The quality of mine waters discharging to the surface in the area of the inactive and reclaimed Jan Šverma hard coal mine, located in the Žacléř mining district in the Czech Republic, was investigated. The mine waters discharge to the surface primarily through abandoned adits. The study focused on discharges from the Prokopi, Antoni, and Egidi adits. These outflows form and feed a watercourse known as the Lampertický Potok. Both the mine waters and the stream waters were subjected to chemical analyses. The following parameters were determined: pH, conductivity, dissolved solids, suspended matter, BOD5, CODCr, chlorides, sulphates, Ca, Mg, Fe, Mn, and As. The mine waters contained high concentrations of dissolved substances, exceeding the regulatory standards for wastewater discharged into the environment. Among the dissolved substances, sulphates, calcium, and magnesium were dominant, though significant amounts of iron, manganese, and chlorides were also detected. Water contamination was selective and spatially variable. The stream waters were contaminated particularly with sulphates, magnesium, and manganese. Neither the mine waters nor the stream waters were found to be contaminated with organic compounds. The research demonstrated that reclaimed post-mining areas can adversely affect the environment – in the presented case, in a selective manner resulting from the geochemical parameters of the rocks, reclamation methods, and targeted protective measures.