Case study: Environment in the Usti region

Air

Poisoned by polluted air, forests in the Ore mountains died, and mining threatened remaining healthy beech forests on the southern slopes the Ore Mountains, key to maintaining ecological stability of the region.

Water

The northern (mountainous) part of the region has the rainy weather and numerous springs are there. On the other hand, in the central and southern part of the region, which lies in the rain shadow, are water resources very poor.

Most important dominant from the historical point of view was the Komořany lake, which was the largest lake in the Czech kingdom. The highest surface area was recorded some 700 years ago, and it was about 5600 ha. The lake was gradually silting with sediments from the Ore Mountains, making the area and depth very quickly dwindled. The lake was stretching between the villages Dřínov, Ervěnice, Komořany and Souš, Dolní Jiřetín and its eastern part was near to Most.

From west to east through the lake flowed the river Bílina; the Lake was several feet deep, surrounded by marshes and peat bogs. Another many streams and rivers from the Ore mountains were flowing into it. Since 1831 the lake was gradually drained artificially for up to 6 km² area in early 90 of the 19th century due to development of coal mining. Later on excavation of its last remnants was a major change in water management in northwestern Bohemia in the postwar period.

Greatest (most watery) and longest flow in the region is the Bílina River, which flows in the Chomutov and flows in Usti nad Labem in the river Elbe. Its total length is 82 km, of which in the Most region is 25 km.

In the Most region, cultural landscape was destroyed due to the brown coal mining, which included drainage and water management systems that were created over hundreds of years and supported the ecological stability of landscape and its agricultural and forestry functions. Water flows were not only regulated, but also their direction changed. An example is the river Bilina, whose direction was changed in several places and all its left-sided (mountain) tributaries as well. The rerouting, with the use of pipes, of the river Bilina through the Ervěnický corridor between Jirkov and Komořany is part of the Podkrušnohorský water supply conduit (in the Lower Ore Mountains). The Podkrušnohorský water supply conduit was built in stages from 1961 to 1982 and used to supply energy industry and the Most and Chomutov and surface water as a protection against the effects of brown-coal mines flooding - it serves as the entire water supply system of North Bohemia replacing the original local sources of drinking water in the area. Railways, roads and other technical infrastructure projects were similarly rerouted through the same corridor.