A number of "valley authorities" like the TVA were proposed in the US at various points in the 1930s and '40s (eg., the 79th Congress had bills proposing a Columbia Valley Authority, a Missouri Valley Authority, a Savannah Valley Authority, and an Ohio Valley Authority, plus some bills for more extensive systems), but none were ever founded due to opposition from conservative Congressional representations and a general feeling of getting away from New Deal programs. (There are some good articles on JSTOR if you have access).
Now, is there any way to cause some additional valley authorities to be formed? And which rivers are most likely to benefit (or suffer, depending on your point of view) from these authorities?