Cama Beach

Last week I got a chance to visit Cama Beach to talk to this spring's Sound Water Stewards class. The weather cooperated for the beach walk - which it seems like it usually does, but this year I wasn't so sure!  I managed to grab a few photos, but not many. When I'm with a group, I'm too busy answering questions or looking for topical material to remember to take pictures.

AERIAL VIEW

The beach at the south end is very low, although not necessarily lower than in 2012 (Cama Beach: May 2009). However, a little farther north, near the old gate in the seawall, it was as low as I've ever seen it. The old wooden piles were completely exposed and there were large patches where the beach veneer was completely absent, with the underlying silt and clay showing through.

At the north end, we checked out the two big slide scars from previous years (see linked posts below). Despite this winter's record rainfall, it doesn't look there's been that much activity.

There was eelgrass hanging from the branches of the trees - a reminder of the interaction between the terrestrial and marine ecosystems. And there was a wonderfully delicate micro-berm of ground up clam shell marking last night's high tide.

Previous posts that mention Cama Beach.

Barnum Point

Thousands of years of wave action has carved off the southeasterly face of this glacial ridge, creating a beautiful high bluff. A thick till drapes the ridge, with outwash sand and gravel below. The relatively straight line of the bluff faces directly down Port Susan, or pretty close to it, making this a nice example of a swash-aligned bluff (something we also see in other places around the Sound). 

AERIAL VIEW

Eroding till inevitably leaves behind cobble and boulders. Some is on the beach, but there were also clearly some very large rocks far offshore (some just barely breaking the surface during the paddle and creating some wonderful little rips where the current was fast).

The eagles were out in force - although they seemed to be too intent on watching me than to actually be catching any fish. There were at least four - and there may have been more but they all looked the same to me and I wasn't sure I was double counting.

Increasing recognition of the importance of eroding bluffs in the overall formation of beaches and spits on Puget Sound has resulted in some significant conservation purchases in the last few years. In the past, coastal conservation acquisitions were mainly focused on salt marsh and estuarine habitat, so it's neat to see beaches and even bluffs getting attention. Not only are these bluffs geologically and ecologically significant, they are iconic Puget Sound landscapes.

Barnum Point is one of the more recent examples of this:
Barnum Point (Nature Conservancy)

For another example, check out Lily Point on Point Roberts.

Driftwood Shores

The spit extends across the mouth of Triangle Cove and is lined with homes and, of course, driftwood. They don't call it Driftwood Shores for nothing. South-facing beaches, particularly on Port Susan, where shorelines have collected north-drifting wood from the Snohomish River and from a century of log-rafting, tend to accumulate this stuff.

AERIAL VIEW

Somewhere back in the office I have a newspaper article describing the heroic efforts early one morning to protect this community from flooding - perhaps during the January 1983 high tide? Even if these people weren't there then, they probably remember February 2006 and December 2012. They are the benchmarks that beach communities use to mark their history.

I often hear folks these days commenting that communities like this will be doomed as sea level rises. But the reality is that these communities will persist, even as the beach that drew people here is buried beneath riprap. Unless the economics of waterfront property change drastically, we can be assured that these folks, and the folks who follow them, will be able to elevate their remodeled homes, to raise the dikes that protect them from flooding on the backside, and to stack rock as high as necessary to protect them from the sea. And because the need to rebuild will be driven by disasters "that no one could have predicted" and that private insurers have little financial interest in covering, a remarkable amount of this work may be done at public expense. This happens all the time in other places that had a head start in us!

Driftwood Heights

I think this is the appropriate name for this stretch of shoreline along East Camano and Lehman Drives, north of Cavalero Beach and south of the spit at Driftwood Shores, although I suppose it applies better to the homes on top than the beach below.

My goal was to paddle over to Barnum Point and check out Driftwood Shores along the way, which I did and which I'll post about shortly, but first I got distracted by this neat section of forested bluff south of the spit. There are a variety of types and vintages of landslides in the trees, some much more evident than others.

Wood is abundant along here and there's a pretty fuzzy distinction between the driftwood and the wood bulkheads. And in some cases, between the forest and the beach cabins. This shoreline may be a nice example of why counting bulkheads or characterizing shoreline structures is a lot more difficult than some folks think!

The large erratic coincides with a small bump in the shoreline. Like Klootchman Rock near Oak Harbor, the boulder acts like a groin, stabilizing the beach slightly on it's southern side and probably resulting in faster erosion on the north. Where the shoreline is buttressed by a long timber pile bulkhead that extends over many properties (timber bulkheads, or their remains, are so ubiquitous on Port Susan (or were) that this is nothing terribly unusual). On the other hand, one of the often overlooked benefits of these structures is that they are biodegradable.

We're still in catch-up mode - with several more May posts still to come, plus a bunch from a long road trip in June. But at least the computer and the photo library are back up and running, so there's some hope. These pictures were taken on the morning of Saturday, May 9th.

Cama Beach

 Cama Beach appeared on these pages frequently last year and probably will again this year.  These are from a brief foray in mid-January following some more landsliding.  Not only has the big gully been active, but a couple of new slides have occurred as well.

The big slide we posted about last year (search on the label 'camano') was quiet all summer and early fall, but has gotten more active this winter.  Water was flowing over the top during this visit and was eroding the sandy unit below the till.  This appears to undercut the till which then fails in larger blocks, although nothing too dramatic has happened yet this year.  Most of the colluvium in the gully still looked like the trodden and rained-on remains of last year's debris.  I would expect more failures as long as the water is flowing, but I wouldn't pretend to guess how large.

One reason for my visit was reports of a new slide south of the one I just described.  Sure enough, there had been a fairly large debris avalanche on the lower half of the slope, in line with a substantial gully that probably corresponds to an earlier slide.  Water was flowing from somewhere mid-slope. This new slide is immediately north of one that occurred in the late 1990s. There is plenty of tree debris on the beach, and a fair amount of dirt, but nothing like the other slide.  There's a steep bare headwall at the very top of the slope, but the upper slope doesn't appear to have failed in this event.  I suppose the recent slide could make that more likely, at least if conditions stay wet.

There was also a small slide - a small earthflow more precisely - on the slope nearer the resort, above where the old bungalows were.  When the park was redeveloped, a decision was made to remove several of the old bungalows at the north end, at least in part due to their vulnerability to slides. Probably a very good idea.

AERIAL VIEW

Camano Island State Park

The best use for a big deep-seated landslide on Puget Sound is probably a forest.  The next best use may be a relatively low-intensity public park.  The northern day-use area at Camano Island State Park sits on a mid-slope bench, the contents of which began their jerky movement to the Sound hundreds or thousands of years ago.  The uneven surface of the picnic area and the offsets in the parking lot suggest nothing has changed.

The head scarp is a high steep, forested slope that rises above the parking lot.  Big drain pipes convey water from the land above (part of which is the park entrance road, but other parts of which are private homes) down to the bench, where hopefully it then gets captured and sent to the beach.  Water is, after all, the grease on which these slides move, and the simplest way to slow their movement is to keep the water out.  Of course, even that may be far from simple.  The bench often slopes landward, making natural drainage tough, and slide movement can break pipes or otherwise disrupt drainage.  And often the water is deeper groundwater, which doesn't lend itself to easy solutions.

These big slides often have portions that are more susceptible to movement than others - often, but not always, due to past or present drainage problems.  The most active portion of this slide is the outside lane of the road down the bluff -- if it expands, access to the day-use area may become a lot more difficult.  Or a lot more expensive.

But again, better a park.  All too often, developers covet these benches for rows of million-dollar homes, and the developer is long gone by the time the foundations start cracking and the septic tank slides past the patio.

AERIAL VIEW

Other Big Landslides:
Perkins Lane, Seattle
Ledgewood Beach, Whidbey Island
Camano Head, Camano Island
Discovery Park, Seattle
Kopachuck State Park, Gig Harbor
Turnagain Heights, Anchorage
Termination Point, Hood Canal

Cama Beach

Two weeks ago, I headed up to Cama Beach to give a Friday night talk.  I've always like Cama for its accessibility - 75 minutes or so, door to door, no ferry to catch, in the middle of the night when the wind is howling and the waves are breaking over the seawall. Which I've done.  But late on Friday afternoon, there was a slow wall of traffic moving north through Everett and it took forever! Somehow I made it in time to get the laptop set up and still had time to wander down to the beach for the sunset and a chance to gather my thoughts.

I've posted from Cama Beach many times and there's no particular geologic message buried here, but the light was nice and the beach always looks different.

Note the band of sandy gravel a couple of feet above the water line.  It corresponds roughly with the morning high tide.  Because subtle differences in wave action sort sand and gravel so differently, and do so differently on rising and falling tides, mixed beaches often record small details. This band is bracketed by two tiny beach ridges - I can picture two boats, maybe 30 minutes apart, going past between 9 and 10 in the morning as the tide was beginning to fall.

The big slide at the north end can be seen in the background of the photo with the two boys walking on the beach.

AERIAL VIEW

Livingston Bay

This log-choked salt marsh originally formed behind a tenuous spit, but sometime last century, a dike was built along the general line of the spit, cutting off tidal influence so the area could to be pastured. There have been years of debate about what to do with this site, in part to address a mosquito problem that tidal circulation would help alleviate.  Now the Nature Conservancy is excavating a portion of the old dike and restoring a tidal inlet at the northern end, which should result in much more efficient exchange and a marsh much more similar to what used to be here.

The beach here doesn't amount to much.  Iverson Spit, located a short distance south, is much larger and probably traps a bulk of the sediment transported from Barnum Point.  The limited sand on this beach may come from the reworking of older marsh or tidal flat deposits, although I suppose some sediment may find its way north from Iverson.  Up here at the north end of Port Susan, most of the wave action is from the south, across the broad flats that extend over from the Stilliguamish Delta.

AERIAL VIEW

Over the past few years, a new sandy spit has grown north from this site into the marsh.  In a year, the new tidal channel will wind out behind this spit.  The big question will be whether the new channel will allow all those trapped logs to escape, or whether they will simply choke the new channel until a really high tide occurs.

Cama Beach

There is a small perennial stream at the south end of Cama Beach.  It emerges from a gully and flows across the beach.  Some years it just ponds behind the berm, seeping out through the gravel.  Other years, it opens a channel through the berm and flows openly.  This is what it's been doing this winter.

Few streams arrive at the beach unimpacted by human activities and this one is no exception.  The historic condition is unknown - perhaps it actually flowed into the old lagoon where the resort is now and exited through the barrier farther north.  Regardless, it's outlet is now fixed with the stream pushed against the adjacent concrete bulkhead.  In addition, at some point, the concrete planks of the old boat ramp were dumped at the outlet (presumably to prevent some historic erosion problem?).  Interestingly, the planks are often buried, but this week they are more exposed than I've seen them in the 16-17 years I've been visiting.

There's always been a small delta on the intertidal beach here, but currently the stream is busy building a fresh gravel fan across it.  People often point to these deltas as evidence of a fluvial source of sediment.  While streams no doubt deliver sediment to the beach, or at least have historically done so, the presence of this kind of feature does not require upstream sediment. Much of the sediment may simply be upper beach sediment, relocated by stream flow to the lower beach.  You could probably form a small delta simply by running a fire hose across the beach for a few weeks.

One consequence of the stream eroding the upper beach is that in areas with significant drift the back beach is often narrower downdrift of the stream mouth.  In this case, the beach widens northward toward the stream mouth, then narrows distinctly on the north side. This is not a function of the bulkhead -- although that may complicate the dynamics a little bit.  Basically, the drift is diverted by the stream, starving the downdrift beach.  I like to think of this as a kind of negative groin.

Other examples, although each bears its own complications, include Seahurst in Burien and Narrows Park south of Gig Harbor.

AERIAL VIEW

Cama Beach

I think there will be two posts from this morning's visit to Cama Beach, one on the landslide and one on the stream south of the resort.

The slide hasn't expanded significantly in the last month.  The sandy layer beneath the till on the headwall has continued to erode and there is now a large overhang.  I also think that there has been continued downhill movement of the debris in the gully itself.  From a fairly cursory comparison with earlier photos, it looks like the debris pile has settled somewhat, perhaps as the material at the toe has been eroded by waves.

Previous posts on the slide:  March 17, March 7

There's been plenty of rain the last few days, including last night, and plenty of water was cascading over the rim and flowing down to the beach.  At least when it's flowing, this may be as important, or more important, than waves in eroding the landslide material.  The stream location hasn't changed - it's still flowing out on the north side of the debris-choked gully.  The beach to the north still shows fresh sand deposition, although it's not like there's a huge thickness of new material once you get away from the slide itself.  There is a lot of very soft sand on the lower beach (the tide during these pictures was around -2' MLLW) and it seems to extend in both directions from the slide area.