A Kalaloch state of mind

 

Manual panorama of the bluff edge at Kalaloch Lodge, 2 September 2016

I've been spending a lot of time of late thinking about Kalaloch. The main reason is that over the past few years I've developed and delivered a whole series of talks on Kalaloch, culminating most recently in a full one-hour presentation as part of this winter's Olympic National Park Perspective Series (that is available to watch here). That built on a few previous, more science-y sorts of talks presented at NPS Science Days in 2024 and 2025, the first of which is available here. That sort of thing always forces me to try to dig into a place a bit, and ring as much of a story as I can out of whatever insight I can find.

The issue at Kalaloch, or at least the issue that consumes my thinking, is erosion of the coastal bluffs there.  In the two panoramas above, taken from about here in 2016 and 2025, you can get some sense for this erosion. Back in 2016 the bluffs in this area were just at the tail end of a period of relative stability and were covered with vegetation.  Over the subsequent decade erosion in this zone just to the north of Kalaloch Creek appears to have accelerated, and the bluffs are now actively eroding, and nearly vertical.  

User-submitted photo from Chronolog station OLY-102 located here, taken 29 February 2024

That rapid erosion has had some significant consequences, including impacts to the trails and stairs used to provide access to the beach, as well as threats to bluff-top cabins rented through Kalaloch Lodge. Olympic National Park, in collaboration with Delaware North, the current concession-holder at Kalaloch Lodge, have instituted a cabin removal program to ensure that at-risk cabins are not occupied, and don't present a risk to human safety. The strategy is quite simple - when the bluff edge comes within 5 meters of a cabin, the cabin is closed and slated for removal. The cabin in the photo above, for example, was removed just a few weeks after that photo was taken:

User-submitted photo from Chronolog station OLY-102, taken 22 March 2024

I think there is more to come from the work that I and others have been doing to try to understand bluff erosion at Kalaloch. In addition to the monitoring that I've been doing at the site for more than 10 years, we also now have our five Chronolog stations at the site, that have been heavily used by visitors and are archiving a record of conditions at Kalaloch that we've only just started to fully utilize. The current erosion has also prompted some examination of the history of the site, which suggests that change is nothing at all new at Kalaloch. The map below, for example, was put together by Olympic National Park, and overlays a 1940s era site map on a more modern aerial photograph of Kalaloch:

There is a lot going on here and it takes some time to digest, but provides some  sense for how much the infrastructure on the site has changed through time (a story that is told admirably by David Emmick in a number of his books about the coast), and also how much the bluff has changed in the last 50 years (the 1974 bluff edge on the map comes from shoreline change assessment work done for Olympic National Park by the Washington Department of Ecology, published in 2002). But one thing that struck me about the 1940's map is what appears to be a sort of embayment where the Kalaloch Creek channel is now. Some of the early historical references to the site talk about "Kalaloch Cove", and this map suggests a waterbody that suits that name used to be there. In my mind this also hints at even more profound changes to the shoreline at the site than what we are seeing now. That is compelling to me, and I'm hoping to be able to continue thinking on the evolution of the shoreline at Kalaloch.

The non-tidal residuals of December

Flooding in Westport, Washington on December 14, 2024

This past December has been notably stormy, including a few events, especially on the coast (photo above) and along the Strait of Juan de Fuca (check out these great aerials from Three Crabs Rd near the mouth of the Dungeness River by John Gussman at DC Productions), that led to some flooding and other damage. The highest water levels of the month occurred on December 14th and were associated with a storm coinciding with one of this year's winter "king tides", But overall, the month has been characterized by a lot of positive "non-tidal residual" (referred to hereafter as NTRs), which is the part of coastal water level controlled by weather and not by the astronomical tides. NTRs are recorded by tide gauges, and for our purposes here are simply defined as the difference between the predictable astronomical tide, and the actual measured water level at a tide gauge.  

The non-tidal residuals recorded by the Friday Harbor tide gauge in December 2012 and December 2024

Back in 2012 I wrote here about a similar December, during which NTRs were generally high for a good bit of the month.  To illustrate this the plot above compares the NTRs from December 2012 and December 2024 as recorded at the Friday Harbor tide gauge. The things to note here are 1) that those NTRs were positive for long stretches of both months - in other words the measured water level at the tide gauge was higher than predicted most of the time and 2) that the maximum NTRs exceeded 0.50 m, or roughly 1.5 feet, on multiple occasions in each month.  For our region those are relatively large NTRs.

The manual staff gauge used by coast watchers on Puget Sound to measure water level

But what I want to focus on a bit here is a bit of a rabbit hole I went down because of an email discussion I had the good fortune to be part of with a group of property owners on Puget Sound. They reached out to discuss some of their water level forecasts and observations, and I absolutely love these kinds of notes, and the thought that there are people out there that really dig into this kind of stuff. This particular group has devised a really savvy system for both measuring (using a manual staff gauge, photo above) and predicting extreme water levels on the coastline so they can prepare for flooding along their waterfronts. Amongst other things they were looking to discuss a few days in November during which their observations and predictions didn't really line up because of the difficulty in predicting NTRs.

NTRs (top) and air pressure (bottom) measured at three tide gauges in Washington over December 2024.  The weird measure early in the month from Friday Harbor is a low-quality measurement that will eventually be removed from these preliminary data, downloaded from NOAA.

The thing about NTRs in Washington is that they generally are well correlated with atmospheric pressure - so high pressure generally leads to low, or negative NTRs (i.e. measured water level is near, or slightly below predicted), and low pressure generally leads to large NTRs, such that coastal water level is higher than predicted.  Above and below, for example, are the NTRs and pressure measurements from three tide gauges in Washington, that show this relationship, referred to as an "inverse barometer" effect. The group that I was emailing with used this relationship in their forecasts, to predict the water elevation for their area by combining the predicted tide with atmospheric pressure forecasts.

NTR vs. Pressure for data collected at three gauges in Washington during December of 2024

But what this group pointed out in our email exchange were time periods when this relationship sort of broke down.  In particular they pointed to a day in November...November 21st, 2024, when this general relationship between pressure and the NTR didn't hold, and diving into the data I think I'm starting to see what they are talking about.  Here, for example, are the pressure vs NTR data for three tide gauges in Washington for November 2024, with the measurements from November 21 highlighted in red:

What is interesting here is that on this day there really is no relationship between pressure and the NTR...the pressure more or less stays the same whereas the NTR at each of these tide gauges is varying by over 0.3 m, or about a foot, over the course of the day. I don't have a great, clear way to explain this, except that it does point to two important lessons.  First, the ocean is messy, and clean relationships almost never hold all the time. While there clearly is some relationship between atmospheric pressure and NTRs when looking at the data in aggregate, when we focus in on this particular day (and there are others like it), the relationship isn't so clear. Second, there are all sorts of other processes that can lead to variations in NTRs. My friend and colleague Eric Grossman at the USGS, for instance, has explored this problem in a paper, describing what they call remote sea level anomalies that are generated in the Pacific Ocean and can propagate into the Salish Sea. While it is not completely clear if the processes that are alluded to in this paper explain these observations, at least its a place to start.