The geochemical estimation of upper above-trap part of sedimentary cover groundwater has been carried out. Zonal subdivisions of the section have been taking into account the mineralization and chemical composition. The fresh and brackish groundwaters were subject of special attention. The dominant part of the water with mixed chemical composition is revealed. The shielding effect of section elements – permafrost and intrusion sheet of traps – on the hydrogeochemical zoning formation have been shown. The possible changes in hydrogeochemical situation due to the technogenic impact – large-scale and long-term water consumption from free water exchange zone are discussed.