Abstract: A novel removable catch basin filter assembly configured to fit within a catch basin of the type that collects stormwater runoff is disclosed herein. The removable catch basin filter assembly comprises an outer support frame sized to fit on the upper perimeter recessed ledge of the catch basin and underneath the grate, and a filtering system detachably connected to a selectively sized outer support frame. The filtering system comprises a lower filter bag made of a water permeable material (e.g., a geotextile) capable of filtering one or more contaminates contained within stormwater runoff, four receiving tabs positioned at or near the four corners of the inner perimeter edge of the upper perimeter flange of the filtering system, wherein the four receiving tabs are configured to detachably receive the four corners of the outer support frame.