Commercial trucks are not being allowed on a ferry that is the only route between Kentucky and Missouri. The detour is about 80 miles for trucks traveling between the two states. The Kentucky Transportation Cabinet says the Dorena-Hickman Ferry restriction is because of the low water level of the Mississippi River. The ferry will continue to allow passenger vehicles and small utility trucks. The cabinet says the water level at Cairo, Ill., was 8 feet Thursday morning, and the ferry won't accept the larger vehicles until it reaches about 13 feet.