The Water Pollution Prevention Complex in Saint Petersburg is the main line of defense to protect this beautiful Russian city against the flood. The complex has two passes with 25.4 km (15.8 miles) of dams and associated hydraulic structures and a six-lane highway with access roads, a tunnel, bridges and junctions through six gates, eleven protective dams and protective dam. When a flood threat occurs, the reservoirs on the dock fill with water, floating gates rise to the surface, and the sea of vessels is moved to the center of the convenient canal by reducing the blistering effect from the storm on the Neva Gulf water surface. When the flood hazard is lifted, the floating gates return to the clit and the water is pumped out.