Army Corps of Engineers Seeking Public Comment on South Jetty

GH LTMS Ltr Report EA March2012

Erosion at the South JettyWaves erode the beach near the South Jetty
In 1993, storm waves plowed through Westhaven State Park into Halfmoon Bay, threatening Westport’s wastewater treatment plant, aquifer, and sewer outfall.

Ongoing erosion and repairs
In 1994, the US Army Corps of Engineers filled the eroded area at Westhaven State Park with 600,000 cubic yards of dredged material. The erosion continued; waves washed away 10,000 cubic yards of sand per year from the site. In 2002, the US Army Corps of Engineers filled the eroding site again. Repairs to the beach totaled nearly $12 million.

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What’s happening near the South Jetty?

  • High wave energy
    Wave action is too intense for sand to build up. As waves bounce and refract around the Grays Harbor ebb-tidal delta, they focus energy. The steep slope of South Beach also allows bigger waves to break closer to shore.
  • Summer sand loss
    During the summer, sand is carried south along beaches by littoral drift.The Grays Harbor entrance, delta, and jetties may block this flow of summer sand, reducing the sand supply.
  • Winter sand loss
    During the winter, sand is carried north along beaches by littoral drift.The South Jetty may interrupt this flow of winter sand, decreasing the sand supply to Halfmoon Bay.
  • Small offshore bars
    Offshore bars help buffer beaches against pounding wave action. Near South Beach however, offshore bars are relatively small.