WatershedEvents

A FLUSH ON BEATTY CREEK

Record rain to begin the New Year - 2.26" fell at the Olympia airport on the 2nd of January, 2021, the day I started working on this post. Our backyard rain gauge showed more than 6" for the week (12/28/20 - 01/02/2021). I plot rain totals sporadically, and by the time I got to the gauge Saturday, it had long since been filled to overflowing. I decided to visit Beatty Creek and see what it was up to.

I headed for the place I've come to call The Bend. It's a great place to study basic stream dynamics. All but the creek's uppermost reaches flow over land once entirely covered in the deep glacial till deposits left behind by the comings and goings of the Puget Lobe of the Fraser Glaciation. The till lies upon large deposits of weathered basalts mostly visible only in the uppermost portions of the watershed. The creek’s headwaters are not far from the Puget Lobe’s terminal moraine, which means it lies in one of the first regions of Puget Sound to be reclaimed by vegetation after the last Ice Age. That was somewhere around 12,000 to 15,000 BPA (source references dependent). The area’s lowland soils consist of a shallow top layer of sands, gravel and decaying detritus lying over a deeper layer of semi-consolidated sands and gravels which covers a deep and highly compacted layer of gravel and sand – “hard pan” it’s called and for good reason. Over the millennia the creek has meandered across these lowlands more or less at will. Maps based on older surveys suggest the reaches I study have migrated over a hundred yards east of their current location.  

Stream flow reaches the Bend after passing through a relatively long and straight reach. For the area I'm discussing, total elevation change is not extreme - about an 80 foot drop over a half channel-mile of terrain. But the flow is still packed with a substantial portion of the energy it gained as it tumbled out of its headwaters area 3 miles and 1200 feet higher in elevation. It's also loaded with suspended solids - rocks, gravels, sands - that add to the abrasive actionof the flow. The weight of the atmosphere and the pull of gravity keeps that powerhouse from literally exploding when it slams into the 90^. angle at The Bend; instead, it boils its way through the curve and continues downstream - checked but not broken and regathering power and material as it flows. As tumultuous as the surface looks, the real action is taking place in the water body below – the cutting, grinding and plucking actions taking place along the steeper portions of the bank are fierce and relentless.  

Artifacts of this continuous process are abundant in the area. For example, in the photo above, the downed tree stretching left to right across the frame was upright and a good foot from the edge of the channel when I first came to this place in 2014. It's been down and in the channel since the fall of 2016. The Bend itself – its hard-left turn – was not quite so pronounced, and the gravel bar directly behind the upright snag (right-center) was not as well developed.

Flow events at The Bend are also impacted by changes in the channel immediately downstream. The large debris pile shown below (right of center in the photo) has split the stream, creating a good sized bar in the middle. This blockage actually dams the flow enough to raise the water level upstream, which increases the height and breadth of the cutting action taking place in what you might call the stream’s elbow. These kinds of obstructions come and go and are constantly changing shape and characteristics. They are crucial to the continued good health of fast flowing streams such as this one. How long they last can vary from hours to decades, many factors dependent. Right now this formation promotes rather than hinders salmon spawning; but other such piles of debris have totally prevented any fish from this year’s chum run making it to these upstream areas. 

Below, a recently fallen tree just a few yards downstream is beginning to trap debris between it’s trunk and the water. I suspect it won’t have much impact on stream flow until it breaks in half, or until the bank supporting one end or the other erode enough to put it directly in the water. That could take several decades.

 

HARD TIMES ON BEATTY CREEK

The two photographs below require a bit of explanation: The first was taken at the confluence of Beatty and McLane Creeks. I was standing at water's edge of McLane, and the view is directly into the mouth of Beatty Creek. For the second shot, I stepped over all that debris and pointed the camera directly upstream. What's important here is what's NOT to be seen, specifically the dark, sinuous motion of several large chum salmon fighting their way up Beatty Creek to their natural spawning grounds. 

It is nearly mid-December. In a typical year I would not be able to stand on dry land at this spot along McLane Creek, even if I might want to - the stream would be so deep and the current so strong it might knock me down. Only a few salmon would be entering Beatty Creek, only a handful sweeping away at their redds further upstream. The peak of the run would have passed. The scene along the way would be mostly one of carnage, the stream and its lower banks littered with rotting carcasses - the bleak aftermath of a successful spawn. Instead, today only a paste of rotting leaves remains on the damp gravel. The heavy and steady rains of November have yet to arrive, and purge the creek. Furthermore, the forecast for the rest of December suggests they may not arrive until 2020, well paste the time for spawning.   

This is not the first time late or otherwise insufficient rain has wrecked an annual run on Beatty Creek. It is an ephemeral stream to begin with, and even in a good year its bottom is dry as a bone by June. In the fall that bottom will be covered in a thick mix of leaves and other detritus offered up by the surrounding deciduous trees and shrubs.

Then, usually in the first week or two of November, a series of wet warm fronts will blow into the area from the Pacific coast, one right after another. They usually come through only a day or so behind each other, creating a kind of wet pulse which soon translates itself into surging crests of stream flow in the creeks.

Then comes the surge - the full force removes virtually anything in its pathway. It’s wonderful to watch the cleaning process; even more wonderful to see what happens when the cycle settles long enough for the chum to run up stream and lay their eggs.

Sitting (or sometimes lying) quietly along the banks of Beatty Creek, just a few feet away from the chum, can be a deeply moving experience. I will miss it this year, it appears. But that won’t diminish my love for Beatty Creek, nor will it keep me from studying and recording its ways. I will not, however, write a book about the experience – been there and done that with Up Fanno Creek. Instead I’ll simply journal my efforts on this blog from time to time. I may also pull a weed or two, and pick up the occasional bits of litter I happen across. If you are a wetlands lover, as I am, stay tuned.