A chamber has an inlet for receiving polluted storm-water runoff and an outlet
for the storm water to flow out. Within the chamber is a collection reservoir having
an adjustable weir with a skimming edge for skimming off floating matter such as
motor oil, other hydrocarbons, and detergents. In alternative embodiments, there
are included a screen, one or more baffles, and/or a pivotal filter for further
dispersing, detaining, and/or filtering the storm water.