Multi-stage water pollution trap

A chamber having an inlet for receiving polluted storm-water runoff and an outlet for the storm water to flow out. Within the chamber are a screen, one or more baffles, a collection reservoir, and a pivotal filter. The screen is elevated for separating and suspending miscellaneous debris such as vegetative matter, paper, and plastic. The baffles increase storm-water residence time to encourage settling of particulate matter such as sand and grit. The collection reservoir has an adjustable weir for skimming off floating matter such as motor oil, other hydrocarbons, and detergents. And the pivotal filter catches clay during typical storm flows and pivots out of the way during higher flows. In addition, a method for maintaining the pollution trap includes removing the screen for cleaning, suctioning out the particulate matter and oil, and replacing the pivotal filter member.