What was once a historic town in the northern Czech Republic was demolished to make way for coal mining. Decades later, the same landscape has been transformed into a vast artificial lake where people now swim, relax and enjoy the surrounding natural environment.
Lake Most, located near the town of Most in the Ústí nad Labem region, was created from a former open-cast brown coal mine. The transformation was part of a large-scale effort to reclaim land that had been heavily altered by decades of mining. The process of filling the former mine with water began in 2008 and was completed in 2014, turning the huge mining pit into one of the Czech Republic’s largest artificial lakes.
The story of the lake is closely connected with the history of the old town of Most. During the 1970s and 1980s, the historic settlement was demolished to allow mining operations to expand and reach the brown coal reserves beneath it. The destruction of the town was a major consequence of the region’s dependence on lignite mining. When mining at the Ležáky mine eventually ended in 1999, the area was left with a massive open pit and a landscape dramatically different from the one that had existed before mining.
One of the few reminders of the old town that survived was the Church of the Assumption of the Virgin Mary. The church was moved to a new location rather than demolished and continues to stand close to the lake today.
Turning the abandoned mine into a lake was far more complicated than simply allowing water to collect in the enormous excavation. Engineers had to prepare the former mining site carefully before flooding could begin. The base of the future lake was sealed with clay, while measures were taken to stabilise the surrounding slopes and protect the banks from erosion caused by waves.
Because the former mine did not have an adequate natural source of water, water from the Ohře River was used to fill the pit. The process began in October 2008 but was interrupted while additional work was carried out to strengthen the banks. After several years of engineering and reclamation work, the filling process reached completion in 2014. The lake was not immediately opened to visitors because further landscaping and development work remained. It eventually opened to the public in September 2020.
Today, Lake Most covers more than 300 hectares and reaches a depth of around 70 to 75 metres at some points. The project reportedly cost about 2.5 billion Czech koruna. Its transformation from a heavily mined landscape into a recreational destination has also created space for wildlife, with more than two dozen bird species recorded nesting in the surrounding area. Visitors can use the lake’s beaches and take part in recreational activities around the water.
The environmental recovery of such former mining areas, however, requires continued monitoring. A 2025 study examining four Czech lakes created in areas affected by mining — Most, Milada, Medard and Barbora — found a variety of microorganisms and plankton in the water. Researchers also observed seasonal changes in the biological communities, indicating that these newly created aquatic ecosystems are continuing to develop.
The study found that the water chemistry of the lakes was generally within acceptable limits, although some measurements exceeded thresholds in individual lakes. At Lake Most, one hydrocarbon-related measurement known as C10-C40 was above the relevant threshold. The findings underline the need for regular monitoring even after a former mining site has been successfully converted into a recreational lake.
Lake Most is part of a wider effort in the Czech Republic to rehabilitate landscapes damaged by coal mining. Another former mining area, Lake Milada near Ústí nad Labem, was filled between 2001 and 2010 and has also become a recreational destination. Further large-scale reclamation projects are being considered, including a proposed lake at the ČSA quarry that could eventually cover around 1,259 hectares.
The transformation of Most illustrates the long and complex process of restoring landscapes after intensive mining. A place once dominated by excavation machinery and coal production has gradually become an area of water, beaches and wildlife. While the environmental consequences of decades of mining cannot simply be erased, the creation of Lake Most demonstrates how abandoned industrial landscapes can be given a new purpose through long-term reclamation and careful ecological management.
