Why? Don’t make no sense to me.
Dams kill salmon. Enviro-wackos never make sense ... don’t even try. Their basic goal is to return most of the US to the 14th Century, except for enclaves (Argos) which would house all the people, the countryside only available by special permit, unless one belonged to the privileged elite on their vast estates (see Ted Turner’s holdings - measured in 10s of square miles).
Most of the largest hydo-dams are on the Columbia River. The river used to be the spawning grounds of the largest Sockeye salmon run in the world, followed by Bristol Bay, Alaska, and in third place the Frazier River, Vancouver Canada. I don’t recall the numbers accurately any longer by I believe the Colombia run average was around 52 million, Bristol Bay around 35 million, and Frazier was 16 million Sockeye returning each year. There are, of course, other salmon species in each of the rivers: king(Chinook), sliver (Coho), pink (Humpie), and chum (Keta/Dog).
In the 30’s under FDR (D), it was decided to dam the Columbia to generate power for the west coast. Commercial fishermen protested saying that the salmon would be killed. “Nonsense,” said the Feds. And proceeded to build the dams killing the fish - the adults could no longer go up river to spawn, and the juveniles coming down were ground up in the turbines. And so a major US food source was destroyed - perhaps akin to the use of corn to make fuel.
Various experiments have been tried since with mixed results, but the river remains mostly barren.
Now the wackos want to tear the dams down. However, over the decades silt has built up behind the dams and, once breached, all that silt will come down river, burring the salmon spawning grounds under 10s of feet of silt. Not only would most of the northwest coast be without a major source of power for years, but it would be decades before the river cleared enough to have any fish in it.
Boeing would be forced to leave Seattle, dealing another major blow to Washington’s economy. The silicon people like M$ would be limited to times when there was enough power to work. They would eventually leave also. Both the Timber and Commercial fishing industries (having already suffered the Enviro predation are mere shadows of what they once were) would be unable to continue.
California would be without backup power and feel the effects with higher electrical rates ... and so on.