Real Rivers Have Curves (Blog Number 1, Spring 2015)

Rocky Brook Ruminations

Real Rivers Have Curves

I live right next to two rivers. One is the Dosewallips (locals just call it “the Dosey”). It is the only river flowing out of the east side of the Olympic mountains with glacial headwaters. The other is much smaller, somewhere between a stream and a creek. It is called Rocky Brook. Both are anadromous, they support wild salmon populations. 

Living right above the floodplain of these two dynamic natural wonders has made me think about the proverbial “hundred year flood”. It was a term I first learned about at university, studying hydrology and landforms. A 100 year flood is a flood event that has a 1% probability of occurring in a given year. It is also called the 1% flood. These areas can be mapped, creating the “100 year floodplain”, important for building permits, regulations and insurance. Such flood events are expected to happen infrequently, more on a geologic timescale than a human life span.

In looking at my part of the Dosewallips and Rocky Brook landscape, the wide, flat area where the river could rise up to is pretty clear. The question always was not if, but when. This winter I experienced the when. I don’t know if this was the proverbial hundred year flood, maybe the concept needs to be reevaluated with our changing climate and weather patterns. It certainly resulted in the highest water levels I and everyone I talked to around here had seen. 

The reach of Rocky Brook I live by is pretty short, about half a mile. Its upper boundary is defined by a sheer cliff creating 225 ft. Rocky Brook Falls, a spectacular piece of natural architecture. From the falls it has two fairly straight runs; one about a quarter mile through the canyon, due south past the bridge, and then a sharp turn east for another quarter mile where it meets the much larger Dosewallips River. This second reach, from the bridge to the Dosey is my domain. It’s nearly straight course was due to the previous landlord, a logging company owner with access to lots of heavy equipment. He thought that one day this site could be developed into a popular summer RV park and wanted things orderly and predictable. 

The winter of 2015’s back-to-back flood events left this lower stretch changed. Rocky Brook reclaimed an earlier channel and added a beautiful sinuous curve to a parallel existing channel. Instead of one stream, there are now two. Both should be good salmon habitat if there is enough water to maintain them during the critical dry summer months. The new channel (which is really the old original channel before logger landscaping decided otherwise) has excellent gravel size for fish spawning. 

The other, more sinuous reach now has a series of deeper pools where little coho salmon like to hide out. Textbooks say that rivers curve to “release” some of their flooding energy, carving out banks and deep pools on the outside of the curve and creating shallow areas with little beaches on the inside of the curve. This is their natural form. Look at a map of most rivers and you will see some incredible backing and forthing, sometimes almost forming a nearly complete circle. 

The Dosewallips River did the same thing, only on a much grander scale. It too had a pretty straight alignment along my property. It too, added cut banks and rocky beaches as it took on a more sinuous path. It too is becoming more diverse, diversity which translates into good fish habitat.

Of course, all that flooding must have been a challenge for all the alevins (tiny salmon that had just emerged from eggs and were living within the gravel) as well as the year-old salmon fry. I can only imagine how they coped with the increased currents, rolling rocks, and water choked with silt, sand and debris. I’m sure they found little back wash and slack water areas to hunker down in and ride out the storm. Some of the old spawning and hanging out areas are gone, but new ones were created. This is how nature works when we leave her alone. 

All in all, the whole landscape looks a bit raw and unruly. But it also feels renewed, more natural, wilder. And, there is something about the beauty of a curve which is quite pleasing to the eye. My eyes are taking notice. 

Rocky Brook, Spring 2015

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