<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">The paper presents a system of environmental monitoring (EM) of Contract Areas, which allows to differentiating the impact caused by the activities of the operator of Contract Area, and the impact caused by extraneous sources of pollution (adjacent oil fields development, industrial, agricultural and municipal discharges, mud volcanoes, dumping, etc.). As impact indicators used benthic communities (motionless infauna), widely used in world offshore practice. System refers to category of knowledge-based support tools of EM. System of this category opens up additional opportunities to improve the adequacy and effectiveness of the EM in the difficult conditions of the Caspian Sea, exacerbated by the “new oil bum” on the Caspian shelf and geopolitical situation prevailing in region after the collapse of the Soviet Union.</span></span></p>