This is the proposed 1890 set of boundaries.
This shows the actual state boundaries dividing the Colorado River's drainage basin. These divisions have caused significant problems, quite apart the serious ecological degradation caused by the unlimited use of water from the Colorado River, and an ongoing dispute with a Mexico that gets hardly any water. The American states in the drinage basin in full or in part, all arid, all with rapidly growing populations, all dependent on Colorado River water, have found themselves still bound by the 1922 Colorado River Compact that many states, particularly California, see as providing insufficient water for growth. Conceivably, if the Colorado River basin was a single jurisdiction it would be better able to handle the distribution of water. Conceivably. As things stand, the inevitable straight lines--inevitable since simple--prevail, in the western United States as elsewhere. Almost all of the borders of western Canada are marked by straight lines, with the exception of the British Columbia-Alberta border that follows the Rocky Mountains for its southern extent.