How (And Why) Europe Is Removing Its Dams

For centuries, Europe dominated its rivers with an extensive network of more than 150,000

dams

. These structures, some of which date back to the early 20th century, symbolized progress and power. Thousands of large

dams

were built along with countless smaller dams and barrages, generating electricity, controlling floods, and fueling industrial growth. However, this came at a hidden cost: dams disrupt the natural rhythms of rivers, harm ecosystems, and threaten the survival of migratory fish. Many of these structures are reaching the end of their useful lives and becoming costly risks across Europe. A silent revolution is taking place. The dams are being dismantled.

Building waterways for the first time in generations The recent removal of three dams on Finland's Holan River offers a glimpse of this transformation, but dismantling these colossal structures is a complex engineering challenge fraught with risk. So how exactly do engineers take down these concrete giants? Finland's Holan River, a 53 km waterway that flows into the vast expanse of Lake Ladoga, is home to a unique ecological treasure, the last surviving population of naturally enclosed salmon in the country; However, for more than a century, this precious ecosystem faced serious disturbances: dams, mainly Kangas kosi lenoski and rakosi, fragmented the flow of the river creating insurmountable barriers to the vital migration of salmon to their upstream spawning grounds.

They extended far beyond the salmon these dams altered the river's natural rhythms altering water levels and sediment transport and fragmenting the habitats of countless species that depended on the river's connectivity the tide began to turn In the late 1970s 1990, with the removal of smaller barriers on the Russian stretch of the river, the reappearance of salmon below the Kangas Koski dam ignited a local movement to restore the holan's natural flow after a decade of legal challenges, a groundbreaking decision was made . Companies would sell their dams and plants. This historic measure paved the way for Finland's most ambitious river restoration project to date.

A multi-year effort was launched to remove the three dams and revitalize the rapids. Between 2017 and 2019, the three old hydroelectric plants were acquired. the stage for its momentous decommissioning in September 2021 the first chapter of this transformation unfolded k gky Dam its demolition sparked an immediate ecological response an exciting sight emerged in just a few weeks salmon spawning nests dotted the newly opened section of the river A year later, in July 2022, the largest Lena Enosi Dam was also removed. The last chapter of this restoration story focused on the Rakosi Dam. This 4 Meer High barrier built in 1921 was the furthest obstacle upstream.

In August 2023, a carefully planned four-month process began to dismantle the dam and restore the surrounding area. Rapids, costing approximately €750,000, the project was made possible thanks to the generous support of public and private donors committed to ecological restoration, while the removal of the rakosi dam coincided with the salmon spawning season in autumn 2023 , making immediate observations that challenge the results below immensely Promising studies here at Kangas Kosi in September 2023 revealed a remarkable density of over 200 salmon fry per 10 x 10 m area, but how exactly dismantle these titans of concrete and steel? Think of dam removal as a giant construction project in reverse, but with the added challenge of working in and around a powerful river, engineers approach each dam like a unique puzzle, studying the size of the structure's age. and the specific conditions of the surrounding landscape.

Their goal is not only to break down the concrete but also to manage the massive volume of sediment that has been trapped behind it for years, maybe even decades. Imagine one way they approach this challenge. Imagine heavy machinery like excavators strategically

removing

sections of the concrete. damn wall it's not about brute force but controlled release, this allows the water to escape in stages Giving the downstream ecosystem a chance to adapt as the sediment that has been accumulating begins to move again, replenishing the riverbed and the habitats below. downstream, but the sediment itself is a wild card: is it full of life-giving nutrients or potentially harmful contaminants?

Understanding trapped sediment. It's key to keeping the river healthy, which is why engineers take samples and carefully analyze what's behind the dam. The answers they find determine the best way to handle it. Do they release it gradually or is a full-scale excavation necessary? Engineers have a toolkit of strategies for dismantling these concrete giants, each with their own advantages and trade-offs, let's dive into some common methods: The notch and release approach think of this as slowly releasing pressure Engineers cut strategic notches In the dam like steps in the concrete wall the water drains in a controlled and gradual manner, imitating a more natural flow, this gives the river time to adapt and the trapped sediment begins to redistribute.

Revitalizing downstream habitats along the way, patience is key here, it can take months, sometimes even a year, to completely drain the reservoir. Iconic projects like the Elwa and Glin Canyon dam removals use this method to achieve great ecological success. The quick release approach needs a faster solution. Imagine a giant tunnel running through the base of the dam creating a sudden, powerful rush of water and sediment. It is the fastest and cheapest method, but it is also riskier. the rise can cause flooding and erosion. Downstream it can damage Riverside ecosystems. It is only suitable in specific situations, perhaps when the reservoir is small or we can drain quickly to a much larger river that can handle the additional volume.

The dig and drain approach is sometimes the only way. First, engineers completely empty the reservoir, exposing a vast landscape of accumulated sediment, then heavy machinery comes in—think excavators and trucks—carefully

removing

this material for safe disposal elsewhere. It is a slow and expensive process that is often necessary when the sediment contains contaminants that could harm the downstream If the sediment retention approach is released, what if moving all that sediment is too expensive or logistically challenging in some cases? Engineers can literally divert the river around the dam. This involves building a new river channel that bypasses the barrier and leaves the sediment intact.

It is often used in remote locations where the cost of excavating and transporting large quantities of material would be astronomical. Dam removal projects can be incredibly expensive. That's why careful planning is so important. Sometimes focusing on smaller or less complex dams offers the greatest ecological rewards for the money spent. an example from France's Saloon River Engineers recently removed two huge dams and reopened a 60km stretch that was blocked for a century. They even use trapped sediment to rebuild river banks, helping nature recover at astonishing speed. Europe is moving forward and restoring its rivers in 2022. A record 325 dams have been dismantled, revitalizing these vital freshwater lifelines.

Spain, Sweden and France led the charge and even newcomers like Latvia and Luxembourg got involved in the majority of these barriers, a staggering 73% if we were smaller structures that still have a big impact on the river flow these efforts are vital restore free flow Rivers help reverse biodiversity loss one of the major threats to our world one of the most inspiring stories comes from war-torn Ukraine even a difficulty removed the 120-year-old bifa dam on the perkalaba river opening up 27 km of habitat for endangered species like salmon Dano the return of thriving fish populations could even create a biodiversity hotspot in the Carpathians Many of these removals targeted obsolete or dilapidated structures in Norway a hydraulic dam centenary on the Tromsa River was carefully demolished after a tireless campaign by local fishermen throughout Europe, projects such as the one that is unblocking kilometers of rivers, such as the 60 km restored after the removal of the Lar Roquba dam in France or the Finland's work on the Lanana Sosi Dam, part of its largest river restoration effort to date in total.

At least 832 km of waterways will be reconnected by 2022, but how much does this transformation cost while hydropower remains a major source of renewable energy? Many dams reach the end of their useful life. In Europe alone there are around 150,000 obsolete dams. A recent study estimates that removing 10m High Dam averages $6.2 million. Are we seeing the beginning of dam removal? Revolution, let us know in the comments below if you found this video informative, please subscribe and hit that notification.