Removing old, obsolete dams restores life to creeks and streams | Hacker News Reader

Removing old, obsolete dams restores life to creeks and streams

riverkeeper.org

130 pointsfludlight37 comments

If anyone's interested in rivers and dams, and some of history and influence they've had on the formation of the US (and vice versa), there's a great book called The Source: How Rivers Made America and America Remade Its Rivers. Not affiliated with the author in any way, but I picked it off a shelf last year and found it a really good read.

This kind of thing brings up a bit of mixed feelings for me. On one hand, it's indisputable that damming rivers has a negative impact on the ecology of those watersheds. On the other hand, in an era of climate change, it seems like trying to hold on to as much freshwater capacity as possible also seems like a prudent idea, and I'm not sure what the best way to reconcile the two would be.

We do have the same issue here in Europe, albeit at a smaller scale. If the old dams can be re-purposed and brought back to use, then that would be a nice compromise.

Some old dams and sluices are beyond repair, though. In those cases it's better to just restore the rivers as far as possible.

That's a fair point. In North America, one of the other things that we should probably consider is the American beaver, which can help with this sort of thing naturally, if they're allowed to. Their activity needs a little management to prevent them from disrupting existing settlements, but compared to effect they had before trappers started in on them, it seems like there's might be some room for a natural solution that checks both boxes to a degree.

Edit: Just kidding, I hadn't realized that the Eurasian beaver had been reintroduced to so much of its original range. Looks like it's not just something for North America.

Yeah, and here in Finland we have North American Beavers too, since someone decided to introduce them in the 30's. They have a somewhat devastating effect on the local forests...

There is a saying in Russian “To kill the beaver, to save the tree”.

In Canada the saying is "save a tree, eat a beaver". I'm not sure if it translates the same way, though.

>On the other hand, in an era of climate change, it seems like trying to hold on to as much freshwater capacity as possible also seems like a prudent idea, and I'm not sure what the best way to reconcile the two would be.

Climate change doesn't mean warmer temperatures everywhere or a dearth of freshwater. The Hudson Valley area referred to here has plenty of fresh water, is projected to become wetter according to most climate change models, and has become wetter recently (significantly so the last few years).

http://www.cnyweather.com/wxrainsummary.php

For regions that rely on snow accumulation on mountains in winter and melting into rivers during other seasons, they could be screwed. And plenty of regions heavily depend on that process.

You're right, and if I came across implying that was the case for this particular dam removal, I apologize for the miscommunication. On the other hand, the rate of dam removal in the United States has increased, and some of them (especially in the Western US) are in areas that don't experience the same frequency of rainfall, and where even existing reservoirs are often far below capacity. It was more of a general musing that a comment on this particular instance, which from the information in the article, seems like a positive step.

I forget the exact numbers, but something like 60% of California's freshwater supply is stored in the Sierra snowpack, and the current models are projecting that California will get more rain overall but vanishingly little snow.

California politically tends to be completely opposed to building new reservoirs, and a large amount of seasonal northern California rainfall ultimately gets routed out to the San Francisco Bay through storm drainage.

The other barrel of this particular footgun is that agriculture is still California's biggest industry and they require an absolutely enormous amount of water. This is already causing strain on state politics, because the central valley keeps demanding more water from northern California, which doesn't want to give up more of it, and southern California has just about drained the Colorado river, and restrictions on water rights are the single biggest driving force behind all the "State of Jefferson" signs you see in the rural northern counties.

I love California but the water situation is about to bite them really hard. "About to", of course, still being a decade or two out, but there don't seem to be any reasonable solutions to this intractable situation on the horizon.

California could trivially afford to just buy out the alfalfa farmers, paying them actually a slight premium compared to the revenue from their alfalfa farming.

That alone would fix most of California's water problem.

That's not to mention using hydroelectric reservoirs from dams to store energy, which is absolutely fundamental in the mainstream "100% renewable" plans you may have heard of. For example, a lot of Green New Deal stuff largely draws from Mark Jacobsen (the Stanford prof who sued the scientists who published a critique of his plan in 2017). His plan depends on increasing hydroelectric capacity by something like 10x in the USA (albeit, he claims, just by adding turbines to existing dams, though that may be a challenge).

It's really not though, renewables have already surpassed coal in the USA for the first time while hyrdo is treading water. The change already happened and all the concerns about peak load capacity and storage were largely mythical. Coal plants are racing to shut themselves down, the miners are all filing for bankruptcy.

We didn't need to build dozens of new fission plants either. Another myth from the think tanks.

> The change already happened and all the concerns about peak load capacity and storage were largely mythical

Do you have a link to more on this? The story I recall was that we can't go fully renewable precisely because of storage issues.

If by surpassed you mean cheaper than building new coal, or even operating smaller coal plants, then yes. Coal generation is still 2.5x wind+solar [1]. Claiming that the intermittent nature of wind and solar is a non issue is a joke. The system can absorb small amounts of intermittent power, but the problem gets progressively worse as the percentage share of the total goes up. We do need, modern, cost effective nuclear, and pumped hydro, and large improvements in grid scale battery storage as well as more long distance transmission to even out the supply.

[https://www.eia.gov/tools/faqs/faq.php?id=427&t=3]

I guess if you want to only look back at 2019 data you will miss the fact that renewables passed coal this year. The rate at which the coal industry is dying is remarkable and is well covered in the media.

The reason we haven't seen the intermittency issue too much is almost entirely because we are building cheap but very high carbon (~400 gCO2-eq/kWh) fracked natural gas plants. This is not a good or scalable low-carbon pathway.

Lots of things are celebrated in the media that are not quite true. While in some areas, on some days, renewables are outpacing polluters, their power peaks and wanes at different rates than demand. Coal is still the baseload energy generator, and will be required until massive energy storage is achieved, or we build more fusion/fission plants. With the exception of hydro, most 'renewable' generation stratigies come with temporal issues (wind, sun, tide, etc).

But nobody wants to think about the fact their teslas are runnig on coal, and we assume some random article we saw on renewables outpacing coal are the truth. It is not.

> The change already happened and all the concerns about peak load capacity and storage were largely mythical.

No they're not. At ~8% I don't see how you can conclude this yet. In the US coal plants were just replaced with natural gas plants. Still a carbon source of power. And these natural gas plants became such a rage in part because of a boom in cheap natural gas. That cheap natural gas boom was provided as a by product of the massive shale oil extraction boom. Which itself was a product of massive amounts of cheap credit that fueled what's probably the largest debt bubble in history, which is currently bursting and taking down a lot of those shale oil companies with it.

With a lot of wells being shut in due to lower oil prices making them uneconomical, we'll have to watch and see what happens to the gas prices. We have just spent half a generation switching from one CO2 polluting source to another, which when all inputs are properly considered is probably just about as polluting. And we did so by wasting a generation of capital. It's been a historical misallocation of capital and it's been entirely green washed.

A friends works as an ecologist and are a scientist at a university. Water Dams disrupt/destroy eco systems downstream. Hydro power is thus not fully green due to that. Water power has to be compared to The alternatives such as oil/coal. One should not view water power as fully “green” energy.

Fish species are for example disrupted by water dams.

I understand the link posted here is specifically about dams on the Hudson. I question in general whether one can really say that all dams are such net negatives for ecosystems. Would we not be able to get hydroelectricity from a beaver style dam? and are those dams not generally seen as helpful to promote certain often very beneficial ecosystems?

Also, in some sense, wind and solar power aren't fully "green" energy because they require giant turbines and solar cells that require a lot of polluting to make, maintain, and eventually dispose of. We still, of course, seem to consider them to be green and beneficial, I assume because someone has done the calculus to see that the costs of their pollution is less than the benefit of their use. I'm willing to bet that many dams are similar.

We can get electricity from any kind of dam except one that blocks all water forever. We get electricity when water flows through, see?

The best kind of dam from the point of view of the power utility is one that allows the water flow to scale freely from zero to overwhelming to match electricity demand, and never allows water to bypass the turbines. But that's an extreme, not the only kind that makes financial sense. If you both reduce the time flexibility and also allow some water to bypass the turbines, you can usually get most of the power at a small environmental cost... usually, not always.

This https://www.outsideonline.com/2413366/steelhead-fish-return-... was posted yesterday about dam removals in the Pacific Northwest, and the subsequent return of steelhead trout to the rivers.

I’ve worked on about 30 different run of river hydro electric projects over the last 15 years. Yes there is some environmental impact but the ones I have worked on have had a team of biologists and years of environmental studies and they would never result in a dead fish any more often that the river would have naturally by itself. If any habitat is destroyed they have to create new habitat such as spawning channels. They probably spend 10%-20% of the entire budget on environmental. These run of river plants don’t flood more than 1000m^2 area, use a weir instead of a dam, leave water in all sections of the river channel, and don’t cause unnatural changes in the river level at a rate greater than 1” per hour which is a very conservative rate compared to what the rivers of this size and nature naturally do by themselves when it rains or melts.

I know you said Dams and not weirs and not run of river plants, and big dams have their issues, but not on the same scale as the oil industry.

I have studies hydropower effects at my university programme, and a vocational aquaculture program, and as you say, there are definitely ways to lower the impact. In Sweden, all the major rivers except for two have large scale dams installed. Most of that was built between 1900 and 1950 and not much after 1970. Not much consideration for biodiversity or environmental impact was taken into account. At some point hydropower supplied 95% of Swedish electricity. Important during the country’s industrialisation.

There is a nice reference list, including many English language reports at the end of this report from the Swedish Agency of Marine and Water Management. [1]

I think they summarise it nicely by saying “Hydropower is one of the biggest impacts on the ecological status of a river. At the same time it is one of our most important energy sources.” [in Sweden]

Sources:

[1] https://www.havochvatten.se/hav/uppdrag--kontakt/publikation...

https://sv.m.wikipedia.org/wiki/Vattenkraft_i_Sverige

I'm curious how well this applies to the short-term effects of filling the Grand Ethiopian Renaissance Dam? [1]

As I understand it a lot of the downstream ecological effects rely entirely on the fill rate the Ethiopians choose (3 years, 5 years, 10 years, 15 years, etc). A fast fill rate (5 years or less) could have significant short to medium term effects on the arable land downstream in Sudan and especially Egypt.

The dam is oversized for its power output (to ensure it can meet peak output demands during the wet seasons) and will operate as a fish trap, cutting the number of fish able to head downstream (and ultimately to the sea / mouth of the Nile) by a significant amount.

[1] https://en.wikipedia.org/wiki/Grand_Ethiopian_Renaissance_Da...

Large dams are a different ball game than the small run of river plants I have worked on and the ones discussed in the article.

Even at large dams it is possible to build fish ladders to allow migration.

When we were filling our head ponds (reservoir) we weren’t allowed to impound more than 10% of the total flow in the river.

There is no fully "green" power, but almost everything is better than climate change.

I think "green" is not the right moniker here; "renewable" covers it better I think. With (with my limited knowledge, naive opinion) solar panels and wind farms having less of an impact than hydro dams.

Judging only on 'renewable' the ecological impact of a hydro-electric dam doesn't matter. The energy extracted here is renewable. Because rain will keep falling and thus the reservoir will keep being filled.

The fact that it damages an ecosystem does not count there. Moreover, the fact that dams damage an ecosystem have very little bearing on the global-warming effects of dams.

Whilst I do not want to say that ecological damage is not important, I think it is an issue that 'green' and 'ecological' have dual meanings. The current main usage being "Does not cause greenhouse gasses" with a less used original meaning of "Is good for the environment". This causes a lot of friction between people who use the same words but care differently about environmental impact beyond global warming.

It used to be that caring about the environment was a fringe movement in so far as getting political change. Global warming has gotten 'being green' on the political agenda. But it sometimes feels like some of the more extremist green ideas have snuck into the greater public discourse under the guise of being 'green'.

Many dams are going to exist due to flooding, irrigation, etc. Extracting hydropower once you have already decided to build a dam is as close to fully green as it gets.

That said, there are many low head dams built exclusively to extract power, and many of those are no longer serving a useful purpose.

The standard term is “renewable”, and yes, there are environmental concerns for any type of human-engineered energy production.

For run-of-river hydro power, one mitigation is fish ladders:

https://en.wikipedia.org/wiki/Fish_ladder

I wish people would distinguishing destroying eco systems from changing them.

A dam changes the eco system, but nature forms a new balance around the new geographical feature that is not inherently worse, just different.

Sometimes there are positive unintended effects. Near my city, there are a number of small hydro plants and dams, built before a grand national syncrhonized system was ready.

While the dams were built inside very preserved forests, so there was initial damage, the surrounding area (tens or hundreds of sq. km) were put under protection to guarantee the water supply, so no reforestation, no agriculture, etc. Now even the surrounding areas are in better shape today than in the 1960s when the dams were built.

Of course it helps the individual size of each plant is small (tens of MW, tops).

See als https://en.wikipedia.org/wiki/Fish_ladder and similar initiatives to allow migratory species to pass dams.

Humans are putting ongoing pressure to all environments.

We need to stop with the bringing it back to how they were BS. It can't happen.

Environments need energy and water to thrive amoungst other things.

It's hard to see dams being bad overall. Yes it might harm certain things. But we need to start looking the bigger picture. Not little factoids like bringing back wolves.

I find India's push on johads perhaps a little off topic but perhaps not. Be need to start keeping fresh water on or in the land.

http://www.ecotippingpoints.org/our-stories/indepth/india-ra...

I'm saying this in a polite tone.

But sorry. Anybody that equals key species with "little factoids" don't understand a single thing about ecosystems. Would be like saying that the motor of a car is an optional part of the car.

Wolves are boosters of biodiversity and change all around them.

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