Would it be possible to turn a dam into a bridge?
Alright, this is for a school project but it's also something I'm interested in personally, being able to write a ten page essay on it is just a bonus. Anyways, for this last trimester before summer, my writing class was assigned to write a ten page essay about the issue here in the Pacific Northwest of Dam removal for the sake of restoring the salmon population. It's been a big area of debate for decades now and I've been doing extensive research these last few weeks, trying to discern based on general principles which would be the most beneficial and cost-effective solution. I don't expect to figure out the answer since I am just a community college freshman, but all throughout my research I keep seeing all of these different solutions like fish ladders and hatcheries as a substitute for dam removal and not much evidence that they're very effective, but a lot of evidence to suggest that dam removal is extremely effective, but expensive and detrimental to local communities and ecosystems that depend on them for hydropower and transportation. But, the specific river that I'm looking at for dam removal (The lower Snake River) doesn't generate a lot of hydropower to begin with, it's mostly transportation that we would need it for.
Which got me thinking, would it be possible to turn these dams into bridges as a sort of compromise? The salmon urgently need action done in their favor to restore their numbers, but we can't afford to lose certain industries here because of that, so would this be a feasible compromise? If so, how come decades of scientists and politicians haven't discussed this yet?