Such erosion, known as bluff recession, eventually causes the bluff crest to recede inland. The average rate of bluff recession in Pennsylvania is one foot per year. During the past two decades of monitoring, losses up to 20 feet in a single year have been recorded in specific locations. Bluff recession is a natural force, and by its own nature is not a problem. However, when homes and other structures are placed too close to the bluff crest, bluff recession becomes a serious threat to the structural integrity or long-term usefulness of these structures.
Bluff recession does cause property loss and can be a threat to public health and safety.
Groundwater and stormwater are other factors that can affect bluff stability and rates of bluff recession. Ice movement and cycles of freezing and thawing can exaggerate this effect. Groundwater occurs naturally on most bluff properties along Lake Erie. Excessive groundwater flows may cause bluff instability and soil movement when more water is present than the vegetation mat can remove through evaporation. Super saturation of sandy, clay or gravel soils can cause soil on the bluff face to flow or slump.