I can see a point to what you are saying. Dams can result in 1000s of deaths, but they already help millions to survive.

>>Are dams ever a good idea?

Yes, I guess, without dams the developed nations would not have been so developed either in terms of technology and even sociology. Without dams there won't be cities, without big cities there won't be mixing of different strata/groups of society.

So, when I think of dams I think of the immense value they provide to humans and their progress. It's difficult to get rid of dams. What we need is a lot better technology to ensure their reliability and robustness.

Another reason why we need dams more is: the sheer population increase is putting a hell lot of pressure on natural resources (including water, of course) these days as compared to 19th century. So we must address this issue also.

Also, the increasing consumerism should be restricted/reduced. The mindless consumerism is also adding to this pressure.

To take issue with your later points: a lot of resource pressure is due to humans being to stupid to not throw away their resources. Take California for instance. They have two really big environmental issues: drought and fires. LA purposely diverted rain water to the sea [1]. This meant they didn't resupply their ground water. Billions of gallons of water effectively lost over the years. The fires are due, in great part, to poor land management at a state and federal level [2]. Historically rational loggers cleaned out the forests. This prevented the type of fires we have now. It also prevented the landslides because the forest survived fires and kept the soil in place.

All this is not to say that we aren't putting pressure on the environment. It just goes to show that the pressure we're applying is a result of decades of arrogance and stupidity.

1 - https://www.marketplace.org/2016/01/08/world/down-drain 2 - http://www.thenewamerican.com/tech/environment/item/16396-bu...

I think it depends on the useful life of the dam, mainly determined by silting, which in turn depends on geology, soils, vegetation, gradients, erosion, rainfall patterns, hence suspended load in tributaries, and the possibilities for sluicing out the silt.

For example, the Three Gorges dam seems to have a problem with silt accumulation that could cause a dramatic reduction in reservoir water capacity. I suspect many such dams will end up as concrete carcasses at the head of muddy lagoons - maybe not so bad for wildlife in the long run.

It depends on your options and the impact of the dam. Historically speaking people were pretty hyped about them, but lately evidence shows they're far from environmentally friendly.

It's a lesser evil. Better a dam that, on catastrophic failure, will kill a few thousand people, or a nuclear reactor that will do that and irreparably pollute the earth for millions of years? (Sure, you can go solar, wind etc, but those are less efficient in terms of space required and on-demand reliability)

Besides, I know of several dams in Italy and only one failed with loss of life, afaik.