The surprising alliance shaping the fate of America’s 90,000 dams

This winter, while visiting my parents in California, I came across a YouTube ad that certainly wasn’t running in Utah, where I was living. Against stock footage of outdoor adventures and fresh produce, the narrator promised guilt-free living powered by “clean” electricity — all from hydropower. The message felt overly tidy, reassuring me that I didn’t need to think about where my electricity came from. Then the ad cut to drone footage of a massive dam — a visual reminder of how central dams are to hydropower.

That image jogged my memory. Just days earlier, I’d listened to a podcast about removing the Klamath River Dams in northern California. I’d gone camping and climbing in that area and remembered the dams and their impact on the landscape. The podcast celebrated their removal as a major win for the surrounding ecosystem, salmon runs, water quality, and Indigenous communities.

The contrast felt striking and obvious. On one side, dams symbolize clean energy. On the other, their removal represents ecological restoration. This raises the obvious question: Which is better for the environment — clean energy from hydropower or free-flowing rivers? And is it really an “either-or” narrative?

Conflicting desires or a shared mission?

When I described this perceived conflict to Malcolm Woolf, president of the National Hydropower Association (NHA), I heard a respectful but clearly exasperated sigh. “So much of public policy is driven by bumper stickers,” he said. “The notion that hydropower and dam removals are fundamentally at odds represents a false dichotomy.”

Katie Schmidt, associate director of the National Dam Removal Program at American Rivers, echoes Woolf’s sentiment.

“Most of the dams we’ve removed had no connection to energy production. In fact, fewer than 50 hydropower dams have been removed since the 1990s. When hydropower dams are removed, it’s usually because they’re no longer generating significant power or because maintaining them isn’t economically viable. Dams are only removed with the dam owner’s consent.”

Their messages were reassuring, but my confusion didn’t just stem from surface-level ads. It also came from the reality that hydropower hasn’t grown in decades. Meanwhile, dam removal, though gaining momentum, remains slow-moving. This imbalance could easily give the impression that the two efforts are fundamentally at odds — that progress in one comes at the expense of the other.

So, if the two aren’t opposing one another, what is slowing things down? Why aren’t we seeing more hydropower and more free-flowing rivers? 

It’s a shared struggle against a slow, complicated system that hinders progress on both fronts. Bureaucratic inefficiency plays a role, as does the inherent challenge of managing the world’s most precious resource: water.

“Water is inherently a finite, public good,” Woolf says. “As it flows downhill through our facilities, it’s used by other people in the community for different purposes. That means any decision involves a web of agencies, from federal to local.”

An “Uncommon Dialogue”

The surprising alliance between these two movements is rooted in a simple fact: The U.S. has built a lot of dams — around 90,000. Only 3% of them generate hydropower, while up to 85% are over 50 years old and in need of repair and management. However, experts like Schmidt say most don’t serve significant functions to justify the cost of repairs.

“The age of building major new dams ended 50 or 60 years ago,” Schmidt says. “Today, the question isn’t about building more — it’s about what to do with the 90,000 we already have. Removing obsolete dams doesn’t reduce energy production. Instead, it opens the door for healthier rivers, improved ecosystems, safer communities, and cleaner water — all while leaving plenty of existing dams available for hydropower expansion.”

Existing dams can also be retrofitted, a process that can be less ecologically harmful than constructing entirely new energy projects like wind or solar farms. That’s because the candidate dams are already part of the landscape and serve critical functions such as flood control, irrigation, or shipping. Their environmental impacts, such as disrupting natural river flows or fragmenting habitats, exist regardless of whether they generate energy. By retrofitting these structures to produce hydropower, we add renewable energy capabilities to infrastructure that would otherwise continue to exist without providing additional benefits.

In other words, retrofitting turns an ecological liability into a dual-purpose asset: The dam continues its original function while contributing to the nation’s renewable energy goals.

This idea led to the “Uncommon Dialogue,” a collaboration between hydropower advocates and dam removal proponents. Facilitated by Stanford University’s Steyer-Taylor Center for Energy Policy and Finance and the Stanford Woods Institute for the Environment, the dialogue brought together seemingly opposing groups to find common ground. Their focus? Remove ecologically harmful dams while retrofitting others for clean energy. To do so, they have to tackle shared challenges, namely the complex regulations governing water.

The state of dam removals: Slow flowing

Since 1999, more than 1,900 dams have been removed in the U.S., restoring thousands of miles of rivers. These projects have revived fish habitats, improved water quality, and boosted recreational opportunities. Often, they demonstrate that dam removal benefits the environment and local communities alike.

However, scientists have studied the impacts of fewer than 10% of dam removals, with even less research on long-term effects. Outcomes can vary depending on factors such as dam type, removal methods, surrounding land use, and watershed conditions. While most experts agree that dam removals often provide environmental and community benefits, the specific impacts differ case by case, and more research is needed to fully understand their long-term effects. 

On average, the United States removes 60 to 80 dams a year, a number Schmidt hopes nudges closer to 100 over the coming years. But there are significant roadblocks that slow down progress.

First, dam removals are complex undertakings that involve navigating state and federal permitting, lengthy fundraising efforts, and detailed hydrology assessments to evaluate post-removal water flow and environmental impacts. If a dam is federally regulated for hydropower, the dam owner must formally surrender their license. Schmidt notes that this process alone can take two to five years, is costly, and doesn’t always result in removal.

Beyond regulatory obstacles, misinformation creates resistance to dam removal. Some community members fear removing a dam will cause floods or leave permanent mudflats. Schmidt explains that only 17–20% of dams provide flood control because they require large reservoirs. As for mudflats, they do emerge briefly after removal, but proper restoration allows vegetation to return quickly. “We’ve seen dormant seeds sprout almost immediately after water levels drop,” Schmidt adds.

Another pervasive myth is that dams make more water. Schmidt clarifies, “Dams manage water, but adding one doesn’t mean you inherently have more water — it’s about controlling the flow and storage of what’s already there.” This misconception, especially prevalent in water-scarce states like California, often leads to misguided policies.

The state of hydropower: Stalled out

If dams suitable for hydropower retrofits exist, why isn’t hydropower growing?

“Hydropower retrofits don’t fail because of money or technology,” Woolf explains. “Companies are ready to invest in the infrastructure, sell the power, and recoup their costs. What slows us down is the regulatory process and a relicensing process that makes surrendering a license sometimes a more feasible alternative for owners.”

In 2018, Oak Ridge National Laboratory identified 100 existing dams with the highest potential for hydropower retrofits. Of those, 88 are owned by the U.S. Army Corps of Engineers, whose priorities often lie in flood control, navigation, and water supply — not energy production. That said, the Corps isn’t opposed to hydropower retrofits. In fact, they are the largest single contributor to clean renewable power in the country, simply because they manage so many hydropower facilities. 

“Retrofitting existing dams for hydropower requires threading the needle between competing priorities,” Woolf says.

Then there’s the licensing process. Every 50 years, hydropower plants must renew their licenses with the Federal Energy Regulatory Commission (FERC), a process that can drag on for eight to ten years. The primary cause? The sheer number of agencies involved in examining key questions one after the other. Woolf compares the process with the nuclear industry: “They have one regulatory body that aims to complete reactor relicensing in 18 months.”

With 30% of hydropower dams up for license renewal in the next decade, some facility owners might opt to surrender their licenses rather than endure the costly, decade-long process. This could trigger a wave of dam retirements, throwing us backward, not forward, in hydropower.

Some argue that dam removals and hydropower relicensing should take as long as they do, given their potential for a huge impact. Woolf says we can speed up the process while still being thorough.

“In particular, every agency with a stake in the dam removal or retrofit process waits for the others to finish their reports before they start their own,” he explains. “We’re essentially doing things in series, not together. Take every issue related to a dam — fish, water quality, recreation — and every agency runs their report one at a time. First FERC, then NEPA [the National Environmental Policy Act], then the state Fish and Wildlife Department. It’s all important, but if these agencies worked in concert instead of sequentially, we’d save years off the process without sacrificing thoroughness.”

And the complexity of balancing these priorities and navigating federal processes slows progress. 

“Since that 2018 report, only two or three of the top 100 dams have been retrofitted,” Woolf says. Meanwhile, alternative energy options like wind and solar can be developed much faster. “In the time it takes to retrofit a dam, you could build and take down a wind farm.”

The costs of leaving outdated dams

While the U.S. drags its feet on hydropower, its electricity demand is skyrocketing — fueled by data centers, air-conditioning needs, and population growth. Hydropower, as the only renewable energy source that can provide 24/7 power, is uniquely positioned to meet this demand. Unlike solar and wind, hydropower can be adjusted to meet demand at any time; it doesn’t rely on the wind blowing or the Sun shining. 

Without retrofits, natural gas is stepping in to fill the gap, locking in decades of fossil fuel dependence.

In 2016, the U.S. Department of Energy released a report with a name as optimistic as those hydropower YouTube ads: “The Vision of Hydropower.” In it, they described a future where we get more and more renewable energy from hydropower and pumped storage facilities. The report estimated that hydropower capacity could grow from 101 GW to 150 GW by 2050 — a nearly 50% increase. The latest statistics, nearly a decade later? In 2023, hydropower was around 80 GW. Clearly, we are not meeting that goal.

Leaving outdated dams in place comes with its own costs: degraded ecosystems, threats to public safety, and missed opportunities for river restoration.

Where there’s a sill, there’s a way …

The potential of hydropower and dam removal working together has concrete success stories, like the  Pawcatuck River project in Rhode Island. There, outdated dams were removed to restore free-flowing river ecosystems while increasing hydropower generation at other sites. By taking a basin-wide approach, they restored over 100 miles of wild river and managed to enhance renewable energy production at the same time.

There are also efforts to streamline the licensing process. In 2023, hydropower and dam removal advocates, alongside other stakeholders, introduced the Community and Hydropower Improvement Act (CHIA) in Congress. The bill aims to accelerate federal permitting for dam removals and hydropower retrofits by reducing redundant agency reviews while preserving environmental protections. With its focus on cutting red tape, CHIA could appeal to the new Republican-led House and Senate, but it has stalled amid broader legislative gridlock and competing priorities.

It’s an issue of vision and political will. “We don’t build these projects for one four-year term; we build them for decades. With the proper maintenance, these are forever assets” Woolf says. “It’s not about choosing one over the other; it’s a rare opportunity where doing both will benefit the environment and help decarbonize the grid.”

As for the future painted by the hydropower ad, well, I still don’t think most of my electricity will come from renewables anytime soon. But it’s reassuring to know we don’t have to choose between healthy rivers and hydropower — in other words, we’re not dammed if we do and dammed if we don’t.