Very good article, with several illustrative cites going back to 1979. The west is dominated by the [0] [https://en.wikipedia.org/wiki/Intermontane_Plateaus ht

Very good article, with several illustrative cites going back to 1979. The west is dominated by the [0] [https://en.wikipedia.org/wiki/Intermontane_Plateaus https://en.wikipedia.org/wiki/Intermontane_Plateaus] , much of it losing water since the pluvial lakes like [https://en.wikipedia.org/wiki/Lake_Bonneville https://en.wikipedia.org/wiki/Lake_Bonneville] reached its greatest height 18000 years ago. "The abandoned shore lines have yielded evidence of past climatic changes second in importance only to those of the Pleistocene glaciated areas."[0] A lot of snow falls in the winter, but for a century the meltwater has had plenty of mouths to feed. A lot of the distribution plans have been based on only a couple centuries of experience.