31     1012 The Cheyenne River Basin
31     1014 Missouri-White
31     1015 The Niobrara River Basin
31     1017 Missouri-Big Sioux
31     1018 The North Platte River Basin
31     1019 The South Platte River Basin
31     1020 The Platte River Basin
31     1021 The Loup River Basin
31     1022 The Elkhorn River Basin
31     1023 Missouri-Little Sioux
31     1024 Missouri-Nishnabotna
31     1025 The Republican River Basin
31     1027 The Kansas River Basin