Saturday, March 14, 2015

Forbes Point

Forbes and Maylor Points mark the southern end of the peninsula that separates Oak Harbor on the west from Crescent Harbor on the east. The 19th century t-sheets suggest that this was once almost an island, connected to the rest of Whidbey Island by a tombolo, but evidence of this is buried benath the large fill associated with the old seaplane base (now the base exchange) and the parking lot behind the Oak Harbor Marina.


In the late 1970s, the Corps of Engineers undertook a national initiative to look at low cost methods of erosion control. One part of this project was an ambitious series of demonstration projects. There were two on Puget Sound - one at Sunnyside Park in Steilacoom and the other here, at the base of the bluff between Forbes and Maylor Points.

Remnants of old gabion baskets
In 1978, the engineers constructed a series of erosion control structures along this relatively uniform stretch of eroding glacial drift. They systematically laid out a series of treatments, including two types of wood bulkheads, a gabion revetment, a revetment made of sacks of concrete, and a bulkhead made of old tires mounted on vertical wood posts. They did some with filter material, some without. It was quite the experiment.

In the winter of 1978-1979, the barely completed experiment was severely tested, and almost destroyed, by two storms, the larger of which was the same February 1979 storm that sunk the Hood Canal Bridge. Some treatments held up better than others.

I visited the site in the early 1990s (and am trying to track down my photos). This was my first time back. I found some of the old Corps' reports and maybe there's a follow-up story we can pull together. But that will take a little more work.

At Maylor Point, at the west end of the project, there is an old concrete structure looks like it was originally constructed to carry electrical conduit (some reports say drainpipes) down the bluff to the beach. It has been left behind as a flying buttress as the bluff has gradually retreated.

This site has been used to estimate historic erosion rates - which were earlier estimated to be about 6"/year here (pretty high for Puget Sound). A quick comparison with an old photo of mine indicates very little erosion in the past 25 years (certainly not 6"/year), but I'll see if I can document this a little better and will report back.

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