Dam it! The Problem with Dams

Earthquakes and landslides can suddenly block a river’s path, or a lack of rainfall can cause groundwater levels to drop and streams to suddenly dry up. However, when these natural incidents occur, we chalk them up as innate and unfortunate phenomena, taking the power of the planet to supplement and heal itself from such incidents for granted. In fact, we are so confident in the earth’s ability to get along without its rivers that we often aid in their decline and even accelerate the flowing water’s descent towards impending doom—by putting up a dam.

Dams, Dams, Everywhere

There are over 91,000 dams in the United States, with more being built every day. They’re constructed for several reasons—from generating electricity to controlling flooding to creating reservoirs of drinking water. Some dams are merely tiny slabs of wood or concrete that are put in place by ranchers and farmers to divert the flow of a small creek, helping to irrigate fields and water livestock. Others, such as the Great Hoover Dam in Nevada, are massive structures that provide power and water for hundreds of thousands of people. Over time, dams have almost become a symbol of the ingenuity and advancement of mankind and stand like concrete monoliths in the center of rivers, like great statues in homage to industry.

For nearly two centuries, we have looked at dams as a way to harness the power of a river and use it for our own benefit. We have viewed and marketed them as an eco-friendly alternative to fossil fuels and a convenient way to procure water and provide power in places that would otherwise have none. Some dams were built to last a lifetime, while others were created as a temporary convenience and were then abandoned when a certain project was done, or advancements in technology made their purpose obsolete. Yet as we hustled from river to river, building dam, after dam, after dam, not a single person thought about just what exactly these dams were doing to the rivers they were built on nor what sort of damage they were doing to surrounding ecosystems.

Dam Damage

While dams may be incredibly helpful to us and seem harmless enough, the reality is that holding back a river’s natural flow can be incredibly debilitating to the environment. Over the years, dams have depleted fisheries, degraded river ecosystems, and some have even changed the nearby lands, making them uninhabitable for wildlife.

A river’s flow develops over thousands of years. Through the passage of time, a river almost decides where it wants to flow and how high it wants its water to be, and the environment around the river is shaped accordingly. When a dam is built, it interrupts these natural river dynamics, throwing the delicate system into complete chaos.

“Dams have an impact wherever and no matter how they are built,” Aquatic Fisheries Biologist William Eldridge said. “They raise water temperature in rivers that are naturally cooler, they cause sediment build up and don’t allow a river to flush toxins and heavy metals downstream, and they block fish passage and prevent many species from spawning. Additionally, they change the substrate of the river which completely alters the habitat around the river both below and above the surface of the water.”

The substrate refers to the type of streambed on the bottom of the river, which can range from mud and fine sediment to gravel and small stones to large boulders. Every streambed is a different environment that holds its own types of vegetation and animal life—all part of a natural food chain. For example, a small stream with a rocky bottom will contain a lot of insects like mayflies and stoneflies which feed fish like trout and salmon. In turn, these fish feed animals like eagles and bears, which come to depend on the river for survival. Yet when a dam is put in place, the river’s flow slows down, allowing sediment to build up over the rocks, wiping out all the insects, which causes the trout to die off, which forces the eagles and bears to leave or to seek out nontraditional prey. This sediment can even build up to a point where it begins to flood riverbanks and will actually endanger human safety.

“We have a lot of concerns about the sediment behind dams,” Elgridge told MeatEater. “I mean we can have more than a 1000 dump trucks or more of it behind a dam, and even though we try to remove as much of it as we can, we can’t remove it call. This sediment plugs up rocks and makes it a hard place for fish to live, and of course, it has a huge effect on water quality with large amounts of phosphorus and other materials that, if we allow them to wash downstream, makes our water quality worse and can make people and animals that drink or even swim in the water quite sick.”

Dams can also raise a river’s water temperature, which drives off or even kills cold water species and can cause algae blooms that can affect animals and humans that drink or even enter the water. They also block natural fish passage meaning that species like salmon, trout, and steelhead, which often need to get to the headwaters of a river to spawn, are unable to do so. This has caused massive drops in the population of many different salmonid species, with some populations vanishing altogether.

Dams can have a negative impact on humans as well, especially dams that have been put out of commission and haven’t been maintained. Sediment build-up behind these dams can be overwhelming and with unregulated flows leading to dam failures and massive flooding across the US.

“These dams are making flooding worse as they aren’t designed to retain water for any large amount of time,” Eldridge said. “And with all the sediment built up behind them rushing out or solidifying along the river’s edge, when you have a flood, it’s just that much easier for a river to flood its banks. When floods happen, we have massive impacts on infrastructure. Roads can get washed out, and then all the sediment that’s held back gets washed out and pollutes water systems. It can be devastating.”

Now, while many dams are still in use and are, in fact, vital to the infrastructure of many towns and cities, the forgotten or useless dams are still in place in many places and are continuing to slowly strangle rivers and the ecosystems around them. Thankfully though, there is a simple solution to this problem—removing the dams.

Taking Dams Down

Removing a dam from a river can and will have immediate positive impacts on that river’s ecosystem, often restoring it to its original healthy foundations. Once a dam is removed, water levels stabilize, and sediment washes downstream, revealing the natural substrate of the river and allowing plant and animal species to once again survive and thrive in an area. However, removing a dam can be a tedious process, but with the right assistance, a river can become all it once was.

“When we remove a dam, we are basically giving the river back the pieces of itself,” Eldridge said. “Removing a dam allows the waterway to decide how it wants to be. We’ll add in some retaining walls and plant a lot of grass and whatnot, but eventually the river will return to a natural channel and pick however it wants to meander. By removing a dam, we’re restoring the natural river processes.”

Impacts from dam removal can be seen almost immediately, especially in places where a dam blocks fish passage. In 2011 and 2014, two dams were removed from the Elwha River in Washington State, washing over 20 million tons of sediment downstream. By 2017 the Elwha saw the return of many species that had been largely absent from its waters, including steelhead and coho salmon. What’s more is that the sediment deposition at the mouth of the river created a perfect habitat and increased the population of coastal species such as sandlace (a forage fish species) as well as shellfish and crabs which increased the population of larger predatory fish species and waterfowl. In short, removing the dam from the Elwha was like lancing a festering sore. The project was so successful that other rivers are now being targeted for dam removal.

In Oregon, the largest and most significant dam removal in US history is currently underway, with four dams being slotted for removal from the Klamath River, which flows through the Cascade Mountains for 260 miles down to California. For years the salmon and steelhead on the Klamath have been declining at an unprecedented rate, affecting both the sport fishing and even the lifestyle of many of the locals who depend on the river.

“The dams on the Klamath are and were terrible for fish and indeed the entire ecosystem, “ Director of Yurok Tribal Fisheries Department and tribe member Barry McCovey Jr. said. “A river is a system that supports so many different species of fish and wildlife, and a dam impacts that and everything that river is associated with. On the Klamath, we’ve seen what a dam can do to a river system and the impacts are terrible. The river is so important to indigenous people, as important as the air we breathe, and to have the river in a degraded state has weighed heavy on our hearts.”

Since the Klamath dam’s construction from 1903 to 1967, the fish population of the Klamath River has been in decline—a tragedy for the people who depend on the river and its salmon to suffer through. In addition, the dam’s presence caused the water of the river to warm to such an extent that massive algae blooms began to show up during low-water years, making the water toxic for both humans and animals alike. So, when the opportunity arose to remove the dams, tribal communities and groups like Trout Unlimited came together to remove the dams and restore the river to its original glory.

“There are four dams that are in the process of being removed on the Klamath,” Oregon Director of Trout Unlimited, Chrysten Rivard told MeatEater. “All three of them were put in place for hydropower. When that project came back in for re-licensing, taking the opportunity to remove them was a no-brainer. These dams were on a river blocking 400 miles of salmon and steelhead spawning grounds and weren’t really powering much at all. The economics of it all just didn’t make sense. So, we’ll replace the green energy with other resources and allow the fish passage, which will bring so much more to the river.”

Indeed, the removal of the dams will hopefully fully restore fish populations within just a few years. When allowed to return naturally and not assisted by any sort of unnatural stocking program, anadromous fish like salmon and steelhead have proven time and time again that their natural instinct to spawn will lead them on the right path. With an additional 400 miles of newly opened spawning grounds for them to access, it’s expected that the fish of the Klamath will repopulate to healthy numbers in just a few years.

“They have been releasing spring chinook in the upper basin above the dams to understand how they are behaving,” Rivard said. “They’re using those releases to prioritize and understand natural colonization in that basin. All the fish are tagged so we can track where they go, and if there are issues with irrigation or predation, all of this will help us learn about how the salmon behave so we can concentrate on restoration and understand what we need to do to recolonize it all once the fish are restored. The bulk of the restoration will be natural recolonization—that’s the vision for the Klamath.”

The removal of the first dam has already been done and the Klamath is already seeing an improvement in water quality. The other three dams are planned to be completely removed by 2024, and with that plan comes anticipation for the future. The removal of the dams has brought a new hope and outlook to the local communities who have had to spend so many dark years watching the river decline.

Going with the Flow

In 2022 alone, 65 dams were removed across the United States, reconnecting more than 430 miles of river across 20 states, allowing fish and wildlife to begin populating areas that they haven’t been seen in centuries!

“The health of the river reflects on the health of our people, and when we see the river restored and see that healing, we will see the healing of the people,” McCovey Jr. told MeatEater. “It’s been a long, long uphill battle and now it feels like an amazing time to be alive. We’re all about restoring balance to these ecosystems, and there is no bigger step that you can take than removing a dam. This is one of the biggest steps forward that we could ever take. Hopefully by this time next year, we will have a free-flowing Klamath River for the first time in 100 years. And though there are still going to be more battles to fight, the removal of the dams will, at least for now, create a time of healing for us all.”