Rocky Brook … By The Numbers

Blog Number 13

Rocky Brook becomes a “winter wonderland” when it snows. Because it is 3 miles from the sea (Hood Canal), and around 50 ft. above sea level, the snow rarely stays for long, though in 2017 it froze on December 5th and did not thaw until January 17th; forty five days of frozen ground (and plumbing).

We humans appear to like the precision of numbers, at least when they are small and we do not have to think about too many of them at once. One to one hundred is easy; a human lifespan, a dozen eggs, the price of a gallon of gas. Begin to talk about fractions and decimals or hundreds, thousands and millions and we tend to let them enter one side of our brains and quickly exit the other.

It is popular today to present some topic or concept “by the numbers”. I first noticed this in The Harper’s magazine, where, in every issue they devote a whole page to what they refer to as “Harper’s Index”. Each is a fascinating and often enlightening perspective on a wide range of topics.

Recently I noticed my local newspaper, The Port Townsend Leader (a weekly) doing the same thing on their second page. And the end-of year issue of National Geographic featuring photographs, had a page called “By the Numbers” with numerical statistics related to its content.

Not to be outdone, here is my version of Rocky Brook “By the Numbers.”

.3
The length, in miles, of Rocky Brook from its confluence with the Dosewallips river to the base of the waterfall. This is essentially the river length where salmon spawning and rearing occurs (the falls presenting an insurmountable barrier).

229
The height, in feet, of the lower falls. There is an upper falls above with an estimated height of 75 ft. which is not visible and essentially inaccessible.

6
The approximate length, in miles, of main channel of Rocky Brook above the falls.

24.5
The approximate length, in miles, of the Dosewallips River, from its estuary to its headwaters on Anderson glacier on Mt. Anderson. Rocky Brook flows into the Dosewallips about three miles up from Hood Canal.

7,756
The height, in feet, of Mt. Constance, the third highest peak in the Olympics and which, with Mt Anderson (7,321 ft., tenth highest) form the upper reaches of the Dosewallips watershed.

4,158
The greatest number of salmon counted in Rocky Brook by the Washington Dept. of Fish and Wildlife. The year was 1967. The fish were pink (a.k.a. humpback) salmon.

20
The average number of coho salmon counted in Rocky Brook each year since 1943.
The most coho counted was 88 in 1980.

22
The number of years that I have lived here, next to Rocky Brook.

1986
The year that the small hydroelectric plant was built along Rocky Brook.

2018
was the last year that the hydroelectric plant operated. It has an intake system in the stream-bed above the falls and the plant is located below the falls, near the road. A four ft diameter penstock pipe brings water from the intake to the plant. The owners have plans and a permit to upgrade the plant, but have yet to do it.

The Dosewallips river floodplain near Rocky Brook is about 300 ft. wide. Quite naturally, the river meanders from side to side. This photo, from 2017 shows the main channel hugging the south bank. Root wads and other large wood debris are important to a healthy river ecosystem. When the river floods, it floats them down until they hang up on shallow water or interlock with other tree parts, sometimes creating logjams from bank to bank. 

Numbers of all kinds make much of the world we live in both functional and understandable. They are the language of engineers, scientists, economists and the like. Fisheries managers need to count fish in order to understand what is happening in a stream or river. The run, catch and escapement help guide their decisions.

The run is the total number of adult fish that have survived life in the ocean to head back to their stream of origin.

The catch is the number within the run that are caught en-route.

The escapement is the number of fish that make it past the “catchers” to spawn.

The run size and allowable catch help ensure that enough fish will “escape” to spawn. Fisheries biologists have to be good at counting fish accurately.

Numbers are data. Numbers in large quantities and over extended periods of time become “big data” and offer opportunities for analysis, often providing insight as to what is happening.

Ever since 1943, the Washington Department of Fish and Wildlife has been walking up Rocky Brook during the fall spawning runs, identifying and counting the fish they see. In the early years they might only walk it once a season. During the last twenty years they may walk it weekly, from September through December. I was able to obtain this data and organized it into a graph which helps me visualize patterns and note trends. Here is what my fish count graph looks like.

Pretty complicated image; lots of bars, colors, numbers and dates. The following five “take-aways”, attempt to make sense of it.

1. Rocky Brook is primarily a coho and pink salmon stream.
2. Coho numbers seem to not get much higher than 60 fish, usually ranging from 30 to 60. In many years less than ten may be counted.
3. Coho numbers indicate both wild and hatchery fish. Those counted during September and October tend to be hatchery (most likely from the nearby Quilcene facility), and should have a clipped adipose (back) fin. Those counted and observed in late November through January tend to be wild fish. Counts in the past twenty years appear to include an increasing number of hatchery raised fish.
4. Pink salmon runs (only every odd numbered year) seem to be highly variable; some years hundreds and even thousands of fish are counted, other years when a run is expected, no fish are counted. Pinks typically arrive in late August to early September, with spawning activity pretty much over by mid-October.
5. Chum runs are highly variable. Many years none are counted. Some years there may be 20 to 30 fish observed in Rocky Brook. All of these are “Fall” Chums, typically spawning in November and December.

This year’s (2022) runs to date have been quite small; less than twenty fish. They have been for the most part hatchery raised coho. Wild coho will, hopefully, arrive sometime this month.

It looks like this may be yet another less than average year, continuing a downward trend.

But as my paternal grandmother always used to say, “You never know.” I remain hopeful (and my grandmother believed in miracles).

Dennis Lloyd Kuklok
Rocky Brook, December, 2022