The entire reservoir is enclosed by a 20-kilometre embankment. Every day, it grows by tens of thousands of tonnes as new material is deposited. It was built on the site of three villages that have since vanished without a trace. Already the largest facility of its kind in Europe, it is set to become something even more remarkable within the next decade or so.
Construction began in 1974 in Lower Silesia, between the towns of Polkowice and Rudna. The villages of Barszów, Kalinówka and Pielgrzymów were submerged and permanently erased from the map. The reservoir began receiving waste in February 1977 and has remained in continuous operation ever since.
The facility is called Żelazny Most, named after a nearby village. It is owned by KGHM Polska Miedź and is a vital part of Poland’s copper production chain. Without it, copper production would have to stop immediately.
The largest in Europe
Today, Żelazny Most covers more than 2,000 hectares. It is surrounded by embankments with a combined length of more than 20 kilometres. The reservoir has a total storage capacity of up to 950 million cubic metres of material.
Each year, it receives as much as 30 million tonnes of waste generated during the flotation process used to concentrate copper ore. Only around 2 per cent of this material is copper; the remaining 98 per cent consists of waste rock that must be safely stored. As much as 75 per cent of the deposited material is reused to raise the embankments, which continue to grow year after year.
Growing for half a century
The crest of the embankments now rises as much as 80 metres above the surrounding landscape in some places. By 2037, it is expected to reach a height of 114 metres. If that happens, Żelazny Most will overtake the Solina Dam, which has been Poland’s tallest dam since 1968, standing just over 80 metres high. All indications suggest that Żelazny Most will surpass it.
At the beginning of 2026, the company obtained an environmental decision authorising the continuation of the expansion project. The approval, issued by the relevant local authorities with immediate enforceability, clears the way for submitting a full application for a building permit to the regional governor.
Why it has to be raised
The copper deposits in the Legnica, Lubin and Głogów region are expected to support mining operations for another 40 to 50 years. Every additional year of production generates millions more tonnes of waste that must be stored safely. According to KGHM representatives, raising the reservoir will extend copper production in Poland by at least another dozen years. Without expanding Żelazny Most, mining operations would have to be scaled back much sooner.
The reservoir is not expanding outwards but upwards. The surrounding area is already occupied by farmland and forests, leaving vertical expansion as the only viable option.