Armoring on Puget Sound: Progress towards a better baseline

The construction of seawalls and similar structures along Puget Sound’s shoreline impacts geomorphic processes and ecological functions. The extent of shoreline armor has been adopted by the Puget Sound Partnership as a vital sign indicator, is used by local, state, and federal groups as a measure of ecosystem function, and has been employed as a tool for prioritizing restoration actions. As a result, we recognized the importance of accurately characterizing the extent, character, and distribution of shoreline armor. The objectives of our project were to review existing data sources, assess methodologies, identify gaps in data quality or coverage, and to recommend steps for developing a reliable baseline for future monitoring and analyses. Previous efforts have suggested that approximately 27% of the region’s 4000 km of shoreline is armored, but our ability to answer important questions has been hampered by the quality and consistency of datasets, poorly documented methodologies, and the ability to relate armor with other shoreline information. In particular, we had difficulty associating armor with its geomorphic setting – bluffs and spits, small estuaries, river deltas, and artificial human landscapes – which greatly influences ecological impacts, management decisions, and restoration strategies. We noted the need for clear definitions and protocols for mapping and characterizing shoreline structures. Some attributes, such as condition and waterward extent, are ecologically important but difficult to measure. Environmentally friendlier soft or hybrid structures are particularly hard to identify and categorize. Our preliminary results provide a clearer picture of where armoring occurs and where there remain significant problems with data reliability and geographic consistency. We have begun a collaborative process to develop a high quality regional dataset of shoreline armor that will provide better understanding of the impacts of existing armor, a reliable baseline for assessing future change, and a tool to support prioritization for protection and restoration