Build a pipeline to bring water to lake Powell.
Two birds with one stone, as this could alleviate flooding on the Mississippi.
Arguments against:
1. Nasty pipelines/canals desecrating sacred Indian homelands.
2. Chinese fish in Mississippi will be able to get into the Green and Colorado Rivers.
3. It'll be TOO expensive.
4. It's not sufficiently green
From where? It’s up hill if your pipeline originates below the highest dam elevation of 3700ft.
Other than that the Green River - which becomes the Colorado - is already downhill to Powell. As well as the San Juan.
Where do you want to get the water from for said pipeline???