An on-location primer on the science & engineering of getting fish around dams.
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All of our lives benefit in some way from this enormous control over Earthâs freshwater resources. But those benefits come at a cost, and the price isnât just the dollars weâve spent on the infrastructure but also the impacts dams have on the environment. This kind of balancing act is really at the heart of what a lot of engineering is all about.
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Source: https://www.youtube.com/watch?v=U6fBPdu8w9U
Video by Grady Hillhouse
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Most of the largest dams in the US were builtÂ
before we really understood the impacts they would have on river ecosystems. Or at least they wereÂ
built before we were conscientious enough to weigh those impacts against the benefits of a dam. And,Â
to be fair, itâs hard to overstate those benefits: flood control, agriculture, water supply forÂ
cities, and hydroelectric power. All of our lives benefit in some way from this enormousÂ
control over Earthâs freshwater resources. But those benefits co
me at a cost, and theÂ
price isnât just the dollars weâve spent on the infrastructure but also the impacts dams haveÂ
on the environment. So you have these two vastly important resources: the control of water to theÂ
benefit of humanity and aquatic ecosystems that we rely on, and in many ways these two are in directÂ
competition with each other. But even though most of these big dams were built decades ago, the waysÂ
we manage that struggle are constantly evolving as the science and engineering
improve. This isÂ
a controversial issue with perspectives that run the gamut. And I donât think thereâs one rightÂ
answer, but I do know that an informed opinion is better than an oblivious one. So, I wanted to seeÂ
for myself how we strike a balance between a damâs benefits and environmental impacts, and how thatâsÂ
changing over time. So, I partnered up with the folks at the Pacific Northwest National LaboratoryÂ
(or PNNL) in Washington state to learn more. Just to be clear, they didnât sponso
r this video andÂ
had no control over its contents.They showed me so much, not just the incredible technology andÂ
research that goes on in their lab, but also how it is put into practice in real infrastructureÂ
in the field, all so I could share it with you. This is McNary Dam, a nearlyÂ
1.5-mile-long hydroelectric dam across the Columbia River betweenÂ
Oregon and Washington state, just shy of 300 miles (or 470 km) upriver fromÂ
the Pacific Ocean. And this is Tim Roberts, the damâs Operations P
roject Manager andÂ
the best dam tour guide Iâve ever met. But this was not just a little walkthrough. WeÂ
went deep into every part of this facility to really understand how it works. McNary is oneÂ
of the hydropower workhorses in the Columbia River system, a network of dams that provideÂ
electricity, irrigation water, flood control, and navigation to the region. Itâs equipped withÂ
fourteen power-generating turbines, and these behemoths can generate nearly a gigawatt of powerÂ
combined! That m
eans this single facility can, very generally, power more than half-a-millionÂ
homes. The powerhouse where those turbines live is nearly a quarter mile long (more than 350Â
meters)! Itâs pretty hard to convey the scale of these units in a video, but Tim was graciousÂ
enough to take us down inside one to see and hear the enormous steel shaft spinning as itÂ
generates megawatts of electrical power. All that electricity flows out to the grid on theseÂ
transmission lines to power the surrounding are
a. McNary is a run-of-the-river dam, meaningÂ
it doesnât maintain a large reservoir. It stores some water in the forebay to createÂ
the height needed to run the turbines, but water flows more or less at the rate itÂ
would without the dam. So, any extra water flowing into the forebay that canât be used forÂ
hydro generation has to be passed downstream through one or more of these 22 enormous liftÂ
gates in the spillway beside the powerhouse. As you can imagine, all this infrastructureÂ
is a lot t
o operate and maintain. But itâs not just hydrologic conditions like floodsÂ
and droughts or human needs like hydropower demands and irrigation dictating how and whenÂ
those gates open or when those turbines run; itâs biological criteria too. TheÂ
Columbia and its tributaries are home to a huge population of migratory fish,Â
including chinook, coho, sockeye, pink salmon, and lampreys, and over the years, throughÂ
research, legislation, lawsuits, advocacy, and just plain good sense by the powers
at be,Â
weâve steadily been improving the balance between impacts to that wildlife and the benefits ofÂ
the infrastructure. In fact, just about every aspect of the operation of McNary Dam is drivenÂ
by the Fish Passage Plan. This 500-page document, prepared each year in collaboration with a litanyÂ
of partners, governs the operation of McNary and several other dams in the Columbia River systemÂ
to improve the survival of fish along the river. This fish bible includes prescriptive details andÂ
sc
hedules for just about every aspect of the dam, including the fish passage structures too.Â
Usually, when we build infrastructure, the people who are going to use it areÂ
actual people. But in a very real sense, huge aspects of McNary and other similar damsÂ
are infrastructure for non-humans. On top of the hydropower plant and the spillway, McNaryÂ
is equipped with a host of facilities meant to help wildlife get from one side to the otherÂ
with as little stress or injury as possible. Letâs look
at the fish ladders first.Â
McNary has two of them, one on each side. A big contingent of the fish needing past McNaryÂ
dam are adult salmon and other species from the ocean trying to get upstream to reproduceÂ
in freshwater streams. They are biologically motivated to swim against the current, so a fishÂ
ladder is designed to encourage and allow them to do just that, and it starts with attractionÂ
water. Dams often slow down the flow of water, both upstream and downstream, which can beÂ
disorien
ting to fish trying to swim against a current. Also, dams are large, and fish generallyÂ
donât read signs, so we need an alternative way to show them how to get around. Luckily, inÂ
addition to a strong current, salmon are sensitive to the sound and motion of splashingÂ
water, so thatâs just what we do. At McNary, huge electric pumps lift water from the tailraceÂ
below the dam and discharge it into a channel that runs along the powerhouse. As the water splashesÂ
back down, it draws fish toward t
he entrances so they can orient with the flow through the ladder.Â
Some of this was a little tough to understand even seeing it in person, so I had a coupleÂ
of the engineers at the dam explain it to me. All these entrances provide optionsÂ
for the fish to come in, increasing the opportunity and likelihoodÂ
that they will find their way. Once theyâre in, they make their way upstreamÂ
into the ladder itself. Concrete baffles break up the insurmountable height of the dam intoÂ
manageable sections
that fish can swim up at their own pace. Most of the fish go throughÂ
holes in the baffles, but some jump over the weirs. Thereâs even a window near the topÂ
of the ladder where an expert counts the fish and identifies their species. This data isÂ
important to a wide variety of organizations, and itâs even posted online if youÂ
want to have a look. Once at the top, the fish pass through a trash rack that keepsÂ
debris out of the ladder and continue their journey to their spawning grounds. The go
al is thatÂ
they never even know they left the river at all, and it works. Every year hundreds of thousandsÂ
of chinook, coho, steelhead, and sockeye make their way past McNary Dam. If you include theÂ
non-native shad, that number is in the millions. And itâs not just bony fish that findÂ
their way through. Some of the latest updates are to help lamprey passage.Â
These are really interesting creatures! Iâm working on another video that will take a muchÂ
deeper look at how this and other fish lad
ders work, so stay tuned for that one, but itâs not theÂ
only fish passage facility here. Because what goes up, must come down, or at least their offspringÂ
do (most adult salmon die after reproducing). So, McNary Dam needs a way to get those juvenileÂ
fish through as well. That might sound simple; thanks to gravity, itâs much simpler to goÂ
down than up. But at a dam, itâs anything but. I definitely wouldnât wantÂ
to pass through one of these, but juvenile fish can make it throughÂ
the spillway
mostly just fine. In fact, specialized structures are often installedÂ
during peak migration times to encourage fish to swim through the spillway. McNary Dam hasÂ
lift gates where the water flows from lower in the water column. But salmon like to stay relativelyÂ
close to the surface and theyâre sensitive to the currents in the flow. Many dams on the ColumbiaÂ
system have some way to spill water over the top, called a weir, that is more conducive toÂ
getting the juveniles through the dam. The o
ther path for juveniles to take is to beÂ
drawn toward the turbines. But McNary and a lot of other dams are equipped with a sophisticatedÂ
bypass system to divert the fish before they make it that far. and that all starts with theÂ
submersible screens. These enormous structures are specially designed with lots of narrowÂ
slots to let as much water through to the turbines while excluding juvenile fish. They areÂ
lowered into place with the huge gantry crane that rides along the top of the power h
ouse. EachÂ
submersible screen is installed in front of a turbine to redirect fish upwards while the waterÂ
flows continues on. Brushes keep them clean of debris to make sure they fish donât get trappedÂ
against the screen. They might look simple, but even a basic screen like this requires aÂ
huge investment of resources and maintenance, because they are absolutely criticalÂ
to the operation of the dam. Once the fish have been diverted by the screens,Â
they flow with some of the water upward int
o a massive collection channel. This was originallyÂ
designed as a way to divert ice and debris, but now itâs basically a fish cathedralÂ
along the upstream face of the dam. The juveniles come out in these conduitsÂ
from below. Then they flow along the channel, while grates along the bottom concentrate themÂ
upward. Next they flow into a huge pipe that pops out on the downstream face of the dam. Along theÂ
way, the juveniles pass through electronic readers that scan any of the fish that have bee
n equippedÂ
with tags and then into this maze of pipes and valves and pumps and flumes. In the past, thisÂ
facility was used to store juveniles so they could be loaded up in barges and transportedÂ
downstream. But over time, the science showed it was better to just release them downstreamÂ
from the dam. Every once in a while, some of the juveniles are separated for counting so scientistsÂ
can track them just like the adults in the ladder. Then the juveniles continue their journey in theÂ
pipe ou
t to the middle of the river downstream. Avian predation is a serious problemÂ
for juveniles. Pelicans, seagulls, and cormorants love salmon just like theÂ
rest of us. In many cases, most of the fish mortality caused by dams isnât the stress ofÂ
getting them through the various structures, but simply that birds and other predatory fish take advantage of theÂ
fact that dams can slow down and concentrate migrating fish. This juvenile bypassÂ
pipe runs right out into the center of the downstream ch
annel where flows areÂ
fastest to give the fish a fighting chance, and McNary is equipped with a lot ofÂ
deterrents to try and keep the birds away. All this infrastructure at McNary Dam to helpÂ
fish get upstream and downstream has changed and evolved over time, and in fact, a lot ofÂ
it wasnât even conceived of when the dam was first built. And thatâs one of the mostÂ
important things I learned touring McNary Dam and the Pacific Northwest National Lab:Â
the science is constantly improving. A to
n of that science happens here at the PNNL AquaticsÂ
Research Laboratory. I spent an entire day just chatting with all the scientists and researchersÂ
here who are advancing the state of the art. For example, not all the juvenile salmonÂ
get diverted away from those turbines. Some inevitably end up going right through. YouÂ
might think that being hit by a spinning turbine is the worst thing that could happen to a fish,Â
but actually the change in pressure is the main concern. A hydropower turbin
eâs job is to extractÂ
as much energy as possible from the flowing water. In practice, that means the pressure comingÂ
into each unit is much higher than going out, and that pressure drop happens rapidly. It doesnâtÂ
bother the lamprey at all, but that sudden change in pressure can affect the swim bladder thatÂ
most fish use for buoyancy. So how do we know what that does to a fish and how newer designsÂ
can be safer? PNNL has developed sensor fish, electronic analogues to the real thing that the
yÂ
can send through turbines and get data out on the other side. Compare that data to what we alreadyÂ
know about the limits fish can withstand (another area of research at PNNL), and you can quickly andÂ
safely evaluate the impacts a turbine can have. Whatâs awesome is seeing how that researchÂ
translates into actual investments in infrastructure that have a huge effectÂ
on survivability. New turbines recently installed at Ice Harbor Dam upstream wereÂ
designed in collaboration with PNNL with f
ish passage in mind to reduce injury forÂ
any juveniles that find their way in. One study found that more than 98% of fishÂ
survived passing through the new turbines, and nearly all the large hydropower dams inÂ
the Columbia river system are slated to have them installed in the future. And itâs not justÂ
the turbines that are seeing improvements. I talked to researchers who study live fish, howÂ
they navigate different kinds of structures, and what they can withstand. Just the engineeringÂ
in th
e water system to keep these fish happy is a feat in itself. I talked to a coatings expertÂ
about innovative ways to reduce biological buildup on nets and screens. I talked to an energyÂ
researcher about new ways to operate turbines to decrease impacts to fish from ramping them upÂ
and down in response to fluctuating grid demands. And I spent a lot of time learning about howÂ
we track and study the movement of fish as they interact with human made structures.Â
Researchers at PNNL have developed
a suite of sensors that can be implanted into fish forÂ
a variety of purposes. Some use acoustic signals picked up by nearby receivers that can preciselyÂ
locate each fish like underwater GPS. Of course, if you want to study fish behavior accurately, youÂ
need the fish to behave like they would naturally, so those sensors have to be tiny. PNNL hasÂ
developed miniscule devices, so small I could barely make out the details. You also want to makeÂ
sure that inserting the tags doesnât injure the fis
h, so researchers showed me how you do thatÂ
and make sure they heal quickly. And of course, those acoustic tags require power, and tinyÂ
batteries (while extremely impressive in their own right) sometimes arenât enough for long-termÂ
studies. So theyâve even come up with fish-powered generators that can keep the tags running forÂ
much longer periods of time. A piezoelectric device creates power as the fish swims⌠andÂ
they had some fun ways to test them out too. Of course, migratory fish arenât
the only partÂ
of the environment impacted by hydropower, and with all the competing interests,Â
I donât think weâll ever feel like the issue is fully solved. These are messy,Â
muddy questions that take time, energy, and big investments in resourcesÂ
to get even the simplest answers. The salmon pink and blue paint in the powerhouseÂ
at McNary really sums it up well, with the blue symbolizing the water that drives the station, andÂ
the pink symbolizing the life within the water, and its environm
ental, economic, and culturalÂ
significance. This kind of balancing act is really at the heart of what a lot of engineering is allÂ
about. Iâm so grateful for the opportunity to see and learn more about how energy researchers,Â
biologists, ecologists, policy experts, regulators, activists, and engineers collaborateÂ
to make sure weâre being good stewards of the resources we depend on. I think Alison Colotelo,Â
the Hydropower Program Lead at PNNL put it best: My crew and I spent two full days inÂ
Washington talking to scientists and engineers about these complicated issues.Â
And I probably learned more about biology in those two days than anythingÂ
I happened to absorb in college, especially about how dams can isolate populationsÂ
of fish if they arenât equipped with well-designed passage systems like those at McNary. AndÂ
thereâs a human equivalent to that too, thatâs really interesting I think, because weâveÂ
found ways of living in super remote places, and the ways people and fish ad
apt to thoseÂ
situations have a lot of similarities. My friend, Sam, of the Wendover Productions channel hasÂ
a video series called Extremities that is all about the most remote places on Earth and how andÂ
why people choose to settle them. Iâve watched all 15 episodes. Theyâre so good, and if you want toÂ
check them out, theyâre available only on Nebula. Youâve probably heard of Nebula before. Itâs aÂ
streaming service built by a group of creators, including me, as a way to boost theÂ
resources
and capabilities of independent creators. Itâs totally ad-free,Â
full of originals like Extremities, and there are no industry executives or bigÂ
production houses deciding what projects live or die. That means people like Brian from RealÂ
Engineering, Scotty from Strange Parts, Integza, and a lot of others get to make the stuffÂ
theyâre passionate about without having to be so careful to please the YouTube algorithmÂ
or so shallow to capture a wider audience. You can think of it like an employ
ee-owned co-op.Â
A place to experiment with bigger projects, different formats, and extra content and perksÂ
from your favorite creators. My videos go live there early, before they come out here, and myÂ
Practical Construction series wouldnât have been possible to make if not for the dedicated peopleÂ
watching on Nebula. I know there are a lot of streaming platforms out there right now, and noÂ
one wants another monthly cost to keep track of, but I also know that if youâre watching aÂ
show like
this to end, there is a ton of other stuff on Nebula that youâre going toÂ
enjoy as well. So Iâve made it dead simple: click the link below and youâll get 40% off anÂ
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you for watching, and let me know what you think!
Comments
đGet Nebula using my link for 40% off an annual subscription: https://go.nebula.tv/Practical-Engineering đSigned copies of my book are back in stock at https://store.practical.engineering đHuge thanks to Pacific Northwest Nation Laboratory and the US Army Corps of Engineers, Walla Walla District for hosting my team and sharing the incredible work they do.
Thanks for coming to PNNL and sharing our hydropower and fish passage science with the world!
This is the 22 minute answer to my how fish survive turbine question Ive been waiting for my whole life.
Not gonna lie, these videos where you go to locations and talk about the science and engineering behind everything are my favorite.
âBest dam tour guide Iâve ever metâ. Well done
"Best dam tour guide..." đ Well played Grady!
I am so thrilled to have found this video. Several years ago I worked on a project relating to the Ardnacrusha power station on the River Shannon in Ireland. Turns out that the fish pass was only built 60 years after the hydroelectric station began its work - with the result that most of the salmon and eels that used to travel far upstream to reproduce had fallen victim to the impossibility of getting over the hurdle. With the remedial work a hatchery was installed that eventually helped restock rivers in Ireland and abroad, e.g. the Rhine. That hatchery attracted me like a magnet and I followed the complete cycle - and fell in love with the hatchlings. Knowing that the whole business can be managed so much better now and the negative impact on the fishes reduced considerably gives me great joy.
It is dam refreshing to have someone talk about the impacts of hydropower on the environment, and what's being done to mitigate it.
Iâm very impressed at the progress over the last few decades in dam management. The ecological impact used to be a much smaller part of the administration of these structures. Itâs great to see these changes
The most compelling thing in this video, IMO, is not the astonishing dam and attendant structures, but rather all the young, alert, committed people each bringing their particular passion to the task at hand. Seeing those people gives me hope for the future.
We had fish ladders in our run of the river hydro generators in Scotland. They were built at the out set at the insistence of the land owners for whom fishing was an important sport income. The fish ladder at Pitlochry is well known as a tourist attraction - it has windows in the side inside the visitor centre as well as a fish counter đ
As a Hermiston local working in electric infrastructure, this is SUPER cool to watch! Thanks for coming out here!
Thanks for coming to PNNL! It is great that you came here.
8:15 that's some Stanley Parable level job there. you clock in, count fish, clock out. in all seriousness, the job is probably the best job you could have. like forget keeping brain cells, just count fish and go home with all the money.
I love hearing about human beings using science and engineering to make life for fish easier. Itâs a welcome change from everything else going on in the world these days. Hats off to the staff at PNNL.
5:43 - this is such a cool idea for an ongoing series! The practical engineering of how humans built things to make life better for ourselves AND the animals that we live beside. My first thought is those over-passes built over roads to let deer and moose pass over highways on naturalistic terrain, and the story of how they researched where to place them, and did that so well that animals were trying to use the overpass before it was finished! We need more hope and answers and good news in the world, and this is a great forum for sharing stories like that, of how human engineers are working towards, and succeeding at, prioritizing both their own needs, and the planet's.
Found this very interesting. My grandfather was one of the engineers that built most of these dams and I got a first hand experience going with him to the different dams to see how they worked. I was always fascinated by the fish ladders and how they worked. I saw this all back in the early 70s and watching this its crystal clear this technology has come a very long way from back then and it was awesome to see. Thanks a ton for sharing this!
Thanks for coming and working with my husband and his team, it was great meeting you guys! This turned out great. đ
Great video! Thank you so much for visiting McNary and for highlighting the good work we're doing for the fish. More info about our dams can be found on our YouTube channel.
Modern engineers and engineering projects like this give me hope. There's so much negativity in the world and people are more divided than ever, so huge collaborative projects like this are a breath of fresh air.