Abstract: A silt filtration system for use with storm water catch basins of the type which include a fixed frame with a drain opening at the top of the catch basin and a grate covering the drain opening and includes a base frame having a pair of end rails and a pair of side rails adapted to fit within the fixed frame at the top of the catch basin. The silt filtration system also includes a pair of lengthwise support bars or rods which are removably positioned within the base frame and a pair of transverse support bars or rods which are removably positioned over the lengthwise support bars and supported by the side rails. The lengthwise and transverse bars suspend a filter bag within the catch basin which includes a pocket at the top end for receiving the lengthwise support bars and the transverse support bars. The silt filtration system may include a deflector for deflecting silt and/or sediment and the like over the grate and into the filter bag.