The Švihov Reservoir on the Želivka River is currently the most important source of drinking water for most of Prague, part of Vysočina, and Central Bohemia, supplying approximately 1.5 million people. With a volume of 309 million m3, it’s the largest surface source of drinking water not only in the Czech Republic, but also in Central Europe as a whole (the famous Lake Macha could fit in it almost 40 times). At the inflow to the plant, the reservoir is supplemented by two smaller reservoirs that trap sediments (gravel, sand and biological pollution) and help to maintain water quality. Thanks to the optimal shape of its floor and its regulated biological equilibrium (which zoologists cleverly maintain by stocking it with plankton‑eating and predatory fish), the reservoir actually functions as a first stage of water treatment.
The dam consists of two directly connected parts: an earth embankment sealed with clay, and an attached concrete structure with an emergency spillway, intake towers and a dam outlet. Each of the two towers has five draw-off points, and water is taken off according to the depth where it is of the best quality. Below the 860-metre long dam is a pumping station, through which raw water is driven to the treatment plant at a rate of up to 7.7 m3/s. A small hydropower plant has also been in operation here since 2004, but it cannot operate constantly as priority is always given to drinking water production.
The Želivka River has its source (as the Hejlovka River) under Bukový Hill just below Pelhřimov, and its water must travel 100 km before it reaches the reservoir. The construction of a reservoir (or reservoirs) and a water treatment plant was first contemplated almost a hundred years ago, when the Podolí and Káraný sources became insufficient for the growing city of Prague. The Želivka was felt to be almost unpolluted by harmful substances from industry, agriculture or human habitation.
Building work didn’t begin, however, until 1965, when the present design was the winner out of six project alternatives. The chosen solution was a single large reservoir on the Želivka River, with water supply to Prague through an excavated tunnel. Seven years later, in 1972, the entire 39 km long valley of the Želivka was flooded with water. During the dam’s construction, a number of towns, smaller villages and isolated settlements were depopulated and submerged – for example Sedlice, Všebořice, Zahrádka, Dolní Kralovice and Onšovec – and over 3,600 people had to relocate to new homes.
...an unfinished bridge can be seen above the surface of the reservoir at Borovsko – a motorway project dating back to 1942?
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