Lake Beyşehir, the largest freshwater lake in Turkey as well as in the Mediterranean basin, has a surface area of approximately 650 km2 and mean and max depth of 5–6 and 8–9 m, respectively. The catchment is situated in a semidry Mediterranean climate having an average temperature of 11 °C and an annual total precipitation of 490 mm during 1960–2012. In this period, precipitation values fluctuated between 317 and 716 mm (Beyşehir meteorology station, www.mgm.gov.tr), and the lowest annual average temperature was recorded in 1992 (8.5 °C) the highest in 2010 (13.1 °C). The catchment area of the lake is 4704 km2. The northern and eastern parts of the catchment are flat and intensively used for crop farming, while the western part of the catchment is dominated by mountains covered with forests and small areas of low-intensity agriculture. Nearly half of the catchment (42.7%) is covered by range-brush, 25.5% by agricultural land, and 13.5% by water (including Lake Beyşehir, the inflows, and wetlands), while forested areas (evergreen and deciduous forests) constitute 11.2%. The elevation ranges between 1027 and 2958 m.a.s.l., with an average elevation of 1370 m.