The paper provides an assessment of environmental impact made by the companies producing and transporting hydrocarbons in Western Siberia. Dynamics of perennial observations over the environment components in the area where hydrocarbon producing and transporting companies operate have been analyzed and justifications provided for a need in the optimal system for environmental air monitoring at the facilities under examination. Dispersion of air pollutants has been simulated using a licensed software ECOLOG (version 3.00), developed by “INTEGRAL” scientific production association. Based on simulation results the list of priority pollutants has been compiled. A method has been developed to determine the quantity of and optimal locations for fixed environmental moni- toring stations with account of emission parameters, and approaches have been proposed to creation of a system for operational environmental monitoring based on geoinformation software.