Monday, December 19, 2022

City Limit Falls

Ok, so back in May of last year I did a post about Keanes Creek Falls, one of the little seasonal waterfalls along the Sandy River stretch of the old Columbia River Highway. (Specifically, the one across from where the old Tippy Canoe dive bar used to be.) I mentioned in passing that it was the southernmost of about five waterfalls along a 0.6 mile stretch of the road, and it should come as no surprise to anyone that I decided I had to go back and visit the others. Which I did, so (after the usual delays) here we are at another of them.

Now, the problem with this sort of mini-project is that blog posts need titles, but none of these waterfalls seem to have names, and the creeks they're on also don't have names. So I figured I'd have to make up some nicknames for them just to tell them apart. Which is the hard part, of course; there's an old tech industry saying dad joke that the two genuinely hard problems in Computer Science are cache invalidation, naming things, and off-by-one errors.

In any case, here we are at the northernmost of the five, which happens to be just a few feet outside, or possibly inside, of the current (as of December 2022) Troutdale city limit along the old highway. That seems to be the only landmark nearby so I went with "City Limit Falls" for this one. Google seems to think there aren't any other waterfalls by that name anywhere on Earth, which may be a clue that it's a dumb name. For one thing, the name instantly becomes wrong if the city limit ever moves. But hey, I just need titles for a few blog posts, I'm not trying to be Columbus or anything.

For a little context on what's going on here, this stretch of the highway runs along a narrow bit of floodplain with the Sandy River one one side and near-vertical basalt cliffs on the other, generally about 150'-250' high. Those cliffs are actually the eroded west side of Chamberlain Hill, an old volcano that's part of the same Boring Lava Field as Portland's Mt. Tabor and Kelly Butte. Above the vertical edges the mountain is mostly gentle rolling farmland, with a steeper cone at the 909' summit. Note that you can't actually visit the top; the road that seems to go to there ends in a cluster of gated driveways, as you can see on Street View here. So you should probably ignore the auto-generated Peakbagger and Lists of John pages about the place. The key point right now is that it rains a lot here, and rain that falls on the west side of the hill has to go off a cliff to get to the Sandy River. This particular creek has carved sort of a north-facing grotto so it doesn't get a lot of direct sunlight even in late afternoons, and it's harder to see from the road than some of the others. You catch a glimpse of it heading south but there's nowhere to park when you're going that direction. Heading north there's room for about one car to park on the shoulder, though you won't really see the waterfall until it's in your rear view mirror going that way. So if you want a good look at this one, you sort of have to study a map and plan it out ahead of time. Honestly it's probably easier to walk or bike this one, though admittedly I haven't actually tried that.

I don't have any fun facts to share about this one, so I guess the next order of business is to figure out how tall it is. I'm not very good at just looking at things and guessing, and I don't own any climbing gear or surveying equipment to measure it either of those ways. But I do know my way around the state LIDAR map fairly well, so we'll see what we can come up with that way. The map has a "Bare Earth Slope (degrees)" layer, where the steepest terrain is coded as white and flattest is a dark grey. So the trick is to find the river/creek/stream you're interested in, then squint at the map and find the points where it becomes very steep and then flattens out again, and and take those as our top and base. Each point on the map has several elevation numbers, up to around 10-12 of them; then the slope at a given point is derived from those altitude numbers with a bit of simple calculus, which you fortunately don't need to compute on your own. For the overall height, take the highest and lowest elevation from both points (124.77' and 117.37' for the top point and 68.06' and 61.54' for the base), then do a little subtraction, and that gives you a range. Sounds easy, right? The only problem (which may not be a problem at all) is that this consistently produces numbers that are quite a bit higher than what I come up with standing at the base and guessing (which -- as I keep saying -- I am notoriously bad at). As in, I get around 50-60 feet (49.31' - 63.23' to be precise) from the map and would not have guessed over 25-30' here. I'm not sure where the discrepancy is creeping in; maybe the map numbers are absolutely spot on, and you just can't see the very top of the falls due to the angle. Or the point I picked as the top is somewhere above the real top and I'm picking up extra height that way. I'm honestly not sure.

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