Sunday, February 24, 2008
State Route 106 winds along the southern shore of the hook of Hood Canal. At the western end, near Union, it probably is all built on fill. At the eastern end, it may follow an old terrace. In many places, it is held in place by a sacrete revetment that may date to the road's construction in the 1920s. (Sacrete is what you get when you stack bags of concrete and let the seawater soak in). The challenge is how to maintain the road and restore a more natural shoreline at the same time. The solution will depend on location, but may include localized nourishment, vegetation and bioengineering, and maybe some clever placement of large wood.
The first two pictures are taken on the road west of Union, where the beach skirts the edge of the Skokomish Delta. The beach (which is mainly under the highway now) consists of gravel supplied by the bluffs and moved along the shore by waves (the gravel was very much in evidence where it had been washed down gullies by the December 3rd storm). But the low tide terrace (under water in these pictures) is basically the low tide extension of the Skok delta, complete with tidal channels and fine grained sediment. Deltas and beaches also overlap at Warm Beach (Stilli), Marietta (Nooksack), and maybe once upon a time, south of Pioneer Square (Duwamish).
Dewatto is about as isolated as you can get on Puget Sound - and still travel to without a boat. The only place that comes close is Coyle, up on the Toandos Peninsula. This small inlet on the eastern shore of Hood Canal probably represents a post-glacial stream valley drowned by rising Holocene sea levels. There was too little stream sediment arriving at the head and the bay was too deep to fill in, so we're left with a narrow embayment. Wave action is probably only significant near the bay mouth, so most of the inner shoreline consists of forested slopes and fringing salt marsh and lacks significant beaches.
The local name is an appropriate one for this winding gravel extension of North Shore Road from Rensland Creek to Dewatto. Until the other day, I hadn't appreciated how much gravel got moved around last December 3rd when all the streams in this part of Washington blew out. Piles of gravel at almost every crossing along North Shore Road and SR 106 still mark the event. I hope some of it made it the beach.
The southern hook of Hood Canal is lined with houses, many reaching out across the beach on concrete promontories. Many probably began as small cabins on piles, but have since grown into something much more. In many places, there's not much room between the road and the water, yet there are still buildings and sometimes, random acts of concrete. Every beach has a story - sometimes we just don't know what it is. There was an elegance to this little artificial headland and the nascent tombolo behind it.
Besides opening up the mouth of Big Mission Creek, the work last year included restoring the shoreline westward towards Little Mission Creek. It will be fun to see how it evolves.
The low campground is protected by a berm - the outer edge of which consists of a gravel beach and a series of cabled logs. The new cove opens westward, into the prevailing winds and waves, so will inevitably accumulate floating debris - large wood, dead eelgrass, and styrofoam. After big storms, this is where folks who live on the Canal will come to find their swimming rafts, floats, and stray dinghies.
Like most (practically all, actually) stream mouths on Puget Sound, Big Mission Creek was domesticated early - it's tendency to wander across a small shoreline floodplain and delta held in check by levees, shoreline fills, and other structures. Until last year, an artificial lagoon occupied most of the stream's mouth, but now the small river fans out across a real estuary.
The December storm washed out every creek along southern Hood Canal, including this one. Not that it undid the restoration, but it probably wasted much of the effort that went into the little details. Sometimes the best restoration may result simply from removing the offending structure or constraint and then waiting for a good storm to begin to put things back together (does this sound too much like Edward Abbey?). I guess we want restoration to be as static and predictable as a levee or a seawall, but ultimately restoration is about allowing the uncertainty and the storms and the floods back in.
Monday, February 11, 2008
Seahurst Park in Burien is a strange blend of good, bad, and ugly. The stream mouth may be the most genuine one left between Seattle and Tacoma, though its original form may have extended north under what is now seawall, restrooms, and lawn grass. The perched beaches, built in the 1970s, are unique in Puget Sound -- probably for good reason. Someone's notion of enhancing high tide beaches has since become an eyesore and a liability. The gabion wall and the riprap at the south end came out three years ago and that shoreline now has a chance to become the forested beach that it once was (and that still exists farther south).
Interest has now shifted to the north end, where there are opportunities to both improve the park and to fix the beach. Maybe we can learn something from Seahurst that will eventually benefit parks and beaches elsewhere on the Sound.
Sunday, February 03, 2008
The bluffs between Point Partridge (OCT2006,FEB2006) and Ebey's Landing consist of a thick pile of gravel left by the retreating glaciers. The lack of cohesive sediments, complex stratigraphy, or forest cover result in uniform angle-of-repose slopes that are distinctly different than others on Puget Sound. Net drift is to the southeast - where the gravel eventually winds up in Keystone Harbor, where it must be periodically dredged to allow the ferry to get in. A couple of miles north of Ebey's Landing, the beach splits from the coastline, forming this large lagoon before reconnecting with the bluffs farther south. The result, with help from the National Park Service and the Nature Conservancy, is a 3+ mile loop that is the best shoreline hike on Puget Sound.
The gentle waves breaking on the beach today were about 10 seconds apart, suggesting they began as much bigger waves out on the Pacific. Occasionally a big storm comes over spit, recharging the lagoon and creating gravel washover fans on the backside of the barrier.
Two years ago, Sound Waters coincided with the big storm. I requested wind and waves again this year, but I guess the organizers were too busy to make this a priority. I took the long way home, swinging by Ebey's Landing which is just a couple of miles across the prairie from Coupeville. It was crowded with beach walkers on this slightly overcast Saturday afternoon.
The northern shore of Point Wilson is looking pretty ragged. A legacy of defensive actions and good intentions have segmented a once continuous beach and dunes into a fraying edge of rocky headlands and eroding pockets. Riprap protecting battery Kinzie, three (sometimes only two are visible) mismatched groins built in the 1980s, and the rock fortress around the northern side of the lighthouse, have mucked up natural sediment transport patterns along the beach and between the beach and the dunes. I suspect this beach is far less resilient to future erosion and rising sea levels than in its original condition. Point Wilson could use some serious rethinking! It will require looking at the whole point, not just the lighthouse or the parking lot.