Draft:Most Lake

Most Lake is an artificial lake in Most in the Ústí nad Labem Region of the Czech Republic. The lake came to be as a result of land rehabilitation of an area formerly used as a lignite mine, and was named after the mine. The lake spans 311 ha (770 acres), has a length of 2.5 km (1.6 mi) and a width of 1.5 km (0.93 mi). The water level is 199 m above the mean sea level. Maximum depth of the lake is 71 m (233 ft), and its volume is 69.8 million m³ as its average depth is 22 m. The lake is open to the public since 12 September 2020.

Location

The lake is located in the northern part of the territory of Most. The lake is below the Hněvín hill (399 metres above mean sea level) (1 km away) and is located directly on top of the Most city which was demolished in the 1970s to make room for the Ležáky lignit mine. There is the relocated Church of the Assumption of the Virgin Mary near the lake and a sculpture of Saint John of Nepomuk.

The lake's premises have been added to the public transport network in May 2021 of the Most city as a part of the line 16 route.

History

The lake was created in place of the former lignite Ležáky mine, which was in operation between the 1970s up until 31 August 1999. The area affected by the mining activity was revitalized by Palivový kombinát Ústí. The lake's name was officially selected on 24 September 2020 by the city councilors. This decision came as a result of the working title that Palivový kombinát Ústí and the statutory city Most agreed upon at the start of the 21st century. This working title was then made public the moment that the filling up of the lake was commenced on 24 October 2008.

A company by the name of Cheminvest built a levee and a wharf at the lake. The wharf's capacity is up to several tenths of ships. The reclamation work was originally to be finished in 2018, however at the start of 2019 an announcement was made that the lake won't be accessible for recreational purposes for another year due to the lake's geological instabilities in the bedrock. In addition to that there were also delays in regards to the construction of the floating piers and other components which were to be the basis of the integrated emergency system. The lake was officially opened to the public on 12 September 2020, albeit without celebrations due to the coronavirus crisis, because of which the Most festivities were also cancelled.

In place of the Church of the Assumption of the Virgin Mary were planted chestnut, cherry and mulberry trees. The trees form the church's former location together with several paths.

Lake's water level regime

Water intake of the lake

View from the lake at the Most city, Hněvín castle and the hill Široký vrch

The original intent from 2002 relied on setting up the river Bílina as the water source, however after further inspection by the regional sanitation station the river was deemed unfit due to a high degree of pollution. The analyzed area from which water would flow into the lake was classified as pollution V (heavily polluted water).

A better water source was selected in the form of the river Ohře, which would be drawn from the Nechranice industrial water supply and from the fixed weir Stranná located by the village of the same name (Stranná) at the 99.230 river mile. Another source of water was also the approximately 5 kilometres distant Kohinoor underground mine, and then some came from the lake's own drainage basin.

Filling up of the lake was officially commenced on 24 October 2008 and according to the project was to be finished by 2011. Festivities were commenced on the occasion of the second anniversary of the project's commencement. During the filling up the area was guarded and free movement in the area was restricted, and the filling up was stopped on 25 June 2012. It was then resumed in May 2014 to get the lake's water level to the final height 199 metres above mean sea level. The final height was reached in September 2014, since when the lake has been in testing phase up until the end of 2019. By 30 June, the lake's water target was 198.03 metres above mean sea level, which corresponds to 297.91 hectares and a total volume of 69.809 million m³. From the commencement of the lake's filling up the water level rose 52.91 metres. From May 2014 do September 2014, the lake received 5.0 million m³ of water, so the 309.41 hectare lake had a total volume of 70.480 million m³.

Water-level maintenance

Map of the north Bohemian reclamation lakes with their individual depths noted down

The year 2016 was warmer than expected and as such the lake didn't intake enough water naturally, thus it was filled up again from the Ohře river, which turned out expensive. The original water level fluctuation of ±60 cm was first lowered to ±5 cm, then removed entirely to prevent drying of the banks and then the subsequent need to resoak them during a filling-up. There was a water treatment plant planned for construction, and it was meant to treat the incoming water from the Kohinoor underground mine. The lake costs 20 million crowns annually, and up to half of this amount can be expenses on securing the water intake from Ohře.

Fauna

6 species of aquatic molluscs were found in the lake in 2013 - a combination of 5 species of freshwater snails and one species of bivalve mollusc.

Water birds

According to one Most ornithology club bird census which took place in January 2019, the number of water birds present was again higher than in 2018. The experts counted a total of 6,042 birds across 22 species. The dominant among these species were black-headed gull (1,700 specimen) and the eurasian coot (1,800 specimen). Then there were also frequent common gull, caspian gull, european herring gull, yellow-legged gull, common pochard and tufted duck. There were also sightings of swans, ducks, herons and cormorants. Among rare sightings were common goldeneye, red-crested pochard, common merganser, smew, black-throated loon, red-necked grebe, black-necked grebe, common reed bunting, meadow pipit and velvet scoter. According to the Most ornithologists the total water bird count is high and puts the Most lake among the top 10 water bird wintering grounds in all of the Czech Republic.

Gallery

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  Ohře intake point
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  View towards Hněvín castle
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  Weir in the lake
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  Landmass created by erosion of mine's borders
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  Educational trail "Napouštění jezera Most"
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  Former Ležáky lignite mine

References

Category:Artificial lakes of the Czech Republic Category:Geography of the Ústí nad Labem Region Category:Most (city)