Not many pumping stations may be needed along the way. One earlier poster noted how it was all downhill. Southern Oregon is high desert. 4K ft. while Las Vegas is low desert 2Kft. Phoenix 800ft. San Bernardino 1K ft.
Hydrology is a marvel, capable of climbing small hills with some creative construction.
I get that as I am a professional civil engineer. I live in the Columbia Basin in eastern Washington. The Tri Cities sits at 470 ASL.
300 miles at +/- 4000 feet of head will take some serious pumping.
Granted it wouldn’t be all uphill based upon the chosen route.