Basic units are not all classic drainage areas. The SCS used some major streams as dividing lines for their watersheds, so it was necessary to make some of the basic units conform to that convention. Some of these basic units cover only the drainage area on the right bank of a stream, and some cover the complementary area on the opposite side of the stream.
Each river basin has been subdivided into the drainage areas of the major streams in the basin. The Little Blue and the South Platte river basins have as few as four divisions while the Republican River Basin has 17. Consequently, the second group of two-digit numbers range from 01 to 17 for each river basin numbered in upstream order.
The last two-digit number further subdivides the major stream divisions into the BHU. These numbers range from 01 to 99. Although these last two digits were originally numbered in upstream order, revisions made during the delineation, digitization, processing, and verification processes and subsequent updates required that basic unit numbers sometimes be added or removed. As a result, these numbers are no longer necessarily in upstream order.
01 Big Blue 02 Little Blue 03 Republican 04 Nemaha 05 Lowr Platte 06 Elkhorn 07 Middle Platte 08 Loup 09 South Platte 10 North Platte 11 Missouri Tribs 12 Niobrara 13 White River-Hat Creek
--------information below is not in standard metadata compliant format------ Table 1 RIVER BASIN FILE SIZE(K) WEST BND EAST BND NORTH BND SOUTH BND bigblue 698 -98.5745 -96.0668 41.2879 39.1808 elkhorn 835 -99.6939 -96.0243 42.6629 41.1207 litblue 436 -99.0865 -96.6771 40.6866 39.5828 loup 1387 -102.3104 -97.3181 42.5259 40.8359 lpllatte 578 -98.0403 -95.8791 41.9315 40.5241 mplatte 642 -101.0433 -99.5073 41.7404 40.4296 motribs 604 -98.0722 -95.8411 42.8741 41.0534 nemaha 641 -96.7609 -95.3075 41.0574 39.6596 niobrara 1617 -104.6684 -97.9460 43.7175 41.9477 nplatte 723 -109.2005 -100.6748 43.1809 40.3262 republicn 1060 -101.4843 -96.8626 41.0621 39.0106 splatte 374 -106.2115 -100.6754 41.4894 38.7991 whitehat 525 -104.2894 -99.3067 44.7822 42.5212