Eco minded 'dopers...Dam-Nation (debate about dams in the US)

Great Debates
1

So, mild spoiler alert…I’ll be making references to a show on NatGeo tonight called Dam-Nation. The show was about dams in the US. It was pretty interesting. My main issue with it is that it was pretty one sided, so thought I’d come here to see if there is a debate here…and maybe get some insights into this that I don’t currently have.

The show revolved around the supposedly sordid history of dams in the US. The main theme of most of the show is that rivers should be free, that to have a healthy ecology you need to allow the rivers to flow, and that dams are bad. There were some with a more nuanced view on this, but the main theme was praising people who want to bring the dams down by any means or put graffiti on the dams to demonstrate they want them down. They gave a number of examples of how dams have been decommissioned and brought down and how that’s helped a lot. I get that, and it seems a good use of resources to me to bring down obsolete dams that have pretty obviously outlived their usefulness and in some cases are doing quite a bit of harm. I also get that many dams built in the 19th and 20th century in the US disregarded the importance of the ecological impact, disregarded the native peoples and, to me importantly, disregarded other industries such as fisheries in favor of power generation, water retention, flood control and such. I’m totally good with bringing down dams that would restore a balance, especially to dams that we don’t even use anymore. According to the show there are over 50k dams over 3 feet in heights in the US…which is a huge amount.

However, I’m not sure that ALL dams really should be brought down. To me, there has to be some sort of cost to benefits analysis…not all dams are worthless, not all serve no purpose, and even if there are negatives to some dams if the positives outweigh those negatives I’m not sure why we’d bring them down. But I have to admit that, outside of looking at the figures of US hydro-electric generation wrt our overall mix occasionally, I haven’t really ever thought much about them one way or the other. I’ve been to and seen the Hoover Dam many times, and been on Lake Mead, I’ve even been to the dam at Bryce Canyon, which were dams they talked about in the show.

So, figured I’d come here to see what folks think of this idea of getting rid of some, most, all dams and returning them to their natural states, or at least to something like their natural state. Also, thoughts on dams in general, on the fact that the US isn’t really building them anymore, and perhaps on other countries that are building them today (China springs to mind, but India is also building them, as are many other countries) and perhaps the cost to benefit of building a dam instead of, say, a coal fired power plant.

2

Ever see a river in flash-flood?

Dams are a civilized amenity, like freeways and bridges. They make nature a little nicer to live next to.

The compromise is, when weather permits, to release water from dams to “freshen up” their rivers. That re-defines channels, washes away accumulated silt, and is good for plant and animal life.

Taking the dams down entirely would result in a loss of life and property, and would not be democratically popular. It would also imperil drinking-water supplies, and we’d lose a lot of hydroelectric power too.

3

AFAIK I can see the concern, but there is one item that I recently found that keeps things in perspective:

Looking around one interesting bit is that this issue of methane production is less of an issue in higher latitudes, but the closest a dam is in the tropics then the methane released becomes more of an issue, still one should point also that this also takes place naturally in lakes over the world, point being that while this is an issue, it is one that nature could take care of as it has been for millions of years; but the big problem now are other sources of CO2 and methane that are man-made and increasing, they are still a bigger issue. The point here is that IMHO this item of methane from dams would not be an issue if not for humans breaking the budget of how much carbon we could release safely into the atmosphere.

One reason why I think like this is because IIRC most of the increase of CO2 observed in the atmosphere (and methane turns into CO2 too) was found to come from fossil fuel sources, this is because of the differences in isotopes in the carbon detected in the atmosphere. If most of the increase in CO2 had come from lakes (and dams) the carbon detected in the increase would not had been of the fossil fuel kind.

4

Leave it to beavers.

5

From a sustainability standpoint, dams and big hydroelectric projects are amazing. One of the best power generation systems we have.

From a conservation standpoint, they’re a problem. People and wildlife flooded out of their homes, & fish migration impeded. They’re not for everywhere.

That’s the story. The details may get annoying, but that’s the story.

6

Many years ago I heard the expression:

The US Army Corps of Engineers never met a stream it didn’t want to pave

And ‘wetlands’ and ‘marshes’ were ‘swamps’ and must be filled in before it can be used for anything.

See a map of San Francisco.
Battery Street was the original coastal road along the bay.
The original Mission Street was a plank road (toll).

That is an extreme case, but it does demonstrate the mindset.
There are a hell of a lot of dams and paved waterways which do little good even for humans, but kill all wildlife

7

In addition to the Engineers, the Bureau of Reclamation considered water that ran freely to the sea as wasted water.

The book Cadillac Desert is an interesting read on the subject of dams (and related water issues).

8

Well, there is the Elwah River test case in western Washington State.