Rudabányai bányató

The Rudabányai bányató (Rudabányai Lake, more rarely Rudabányai tengerszem) is an artificially created mining pond in Hungary, in the outer pit of the former Rudabánya iron ore mine, in the administrative area of Felsőtelek. It is one of the deepest standing waters in Hungary.

Location

It is located in Borsod-Abaúj-Zemplén County, northeast of the town of Rudabánya and south of the settlement of Felsőtelek. The pond was formed at the junction of the Vilmos and Andrássy II mining sections in the outer pit of the former Rudabánya iron ore mine. The lake lies on private land and can be approached via a private road from the Szuhogy side of the town. Adjacent to the lake is the area called Majomsziget, the Rudapithecus exhibition, one of Hungary’s important paleoanthropological sites, where in 1965 the more than 10‑million‑year‑old Rudapithecus hungaricus specimen was discovered.

Description

The existence of the mining pond is thanks to the large‑scale iron ore mining that began in 1880. Iron ore mining and enrichment in Rudabánya were discontinued on 31 December 1985, and the necessary liquidation and reclamation works were carried out in 1986‑88. The mining ponds then formed after extraction ceased, along with the pumping of the tunnels and outer pits. The mining pond is not fed by a stream or other watercourse; it receives its water from infiltration from the surrounding surface and mainly from underground groundwater. As rainwater filled the cavities, one of Hungary’s deepest lakes was created. A previous collapse divided the lake into two parts, creating a shallower section with a deepest point of 16‑17 metres and a deeper section where the deepest point is around 35‑36 metres. On the northeastern side of the pond the water depth changes abruptly, and the mining levels can still be traced beneath the water.

The lake's turquoise‑green water level rises year after year during wetter periods and falls in drier years. Bathing is dangerous and therefore prohibited. Because the mine lake's water is cold, nutrient‑poor, and its fauna is sparse, it is not suitable for fishing. The water temperature drops to 6 °C below a depth of 15 metres, but below that depth the influence of external environmental factors is no longer typical, and the temperature does not change. One characteristic of the mine lake water is the high proportion of sulfate ions. This ion composition, rarely found in our domestic waters, together with the exceptionally high salt content makes the lake water unique. The sulfate partly dissolves from the bedrock and partly forms from sulfur compounds (e.g., pyrite) that have entered the sediment and oxidize.

Water‑quality measurements have shown that in the upper parts of the mine lake copper and barium were the dominant pollutants, while at deeper points iron and manganese prevailed. The mine lake’s sludge contains heavy metals above the permitted limit, such as mercury, manganese, barium, lead, copper and aluminium. This may be because these metals are present in large quantities in the lake’s sidewalls, where they are leached out, but at depth they can no longer oxidize, so their amount will continue to increase in the future.

Since the 2000s the lake has become an increasingly important tourist destination, especially among hikers, nature photographers, wedding photographers and filmmakers. A nature trail runs around the lake, with viewpoints, information boards, benches and a large pier along the route.

Lake depth

Although it is widely spread on internet sites and tourism pages that the lake is Hungary’s deepest water body at nearly 60 metres deep, some unreferenced sources also mention depths of 70–75 metres; scientific measurements have not confirmed this. Several independent instrumental hydrological measurement series have determined the lake’s deepest point at 34–36 metres.

The lake and its surroundings in feature films

The Hungarian scientific fantasy TV film *Gyémántpiramis* (1985, directed by Rajnai András) was made before the lake was formed. The barren exterior cutaway represents the surface of an alien, uninhabited planet.

The lake is one of the locations – the Italian carrier pigeon station – of the Hungarian World War I film *Szürke senkik* (2016, directed by Kovács István).