The most silted up lake of the Carinthian Lowland, the Gösselsdorfer See, is situated in the south east of the Turnersee. From originally about 1 km² water surface there are only 32 ha left. The highest depth is 3 m. Large parts of the lake ground are not more than 2 or 2, 5 m deep, that is why a thermal stratification cannot be build up there. Lake fed by ground water. The lake has only negligible surface-inflows, the feeding is mostly done by the ground water. The runoff with a water volume of 150l/s leaves the lake in the north and drains into the Drau.
Lake with boggy character. The Gösselsdorfer See is mostly surrounded by a broad reed stand. The water surface itself is covered by a rich amount of water lilies, pond lilies and underwater vegetation. The neighboring silting up areas in the south and north give the lake a swampy character. The high contents of humane acid cause the brownish color of the water.
Important for the birds` passage. The Gösselsdorfer See serves a resting place for the migrant birds after having crossed the Karawanken. There are many brooding birds such as great crested grebe, mallard and reed bunting.
Landscape protection area. The Gösselsdorfer See is situated in the landscape protection area Gösselsdorfer See with about 476 ha. (LGBL.51/70, 101/79, 75/ 86) In the south of the lake another landscape protection area called Gösselsdorfer See Süd with about 23, 4 ha (LGBl 71/86) was established.
Regressive fish population. The carp reproduces itself, there can be found "Spiegelkarpfen" as well as wild carp. The Gösselsdorfer See also shows a good population of catfish, whereof you can find all age-groups. Grass carp and silver carp were stocked in the 1970s, but the stock is regressive. There are neither bleak nor pike perch.