The primary objective of this report is to describe the effectiveness of two prefabricated-treatment devices in removing a suite of inorganic and organic water-quality constituents from stormwater runoff. This report also describes methods and techniques used to determine the effectiveness of these devices. Detailed data describing water quality, flow, constituent loads, and removal efficiencies are presented for inlet and outlet samples collected between June 2002 and October 2004. Another objective of this report is to add to the understanding of stormwater-runoff quality and quantity in an urban environment.