I don't see it the same way as you. The dams are in. The damage is done. There's no more damage being done by using the energy they produce. The same argument does not apply to the coal plant, tar sands or fracking. There's just no comparison. You don't see the difference?
I know you are a good guy. Just having a debate. Your point is reasonable, and I lived in the PNW for a long time, I have seen it before. Now, here is what I think. Just trying to point out the hole in the argument.
If you take the dams down, the wild fish come back, the ecosystem will quickly repair itself. The dams are still damaging everything around them, where do you think the wild salmon went? There is a trade off there, I think some dams should come down, but most should not. I accept your argument that most dams are for the common good. Your argument only works in that part of the world, and only if you can intellectually carve out that hydro power for yourself. Your neighbors are using power that isn't clean, but that is OK.
Now let's extend the argument you made - The day after a solar system is built, I guess we can all say that it polluted to make this, but hey that is in the past. Now I can use it and feel superior to people who haven't installed one yet? Take natural gas out of the ground by fracking, hey it is done, no harm no foul, that is in the past? I guess if everyone had access to green energy, that wrecked the environment in the past, your argument has merit? Until then, it just kind of stinks IMHO.
I have seen this kind of argument before, as you can tell, I think it is self serving. Unfortunately, we are all trapped here on this planet. You bought a Tesla, what do you think EM is spending his time doing? Building a cool car for you? I think he is trying to fundamentally save the world. I only ordered a MS after I read his Part 2 plan. Saving the planet and order a cool car, OK I'm in.
Now, if you live in the NW, or SW Canada, maybe solar isn't great there? But, if you can afford a $100k car, you can afford a $25k solar electric system in most of the country, or a windmill in windy places. You will make money over time, you will be benefiting the environment, and slowing down global warming. No, it will not be 100% good, it will be a trade off like a hydro dam is. But, the stupidest thing we can do is to keep burning fossil fuels, we know the result from that.
For half of the money the US spent invading Iraq ($3T), the US could have installed a $25k solar system on every home in the US. We can afford to do the right thing, we just choose not to.
Best wishes to all, and consider spending some money on green energy generation.