was established in 1956. However, comparatively minor fluctuations of the lake's level continue to occur. In 1965 the lake gained of water within a single month, raising its level by . The water level decreased to a similar extent, by within one year as a result of the drought of 2003. Both types of events are perfectly within the normal range, and because of the shallowness of the water can be either exacerbated or compensated by the effects of wind pressure, which can temporarily raise or reduce the local water level by as much as . However, the lake remains sensitive to changes in its equilibrium, as recent climate change scenario simulations have shown. Before the regulation works of the 19th century, the lake extended in the southeast to the marshlands of the Hanság () which have been increasingly drained and claimed for agriculture from the 16th century onward. Originally, the lake was thus closely connected to the Danube and the Rába river systems. Nature and wildlife Most of the lake is surrounded by reeds which serve as a habitat for wildlife (making the lake an important resting place for migratory birds) and are harvested in winter as soon as the ice is solid enough. This serves a double purpose, one ecological (removal of the bulk of organic matter that would otherwise decay in the lake) and one economic (the reed is sold for various purposes, mostly related to construction and housing). During the summer months, there are occasional reed fires, as dry reed is easily flammable, and fires spread quickly because of the almost constant wind. Water quality is determined by temperature, wind, and by the amount of salt and mud emanating with the ground water from the sediments. Several plans for dams and other intrusive construction works which would have destroyed the lake and its biotopes were discussed during the first half of the 20th century but came to nothing. Detailed plans to divide the lake bed with earthworks so that certain parts with reasonably fertile soil could be permanently drained and claimed for agriculture while the remaining parts would be used for intensive aquaculture had been finalized and approved in 1918 but were abandoned when most of the lake became Austrian territory after World War I. In 1971 plans for a bridge across the Austrian part of the lake were thwarted by environmentalists. In 1993 the National