Seasonal and daily dynamics of pollutants content in municipal and mixed wastewaters of Barnaul has been studied; on account of which calculation method of maximum acceptible concentration of pollutants in industrial wastewater entering to urban-combined sewage system has been justified. At relatively uniform spatio-temporal distribution of pollutants in the municipal wastewater occasional sharp increases of some specific contaminants concentration have been registered which is connected with their burst release. Seasonal variations of pollutants concentrations in municipal wastewater of Barnaul have not been found (cyanides are the exception). There is constantly high concentration of such typical pollutants in municipal wastewater as suspended substances, BOD5, ammonia nitrogen, phosphates, sulfates, sulfides and cyanides; and their concentration significantly exceeds acceptable concentrations established by Barnaul administration for enterprises wastewater entering to urban sewage system. Currently industrial wastewaters of Barnaul practically have no effect on the quality of mixed wastewater entering to wastewater treatment plant.