Armoring impacts on puget sound beaches

Impacts of Armoring on Puget Sound Beaches: Diverse Effects on Diverse Scales

Researchers provided long-needed data and protocols for evaluating beach armoring impacts and shoreline restoration benefits, leveraging state funds to expand this research.

Principal Investigator

Megan Dethier, University of Washington, Friday Harbor Laboratories


Washington Sea Grant-funded researchers monitored and compared key ecological indicators at 31 pairs of armored and unarmored beaches on south and central Puget Sound. The study provided groundbreaking data that identified the physical and biological characteristics of shoreline environments that may be affected by armoring, including beach wrack, riparian vegetation, important invertebrate populations, sediments, and bird and fish populations.

Research Updates


About a third of Puget Sound’s 2,500 miles of shoreline are altered, and many beaches have been extensively armored with bulkheads and other hard materials. The Puget Sound Action Agenda establishes armor removal and beach restoration as a regional priority, and a net decrease in armored shorelines is one of the restoration targets for 2025. However, there is little objective scientific information available to assess armoring impacts and restoration responses.


The study provided the impetus for a systematic evaluation of armored and unarmored sites throughout Puget Sound, and state agencies funded its extension to northern beaches. Managers recognize the importance of monitoring shoreline changes, and the study-identified indicators and measurement procedures are being used to establish sound-wide monitoring protocols.


Heerhartz SM (2013) Shoreline armoring disrupts marine–terrestrial connectivity across the nearshore ecotone. PhD dissertation, University of Washington, Seattle, WA.

Heerhartz SM, Dethier MN, Toft JD, Cordell JR, Ogston AS (2013) Effects of shoreline armoring on beach wrack subsidies to the nearshore ecotone in an estuarine fjord. Estuaries and Coasts, (online).

Kuehne L (2012) Science on the edge: birds on beaches and the quest for a better seawall. Earthcare Northwest, Summer.

“Shoreline armoring in Puget Sound.” Dethier M. University of Washington Friday Harbor Laboratories. Created 2011.