The article presents some results of the research on the treatment of highly mineralized sulfate-containing wastewater. Starting from the experiments with model and full-scale trials, the author has developed a technology that allows to clean such wastewater to correspond to MPC of fishery waters. The suggested technology has its basis in the separate treatment of wastewater with different initial sulfate content using step by step lime process: 1st stage of adjusting the pH to 8-9 with separation of metal hydro-xides and, partly, plaster; 2nd stage is adjusting to pH 12 and releasing of the residual sulphate as gypsum. Wastewater conditioning after overalkalization is suggested to be performed by recarbonation through carbon dioxide blowing; aftertreatment for discharge into water courses or the repeated use is carried out through membrane or biotechno-logy (bioplato) methods.