Abstract: A method is provided of removing hydrocarbon pollutants from a surface of a body of water in a storm water filtration system containing an oil separation chamber including a removable top cover to provide access to the chamber for removing oil, a side wall with a storm water inlet, another side wall with a filtered storm water outlet in a region of the chamber lower than the inlet and an overflow storm water outlet located above the filtered storm water outlet. A porous container having an interior filled with oleophilic and substantially buoyant material is located upon the surface of the water in the oil separation chamber so that oil floating on the surface of the storm water in the chamber is adsorbed by the oleophilic and substantially buoyant material.