Dam removals are bringing fish back across the northeastern United States
smithsonianmag.com
smithsonianmag.com
I think it's a testament that human activity and nature don't have to be all or nothing, but we need to consider and mitigate the impact of our actions and always leave space for nature.
There is an aspect of property value as well - dams maintain a certain river level and removal may impact how nice people's river houses are. (Source: Dam near me partly removed, turned into a kayak course.)
It's absurdly funny/weird/scary
So basically all these 100-200yo dams are stuck in this limbo where doing anything with them is a non-starter until they're at the point the government decides they could fail any day now and starts pulling out stops.
The mean, median and modal dam being removed is a low head dam constructed in the early 20th century or before to create a mill pond for some factory. They are almost never federally regulated because they almost never meet the height/size requirements.
Amazing how people just believe assertions because they like them. Anyway, as I told him the typical dam we're talking about here is some mill pond dam that's too small to be federally regulated.
> Two, theres a lot more DuPonts "dying the river blue" than there are good samaritans building fish ladders
If you'd put down your ideology for a second you'd realize that there's more BigCos running through the approval processes to do their sketchy things because the process was built for them. The fish ladder people see the requirements (like non-starter remediation bonds) and realize it's not for them.
My understanding is that the first few victories on this were very very hard but it seems to have created a precedent and a growing example emulated across the country.
https://themainemonitor.org/dams-sale-salmon-return-kennebec...
1. Keep dam: -$2M to -$10M
2. Dam removal with 5 MW capacity replaced/absorbed by natural gas plants (no solar/wind/BESS): -$28.3M to -$249.8M, depending on whether you use the EPA's $190/tCO2 cost of damage or $1000/tCO2 DAC remediation.
3. Dam removal with 5 MW solar/wind/BESS replacement: -$3.5 to -$25M
In other words, removing the dam without equivalent solar/wind/BESS immediately in place is a net negative for society (and even then, keeping the dam might be neutral or still better).
You did not calculate the impact on the salmon population since dams were added to the Kennebec since 1837. Both the impact on the salmon themselves as well as all of the other animals and people who relied on that salmon fishery.
It's certainly a lot larger than the benefits of the dams in my calculation.
It's not that the cost never matters but I think if the cost is really just $25MM for a transformatively beneficial environmental impact that has equivalent no alternative, in exchange for scaling back a fungible resource, is a no-brainer.
Ok, I found a study estimating a net willingness to pay per citizen for this type of ecological restoration at ~$72.31/per person/year. If we assume 100,000 people derive this level of benefit over a 30-year time horizon (same as I used for the previous numbers) that yields $21,693,000 which brings the removal WITH immediate solar/wind/BESS replacement scenario on par or marginally better than keeping the dam as is.
But even then, I believe that is being overly generous to the dam removal because electricity demand has been rising steeply recently and is projected to continue doing so. Until we are meeting 100% of current and future demand with new renewable energy, every existing carbon-neutral source that gets removed is creating a gap in future demand that will be partially filled by new fossil fuel generation and therefore incurring many of the same associated negative societal costs.
You can't just leave them, they'll eventually fail and it costs way too much to bring them up to code and maintain them.
This is one of the very rare "everyone wins" stories. Environmentalists, cities, water districts and wildlife all come away better.
And a hat tip to all of the people who made the projects as successful as they have been in saving fish populations. IIRC, they ran into some surprises with volunteer fish which reduced the amount of hatchery fish they anticipated needing.
Install dedicated water tanks to store water, evaporation rates are much less.
Dams can make rivers more resilient.
Thaaaaaat said, moving from "slap up a damn somewhere" based stormwater management to local stormwater management is probably gonna go down in history as one of the biggest boondoggles in the history of environmentalism in the wet eastern half of the country (the desert west where aquifer replenishment is a concern is a different story)
In Washington State we have some of this happening too. A few years ago the long delayed projected to remove the damn on the Elwha on the Olympic Peninsula finally happened - https://en.wikipedia.org/wiki/Restoration_of_the_Elwha_River.
The biggest success so far was in the Klamath River watershed.
https://washingtonfishinghub.com/the-elwha-salmon-runs-recov...
https://www.elwha.org/wp-content/uploads/2026/01/Spatial-Spa...
> While annual estimates of the proportion of hatchery-origin natural spawners (pHOS) were initially 94-97% during and immediately following dam removal (2014-2019), pHOS declined to 82-85% during 2020-2024 (Weinheimer et al. 2022, WDFW unpublished).
And the absolute numbers are also not that great.
Elwha dam removal was a no-brainer as it was entirely useless. But it does cast doubt on the efficacy of larger dam removal projects, they are not necessarily going to result in automatic recovery.
WA is also spending about $10B on improving culverts on smaller streams. So far this hasn't resulted in meaningful effects on salmon runs. These moneys would be much better spent on other environmental projects.
Don't Tread on the Bear!
Also once it’s gone it can’t come back
Nothing will bring waters back to their pre-industrial state though.
'Removing barriers to salmon migration' became a huge deal about 20 years ago, with conservation bodies removing weirs. Yes weirs not dams. Old Mill weirs, for instance, that were there when salmon stocks were high.
A lot of money has been spent, especially in the River Wye, which wriggles between Wales and England. The salmon stocks have plummeted, and got worse since they started.
The thing is Salmon could jump weirs in a flood. That is their evolutionary advantage. They had access to tributaries that no other fish could get too. Now Salmon can get their, along with Barbel, who eat fish eggs... and are not native to the Wye. Just saying.
One 'expert' (at fundraising at least), said 'Salmon could only cross these barriers in high flows' which is fine, because Salmon only run the river at all at high flows.
Weirs also provided varied habitat, and more oxygenated water... that is now lost.
I went to a seminar lead by two of these groups. One gave a presentation about all the dead trees they had removed from the river to 'remove barriers'. The second speaker talked about the dead trees they put in the river to create fish nurseries. I seemed to be the only person that find this absurd.
Now the barrier removal people are claiming success. As in they successfully raised the money and removed the 'barrier', one presumes. Salmon stocks have got worse.
There is more, but that was sad enough on its own
https://publibrary.sec.usace.army.mil/api/download?id=52f6cb...
But oxygenation not really an advantage of low-head dams, when the dam is often contributing to the oxygen depletion in the first place. Free-flowing streams are typically adequately oxygenated.
I used to hate the "but what about historical site upstream?" argument often used against dams. The prioritisation of a few tombs and piles of stone over what would improve the lives of thousands to tens of millions living now. It's kinda ironic seeing the same asinine argument being used from the other side...
That said, reducing dams to just hydroelectric generation is probably going to skew the narrative to the wrong direction.
An example would be Lake Pillsbury in Northern California which the dam has not done hydroelectric for decades but the fight to prevent demolishing the dam has had plenty of local support.
What's more, the dam installation changed the local water table level, and residential wells drilled since the 1940's only had to go down so far. If the dam is removed, all these wells will dry up, and the state is beginning to make it difficult to drill new wells, and they certainly don't want to shell out to install plumbing to unincorporated communities which don't vote for the majority party anyway.
Another dam nearby held a massive amount of water for one of the bigger cities in the state. This is on the west coast, and if we get the Big One, it'll flood a populated area with hundreds of thousands of people. So they've had to draw down on the water levels and it's basically useless now, but deconstructing the dam would probably be a project requiring federal money, and since it's an earthen dam in a seismic zone there isn't really any retrofitting that you can do to fix it.
Basically, dams will give you some cheap electric and a water supply for a while but after 50-70 years they're a huge liability.
https://practical.engineering/blog/2019/3/16/drowning-machin...
That this hazard is tied to a structure with no utility is a specific scenario. But in another where the structure does serve a purpose then restricting one recreational activity in its vicinity may be an acceptable cost. Par exemple, would you be against fencing a substation or prohibiting kite/drone flying near high voltage lines?
That said, any structure spanning the width of a channel alters the flow in ways that are hazardous to swimmers and boats.
> In Plymouth, Massachusetts, a former dam has been converted to a bridge that lets fish pass unimpeded beneath it
They tried to make it look "natural" with the rock tiles but there's absolutely nothing natural about it.
A plain concrete bridge would have been less of an eyesore.
It's clearly being empathetic to the area's history, and it's taken from a vantage point that you won't often see anyway.
It's a bridge that looks like it's made from stone. It looks slightly different from other bridges. It's not bad. There are probably many eyesores in the surrounding towns that look much worse.
Removing these dams will exacerbate the crisis in baseload generation, and add hundreds of thousands of trucks a year to the Columbia gorge.
These dam removal projects are driven by anti-growth misanthropes who hate prosperity and aim to dismantle infrastructure.
For the fish!