Tuesday, March 13, 2007

Salsbury Point

Salsbury Point has suffered several insults over the decades. The eastern portion of the spit and back barrier lagoon, including the historic tidal inlet, were replaced with houses. The western part was filled for the boat launch and the park. I understand the fill material was from the excavation of the approaches to the Hood Canal Bridge.

The bridge itself appears to have had a profound effect in this beach. Littoral drift (net) was originally north up Hood Canal and east around the point (it's why there was a recurved spit here in the first place), but the bridge acts like a big breakwater, effectively reducing fetch from the south and increasing the influence of northerly storms. I believe the bridge has reversed the net drift pattern, so that sediment eroded from the park now moves south and cannot be replaced. (In an earlier post, I noted that the west side of Point Roberts is another place where net drift may have been reversed).

Erosion had been met for years with haphazard dumping of large rocks, but in October, 1995, Kitsap County Parks replaced the rock and some of the fill with a gravel beach. 11 years later, it is doing great, except that it continues to spill gravel arond the corner toward the bridge. The beach at the eastern end has dropped at least a foot. What this beach really needs is an infusion of a few truckloads of sandy gravel every few years! Otherwise, someone will panic some November night and bury the beach under riprap again.

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