forth in this chapter.