Saturday, March 18, 2006

Jefferson County

Kala Point.Great place to bring a class. Steep, forested bluffs, a beautiful spit with small dunes and a large lagoon, the 100-year remains of a lumber ship, and big logs. Really big logs - cut into chunks the size of box cars. Kala Point is a cuspate foreland surrounding a lagoon and salt marsh, the entrance to which is on the south limb. Like most of these barrier beaches, the tidal entrance favors the side more protected from wave action and with less abundant sediment.

Oak Bay.This large barrier (a tombolo) was sliced in half by the cutting of the canal from Oak Bay into Port Townsend Bay. The portion of the barrier left on the western side of the cut is the site of Oak Bay Park. A large lagoon lies behind it. Prior to the cut, the lagoon drained north into Port Townsend Bay but the now jetty prevents this and for almost 100 years the lagoon has cut through the barrier on the south. This has allowed beach sediment to be transported into the lagoon - a substantial flood tide delta has formed - and I suspect this is the main factor in allowing the barrier to migrate northward. In addition, much of the spit has been riprapped (yes, that's a verb, or at least it should be) and a boat ramp was built that aggravated erosion immediately east (downdrift). This, and continued shoaling adjacent to the jetty, may help explain why in 2003 the tidal channel jumped westward.

The February storm ripped asphalt off the road in the county park, behind the riprap, sparking discussion of possible improvements. Improvements to the beach, not to the riprap. Maybe we could start by removing the boat ramp and pulling a few hundred feet of riprap from the eastern end? A strategic retreat.

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