The Lipno Reservoir (Czech Vodní nádrž Lipno, German, Lipno Reservoir) is a lake in the southwestern part of the Czech Republic, part of the Vltavská Kaskáda (czech Vltava cascade) and forms its fourth oldest and highest level. It is located on the border with Austria in the National Park and Protected Landscape Area Bohemian Forest (Czech Národní park a chráněná krajinná oblast Šumava) in Okres Český Krumlov (Krumlov region), only a small spur of the lake in the northwest is in Okres Prachatice (Prachatice district), im Southwest a very small part on Austrian territory (district Rohrbach, Upper Austria).
The reservoir was built in 1959, after 1952 to 1959 a dam with power plant was built in the Vltava valley. The measure was intended to protect the region, and in particular the downstream towns of České Budějovice and Prague, from flooding. Even then, the lake was nicknamed Jihočeské moře (German South Bohemian Sea) or Šumavské moře (German Bohemian Forest Sea).
Size and scope
Today, the lake has a volume of 309.5 million m³ and a total area of about 4650 ha, making it the largest lake in the Czech Republic by area. Its level is at full traffic at about 725.6 m n.m. Its length is 42 km with a maximum width of 5 km at Černá v Pošumaví (German Schwarzbach, hereinafter simply called Černá). The average depth is 6.5 m, the maximum 21 m. The storage area extends to the mouth of the Hajný creek in the Vltava and Ovesná.
The dam has a length of 296 m, is 25 m high and is located at the river kilometer 329,543. It is partly a Erdschüttdamm (right bank) and partly to a gravity dam (left bank) made of concrete. The storage power plant Lipno I has an output of 120 megawatts. The power plant is a cavern power plant located 160 meters below the dam. The tunnels for water drainage end a few kilometers downstream in the reservoir of the Lipno II hydroelectric power station ♁⊙. This lake serves as a reservoir for the irregular discharge of the power plant Lipno I. Originally fell between the power plants, the riverbed of the Vltava river on nine kilometers dry, only since 1996, a rehabilitation flow of 1.5 m³s-1 is drained. Only for water sports events and flood more water is drained.
The reservoir has an unstable temperature stratification, is eutrophic at a depth of view of 1.3 to 1.8 m  and has a recurrent blue-green algae infestation. Characteristic are low NO₃-N values (see nitrate) in the summer of about 0.1 to 0.5 mg / l in the entire water column. The eutrophy of the water began at the earliest after 1968, but at the latest in the 1980s. This is mainly due to effluents that contain excessive phosphorus, which in turn leads to excessive chlorophyll production. Although numerous treatment plants were built in the 1990s, which reduced the supply of phosphorus in the lake, but the trophies hardly improved. In order to better understand and improve the trophy of the lake, numerous studies (cf.) dealt with the topic. It turned out that in the 1990s mainly agriculture with 35 to 68 percent and municipal waste water with 21 to 42 percent were responsible for the high phosphorus content. As a solution, a greater clarification of the wastewater is considered. Recent data suggests a decrease in chlorophyll-a concentration following a sharp increase in 2001 and 2002. Despite these problems, drinking water can be extracted from the lake, both surface water and groundwater, which occurs in several places.
Flora and fauna
For some decades, there are moose in the region again
The lake is surrounded by large spruce forests, numerous swamps and larger agricultural land. These landscapes provide a home for many animals. Among them are numerous butterfly species, such. B. the peacock butterfly, Saateulen and the little fox. Other insects are z. B. various ground beetles and longhorn beetles. Also to be found are corncrake, whinchat, red-backed shrike, black grouse, peregrine falcon, partridge, woodpeckers, owls, the eagle owl and the white-tailed eagle. Among the mammals include field mouse, birch mouse, bats, deer, deer, wild boar, fox, marten, badger, lynx, and for some time the European moose in the woods near Svatý Tomáš (German "St. Thomas"). In the lake itself there are carp, pike, pike-perch, trout, brook trout, peltery, silver carp, perch and catfish, as well as crayfish and freshwater pearl mussels, which are very vulnerable.
The forests consist to a large extent of spruce, but also beech, which are the original vegetation. Other important species are the Great Anemone, Crested Finial, Noble Gamander, Grape Gamander, Three species of Woodland Bird, Riedgrass, Grape Pippau, Sage, St John's Wort, Heather (especially at the Devil's Wall and the Luč Mountain) and Stone Herbs, Pale Sheep's Fescue and Berglauch settled.
The climatic conditions at the lake are slightly different than those in the Český Krumlov district. Characteristic here is especially the short summer, which is also cool and humid. The average annual temperatures here are around 5 to 5.5 ° C, around 2 ° C lower than in the surrounding area. The highest temperatures are reached in July, with an average of 15 ° C, in the surrounding area 17 ° C. Rainfall is around 25 percent higher than in Budweis. Summer days (days when the temperature reaches at least 25 ° C) in warmer zones of the Český Krumlov Region are on average 38 each year, in the area around the lake 34. There are frosty days (days when the temperature drops below 0 ° C) on average 120, in the area of the lake it is 150 a year. The lake as a border area The post-1945 largely depopulated towns along the new border Austria-CSSR were declared by the Communist government shortly after the war as a restricted military area, many villages fell or were destroyed (see: military training area Boletice). This meant that after the emergence of the reservoir the right bank could be entered with some exceptions at Přední Výtoň. Likewise, it was forbidden to cross the middle of the lake in the direction of Austria; Military and border police strictly controlled this. Nevertheless, several people managed to flee over the green border to Austria, including in the Rakovská Bay on the right bank of the lake, since the shore is already Austrian territory. For the emergency, meaning the war, there was already since 1961 the plan, the reservoir Lipno accelerated to empty two-thirds to bring troops faster on the other side of the can can, similar plans for other reservoirs of the Moldau cascade , In addition, the military should control access to Moldova and all waters of the Moldova cascade. According to the same plans, the dam should be destroyed before it falls into the hands of the enemy.
The case of Barry Meeker aroused particular attention in 1975. On behalf of Heinz Heidrich, who had fled the GDR in 1973, the US pilot flew three times in a helicopter (Bell 206 JetRanger) flying low over the Czechoslovak border (on 17 August 1974 and on 15 and 17 August 1975) ). He landed at Dolní Vltavice, a district of Černá, and brought to these three flights nine GDR refugees, who were mostly relatives and acquaintances of Heidrich's, to West Germany. The third flight on 17 August 1975 did not succeed as planned, as happened to be border guards in construction near the intended landing site. These soldiers fired at the helicopter and prevented two people from escaping.  A few minutes later, Meeker landed at the hospital in Traunstein, for which he had been working as a rescue aircrafts for one and a half years, due to the shots and damaged helicopters.This spectacular incident went through the international Press. For example, Der Spiegel, Time Magazine and The Economist, as well as KSČ's party paper, Rudé právodarüber.1976 ZDF released a thirty-minute documentary titled Barry Meeker or I was just the pilot, in 2008 Czech television published a 10 - Minute reportage with contemporary witnesses. After the turn of 1989, the restricted area was dissolved in 1991 and the area developed touristically. Seen in this way, the restricted area proved to be a lucky factor for today's use, since there the barely touched nature is very well preserved.
The role of the reservoir at high tide
Open weirs of the Lipno reservoir during the flood 2002 The reservoir is used for flood control on the Vltava river above Prague. At the headwaters, at the edge of the low mountain range, precipitation is particularly high (see section "climatic characteristics"). Since Moldau and Elbe at the confluence similar flow rates, the regulation to the upper reaches of the Elbe is noticeable (see: flood protection in Dresden). Like other reservoirs in the floodplain of that time, the Lipno Reservoir was able to hold part of the flood in August 2002, initially relieving cities such as Český Krumlov, České Budějovice and Prague. Several newspapers later blamed the operators of the power plant for not having drained enough water when 11 and 12 August saw further rains. The charges against Zdeněk Zídek were particularly high, as he was also the manager of the dam, the manager of the port in Lipno (where many sailboats were moored) and Mayor of Lipno. He was accused of a conflict of interest. These claims were untenable. A study by the Czech Ministry of the Environment in 2003 did not detect serious shortcomings in coping with the flood.
At low tide you can see stumps, remnants of the trees cleared by the lake Since this flood, the level of the lake is constantly lowered by one to two meters, so that more leeway exists to absorb larger amounts of water. As additional water was drained in 2004 for a rafting championship on the Vltava River, it resulted in the emergence of some objects from the water that had been submerged there for almost 50 years, such as the water. B. rails and the former railway station of Horní Planá. The lake had a reserve of 127.7 million cubic meters in 2006, which allowed it to regulate the level of the Vltava during the floods of the same year so that the floods were not as bad as initially feared. electricity generation The original economic use of the reservoir includes the generation of energy by means of the accumulated water. The storage power plant Lipno I has a capacity of 120 megawatts and can be started up within three minutes if required. Increased water drainage can influence the downstream power generation of other power plants, including the Lipno II run-of-river power plant, which supplies up to 1.5 megawatts. These two power plants of the Czech energy operator ČEZ supply the Greater Lipno with electricity.
Drinking and process water treatment
The seawater is extracted in several places as groundwater and surface water, treated and used as drinking or industrial water. This happens among others in Hůrka (district of Černa), Lipno, Loučovice and Plískov. From here, the places around the lake and the farms are supplied with water. However, there is no management system for the entire region, so many households and entire resorts supply themselves with water from private wells. farm Fish farming in the Lipno lake is limited almost exclusively to the exposure of several thousand fish annually (details in the tourism section). In the 1990s, there were attempts to breed fish. For this purpose, at the mouth of the Black Brook (Černý potok) in the lake pots were created in which trout were bred from 1991 to 1995. At two to six percent, this breed contributed significantly to the phosphorus load on the water body
The lake, one of the most popular tourist destinations in Bohemia since the 1960s until the fall of 1989, is today an important economic factor in the region and not only a tourist destination for Czech tourists, but also German, Austrian and Dutch tourists. On the one hand, this may be due to nature, which is still very well preserved, especially on the right bank, but also because the region is very well developed for tourism. So can be here z. Hiking, cycling (there is a bike path around the lake), camping, rowing, swimming, swimming, sailing or surfing. Due to the good conditions, international kayaking and sailing competitions have been held here since the 1960s. Motorboating is allowed on the lake with engines up to 1oKw drive power. Popular is the uninhabited island Tajvan, which is 2 km away from the shore and 150 x 200 m (rare Czech spelling for Taiwan, located near Černá). The wooded island has no sights, but is used by anglers and geocachers and is easily accessible by boat. One of the newest attractions are rabbits on the small island, about 400 meters away from the dam. [ Important for tourism is the abundance of fish in the lake, which attracts many tourists, who often come only for fishing. As a result, around 4 to 4.5 million Czech crowns worth of fish, including around 60,000 one-kilogram carp, and pike-perch, pike and trout are released here every year, thanks to the sale of fishing permits in every major town gives, is financed.
Other attractions include the historic town centers of Frymburk and Horní Planá (Adalbert Stifter Birthplace), the all-summer fair in Černá and the numerous marinas such as. In Černá, as well as the newly built marina in Lipno in 2003 with attached swimming pool. In winter there are numerous cross-country skiing opportunities around the lake, as well as downhill slopes in Lipno and Frymburk, as well as an annual skating marathon and ice-skating events. Above the Olšina cove near Černá, the Olšina pond, which is one of the highest artificial ponds in Bohemia, is located on the tributary of the same name. Since 2003, an information center has been located above the dam and the power station, which is located in former premises of the power plant. Three ferries (Horní Planá-Bližší Lhota, Dolní Vltavice-Kyselov, Frymburk-Frýdava) cross the lake today, there are two bridges (one of which spans the small Rakovská Bay, as the bank here already belongs to Austria) and a railway bridge , It can be reached from Germany via the Philippsreut border crossing, from Austria via the B 126 Leonfeldener Straße and the Weigetschlag border crossing (municipality of Bad Leonfelden), from Prague via the E 55 or by train via the stops in Černá or Lipno. Sports Various national and international water sports championships have already taken place on the lake, such as sailing. Directly behind the dams of the dam, which drain more water for this purpose, national and international championships are carried out, for example in the rafting (last world championship 2003) and in the canoe slalom (last world championship 1967, the GDR won four gold medals). In 2007, Prague considered bidding for the 2016 or 2020 Summer Olympics, but this project was dropped due to the financial crisis. Since there is no possibility in Prague to host Olympic sailing competitions, the Lipno Reservoir has been proposed as a venue and has been deemed suitable by Paul Henderson, President of the International Sailing Federation. This was critically discussed in the press and among the population, partly because of the construction of the new highway, which would have been necessary in this case.