Impacts of Shoreline Armoring

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University of Washington is conducting research to identify the physical and biological impacts of shoreline armoring in Puget Sound. The Puget Sound Partnership has identified armoring as a significant threat to the health of the Sound and a key feature in need of restoration. Research is needed to understand impacts of armoring and to determine under what circumstances armoring has negative effects. We are investigating physical and biological features of paired armored and unarmored beaches throughout Puget Sound. This broad survey of sites will provide information about large-scale and long-term changes associated with armoring, and how these might vary among locations.


  • The research team maintains a google site.
  • EPA Funding has been provided through the Puget Sound Marine and Nearshore Grant Program.
  • ESRP provided some data collection at the Edgewater Beach Bulkhead Removal
  • Dethier et al 2016 impacts of armoring provides an extensive control-impact study of armoring effects in Puget Sound.
  • Reduction in wrack and log accumulation occurs alongside a reduction in intertidal invertebrate populations in armored beaches compared to unarmored beaches, particularly where armor occurs below MHHW.
  • There appears to be a relationship between cummulative beach armoring at the drift cell scale and physical attributes of beaches, specifically a coarsening of sediment texture, in Puget Sound, consistent with studies completed in other ecosystems.
  • Hypothesized effects of armoring on low intertidal systems was not detected.
  • There is high variation among beaches not related to the predicting variables, making change difficult to detect.
  • Work is led by Megan Dethier at Friday Harbor labs, University of Washington.