Abstract: An object of this invention is to provide a geotextile silt fence that has increasing permittivity with increase in height thereby allowing larger storm events, which impound at greater depths behind the fence in proportion to the runoff volume collected, to flow through the fence without overtopping. A further object of this invention is to provide a stiffening device at the top of the silt fence to reduce sagging and improper overtopping. This stiffening device is either a mono-directional extruded geogrid structure that is a higher mil thickness than the geotextile monofilament structure of the silt fence which is affixed to the geotextile continuously throughout the silt fence length by either thermal welding, sewing, or adhesives. A further object of this invention is to provide an overflow preferential pathway at the top of the silt fence through large voids either within the mono-directional extruded geogrid to allow controlled overflow of impounded water.