Impact of Mine Waters on River Water Quality in the Upper Silesian Coal Basin

The Upper Silesian Coal Basin (USCB) is located within the Vistnla and Oder basins in the southern part of Poland. The coal seams in the USCB are exploited by the underground mining of average depth of 650 m, up to 1200 m. Studies on hydrogeochemical environment showed a normal vertical and horizontal hydrogeochemical zonation in the whole of USCB. As a general trend the level of groundwater mineralization increases with depth and is independent of the age of the strata. Thus the coal mines pump groundwaters of different mineralization which varies from 0.2 to 372.0 g/dm3 The natnral inflow of groundwaters into the mines equals 630 m3/min. There is a high degree of diversification of mine waters total dissolved solids (TDS), pumped out from the mines into the rivers. Mean mineralization of these waters is about 11 g!dm3. The discharge of the saline mine waters with the content of7069 Mg/d of Cland S042has resulted in degradation of the river water quality. About 66% of the overall length of the rivers in USCB carry excessively polluted water which is unsuitable for any use and 91% of the surface water resources belong to the out-of-class purity class.