Many of the problems the operation was intended to solve and or alleviate. Have been bypassed or rendered non-factors with other technological advances.

There might be knock on effects of fueling development in the Great Plains. With the proposed Canals/Rivers.

But development along Riverbanks in the central and Eastern U.S has been heavy in the ensuing Decades. So you’d need to clear a lot of territory. To account for the increased width of the Rivers.