Do you know how the water rights agreements are set by law?
The Colorado River in particular.
https://en.wikipedia.org/wiki/Colorado_River_Compact
Colorado, New Mexico, Utah, Wyoming, Nevada, Arizona, and California are all guaranteed a certain amount of water by law. Except you know, the law was written poorly and there's not enough water. Either way, the dams in the area
must follow the current agreement, until Congress changes it.
To steal the chart from Wikipedia:
Upper Basin, 7.5 million acre·ft/year (293 m³/s) total | | |
Colorado | 51.75%* | 3.86 million acre·ft/year (150.7 m³/s) |
Utah | 23.00%* | 1.71 million acre·ft/year (67.0 m³/s) |
Wyoming | 14.00%* | 1.04 million acre·ft/year (40.8 m³/s) |
New Mexico | 11.25%* | 0.84 million acre·ft/year (32.8 m³/s) |
Arizona | 0.70% | 0.05 million acre·ft/year (2.0 m³/s) |
*Percentages with a star are a percentage of the total after Arizona's
0.05 million are deducted. Arizona's percentage is of the total. | | |
Lower Basin, 7.5 million acre·ft/year (293 m³/s) total | | |
California | 58.70% | 4.40 million acre·ft/year (172 m³/s) |
Arizona | 37.30% | 2.80 million acre·ft/year (109 m³/s) |
Nevada | 4.00% | 0.30 million acre·ft/year (12 m³/s) |
These are the requirements.
You can't pump the water from lower-to-upper, because California / Arizona / Nevada are
drinking the water. What, are you just gonna let the people down-river die of thirst?
Furthermore, the contract doesn't match reality, the Colorado river
literally doesn't have enough water to match these allotments.
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Pumped Hydro works when pumping water from lower-to-upper is allowable and legal. If you have water-contracts (because cities downstream need the water to live), things get a lot more hairy. As such, the rivers in the area can be used for power-generation (because releasing the water follows the contract), but NOT for pumped-hydro (because pumping the water back upstream breaks the Colorado River Compact).
Blame poor laws and poor water management. This river is 100% allocated.