How Fish Survive Hydro Turbines

Practical Engineering
5 Mar 202422:21


TLDRThe video script delves into the intricate balance between the benefits of dams and their environmental impacts, particularly on fish migration and ecosystems. It explores the evolution of dam management, highlighting the collaborative efforts between scientists, engineers, and stakeholders to mitigate adverse effects through innovative technologies and research. The narrative follows the example of McNary Dam, showcasing various fish passage structures, monitoring systems, and ongoing scientific advancements aimed at promoting sustainable hydropower while preserving aquatic life. The script underscores the continuous pursuit of solutions to strike a harmonious equilibrium between human needs and environmental conservation.


  • 🌊 Many of the largest dams in the US were built without fully considering their impacts on river ecosystems, but we're now working to balance the benefits of dams (flood control, hydropower, water supply) with environmental protection.
  • ⚖️ Finding the right balance between a dam's benefits and its environmental impact is a complex and evolving challenge, but improving science and engineering are helping us strike a better equilibrium.
  • 🐟 Dams have extensive infrastructure like fish ladders and bypass systems to help migratory fish travel upstream and downstream with minimal harm, though these facilities were often added later as our understanding improved.
  • 🔬 Researchers at places like Pacific Northwest National Laboratory (PNNL) are constantly advancing the science and technology around fish passage, using tools like sensor fish, acoustic tags, and fish-powered generators.
  • 🌊 Dam operations are increasingly governed by detailed Fish Passage Plans developed in collaboration with various partners to prioritize the survival of migratory fish populations alongside human needs.
  • 🔩 Improvements like new turbine designs with reduced pressure changes and better surface pathways are being implemented to enhance fish survivability when passing through dams.
  • 🐠 Factors like avian predation, pressure changes, and disorientation can pose significant risks to migrating fish near dams, so deterrents and mitigation measures are crucial.
  • 🔄 The science and engineering around dam infrastructure and fish passage is an ongoing, iterative process, with constant refinements and adaptations as our understanding evolves.
  • 🌉 Balancing the competing interests of energy, water management, and environmental protection is a complex but essential aspect of responsible dam engineering and operation.
  • 🤝 Collaboration between engineers, biologists, policymakers, activists, and other stakeholders is vital for achieving sustainable solutions that serve both human needs and ecological preservation.

Q & A

  • What are some of the major benefits of large dams in the US?

    -Some of the major benefits of large dams mentioned in the script include flood control, agriculture, water supply for cities, and hydroelectric power generation.

  • What is the main environmental cost of dams discussed in the script?

    -The main environmental cost discussed is the impact dams have on river ecosystems and migratory fish populations, such as salmon.

  • What is the name of the dam featured in the video, and where is it located?

    -The dam featured in the video is McNary Dam, located across the Columbia River between Oregon and Washington state.

  • What are some of the key features and facilities of McNary Dam designed to help fish passage?

    -Key features include fish ladders, attraction water systems, juvenile bypass systems with submersible screens, collection channels, and release pipes to help both adult and juvenile fish migrate past the dam.

  • What role does the Pacific Northwest National Laboratory (PNNL) play in improving fish passage at dams?

    -PNNL conducts research and develops technologies to improve fish passage and survival at hydroelectric dams, such as sensor fish to evaluate turbine impacts and innovations in turbine design.

  • How has the management of fish passage at dams like McNary evolved over time?

    -The script mentions that many fish passage facilities were not originally part of the dam design, but have been added and improved over time as scientific understanding and regulations have evolved to better balance the impacts on fish with the benefits of the dam.

  • What is the purpose of the Fish Passage Plan mentioned in the script?

    -The 500-page Fish Passage Plan is prepared annually in collaboration with various partners, and it governs the operation of McNary and other dams in the Columbia River system to improve the survival of migratory fish along the river.

  • What are some of the techniques used by researchers to study and track fish behavior and movement around dams?

    -Techniques mentioned include implanting acoustic tags and receivers to track fish like underwater GPS, developing tiny sensors and generators to power them without harming the fish, and studying fish behavior in controlled environments.

  • How does the script emphasize the importance of collaboration and ongoing research in balancing the needs of hydropower and environmental conservation?

    -The script highlights the involvement of various experts, including engineers, biologists, ecologists, policy experts, regulators, and activists, in continuously improving and refining the balance between the benefits of dams and their environmental impacts through research and collaboration.

  • What is the significance of the salmon pink and blue paint colors used in the McNary Dam powerhouse, according to the script?

    -The blue color symbolizes the water that drives the hydropower station, while the pink color symbolizes the life within the water and its environmental, economic, and cultural significance, representing the balancing act at the heart of the dam's operations.



🌊 Balancing Dams and River Ecosystems

This paragraph introduces the topic of the video, discussing the benefits and environmental impacts of large dams in the US. It highlights the importance of finding a balance between controlling water resources for human benefit and preserving aquatic ecosystems. The paragraph sets the stage for an exploration of how this balance is being managed and evolved over time through improved science and engineering.


🐟 Fish Passage Facilities at McNary Dam

This paragraph delves into the fish passage facilities at McNary Dam, designed to assist migratory fish in navigating the dam. It explains the workings of fish ladders for upstream migration, including attraction water, entrances, and baffled sections. It also discusses the juvenile bypass system for downstream migration, involving submersible screens, collection channels, and release pipes. The paragraph emphasizes the importance of these structures in improving fish survival rates.


🔬 Advancing Fish Passage Technology

This paragraph focuses on the research and technology advancements happening at the Pacific Northwest National Laboratory (PNNL) to improve fish passage through dams. It discusses the use of sensor fish to evaluate turbine impacts, the development of fish-friendly turbine designs, and studies on fish behavior and navigation. The paragraph highlights the collaboration between researchers, engineers, and policymakers to continuously enhance the balance between hydropower and environmental protection.


🚀 Innovative Fish Tracking and Monitoring

This paragraph explores the cutting-edge technologies used by PNNL researchers to track and monitor fish as they interact with dam structures. It covers acoustic tags for precise fish location tracking, miniaturized sensor implants, fish-powered generators, and methods for safe tag insertion. The paragraph emphasizes the importance of studying fish behavior and adapting infrastructure accordingly.


🌟 Promoting Independent Creators on Nebula

This paragraph shifts focus to promote the Nebula streaming platform, which supports independent creators like the video's host. It highlights Nebula's ad-free environment, original content, and the ability for creators to experiment without algorithmic constraints. The paragraph encourages viewers to subscribe to Nebula using a special discount, supporting the future of independent video creation.




Dams are large, man-made structures built across rivers or streams to control the flow of water. In the video, dams are discussed in the context of their benefits (flood control, agriculture, water supply, and hydroelectric power) and their environmental impacts on river ecosystems and aquatic life (such as salmon and lamprey populations). The script highlights the need to strike a balance between the benefits dams provide for humanity and their ecological consequences.

💡Hydroelectric power

Hydroelectric power refers to the generation of electricity by harnessing the force of flowing water. The video mentions McNary Dam, a nearly 1.5-mile-long hydroelectric dam across the Columbia River, which is equipped with fourteen power-generating turbines that can generate nearly a gigawatt of power combined, enough to power more than half a million homes. Hydroelectric power is one of the significant benefits of dams, but it comes with environmental trade-offs.

💡Fish passage

Fish passage refers to the structures and systems designed to help migratory fish species, such as salmon and lamprey, navigate around dams and continue their upstream or downstream journeys. The video explores various fish passage facilities at McNary Dam, including fish ladders for adult fish to swim upstream, and bypass systems to divert juvenile fish away from turbines and safely release them downstream. These structures aim to mitigate the impacts of dams on fish populations.

💡Environmental impacts

Environmental impacts refer to the effects that human activities, such as dam construction and operation, have on natural ecosystems and wildlife. The video highlights the negative impacts dams can have on river ecosystems and aquatic species, particularly migratory fish. These impacts include disrupting natural water flows, creating barriers to fish migration, and altering habitats. The script emphasizes the need to consider and mitigate these environmental impacts when constructing and managing dams.

💡Research and innovation

The video emphasizes the importance of ongoing research and innovation in improving the balance between the benefits of dams and their environmental impacts. It features the Pacific Northwest National Laboratory (PNNL), which conducts research on topics such as turbine design, fish behavior, and tracking technologies to better understand and minimize the impacts of dams on fish populations. The script highlights how scientific advancements and innovative engineering solutions are continuously evolving to address these complex issues.

💡Migratory fish

Migratory fish are species that travel between freshwater and saltwater environments as part of their life cycle. The video focuses on several migratory fish species in the Columbia River system, including chinook, coho, sockeye, and pink salmon, as well as lampreys. These fish are particularly affected by dams, which can disrupt their migration routes and spawning grounds. The need to facilitate safe passage for migratory fish is a major consideration in the design and operation of dams.

💡Fish ladders

Fish ladders are a type of fish passage structure designed to help adult migratory fish swim upstream past dams. The video describes the fish ladders at McNary Dam, which use attraction water, concrete baffles, and weirs to create a series of manageable steps for fish to climb. Fish ladders aim to provide a continuous passage for adult fish to reach their spawning grounds, allowing them to navigate around the dam without interrupting their natural migration patterns.

💡Juvenile bypass systems

Juvenile bypass systems are structures designed to divert and safely transport young, downstream-migrating fish around dams and powerhouses. The video showcases the intricate bypass system at McNary Dam, which includes submersible screens to redirect fish away from turbines, collection channels, and large pipes to release the juveniles back into the river downstream. These systems aim to minimize the impacts of dams on vulnerable juvenile fish populations during their downstream migration.

💡Balancing act

The concept of a balancing act is central to the video's narrative. It refers to the ongoing challenge of weighing and reconciling the benefits of dams (such as hydroelectric power, flood control, and water supply) against their environmental impacts on aquatic ecosystems and wildlife. The script emphasizes that finding this balance requires collaboration among various stakeholders, including energy researchers, biologists, ecologists, policy experts, regulators, activists, and engineers.


Stewardship refers to the responsible management and protection of natural resources for present and future generations. In the context of the video, stewardship is discussed in relation to being good stewards of the water resources and aquatic ecosystems affected by dams. The script highlights the ongoing efforts and investments made to mitigate the environmental impacts of dams and ensure the sustainable use of these resources, emphasizing the importance of responsible stewardship.


Most of the largest dams in the US were built before we fully understood the impacts they would have on river ecosystems, but they provide immense benefits like flood control, agriculture, water supply, and hydroelectric power.

McNary Dam is a nearly 1.5-mile-long hydroelectric dam across the Columbia River, equipped with 14 power-generating turbines that can generate nearly a gigawatt of power.

The operation of McNary Dam is driven by the Fish Passage Plan, a 500-page document governing the operation to improve the survival of migratory fish like salmon and lampreys.

McNary Dam has fish ladders to help adult salmon swim upstream, with features like attraction water and concrete baffles to facilitate their passage.

For juvenile fish going downstream, McNary has a sophisticated bypass system with submersible screens and a massive collection channel to divert them away from turbines.

The science of improving fish passage at dams is constantly evolving, with researchers at PNNL developing innovative technologies like sensor fish, coatings to reduce buildup, and tiny implantable sensors to track fish behavior.

PNNL has developed minuscule acoustic tags and fish-powered generators to track fish movements without harming them or running out of battery power.

Balancing the benefits of hydropower dams and their environmental impacts, especially on migratory fish populations, is a complex issue that requires collaboration between engineers, biologists, ecologists, policymakers, and activists.

New turbine designs developed in collaboration with PNNL have significantly improved fish survivability when passing through hydropower dams.

The presenter learned about the similarities between how dams can isolate fish populations and how humans adapt to living in remote places, as explored in the Nebula series 'Extremities' by Wendover Productions.

Nebula is a streaming service built by independent creators, offering ad-free original content without interference from industry executives or algorithms.

The presenter's Practical Construction series would not have been possible without the support of Nebula subscribers.

A 40% discount on an annual Nebula subscription is offered, making it an affordable way to support independent creators.

The video highlights the importance of fish passage structures like fish ladders and bypass systems in mitigating the impacts of dams on migratory fish populations.

The video emphasizes the ongoing research and evolution of technologies aimed at improving fish survivability and reducing the environmental impacts of hydropower dams.



Most of the largest dams in the US were built  before we really understood the impacts they would  


have on river ecosystems. Or at least they were  built before we were conscientious enough to weigh  


those impacts against the benefits of a dam. And,  to be fair, it’s hard to overstate those benefits:  


flood control, agriculture, water supply for  cities, and hydroelectric power. All of our  


lives benefit in some way from this enormous  control over Earth’s freshwater resources.


But those benefits come at a cost, and the  price isn’t just the dollars we’ve spent on  


the infrastructure but also the impacts dams have  on the environment. So you have these two vastly  


important resources: the control of water to the  benefit of humanity and aquatic ecosystems that we  


rely on, and in many ways these two are in direct  competition with each other. But even though most  


of these big dams were built decades ago, the ways  we manage that struggle are constantly evolving as  


the science and engineering improve. This is  a controversial issue with perspectives that  


run the gamut. And I don’t think there’s one right  answer, but I do know that an informed opinion is  


better than an oblivious one. So, I wanted to see  for myself how we strike a balance between a dam’s  


benefits and environmental impacts, and how that’s  changing over time. So, I partnered up with the  


folks at the Pacific Northwest National Laboratory  (or PNNL) in Washington state to learn more. Just  


to be clear, they didn’t sponsor this video and  had no control over its contents.They showed me  


so much, not just the incredible technology and  research that goes on in their lab, but also how  


it is put into practice in real infrastructure  in the field, all so I could share it with you.  


This is McNary Dam, a nearly  1.5-mile-long hydroelectric dam  


across the Columbia River between  Oregon and Washington state,  


just shy of 300 miles (or 470 km) upriver from  the Pacific Ocean. And this is Tim Roberts,  


the dam’s Operations Project Manager and  the best dam tour guide I’ve ever met.


But this was not just a little walkthrough. We  went deep into every part of this facility to  


really understand how it works. McNary is one  of the hydropower workhorses in the Columbia  


River system, a network of dams that provide  electricity, irrigation water, flood control,  


and navigation to the region. It’s equipped with  fourteen power-generating turbines, and these  


behemoths can generate nearly a gigawatt of power  combined! That means this single facility can,  


very generally, power more than half-a-million  homes. The powerhouse where those turbines live  


is nearly a quarter mile long (more than 350  meters)! It’s pretty hard to convey the scale  


of these units in a video, but Tim was gracious  enough to take us down inside one to see and  


hear the enormous steel shaft spinning as it  generates megawatts of electrical power.  


All that electricity flows out to the grid on these  transmission lines to power the surrounding area.


McNary is a run-of-the-river dam, meaning  it doesn’t maintain a large reservoir. It  


stores some water in the forebay to create  the height needed to run the turbines,  


but water flows more or less at the rate it  would without the dam. So, any extra water  


flowing into the forebay that can’t be used for  hydro generation has to be passed downstream  


through one or more of these 22 enormous lift  gates in the spillway beside the powerhouse.


As you can imagine, all this infrastructure  is a lot to operate and maintain. But it’s  


not just hydrologic conditions like floods  and droughts or human needs like hydropower  


demands and irrigation dictating how and when  those gates open or when those turbines run;  


it’s biological criteria too. The  Columbia and its tributaries are home  


to a huge population of migratory fish,  including chinook, coho, sockeye, pink salmon,  


and lampreys, and over the years, through  research, legislation, lawsuits, advocacy,  


and just plain good sense by the powers at be,  we’ve steadily been improving the balance between  


impacts to that wildlife and the benefits of  the infrastructure. In fact, just about every  


aspect of the operation of McNary Dam is driven  by the Fish Passage Plan. This 500-page document,  


prepared each year in collaboration with a litany  of partners, governs the operation of McNary and  


several other dams in the Columbia River system  to improve the survival of fish along the river.


This fish bible includes prescriptive details and  schedules for just about every aspect of the dam,  


including the fish passage structures too.  Usually, when we build infrastructure,  


the people who are going to use it are  actual people. But in a very real sense,  


huge aspects of McNary and other similar dams  are infrastructure for non-humans.  


On top of the hydropower plant and the spillway, McNary  is equipped with a host of facilities meant to  


help wildlife get from one side to the other  with as little stress or injury as possible.  


Let’s look at the fish ladders first.  McNary has two of them, one on each side.


A big contingent of the fish needing past McNary  dam are adult salmon and other species from the  


ocean trying to get upstream to reproduce  in freshwater streams. They are biologically  


motivated to swim against the current, so a fish  ladder is designed to encourage and allow them  


to do just that, and it starts with attraction  water. Dams often slow down the flow of water,  


both upstream and downstream, which can be  disorienting to fish trying to swim against a  


current. Also, dams are large, and fish generally  don’t read signs, so we need an alternative way to  


show them how to get around. Luckily, in  addition to a strong current, salmon are  


sensitive to the sound and motion of splashing  water, so that’s just what we do. At McNary,  


huge electric pumps lift water from the tailrace  below the dam and discharge it into a channel that  


runs along the powerhouse. As the water splashes  back down, it draws fish toward the entrances so  


they can orient with the flow through the ladder.  Some of this was a little tough to understand  


even seeing it in person, so I had a couple  of the engineers at the dam explain it to me.


All these entrances provide options  for the fish to come in, increasing  


the opportunity and likelihood  that they will find their way.


Once they’re in, they make their way upstream  into the ladder itself. Concrete baffles break  


up the insurmountable height of the dam into  manageable sections that fish can swim up at  


their own pace. Most of the fish go through  holes in the baffles, but some jump over the  


weirs. There’s even a window near the top  of the ladder where an expert counts the  


fish and identifies their species.


This data is  important to a wide variety of organizations,  


and it’s even posted online if you  want to have a look. Once at the top,  


the fish pass through a trash rack that keeps  debris out of the ladder and continue their  


journey to their spawning grounds. The goal is that  they never even know they left the river at all,  


and it works. Every year hundreds of thousands  of chinook, coho, steelhead, and sockeye make  


their way past McNary Dam. If you include the  non-native shad, that number is in the millions.


And it’s not just bony fish that find  their way through. Some of the latest  


updates are to help lamprey passage.  These are really interesting creatures!


I’m working on another video that will take a much  deeper look at how this and other fish ladders  


work, so stay tuned for that one, but it’s not the  only fish passage facility here. Because what goes  


up, must come down, or at least their offspring  do (most adult salmon die after reproducing). So,  


McNary Dam needs a way to get those juvenile  fish through as well. That might sound simple;  


thanks to gravity, it’s much simpler to go  down than up. But at a dam, it’s anything but.


I definitely wouldn’t want  to pass through one of these,  


but juvenile fish can make it through  the spillway mostly just fine. In fact,  


specialized structures are often installed  during peak migration times to encourage  


fish to swim through the spillway. McNary Dam has  lift gates where the water flows from lower in the  


water column. But salmon like to stay relatively  close to the surface and they’re sensitive to the  


currents in the flow. Many dams on the Columbia  system have some way to spill water over the top,  


called a weir, that is more conducive to  getting the juveniles through the dam.


The other path for juveniles to take is to be  drawn toward the turbines. But McNary and a lot  


of other dams are equipped with a sophisticated  bypass system to divert the fish before they  


make it that far. and that all starts with the  submersible screens.   


These enormous structures are specially designed with lots of narrow  slots to let as much water through to the  


turbines while excluding juvenile fish. They are  lowered into place with the huge gantry crane that  


rides along the top of the power house. Each  submersible screen is installed in front of a  


turbine to redirect fish upwards while the water  flows continues on. Brushes keep them clean of  


debris to make sure they fish don’t get trapped  against the screen. They might look simple,  


but even a basic screen like this requires a  huge investment of resources and maintenance,  


because they are absolutely critical  to the operation of the dam.


Once the fish have been diverted by the screens,  they flow with some of the water upward into a  


massive collection channel. This was originally  designed as a way to divert ice and debris,  


but now it’s basically a fish cathedral  along the upstream face of the dam.


The juveniles come out in these conduits  from below. Then they flow along the channel,  


while grates along the bottom concentrate them  upward. Next they flow into a huge pipe that pops  


out on the downstream face of the dam. Along the  way, the juveniles pass through electronic readers  


that scan any of the fish that have been equipped  with tags and then into this maze of pipes and  


valves and pumps and flumes. In the past, this  facility was used to store juveniles so they  


could be loaded up in barges and transported  downstream. But over time, the science showed  


it was better to just release them downstream  from the dam. Every once in a while, some of the  


juveniles are separated for counting so scientists  can track them just like the adults in the ladder.  


Then the juveniles continue their journey in the  pipe out to the middle of the river downstream.


Avian predation is a serious problem  for juveniles. Pelicans, seagulls,  


and cormorants love salmon just like the  rest of us. In many cases, most of the fish  


mortality caused by dams isn’t the stress of  getting them through the various structures,  


but simply that birds and other predatory fish take advantage of the  fact that dams can slow down and concentrate  


migrating fish. This juvenile bypass  pipe runs right out into the center  


of the downstream channel where flows are  fastest to give the fish a fighting chance,  


and McNary is equipped with a lot of  deterrents to try and keep the birds away.


All this infrastructure at McNary Dam to help  fish get upstream and downstream has changed  


and evolved over time, and in fact, a lot of  it wasn’t even conceived of when the dam was  


first built. And that’s one of the most  important things I learned touring McNary  


Dam and the Pacific Northwest National Lab:  the science is constantly improving. A ton of  


that science happens here at the PNNL Aquatics  Research Laboratory.  


I spent an entire day just chatting with all the scientists and researchers  here who are advancing the state of the art.


For example, not all the juvenile salmon  get diverted away from those turbines.  


Some inevitably end up going right through. You  might think that being hit by a spinning turbine  


is the worst thing that could happen to a fish,  but actually the change in pressure is the main  


concern. A hydropower turbine’s job is to extract  as much energy as possible from the flowing water.  


In practice, that means the pressure coming  into each unit is much higher than going out,  


and that pressure drop happens rapidly. It doesn’t  bother the lamprey at all, but that sudden change  


in pressure can affect the swim bladder that  most fish use for buoyancy. So how do we know  


what that does to a fish and how newer designs  can be safer? PNNL has developed sensor fish,  


electronic analogues to the real thing that they  can send through turbines and get data out on the  


other side. Compare that data to what we already  know about the limits fish can withstand (another  


area of research at PNNL), and you can quickly and  safely evaluate the impacts a turbine can have.


What’s awesome is seeing how that research  translates into actual investments in  


infrastructure that have a huge effect  on survivability. New turbines recently  


installed at Ice Harbor Dam upstream were  designed in collaboration with PNNL with  


fish passage in mind to reduce injury for  any juveniles that find their way in. One  


study found that more than 98% of fish  survived passing through the new turbines,  


and nearly all the large hydropower dams in  the Columbia river system are slated to have  


them installed in the future. And it’s not just  the turbines that are seeing improvements. I  


talked to researchers who study live fish, how  they navigate different kinds of structures,  


and what they can withstand. Just the engineering  in the water system to keep these fish happy is  


a feat in itself. I talked to a coatings expert  about innovative ways to reduce biological buildup  


on nets and screens. I talked to an energy  researcher about new ways to operate turbines  


to decrease impacts to fish from ramping them up  and down in response to fluctuating grid demands.


And I spent a lot of time learning about how  we track and study the movement of fish as  


they interact with human made structures.  Researchers at PNNL have developed a suite  


of sensors that can be implanted into fish for  a variety of purposes. Some use acoustic signals  


picked up by nearby receivers that can precisely  locate each fish like underwater GPS. Of course,  


if you want to study fish behavior accurately, you  need the fish to behave like they would naturally,  


so those sensors have to be tiny. PNNL has  developed miniscule devices, so small I could  


barely make out the details. You also want to make  sure that inserting the tags doesn’t injure the  


fish, so researchers showed me how you do that  and make sure they heal quickly. And of course,  


those acoustic tags require power, and tiny  batteries (while extremely impressive in their  


own right) sometimes aren’t enough for long-term  studies. So they’ve even come up with fish-powered  


generators that can keep the tags running for  much longer periods of time. A piezoelectric  


device creates power as the fish swims… and  they had some fun ways to test them out too.


Of course, migratory fish aren’t the only part  of the environment impacted by hydropower,  


and with all the competing interests,  I don’t think we’ll ever feel like the  


issue is fully solved. These are messy,  muddy questions that take time, energy,  


and big investments in resources  to get even the simplest answers.


The salmon pink and blue paint in the powerhouse  at McNary really sums it up well, with the blue  


symbolizing the water that drives the station, and  the pink symbolizing the life within the water,  


and its environmental, economic, and cultural  significance. This kind of balancing act is really  


at the heart of what a lot of engineering is all  about. I’m so grateful for the opportunity to see  


and learn more about how energy researchers,  biologists, ecologists, policy experts,  


regulators, activists, and engineers collaborate  to make sure we’re being good stewards of the  


resources we depend on. I think Alison Colotelo,  the Hydropower Program Lead at PNNL put it best:


My crew and I spent two full days in  Washington talking to scientists and  


engineers about these complicated issues.  And I probably learned more about biology  


in those two days than anything  I happened to absorb in college,  


especially about how dams can isolate populations  of fish if they aren’t equipped with well-designed  


passage systems like those at McNary. And  there’s a human equivalent to that too,  


that’s really interesting I think, because we’ve  found ways of living in super remote places,  


and the ways people and fish adapt to those  situations have a lot of similarities. My friend,  


Sam, of the Wendover Productions channel has  a video series called Extremities that is all  


about the most remote places on Earth and how and  why people choose to settle them. I’ve watched all  


15 episodes. They’re so good, and if you want to  check them out, they’re available only on Nebula.


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