Across the United States, dams generate hydroelectric power, store water for drinking and irrigation, control flooding and create recreational opportunities such as slack-water boating and waterskiing.
But dams can also threaten public safety, especially if they are old or poorly maintained. On May 21, 2020, residents of Midland, Michigan were hastily evacuated when two aging hydropower dams on the Tittabawassee River failed, flooding the town.
I’m an ecosystem scientist and have studied the ecology of salmon streams in the Pacific Northwest, where dams and historical over-harvest have drastically reduced wild populations of these iconic fish. Now I’m monitoring how river herring are responding to the removal of two derelict dams on the Shawsheen River in Andover, Massachusetts.
There’s growing support across the U.S. for removing old and degraded dams, for both ecological and safety reasons. Every case is unique and requires detailed analysis to assess whether a dam’s costs outweigh its benefits. But when that case can be made, dam removals can produce exciting results.
Pros and cons of dams
It’s relatively easy to quantify the benefits that dams provide. They can be measured in kilowatt-hours of electricity generation, or acre-feet of water delivered to farms, or the value of property that the dams shield from floods.
Some dam costs also are obvious, such as construction, operation and maintenance. They also include the value of flooded land behind the dam and payments to relocate people from those areas. Sometimes dam owners are required to build and operate fish hatcheries to compensate when local species will lose habitat.
Other costs aren’t borne by dam owners or operators, and some have not historically been recognized. As a result, many were not factored into past decisions to dam free-flowing rivers.
Research shows that dams impede transport of sediment to the oceans, which worsens coastal erosion. They also release methane, a potent greenhouse gas, as drowned vegetation beneath dam reservoirs decomposes.
One of dams’ greatest costs has been massive reductions in numbers and diversity of migratory fish that move up and down rivers, or between rivers and the ocean. Dams have driven some populations to extinction, such as the iconic Baiji, or Yangtze River dolphin, and the once economically important Atlantic salmon on most of the U.S. east coast.
Old dams under stress
As dams age, maintenance costs rise. The average age of U.S. dams is 56 years, and seven in 10 will be over 50 by 2025. The American Society of Civil Engineers classifies 14% of the nation’s 15,500 high hazard potential dams – those whose failure would cause loss of human life and significant property destruction – as deficient in their maintenance status, requiring a total investment of US$45 billion to repair.
Like the failed Michigan dams, which were built in 1924, older dams may pose growing risks. Downstream communities can grow beyond thresholds that determined the dams’ original safety standards. And climate change is increasing the size and frequency of floods in many parts of the U.S.
These factors converged in 2017, when intense rainfall stressed the Oroville Dam in Northern California, the nation’s tallest dam. Although the main dam held, two of its emergency spillways – structures designed to release excess water – failed, triggering evacuations of nearly 200,000 people.
Benefits from free-flowing rivers
As dam owners and regulators increasingly recognize the downsides of dams and deferred maintenance costs mount, some communities have opted to dismantle dams with greater costs than benefits.
The first such project in the U.S. was the Edwards Dam on the Kennebec River in Augusta, Maine. In the mid-1990s when the dam was up for relicensing, opponents provided evidence that building a fish ladder – a step required by law to help migratory fish get past the dam – exceeded the value of the electricity that the dam produced. Federal regulators denied the license and ordered the dam removed.
Since then, the river’s river herring population has grown from less than 100,000 fish to more than 5,000,000, and the fish have drawn ospreys and bald eagles to the river. This project’s success catalyzed support for removing more than 1,000 other dams.
I’ve been studying one such project – removal of the derelict Balmoral and Marland Place dams on the Shawsheen River in Andover, Massachusetts. The owner of the Marland Place dam, originally built in the 18th century to power a mill, faced a $200,000 bill to restore it to safe condition. The Balmoral, an ornamental dam built in the 1920s, had changed hands so many times that the latest owner – a company in another state – wasn’t even aware that it owned a century-old dam in Massachusetts.
The project was a broad team effort. State environmental officials wanted to help restore the river’s health. Federal regulators supported removing the dams to open up historical habitat to migratory fish such as river herring, American shad and American eels. And Andover leaders wanted to improve recreation on the river.
Dam removals require extensive permitting and a lot of negotiation. For the Shawsheen project, experts from the nonprofit Center for Ecosystem Restoration in Rhode Island guided the many organizations involved through the process.
My role was organizing a volunteer effort to monitor the response of river herring that migrate from the ocean to spawn in freshwater systems. The fish didn’t disappoint. Although the first spawning season was less than three months after the dams were removed, data collected by local volunteer monitors – who number over 300 – indicated that the newly opened habitat had hosted approximately 1,500 river herring spawners for the first time in more than 100 years. Since then, numbers have fluctuated, following the pattern on the Merrimack River, into which the Shawsheen flows.
Like salmon, river herring mostly spawn where they hatched. During the previous three years of monitoring, spawners in the Shawsheen were all strays from elsewhere in the system. But this year we expected to see a large number of newly matured adults from our first year of monitoring. Our work is on hold during the COVID-19 pandemic, but we look forward to measuring increased numbers in the spring of 2021.
Still growing
In April 2020, California’s State Water Resources Control Board approved two key permits for removing four large aging hydropower dams on the Klamath River in California and southern Oregon. This would be the largest dam removal in the U.S.
The board acted based on evidence that dam removal would improve drinking water quality by reducing algal blooms, and would restore habitat for endangered salmon and other organisms that rely on free-flowing rivers. The project still needs approval from the Federal Energy Regulatory Commission. Assuming it goes forward, I expect that a restored Klamath River will further fuel the movement to remove dams whose costs now clearly outweigh their benefits.
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Jon Honea, Assistant Professor of Science, Emerson College
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Mixed bag in this report. The dams in the Pacific Northwest all have either fish-ladder by-passes or hatchery offsets, so their impact of salmon and steelhead numbers were minimal. The reduction of salmon and steelhead in the Pacific Northwest was due to the signing of the Marine Mammal Protection Act of 1972, wherein sea lions were allowed to flourish and eat all of these fish they wanted, even swimming a hundred miles up rivers to chase them. The waters directly below dams with hydroelectric turbines are commonly home to very large sturgeon, which eat the fish chopped up by the turbines.
Yes, a mixed bag. But full of half truths. For instance “building a fish ladder…..exceeded the value of the electricity that the dam produced”, is ridiculous. The fish ladder is a one time cost. The electricity value is over a very long time.
Also, “Like salmon, river herring mostly spawn where they hatched”. Yes, so build some hatcheries. On Vancouver Island a few years ago, we visited a salmon/trout hatchery. Fascinating. It’s on a stream connected to the Pacific. Each year the fish that were previously hatched there come back. They’re captured and killed (gonna die anyway) and their eggs and sperm are harvested for test tube” fertilization. Much greater than 50% success as opposed to 10% or so in the wild. They’re reared in tanks, and when mature enough, released to go back to the ocean. They’re still wild salmon. As natural as if, nature alone, had been involved.
This is exactly why Alaska has such an abundant Salmon fishery, and British Columbia in general doesn’t, and they blame it on climate change. When in reality, it is overfishing, including some of the indigenous catch like the Stolo tribes who can legally drift net across the entire Fraser River that wipe out the returning spawners to creeks and rivers up stream 300-400 miles where they spawn. Sure they do some closures, but a lot of fishing still takes place illegally during spawning season when the Salmon all return to make that final swim up stream.
They built a lot of similar hatcheries in Alaska as you explained similar to Vancouver Island, and the fish return to the hatchery where they are commercially fished at the mouth of the river and milked for the next years hatchlings and rearing. And done privately whereas DFO in Canada ran a bunch of inland satellite hatcheries up river 300-400 miles, and collected eggs/milt from all the creeks in a 200 mile radius where they were raised in well water in a satellite hatchery, and then released back to the original stream their eggs were originally taken from. Because it was Gov’t run, it turned into a failure trying to supply hatched wild yearlings up river hundreds of miles. It should have been privatized with a licence for a catch, and built upriver from the ocean a few miles on a salmon bearing river using the fresh river water. Would have been a success like Alaska, and still could be, but the red tape and regulations in BC are now so thick and ethnic based, why bother.
The artificial spawning is a good means of maintaining stocks but it eliminates a very harsh natural selection process of the upstream battle and competition of males whose jaws undergo quite dramatic change at the period.
Removing natural selection is probably not a good long term strategy for the species involved.
There is still a resident population upstream in the River past the hatchery that those wild spawning fish still make it to, to spawn again naturally. Or some of those upstream fish are caught and milked, raised in the hatchery and then they release those fish back in that same river upstream where they were originally caught, which is where they are imprinted to return to as it is still the same river water. Some of that school are caught as bycatch in the fishery at the mouth of the river, but enough swim right by the hatchery and continue upstream for as long as the river/creek flows, and they spawn and rear naturally for a year in the creeks and rivers before heading back down to the ocean just as it was pre-hatchery. They can actually do an electronic count, since the hatchery fish get tagged that respond to a type of fish ‘radar’ detection when they swim up to or past the hatchery.
The hatchery raised fish take the pressure off these ‘natural’ spawners, so the local river upstream maintains a biological intact resident fishery. This appears a win-win for everyone, including the bears, wolves and forest/trees that rely on Salmon for widespread nutrition. This hybrid hatchery system, run privately by fisherman or by tribal peoples seems to be the best of both worlds for increasing the fishery, the catch, and preserving the natural river and creek ecosystem.
Maintaining upper watershed water flows is another issue, but can also be managed with small storage weirs on the outlet of small lakes upstream, some just made out of piled up rocks in a V-Notch config that pool the water in a larger lake that leaks out water through the notch that the fish also swim through in low water season and provide water flows in the summer/fall spawning season. Alaska does this quite well, and it is all considered a natural wild fishery. The hatchery fish might lose some natural selection, but of course they are the commercial catch, so it doesn’t matter as the original watershed still has its natural fishery intact upstream. The hatchery just provides the yearlings to the big Ocean where they raise themselves in the wild as they are wild Salmon from that river watershed. The hatchery basically has a small fish processing plant to commercially process the caught adults for fresh wild Salmon and how they fund themselves and make a profit. Fisheries like this, if properly managed, can work well. Just can’t get greedy and take all the fish for the commercial fishery, as many of these fish are still caught in the wide open ocean outside of national boundaries that other nations are fishing on the high seas.
Fish ladders do work reasonably well. But most of the mortality increase caused by dams is to the fingerlings trying to make their way back to the sea. Instead of being carried by the current they have to swim their way across large lakes filled with trout that grow bigger in the lakes than they did in the flowing river. And of course avoid the generators.
Flushing smolts down the Columbia in spring floods used to take a couple days. Now it takes weeks to navigate down the series of “lakes”.
The Oroville dam was never in danger of collapsing, much less “catastrophically”.
Bingo!! Just neglect from the ones who were supposed to be “managing” it.
I found this caption under the PBS video insert interesting
Huge Rains CAUSED BY early Snow Melt…
Now how does Snow Melt cause Rain exactly?
Yes, they probably were trying to refer to the influx of water into the reservoir, caused by melting snow, but did have so little understanding they confused it with captured rainfall which feeds many dams. Since Ass. Prof. Honea was the author, I guess he has to be responsible for the blunder.
What kind of a job title is that ?! All “science” , any science, or sciency science. Another BS liberal professorship IMO.
What are you basing that assertion on?
I remember following that event here on WUWT. The concrete cladding on the spillway was breaking up and erosion leading to a major breach was a very real possibility. They did not evacuate down stream communities for nothing.
Everyone was holding the breath for about a week and it was only saved by easing meteorological conditions.
Being a skeptic does not mean mindlessly refuting everything you read without any justification.
Don’t forget that it was known for many years that the spillway was deteriorating … Federal money for dam repairs was diverted to blue districts with lesser needs for the benefit of those who voted for the government in Sacramento …
The dam is separated from the spillway by a ridge of rock. The spillway itself sits on rock.
Politicians over reacting is only evidence of the stupidity of politicians.
Falling rain does increase the rate of snow melt.
“Huge rains caused by early snowmelt led to erosion and risk of a catastrophic failure at California’s Oroville Dam”
Which is almost half the truth. Yes they caused the failure, but that is what the dam was built to do. The state and feds had been warned for years that the damn was failing. The local government had expressed concerns.
MarkW I recommend you educate yourself into the enormous benefit and potential of well built hydropower AND the major catastrophic dangers of poorly managed dams. See:
Will the Oroville Dam survive the ARkStorm?
The next one in 1000 year ArKStorm will likely cause more damage and loss in California than the next “Big One” earthquake.
There were major dangers of catastrophic failure with the Oroville Dam
Remember China’s Banqiao Dam failure.
Let me get this right…increasing climate change is causing more and bigger floods…so we must get rid of dams that have importance for human environments to entice fish to breed?? Dams that are over a 100 years old still have remnant vegitation still rotting and emitting methane? Would it not be logical to build a bigger dam if there are more and bigger floods just for mitigation alone? California, the driest state, can make an argument to remove a dam? Must be something in the water!
The CA Loonies are in charge of the asylum
This is just one half of “some regions will get more flooding , some regions will get more drought” mantra which basically means climate will continue to vary as it always did. That kind of non statement will be true whatever the cause of any future warming and whether the world warms or cools.
Climate is not constant : SHOCK, HORROR.
The underlying mentality here seems to be that we must return the planet to the pristine natural paradise that is was because before humans existed.
Extermination of the “human cancer” being entlicher lösung of the eco-fascists.
Dams recharge aquifers, prevent massive flooding in flood plains, etc. The Russian River (Slavianka) flooded communities on its banks on a regular basis, until the Mendocino dam was built.
Damn those damned dams. Damn them.
Most of these dams were built to generate electricity, protect against floods, and provide water for irrigation. Next time one of the rivers were the dams have been removed floods, it will be interesting to see whether the public continues to support dam removal. As someone who owns property in the Traverse City, Michigan area, I get nervous in the spring when snow is melting and we get heavy rain now that the dam on on the Boardman river that protected the city has been removed. On the other hand, as a fisherman I hope you right about the restoration of fisheries.
A much bigger problem results from the additional pavement in the U.S. 31 corridor through Garfield Township, (GT Mall, Meijer, etc., etc.). Last week the lower section of Kid’s Creek was out of it’s banks from 11th street down to the Front Street fire station., that’s a lot water going into a lot of basements.
Don’t most dams create reservoirs that people enjoy? Many large rivers aren’t even obstruction-free for boat traffic without dams. Note that the only advantages of dam removal are mental, environ mental. Weird how wind turbines killing many different species of birds and bats completely falls on death ears. At least dams offer the opportunity of fish ladder or fish hatcheries. Those are always fun tourist spots.
It’s true, when I grew up in Yorkshire, some of the most beautiful parts of the Yorkshire Dales were the artificial lakes known as reservoirs. They were, and I assume still are the areas that attract the most abundant and diverse bird life, etc.
The only reason dams will fail is if authorities fail to adhere to proper monitoring and maintenance plans for such dams, and if water levels are allowed to exceed the engineering limitations, as happened in Queensland in Australia, resulting in the urgent need to release enormous amounts of water that caused severe flooding.
Libs are trying really hard to reduce acceptable energy choices to only solar or wind. It won’t work without billions dying.
“It won’t work without billions dying.”
Billions dying is part of the plan.
It’s what they invested in. They picked those two and they’ll do anything to try to make their poor investment choices work. I can’t believe that our elected officials are so stupid to continue this handout.
One thing is certain from this, is that you don’t want to be the one (or community) holding the water licence for one of these dams, especially if it privately owned and is an old earth filled dam built a long time ago. Gov’t engineers and Gov’t biologists will make you certify and re-certify all this, every 5-10 year review, whatever regulation you fall into. Generally anything over 30 feet is considered a major dam for consequence rating, if it were to fail. The cost on engineering, drilling/coring, and doing an extensive review, including climate change now, is an impossibility to economically meet. That is how they are getting rid of a lot of the smaller dams. I am on that list unfortunately…
When the smaller dams are removed from the smaller watersheds, then the creeks/rivers that were regulated year round through turbine releases will go nearly dry for 4-6 months of the year, (especially spawning season for Salmonids) and there will be no more year round resident fishery, or much reduced since the hydrology reverts to pre dam flows which is usually a freshet high flow that was captured in the reservoir which gets released more slowly year round. So much for saving the fishery, as the increased year round flows from the dam release created the resident fishery in the first place. And supplied some flood protection downstream and recreation opportunities for the reservoir.
If initially constructed and operated properly with proper materials and compacted, with adequate spillage for a 500 year flood, nothing will go wrong, but now you have to prove that it is as safe or safer than when constructed. Things have been reasonable until earlier this century with Gov’t red tape, but now there is an active Gov’t sponsored effort to condemn a lot of these dams the last 10-15 years by making it so expensive to have independent engineering and biological assessments so as to just to force private owners to abandon them. Part of this is to do with the collapse of a few highly publicized mining tailing dams, such as what happened recently in Brazil and British Columbia the last half dozen years. Which is really a different kettle of fish. But it serves and fits the narrative that all dams are bad which I gather was the point of this post.
Coastal erosion: why is it such a horrible thing if the coastline reaches equilibrium a few meters inland of where it might if a dam weren’t upstream?
Methane: a) because we all know vegetation that ISN’T under reservoirs never decomposes and b) because a warmer greener higher-carbon world is so awful for the environment.
“climate change is increasing the size and frequency of floods in many parts of the U.S.” If you subtract idiots building roads &c where overflow ought to go, idiots building on flood plains, greater value of buildings &c in areas flooded and possibly inflation of the currency, I suspect there is nothing left to blame on “climate change”.
They put fish ‘steps’ up the side of dams here. A series of pools, each one a foot or so higher, the fish leap up them. Works great.
One would think that a “Professor of Science” would get the facts before writing. Two dams in Michigan did not fail. An upstream one did, the other is downstream and was simply overtopped. Is the rest of the article any more accurate?
Many years ago, at least 25, I remember reading about over fishing of Atlantic Salmon in the North Atlantic before they returned to spawn. I think the Danes were blamed as they were the ones who found where to go. Pollution and over fishing of the few left to return were also blamed. More recently Salmon Farming introduced disease and escapees being genetically inferior species
I hadn’t thought about minced smolt though.
IIRC the US submarine Nautilus observed salmon feeding under the ice off Greenland, and the Danes took up the opportunity to fish for them as Greenland comes under their jurisdiction.
The Danes have also been catching enormous tonnages of sand eels which have been crushed for their oil to fuel power stations and provide fishmeal for use in salmon farms and feeding pigs.
http://www.ffl.org.uk/3311-2/
The resulting fall in sand eel numbers has had a big effect on food supplies for salmon and other fish, and caused dramatic falls in sea bird populations esp.puffins.
As regards damming/blocking rivers and the effect on running fish, Neglect Carson in his book Going Fishing told the Sage of the Pacific Salmon.
Apparently the Fraser River had big runs of salmon, but every four years was a ‘big year’ when Sockeye salmon ran in prodigious numbers.
When the Canadian Northern Railway’s tunnel at Yale was being built in 1913 the engineer miscalculated the strength of a blast and blew an entire cliff face into the river just when the big run was taking place.
The result was a disaster as the salmon couldn’t reach their spawning grounds and four years later when there should have been another Big Run the catch was down by 80%, and in 1921 it was down by 93%.
“Although the first spawning season was less than three months after the dams were removed, data collected by local volunteer monitors – who number over 300 – indicated that the newly opened habitat had hosted approximately 1,500 river herring spawners for the first time in more than 100 years.” 300 monitors for 1500 herring sounds a bit costly in terms of man-hours and expended resources. Not to mention the environmental damage and also the CO2 involved in getting that mass of people out there and back. Also, sounds like no extinction in 100 years of the dam. I’ll take “Pros and Cons” for $300, Alex.
Methane from submerged vegetation? Seriously?
Dams work great for stopping migration of invasive species like Asian carp.
“Methane from submerged vegetation? Seriously?”
Methylmercury perhaps would be a more significant problem in a larger reservoir for the fishery, if there was any honesty. The rotting vegetation was going to rot anyway, (or burn) whether it was under water or not. Well, it wouldn’t burn under water, but hopefully you get my point. Methane from rotting vegetation is a moot point in the scheme of things, but there is little intellectual honesty left these days it seems.
And methane is NOT a “potent greenhouse gas”. That has been reviewed and discussed over and over numerous times on this website. It is hundreds of times less common in the atmosphere than CO2, it oxidizes readily, and so it will never make a significant contribution to absorption/re-radiation of thermal energy in the big scheme of atmospheric physics.
It’s like Whack-a-Mole with these greenies – they keep throwing up the same old tired tropes and we keep beating them back. Preaching to the Choir
Natural fisheries are going to suffer greatly on river systems with dams. That we can’t argue. We definitely are sacrificing self-supporting fisheries with expensive spawn taking and hatchery rearing and end up with a poorer performing fish that often ends up providing poor returns due to higher mortality factors. It’s just a fact. Yes, you get a reservoir fishery, but you are replacing a natural fishery with a more expensive artificial one. The only justification is that the benefits that the dam provides outweigh the value of a natural fishery. Period. A fish isn’t just a fish. The best suited fish for the river system is the one whose genetics have been honed by the river system over many years. Not ones produced in jars and concrete/plastic raceways.
Best book I’ve ever read about the decline in salmon runs is Salmon without Rivers by Jim Lichatowich.
They didn’t evolve in man made lakes.
” He describes the multitude of factors over the past century and a half that have led to the salmon’s decline, and examines in depth the abject failure of restoration efforts that have focused almost exclusively on hatcheries to return salmon stocks to healthy levels without addressing the underlying causes of the decline. “
Sorry, don’t like to pre-judge, but from decades of experience it’s hard to trust anything from an “ecosystem scientist”. The actions of so many socialist-scientist-apparatchiks have ruined reputations whether this one is credible or not.
I remember when hydroelectric was “green energy.”
Half of it in the US is in green states Oregon, Washington, and California.
East of the Mississippi River, the highest state is New York.
It still is green energy. The only thing that makes it less “green” is that it delivers reliable electricity and thus undermines the investments of the solar and wind promoters.
Best book I’ve ever read about the decline in salmon runs is Salmon without Rivers by Jim Lichatowich.
They didn’t evolve in man made lakes.
” He describes the multitude of factors over the past century and a half that have led to the salmon’s decline, and examines in depth the abject failure of restoration efforts that have focused almost exclusively on hatcheries to return salmon stocks to healthy levels without addressing the underlying causes of the decline. “
About the May 21, 2020, Midland, Michigan evacuation when two aging hydropower dams on the Tittabawassee River failed:
The Edenville dam’s license was terminated by the Federal Energy Regulatory Commission (FERC) in 2018, because of its “inability to pass the Probable Maximum Flood (PMF). The federal government was concerned that “the dam may not have the ability to pass enough water, if a severe flood were to hit, among other issues and violations.” Regulation then passed to the Michigan Department of Environment, Great Lakes, and Energy (EGLE).
Under threat of lawsuit by EGLE, the dam’s operator said it began to raise the lake’s water level in April 2020, and that it reached “normal pond level” in the first week of May.
The last day of April 2020, EGLE sued Boyce anyway, alleging it had lowered the water level without permission in 2018 and 2019, killing thousands of freshwater mussels.
Michigan’s Attorney General confirmed EGLE had directed the operator to raise the water level, stating: “Michigan EGLE directed Boyce to follow the court-ordered lake level requirements,” but challenged that the operator had lowered it for safety reasons.
Having grown up in eastern Oregon, the thought of removing dams on the Klamath River worries me. It sounds like an attempt to depopulate the more self-reliant parts of the state. Farmers in that part of Oregon and California rely on that irrigation water to make their living. They’re not going to just move to Portland and San Francisco and vote Socialist because they’ve been driven out of the Klamath River basin.
Problem is not the dams, sustainable development requires importance of economic growth also.\It is the problem of lack of coordination and maintenance.