The so-called GST Pond (“Gesellschaft für Sport und Technik”, or Society for Sport and Technology) is the post-mining body of water formed by pits II and III of the former “Providentia” open-cast mine, northwest of the town of Döbern. In the GDR (former East Germany), the GST operated a shooting range and water sports facilities here, among other things. The sports camp for Döbern and the surrounding area was located a little north of the lake, on the B115 federal road. The “Providentia” mine field measures about 2.6 km N-S and 2.0 km E-W and includes five mining pits (numbered from West to East). Today’s lake extends along the confines of the pits in a NNW-SSE direction, reaching a maximum longitudinal extent of about 830 m.
The area of the mine belongs to the glaciotectonic, large-scale structure of the “Döbern-Triebel Arc”. Compared to other mines in the Muskau Arch, the layers of this structure dip to the east at a shallower angle and exhibit a wider scale spacing. Due to this characteristic, the thickness of the outcropping seams at the surface is relatively large, so that portions of the coal were able to be mined above ground.
The mine was operated over a period of 70 years in total, from 1864 to 1934. Pit II was the main mining pit and was excavated intermittently in various sections, largely via open-cast mining, though also in part via underground mining, until it was closed in 1934. Pits IV (“Friedhofsmulde”, or Cemetery Pit) and V (“Mühlenteichmulde”, or Mill Pond Pit), east of federal road B115, were the smallest deposits in the mine field and were first developed in 1928/29, operating for only a few years.
Today, more than 80 years after the end of mining, the water is still acidic and is not freshening out. This is impressively visible in the brown iron hydroxide sludge that accumulates at the edge of the lake. Inflowing springs in the immediate vicinity continue to supply the lake with iron sulfate waters. After mining activities altered the headwater region of the Malxe River (which gave its name to the municipality of Neiße-Malxetal), the overflow of “GST Pond” became one of the two headwaters of the river.