Abstract—Data of field studies elucidate how the chemical composition of groundwaters is formed at urban territories in the southern Fore-Ural areas. These data were used to determine the changes in the salt composition of pore-waters in the clay rocks, their exchange–adsorption characteristics, and the distribution and accumulation of supertoxicants in the rocks and waters. The effect of the chemical composition of the waters on hazardous geological processes is estimated. It is determined that the geological environment is most strongly impacted within the depth range from the surface to 15–20 m. Dioxins and heavy metals are concentrated in the ground at the sites of industrial facilities near the surface (at depths up to 5–7 m), and their concentrations drastically decrease at depths from 5–7 to 20 m. Liquid organic contaminants and water-soluble salts penetrate through almost the whole circulation zone. The self-clarification of the aquifers and the recovery of the natural parameters takes dozens to hundreds of years, even after the contamination source is eliminated, i.e., the characteristic time of this process exceeds the lifetime of one generation of humans.