Field Measurements of Shore Conditions to Assess Bulkhead Effects in Thurston County, South Puget Sound

This study investigated the effects of bulkheads and other armoring on beach conditions in Thurston County, Washington. Beach characteristics were measured at paired beach sites — neighboring and otherwise similar sites with and without bulkheads or other armoring. The study focused on beach characteristics relevant to spawning habitat for pacific sand lance and surf smelt, known as forage fish because of their importance to salmon. Armored locations, particularly in reaches of the shoreline where armoring was common, were found to have narrower beaches, with the greatest loss of beach typically at the higher elevations. Beach slope and sediment size were not significantly affected by the armoring. In a separate GIS-based investigation, it was determined that smaller, typically unnamed creeks contribute insignificant amounts of sediment in this area compared to the potential sediment supply from larger rivers or (most likely the largest contribution) from landslides and other mass wasting.