Good for the fish but as winters get warmer these dams will be useful to store rain that doesn't stay put in the mountains as winter snow. This might mean more summer droughts. Also a nice clean source of power. I would rather see fish ladders.
Install dedicated water tanks to store water, evaporation rates are much less.
Dams can make rivers more resilient.
Thaaaaaat said, moving from "slap up a damn somewhere" based stormwater management to local stormwater management is probably gonna go down in history as one of the biggest boondoggles in the history of environmentalism in the wet eastern half of the country (the desert west where aquifer replenishment is a concern is a different story)