Greifensee
The Greifensee located in the Zurich canton in Switzerland about ten kilometers east of the city of Zurich, separated by the Pfannenstiel chain from Lake Zurich. With a length of 6 km and a maximum width of 1.6 kilometers, it is the second largest lake in the canton. Its shape resembles that of a fish: In the middle of the lake narrows to a width of less than 800 meters.
The catchment area of Greifensee is 160 km ². Main tributaries are the Ustermer Aa ( outflow of the Pfäffikersee ) and the Aabach. The drain is the smoothness that drains a large part of the Zurich Highlands.
Location and origin
The lake is located in a shaped from Linth glacier hills in an incurred during the last glacial trough. To the west rises the Panhandle Mountains in the east begins the Zurich Oberland. Despite these hills on both sides of the banks are flat. Islands there are in Greifensee no.
Originally the Greifensee accumulated on a terminal moraine at Dübendorf. Due to silting and melioration lost the lake since its creation more and more of its original size. Moore and plains in the north and south are witnesses of this thousand-year- long development.
Directly on the Greifensee is the old town of Greifensee. Separated by a shore zone of the water are the places Niederuster, Schwerzenbach, Maur and Fällanden. A little further away from the water are the city of Uster and Monchaltorf.
Conservation
The lakeshore are protected. The banks are not installed and are accessible only in a few places. Thus, the reed and fens and sedge meadows with a rich flora and fauna have been preserved in many places: Around the lake there are 400 plant species in the lake and its tributaries, 19 species of fish. The nature reserves are important for bird life. There are more than 120 types of migratory birds were detected. For the supervision and information of the nature reserve the Greifensee Foundation is responsible.
Due to the strong settlement and agricultural use in the region around the lake was long to discover a very strong concentration of phosphorus in the water, which damaged the biodiversity of the lake. Algae and stench kept away from the people. Since 1970, could be significantly improved by ventilation and reduction of phosphate initiate the situation. Since 1972 there are in the whole catchment area treatment plants.
The values are still lagging at more than twice the target value. Per year today reach around 10 tonnes of phosphorus into the lake. The oxygen content in the water especially during the summer months often too low. Therefore, in years with hot summers, there have been repeated a fish kill. In particular, whitefish and lake trout suffer from too high temperatures and the resulting algae. The Cantonal Office for Waste, Water, Energy and Air planned, therefore, to the west of the Aa - mouth a seawater ventilation system - as in Nachbarsee Pfäffikersee and other small lakes Zurich is in use already - to install. In spring 2009, a ventilation system was installed, which accumulates water from a depth of 12.5 meters by two diffusers with atmospheric oxygen. This system is intended to create an area of approximately one square kilometer a layer even in summer provides the fish sufficient oxygen and favorable temperature conditions.
Use
The nature around the lake and the quiet location attract many leisure seekers. Round -around popular hiking and biking trails. Private motor boats are prohibited on the Greifensee. The passenger ships of the shipping Cooperative Greifensee, however, offer on tours and operate a course traffic between Maur and Niederuster. In addition, still use rowing boats, stand-up paddlers and some sailboats the idyll. For bathers several bathhouses are available.
On the west bank there are several campsites. In Fällanden is close to the water a hostel.
Even today (2012 ) deserves a professional fisherman make a living on the lake.
Initially, autumn is held annually the Greifenseelauf. This half marathon leads around the lake.
History
On the eastern and northern shores of various prehistoric pile dwellings were found in the second half of the 19th century. The first bank settlements were inhabited since the Mesolithic period since about 8000 BC. They thus belong to the oldest archaeological sites in the canton of Zurich. The prehistoric site Storen / Wild Mountain on the right bank before the town Greifensee is a UNESCO World Heritage Site Prehistoric Pile Dwellings around the Alps.
When the castle Greifensee was built in the 12th century, the lake was still called Glattsee. It received its current name until 100 years later.
By correcting the smoothness and 1891 attached weir the average level of the lake was reduced by about 80 centimeters. The regulation time was important so that the industries on the Glatt possessed even in dry times sufficient water.
Since 1890, a regular boat service connects the western and eastern shores. On April 3, 1892 capsized an overloaded ship. Four people drowned there. The new steamship " Greiff " from 1895 was driven from 1916 with gasoline. Restored it chugs today, again driven by steam, over the lake. It is the oldest steamship in Switzerland. In 1933 the first motor ship on the operation.
1941, the lake and its banks were put under protection.
On April 24, 1944 fell a wounded American B -17 bombers of the United States Air Force in the lake, with several crew members died.
1994 issued to the Government of the Canton of Zurich, a revised protection regulation.