This small, unadvertised state park at the southern tip of Whidbey is a great place for an early morning walk on the beach below Possession Head, a tall landslide prone bluff that faces south down the Sound. Wave action erodes the bluff, carrying sediment northward up the southeast side of the island, past this state park, the county boat ramp, and the Glendale pier. Later it sneaks under the Clinton ferry dock, along Brighton Beach, and eventually to Sandy Point. Much of the sediment probably never makes it, getting detoured to the bottom of Puget Sound by the steep offshore slope, which in some places is not far from shore at all.
The old house at the park is built on what appears to be fill at the mouth of a steep ravine. The shoreline had been held together by an old timber pile bulkhead for many decades, but by 2004 when I first saw it, it was in serious disrepair. There was discussion of replacing it, but a few years ago the old wall was removed, the bank regraded and planted, and some of the large wood rearranged. I wondered how this site would behave - fill usually erodes rapidly and this site is exposed to strong oblique waves from the south. But it looks like it is doing just fine without the wall. There is some continuing erosion, but not much.
Rounding the corner from one of these south-facing headlands, we often encounter local complications in the beaches. Small spit-like accretional features are common. Basically, the beach can't turn the corner that fast and it overshoots before gradually reconnecting with the drift-aligned shoreline farther north (in reality it is a little bit more complicated than this). There's another neat example just a few miles west at Maple Point.
Here, there is a small accretional bulge right in front of the site and bank erosion is reduced as a result. Thus the success of the bulkhead removal. Sure it would be great if you could apply general principles and regional assessments to beach projects, but in the end, it's all local.
Despite the wide place in the berm, the beach itself is incredibly narrow here. In one spot along here, a good spring low tide will actually expose the edge of the platform - which is abrupt and plunges into several hundred feet of water. I'll come back at one of those tides someday and then post a picture.