Lake Starnberger (the second widest of Bavaria) is located 20 km north to the northern periphery of the Alps and was formed during the last glacial period ("Isar-Loisach-glacier") some 15,000-20,000 years ago. With a maximum depth of 128 m and a volume of about 3 billion m2 Lake Starnberger is the greatest water body of Bavaria. The lake measures 20 km from north to south and reaches an average width of 2.8 km. The catchment area is 5.6 times as large as the lake itself. The water residence time is about 21 years since only a few small rivers flow into the lake (danger of eutrophication). Thirty-six% of the catchment area consist of woody vegetation - half is afforested plantation of conifers (Picea, Pinus) and half is mixed deciduous forest consisting mostly of beech (Fagus sylvatica). Additional 46% are farmlands (67% pasture land, 33% crop field). Surrounding settlements are mostly rural with Starnberg (located at the lake outlet) being the largest city with 17,000 inhabitants. As Munich, the capital of Bavaria with a population of 1.5 million is situated nearby (15 km), the area is much frequented for recreation activities. The originally oligotrophic lake has been influenced by economic development since the 1950's by nutrient loading of municipal sewage. The installation of a circular sewer line system from 1964 to 1976 and a treatment plant at the lake outlet improved the water quality tremendously, so that Lake Starnberger can now be called mesotrophic with a tendency to oligotrophic (Q1, Q2).