Abstract: An geotextile silt fence has an increasing permittivity with increase in height thereby allowing larger storm events to flow through the fence without overtopping. A stiffening device is provided at the top of the silt fence to reduce sagging and improper overtopping. This stiffening device may be a mono-directional extruded geogrid structure that is a higher mil thickness than the geotextile monofilament structure of the silt fence and which is affixed to the geotextile continuously throughout the silt fence length. An overflow preferential pathway may be provided at the top of the silt fence through large voids within the geogrid providing controlled overflow of impounded water which mitigates structural failure of the silt by eliminating the typical overtopping failure mechanism.