Upper Multnomah Falls

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Ok, it's time for the next stop on our ongoing (and very slow) virtual hike around the Multnomah-Wahkeena Loop. The Larch Mountain Trail (which we've been on so far, other than the detour over to Little Multnomah Falls) has a junction with the Wahkeena Trail at the 1.8 mile mark, and right around that point Multnomah Creek goes over a cluster of 5'-10' drops, maybe 35' overall. It's a pleasant enough spot, though not one of the scenic highlights of the trip, and I was surprised to learn it's been saddled with the name "Upper Multnomah Falls", a name that leads to all sorts of unmet expectations. After figuring this out, I went back and found that I'd taken photos of it on at least three separate occasions, never thinking "hey, cool waterfall", just that it was an especially photogenic spot along the creek. Still, it had a name (albeit a dumb one), and I had photos of it, and that meets what I admit is a low bar to be included here, so here we are.

The name made it harder to research this post than it needed to be, since the majority of places we've visited in this project have been called "Upper Multnomah Falls" at some point or other, and the one we're visiting now is way more obscure than any of these others. Once you wade through all of the irrelevant search results, there isn't a lot of material left out there on the interwebs. Because I'm hanging out at home with the cat during a pandemic, I went ahead and waded through said results. You'd think this would've been a quick and easy post to write once I was done collecting every last thing I could possibly find on the internet about this little spot. But no, it ended up as a lengthy depth-first exploration of every last side diversion I've bumped into along the way -- again because pandemic -- none of which I can quite bring myself to delete. I am at least slowly learning to kick stuff down to the footnotes when it doesn't relate to the main point of a post, though, the first footnote being an extended bit about the name, and where it came from, and when, and why you probably haven't heard of it. The TL;DR is that the waterfall (and the use of the name here) may have originated with a 1983 guidebook, and then it largely fell out of favor by the mid-2000s. As far as I know the waterfall itself did not change at all during this time, and this is all just people having opinions and a consensus slowly shifting over a few decades.

In any case, the Upper Multnomah we're visiting right now does have one minor claim to fame. There's an undated infographic I've run across a few times that explains that there are precisely eight kinds of waterfall out there in the world [footnote: 'geology'], and you can collect the whole set just by visiting a few spots in the Gorge. In particular, you can see five of the eight just by doing the Multnomah-Wahkeena Loop, with Upper Multnomah here representing the "cascade" variety. (Hiking to Triple Falls from the Horsetail trailhead will get you two of the remaining three, and you can finish off the set at the first falls on Eagle Creek, fwiw.) The standard caption for cascade-type waterfalls explains this variety "[t]umbles along a series of rock steps. You'll find a fine model by following the directions to Dutchman Falls, then hiking 0.2 of a mile (a total of 1.9 miles from the trailhead) to Upper Multnomah Falls, near the junction with Wahkeena Trail #420.". Here are a few contemporary examples of where this infographic has showed up:

• The 2005 edition of the guidebook Oregon Off the Beaten Path used the infographic, and the first edition of the book was first published in 1991 so it might go back at least that far.
• A page at ColumbiaRiverGorge.info uses the same example, crediting the US Army Corps of Engineers for the information.
• The same phrasing has showed up in a recent tourist pamphlet from the Forest Service.
• A visitor pamphlet given out at the Vista House, though it mangles the description a bit as of the most recent (July 2020) version.

So my personal theory, which I can't prove, is that the name was bestowed here and persists because of this grand tour of waterfall types. There are probably dozens of similar spots around just the Oregon side of the Gorge where some creek drops at least X number of feet over a distance of no more than Y feet, for whatever threshold values of X and Y you've picked out, and almost none of them have names, but this one gets singled out because it's on a route visitors would be on anyway on their way from the "Block" example at Dutchman Falls, and the "Fan" example at Fairy Falls over on Wahkeena Creek, or vice versa.

Some assorted sightings of the falls from around the interwebs:

• Oregon Hikers Field Guide has a nice pre-fire photo titled "UpperMultnomahFalls.jpg", used but not named in the Larch Mountain Trail article .
• It also gets mentioned in passing in a few of their forum threads:
  • A post in this thread calls it the "Rodney Dangerfield of Multnomah Creek Waterfalls"
  • This one includes an artsy photo labeled Upper Multnomah but which might be Little Multnomah; it's hard to be sure because artsy.
  • Another thread says it was actually impressive when they visited, unusually, but they didn't take a photo
  • Someone else was unusually impressed by it in a 2013 thread, and included a nice photo.
  • Yet another thread miscaptions Little Multnomah as Upper, but also has a photo of the "real" Upper Multnomah. I think. It can be hard to tell from some angles.
• On Flickr, an artsy pinhole photo that might(?) be of the right place
• A few more photos by various Flickr users, found either by name or by geotag, at least some of which seem to be of the same spot I keep taking photos of: [1] [2] [3] [4] [5] [6] [7] [8] [9]
• Someone's blog post with a bunch of Boy Scout hiking photos, including a view of Upper Multnomah taken while doing the Multnomah-Wahkeena Loop.
• Someone else's 'I should take a photo of that' photo, part of a longer hike, including stopping by Nesika Lodge, and the weird trail with the christmas ornaments and/or toothbrushes somewhere up in Multnomah Basin. Fwiw if you happen to be in that area, there's also a long-abandoned 1931 Buick up there somewhere, though I've personally never bothered to go looking for it. Just not my thing, I guess.
• An undated OregonWaterfalls.net photo captioned "Upper Multnomah" doesn't quite look like the place pictured in the blog post, but it might still be the same from a different angle.
• A Youtube video of hiking down the Larch Mountain Trail from the third footbridge to Ecola Falls, with a chunk in the middle lingering over Upper Multnomah. Kind of the same thing I didstarting at 1:23
• It showed up in someone's 2003 blog post (with a tiny photo) about the Multnomah-Wahkeena loop.
• Was also mentioned on a somewhat idiosyncratic list of waterfalls at The Columbia Experience. I'm not 100% sure he's talking about the same place, but the list is mostly ordered geographically, east to west, then north to south, and it's in the right location in the list anyway. Though Dutchman and Little Multnomah are swapped, and the whole Wahkeena list is swapped with the Multnomah list, so who knows.
• A stock photo on Alamy

Oh, and I did find one possible historical photo, in a 1924 issue of The Camera. The magazine featured a monthly Print Criticism section, in which you -- the hopeful reader -- could submit a photo, and the magazine's team of experts would make fun of it (and you) to a national audience. But at least a small copy of your photo would be seen by a national audience, which is fantastic if you believe the old adage about there being no such thing as bad publicity. Here's what the critics had to say:

“Leaping Waters”, by B.G. Smith.

We have no doubt but that this subject looked most beautiful to the artist. He looked at it with a poetic eye, as his title betrays, but the glamour of the theme veiled his eyes to its lack of pictorial interest. He fails to do even justice to the facts, because he surrounds them with so much uninteresting matter that these surroundings become of more importance as space fillers than the falls itself. There is everything here one could want to make a picture with, the falls, the dominant feature, but by the failure to identify interest where it is demanded, we have, instead of a picture, a mere mass of conglomerated areas of almost equal intensity, and a mere bit of white supposed to represent the beautiful falls, no separation of the planes whatever. Everything in the one vertical plane, no depth or distance. Had the photographer, first of all, studied the proper angle of light, we would have had the water of the falls look like agitated water instead of wool, and the quiet pool transparent, instead of an ink well. We do not know whether the photographer was pleased with his results or not. We credit him, however, with enough taste not to be — and that he sent the subject to get our opinion of it. Our suggestion is to try it again, but spend the whole day if necessary to get it pictorially.

Made on the Larch Mountain Trail with a Korona view camera equipped with a Goerz f/6.8 lens. The exposure was 1/10 second in the shade at 2:30 P.M. in September; Eastman cut film developed with pyro; print on Artura.

Ouch! Sadly the scanned copy of the magazine is too dark and lo-res to form a fair opinion of the photo, quality-wise. On one point of the critique, a 1/10 second exposure of any waterfall made by anyone, will tend toward the "wool" look as they call it, not agitated waters. And given the slow film speeds of 1924, and the lens's max aperture of f/6.8, and how rarely you get direct sunlight in the Gorge's north-facing canyons, giving them their agitated waters might not have been as easy as just hanging around the right spot waiting for inspiration to strike. Besides, the "wool" look is now the standard aesthetic for quality photos of Gorge waterfalls and it's been that way at least as far back as the 1960s Ray Atkeson photo books. So a big "pshaw" to the whole agitated waters thing. I do think Smith could have improved his photo by cropping it a bit, though. Although it's not as if I usually bother with that for my Flickr photosets, so take that with an appropriately-sized grain of salt, I guess.

And just as a little curveball, another OregonHikers thread I ran across includes a map that places an "Upper Multnomah Falls" another mile upstream around the point where the Larch Mountain Trail splits into Low and High Water routes, and a "Double Falls" maybe 1/4 mile downstream, and nothing at the Wahkeena trail junction. I don't recall seeing anything that looked like a waterfall upstream of the one here, and I think I would have noticed one, but I've been wrong before. Multiple times, even. I suppose I'll have to go look again after the pandemic's over.

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footnotes

Naming

If you do any sort of search for the phrase "Upper Multnomah Falls", nearly all of the results will be for the upper tier of Multnomah Falls (here for example, and here.), which -- to me -- is the most logical place to apply the name. But it's also an old name for the Wiesendanger Falls & Ecola Falls combo, so there are a few results for both of them as well, like this page , and this circa-1992 jigsaw puzzle, sold nationwide, and most of the then-canonical guidebooks by Don & Roberta Lowe. Their original 100 Oregon Hiking Trails (1969) didn't use the name, but the ones that followed did, starting with 70 Hiking Trails - Northern Oregon Cascades (1974) and running thru at least the late 1980s. A few other search results point at Little Multnomah Falls (like these photos), I guess on the entirely reasonable theory that it's right above regular Multnomah Falls so it must be the upper one.

The earliest use I've found of "Upper Multnomah Falls" for this modest spot is in Gregory Plumb's 1983 guidebook Waterfalls of the Pacific Northwest, which evolved into the long-running A Waterfall Lover's Guide to the Pacific Northwest, published in five editions (so far) beginning in 1989. The 1989 Waterfall Lover's Guide is the earliest version Google Books has, and it (like the 1983 book) describes the falls briefly, rating it at one star out of a possible five: "This 15-to-20-foot drop can be viewed from Larch Mountain Trail #441 about 0.2 mile past Double Falls (see directions above), a total of 1.8 miles from the trailhead near the junction with Wahkeena Trail #420.". The book's present-day companion website also has a page for the falls, still rating it as a single star.

I haven't found any examples of it being called anything else before 1983, or of it being singled out as anything special apart from all the other rapids and cascades above Ecola Falls. The book doesn't claim to have originated using the name here, but any prior uses of it don't seem to be online anywhere. The one-star rating is a common theme, as you'll see in a bit here; I think it gets docked points due to a) not measuring up to the grand-sounding name, and b) being compared to everything visitors have just walked by on the way there. In many US states it would qualify as a major local tourist attraction on its own merits. (I was originally going to make a wisecrack here about waterfalls in Kansas, but then I googled it, and then a few other even flatter states, and (because pandemic) that particular tangent became another footnote.)

The undated infographic I mentioned up above might be older than 1983, but I can't prove it. Oregon Off The Beaten Path was first published in 1991, though I don't know whether it used the graphic before 2005, and the hand-drawn illustrations of 'generic' examples of each waterfall type are in a style that to me looks very 1970s or early 1980s.

The 1998 guidebook Romance of Waterfalls mentioned the falls briefly in its Hidden Falls (aka Ecola Falls) entry, saying that from there it was ".2 miles, 10 minutes to Upper Multnomah Falls, a rather insignificant falls which is often barely noticeable under logjams". Later on the entry explains "We have chosen not to include Upper Multnomah Falls, a few minutes upstream from Hidden Falls, in the book. It's an artistic judgement. Take a look anyway, and decide if we did the right thing."

The Northwest Waterfall Survey once had a listing for it, per a December 2001 Wayback Machine snapshot, said "Though there isn't any "real" waterfall past Hidden Falls, as long as you're here, you may as well walk the .2 mile from Hidden Falls to this rather sad little drop along Multnomah Creek.". Because this was posted close to twenty years ago, the page's hint to photographers said "Don't waste film here like I did (unless you need to finish a roll)." A 2006 version of the page mellowed out a bit toward the little waterfall, albeit while explaining it shouldn't be in the datatabase at all:

While the last major waterfall along Multnomah Creek is technically Ecola Falls, the stream beyond is exceptionally scenic, pockmarked with small drops here and there. This 10 foot ledge is the largest of those. This drop is included in here more as a disambiguation than anything else. Future overhauls to this database will see this entry removed. ... Photography Tips: This one is scenic, worth taking pictures of, but not necessarily as an illustrative waterfall scene.

And sure enough, no trace of it remains in the present-day database. I think they came up with the 10' height by just counting the single tallest drop and not the ones immediately above or below it.

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Waterfalls in very flat states

As I mentioned above, Upper Multnomah would qualify as a major waterfall in Kansas on its own merits, and possiby as an important visitor attraction, or at least a local swimming hole. Note that I am not making fun of Kansas here, just noting things are always graded on a curve, and Kansas has a different set of local standards. For one thing, some of the ones listed in the two links above are artificial ones including dam spillways and others where water just sort of finds a different, natural-looking path out of a reservoir, and a 3' drop is worth writing about if it looks impressive enough otherwise. The deal is that while the state certainly looks flat, it's kind of tilted like a table with a bum leg. So the highest point in the state is tongue-firmly-in-cheek Mt. Sunshine, on the Colorado border, at 4309 feet above sea level, while the lowest point is somewhere on the Oklahoma border at 679 feet elevation. 3630 feet is equivalent to Multnomah Falls stacked on top of Yosemite's El Capitan, but it's barely noticeable when spread out evenly over the width of the state.

A news item out of Chicago points out that Kansas is only the seventh-flattest state, with Florida in the lead and Illinois taking second; it reads kind of like they're proud of the fact. That article is based on a 2014 paper "The Flatness of US States" by two University of Kansas geographers, one of whom describes the work here. So I wondered what the six ahead of Kansas had in terms of waterfalls, and got to googling, because pandemic.

1. Florida. Most search results on Google Maps named something-something falls are retirement communities, garden stores, or tourist traps, but I did find a few results, largely concentrated in the panhandle or the stretch along the Georgia border:
   • Boonie Falls just 3', between Orlando & Cape Canaveral. Naming a 3' waterfall seems absurd if you've never been to this part of Florida, but it really is that flat. I might actually go track this one down the next time I'm in Florida, since it's the only part of Florida I visit on anything close to a regular basis, due to rocket launches.
   • Falling Creek Falls, 10'
   • Steinhatchee Falls 4-5'
   • Falling Waters Falls, a whopping 73' but flow depends on having rained recently, and water is falling into a deep sinkhole
2. Illinois has several completely normal ones; I guess the deal is that they're concentrated in the far southern tip of the state, the rest of which is pancake-flat.
3. North Dakota has exactly one waterfall, according to the internet, and it's... not spectacular. This actually surprises me, given the (relatively) rugged and remote western end of the state, home to a two-part national park. But if there are any others, either nobody's talking about them or nobody's discovered them yet. I would have expected a colorful tall tale about it, like Teddy Roosevelt somehow lassoed it, or bested it in a fistfight, and then had a change of heart and decided it needed protecting.
4. Louisiana waterfalls tend to be of the trickle of water going over a low cliff variety; I was prepared for them to not be very tall, but I somehow thought Louisiana had more running water than what you see in the given examples. But ok. Lots of good writeups though, so clearly the local demand for waterfalls seems to outstrip the supply by a great deal.
   • "9 Amazing Waterfalls in Louisiana"
   • Rock the Falls - Finding Louisiana's Tallest Waterfall"
   • "Waterfall Hiking Trail Near Baton Rouge is a Tranquil Day Out"
   • Google Sites page dedicated to the subject
   • "Hiking Clark Creek With Pack and Paddle"
   • And then there's mysterious Odum Falls, which is said to exist somewhere on a large military base near Nachitoches, LA. There seem to be no photos of it online anywhere, though; it could be the Niagara Falls of West Louisiana and nobody would ever know. Maybe the whole military base is a decoy, and the real secret base is entirely behind the waterfall. Maybe that's where they hide the aliens. The truth is out there, amirite?
5. Minnesota not only has waterfalls, it has some that are major tourist attractions, despite the state not being famous for majestic snow-capped mountains. Which kind of kills the "flat = boring" hypothesis. Downtown Minneapolis has the Falls of Saint Anthony on the Mississippi River, along with at least two significant falls in the wider metro area. A few things around the rest of the state:
   • "9 Minnesota Waterfalls You Can See on a Daytrip"
   • "15 Amazing Waterfalls in Minnesota"
   • "Best Minnesota Waterfalls"
   • Guide to waterfalls along the state's "North Shore" on Lake Superior
   • Waterfalls of Minnesota at Michele's Waterfall Page.
6. Delaware is the only state that legitimately seems to have no real waterfalls at all. The top search hit I found is a Wikipedia list of waterfalls in the Delaware Water Gap, a scenic stretch of the Delaware River north of Philadelphia that forms part of the Pennsylvania-New Jersey border and does not include a single square inch of the state of Delaware. Waterfalls in Delaware at Michele's Waterfall Page came up with precisely two, a "Rockland Falls" and some unnamed bits of whitewater on a creek near the Wilmington zoo. The World Waterfall Database only lists Rockland Falls, and lists it as "Disqualified" seeing as it's the collapsed remnant of an old mill dam. This actually puts Delaware behind Washington DC, which has half of Little Falls on the Potomac (which the World Waterfall Database says is "Disqualified", though DC opinion seems to run the other way, with articles calling it a "natural wonder" and a hidden treasure"), plus an old mill dam in Rock Creek Park.

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Geology

The "eight kinds of waterfall" model is by no means the only way to slice and dice the subject, oh no; two Wikipedia lists add a few more types to the jumble (but not the same ones), both citing a page that came up with 28 varieties for people to argue over. Meanwhile the Northwest Waterfall Survey folks came up with a 5x8 matrix classifying things by steepness and how it interacts with the surface it's flowing over. Which would give you 40 flavors, except that close to a third of the combinations are impossible (a clue the two axes are not quite independent variables), so with those removed they're back to 28, but a different 28 than the set Wikipedia relies on. And of those, the three in the 'Talus' row -- meaning the water's flowing down loose rocks or boulders -- don't meet their definition of what a waterfall is and are either not listed at all, or are tagged as "Disqualified", which seems a bit on the harsh side.

Also found a page on classifying waterfalls in Finland. It turns our they are basically like US waterfalls, except that you have health care if you get hurt exploring them.

I was sort of expecting to bump into something a bit more academic than those, but I haven't. Although it turns out the author of the Waterfall Lover's Guide is a professor of cartography and geography at a university in Oklahoma, and Google Scholar says the book has been cited at least eight times, along with another three citations for Waterfalls of the Pacific Northwest, the book's 1983 predecessor. Also here's a 1993 paper of his (PLUMB, GA. "A scale for comparing the visual magnitude of waterfalls." Earth-science reviews 34.4 (1993): 261-270, 14 citations), which the Northwest Waterfall Survey cites as an inspiration for their rating algorithm. I'm kind of curious about the math, even though my general rule is that if your rating system has decimal points, you might be taking things too seriously. I am not sure how the math works, though, because the journal is an Elsevier one and they want about $40 for a PDF of the paper. Which I could afford, except that academic publishing is a grift and my tax dollars are already subsidizing those parasites quite handsomely, and in short we aren't going any deeper down the math rabbit hole. Watch as this theme develops further throughout this footnote.

The original 1983 book came two years before the paper that I keep seeing cited as the first to treat waterfalls as something serious geologists can write papers about: Young, R. W. "Waterfalls: form and process." Zeitschrift für Geomorphologie. Supplementband 55 (1985): 81-95. I gather it's in English despite the long German journal name, but I couldn't find a copy of it online, or a tech-savvy publisher who'd deign to gouge me for a PDF of it. I even approached it like a Real Scientist and tried searching Sci-Hub for a 'bootleg' copy but couldn't find it there either, so either they don't have it, or they do but it has the wrong sort of unique ID and I can't search for it. (Adapting an old tech joke, the great thing about unique IDs is that there are so many to choose from.) I could maybe check my local university library, local being just blocks from here, to see if they have a print copy, but it's currently closed because of the ongoing global pandemic.

1985 seems awfully recent given that people have been doing geology for centuries, but waterfalls don't tell you anything about earthquakes, and they don't show you where to drill for oil, or mine for coal, or feed into any other sort of practical concern that drives grant money. The old trope about hidden treasure behind waterfalls is rarely true in real life, unless maybe you count geocaches, which I don't. Enough people found it useful, though, that Google Scholar shows 58 citations for it. (Note: I have no idea whether 58 is a lot for a 35-year-old paper of this sort.) Most of the papers citing it seem to be about erosion processes, and some about their economic value for attracting tourists. Here are a few that caught my eye, and some tangents they led to, because I do that:

• "The Naming of Waterfalls" caught my eye, as something potentially (and regrettably) relevant to my interests. The publisher wants $42 to download a PDF, though you can read it online for 48 hours for $7, or... obtain one via Sci-Hub here (though that URL is likely to break as the copyright police pursue Ms. Elbakyan around the globe like a sciencey Carmen Sandiego).
• An open access paper exploring whether seepage from underground springs could pack enough of a punch to erode a canyon in solid rock on its own. This has been proposed as one possible origin of canyons on Mars that wouldn't require any water flowing on the planet's surface. Terrestrial analogs in Colorado and Hawai'i suggest the answer is a big no, and in the Hawaiian case you don't get an erosional valley without a waterfall at the head of it. One of the cited examples is 'Akaka Falls on the Big Island, which this humble blog 'visited' back in 2012, although the photos are from late 2000 and most of the post is about working at a dot-com company back in the day, since they paid for that particular Hawai'i trip. So the takeaway here is that there might have once been waterfalls on Mars, although they haven't identifed any specific spots where they might have been. This, if true, does not quite imply the existence of ancient Martian blogs temporarily focusing on the local waterfalls, but it would satisfy one of the necessary preconditions.
• Speaking of which, back in the late 90s and early 2000s, there was a lot of speculation about what NASA's Cassini probe, and its European passenger the Huygens lander, would find at Saturn's mysterious moon Titan. As hypothesized, the moon does have seas and rivers of extremely cold liquid methane and ethane, leading some planetary scientists to wonder if there might be waterfalls too, or whatever they'd be called when the flowing liquid isn't water. This led to concept art and even simulations of what such an alien waterfall might sound like. As luck would have it, Huygens happened not to land near any seas or rivers so the earliest this particular question might be answered is 2036 when NASA's Dragonfly octocopter arrives, though they don't plan to visit the moon's liquid parts. Back in the early 2010s NASA seriously considered sending a boat to drift around of the major seas, and has even studied sending a submarine someday. The problem, of course, is that planning for and then going to Saturn takes decades, and you can't plan followup visits until after you do that, and as a recently-minted 50-something I see some of the proposed dates and realize how old I'll be at that point and have to wonder how much more Saturn exploration I'll actually get to see. As one more data point, a recent design study on making a return visit to Pluto would launch in 2031 and arrive in 2058(!), just five years before Zefrem Cochrane is supposed to invent warp drive and meet some Vulcans, presumably making the little Pluto robot instantly obsolete.
• Um, anyway, here's "Conservation value of waterfalls as habitat for lotic insects of western Victoria, Australia", concerning Australian insect species that are 'waterfall specialists' and live nowhere else, making them biodiversity hotspots that might need protecting. The Columbia Gorge has a few insect species like that too, so this paper took me down another tangent that I pushed off to another footnote. Yes, this footnote has a footnote of its own. I have not yet achieved a state of footnotes all the way down, but it's a start.
• For anyone who's actually clicking through to any of those things, you'll see the word "knickpoint" a lot. Which is kind of a silly word, but it's a technical term in geology, meaning a point where the angle of a river or channel changes sharply. Bent one way, your stream goes over a cliff and you have a waterfall, or at least you get some rapids, depending on the angle, while bent the other way you get a lake. In neither of these cases do you get amazing deals on licensed NBA merchandise, though you might as well check the outlet mall in Troutdale while you're in the area, if that's your thing. In any case, I must have asked Google about "knickpoint oregon" or "knickpoint portland" at some point because the next few links I have are about that.
• A brief item titled "River Knickpoints: Distinguishing Between Mobile and Fixed Steps in River Channels" explains that some knickpoints are mobile (over geological time) due to erosion, while others basically aren't because erosion has bumped up against harder rocks that the eroding body of water can't make any headway against. The latter case is illustrated by waterfalls in the Oregon Coast Range, where various creeks and rivers have eroded through local sandsone until they bumped up against volcanic basalt and have been stuck at that point ever since.
• A 2018 masters thesis on rapid erosion at Bull Mountain in the suburban Portland area kind of illustrates the 'mobile' knickpoint variety. This doesn't imply there are actual waterfalls at Bull Mountain; if there were, there would be upscale subdivisions with 'Falls' in the name, named for the developer's kids or current trophy wife, and the houses would be at least twice as expensive.
• A 1998 article in Oregon Geology (a publication of Oregon's Department of Geology & Mineral Industries) mostly about sediments in the tualatin valley, points out that the Tualatin River has a knickpoint 2.8km upstream of where it flows into the Willamette River, which I gather is unusually close. It seems the river is flowing over Columbia River Basalt when it gets to West Linn, the same rock that forms Portland's West Hills, and the river isn't powerful enough to erode the rock very well, so the knickpoint hasn't really moved since the Missoula Floods 13,000 years ago, and thus the river is quite flat above it. The article references a 1969 paper that argued the whole Tualatin Valley is technically a hanging valley above the Willamette due to this situation. All due to what -- to a layperson -- looks like a series of innocuous gentle rapids from that point to the Willamette, just upstream from Willamette Falls. Parts of these rapids can be seen from West Linn's Fields Bridge Park and Swiftshore (aka Swift Shore) Park & maybe Tualatin River Open Space; most of the river through there is surrounded by McMansions, this being West Linn and all. To give you some numbers, the river drops about 32 feet over the 1.6 river miles from Fields Bridge Park to where it joins the Willamette, and another 10 feet from Fields Bridge to just below the low dam that diverts water into Oswego Lake.
• To find a point where the Tualatin River is another 10 feet above there, you'll have to go somewhere a bit upstream from Rood Bridge Park in Hillsboro, another ~37 miles away as the river meanders. If you keep going upstream from there the river eventually bends upward again somewhere around Cherry Grove, south of Forest Grove, where it exits the Coast Range. Above that point there are at least four known waterfalls, all of them obscure due to limited access and hostile locals. Finding the uppermost one involves a bit of advanced wayfinding around the Coast Range's vast maze of current and abandoned logging roads. I've never attempted visiting any of them, and I usually love obscure stuff like this.

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Biology

The term "lotic ecosystem" in that title means an environment with running water, as opposed to a "lentic ecosystem" where the water just sits there. A waterfall is obviously in the "lotic" category, and as with the linked Australian paper -- the Gorge has a few waterfall specialist bugs of its own.

In a post that was ostensibly about the highway bridge at Wahkeena Falls, I wandered off on a long tangent about Parasimulium crosskeyi, a species of primitive black fly that -- as far as anybody knows -- only exists along Wahkeena Creek and nowhere else in the universe. Per a 2016 Forest Service study, there's also the caddisfly Neothremma andersoni, and the stonefly Nanonemoura wahkeena, which again -- as far as anyone knows -- only exist in and around Wahkeena Creek, to the exclusion of all other equally nice creeks nearby. That study also looked at Farula constricta a slightly more cosmopolitan caddisfly known from a few creeks along the Oregon side of the Gorge, generally toward the west end between Mist Falls and Eagle Creek. F. constricta is described as "a small, moth-like insect, uniform dark brown in color, with a forewing length of 5 mm (0.2 in.) in both sexes". The doc further explains "Farula constricta is known from small, cold-water streams in the Columbia River Gorge. Populations of F. constricta appear to be extremely localized and limited to talus slopes, typically found at the base of small waterfalls." So Upper Multnomah Falls might actually be ideal habitat for these little dudes.

As often happens, when you run across a rare species with such a limited range, it often means there are other closely related species nearby, and at some point an entomologist decided some of them were a new species and not just an isolated population of the same species. In this case it seems there are eight eight other recognized species in the genus Farula in the family Uenoidae, and one of them -- Farula rainieri -- quite closely related. The doc at the the "eight species" link explains that you can only tell them apart by a close examination of the male genitalia, and goes on for a long paragraph on exactly what to look for, if you're into that sort of thing.

In the same vein, the 2016 USFS study also mentions some sightings of what it calls Neothremma near andersoni, a potential new species only seen (so far) at two sites along Multnomah Creek, where the Larch Mountain Trail crosses small side tributaries. Per a map in the doc, one site seems to be on a small creek near the Wahkeena trail junction & thus quite near Upper Multnomah Falls. So if you're doing the loop either way and a tiny unobtrusive caddisfly tries to hitch a ride to the next watershed over to go a-courtin', I'm not sure what advice to offer there.

On the other hand, N. wahkeena seems to have no close relatives and has the whole genus Nanonemura all to itself, per a 2001 paper, and only exists at a couple of water seeps along the trail near Wahkeena Spring.

If you think studying tiny caddisflies is a useless subject nobody outside academia could possibly be interested in, you would be quite wrong. For example, F. constricta is mentioned on a site devoted to flyfishing entomology. The idea behind flyfishing entomology is that the more you know about aquatic insects, the better you can imitate them and turn their natural predators into dinner, because circle of life, and all that. Someone in an OregonHikers thread mentions bumping into a couple of fly fishermen at the base of Wiesendanger Falls, one of whom caught a fish of some sort. The poster didn't mention what species the fishermen were pretending to be at the time, and possibly neglected to ask.

That made me wonder whether fishing is even legal at Wiesendanger Falls; I'm not entirely sure about this but I think the answer is a big no, you aren't supposed to drop a hook in the water anywhere upstream of the railroad bridge, according to a pile of fishing-related links I dredged up: [1] [2] [3] [4] [5]. Now, Multnomah Creek does flow into Benson Lake, which the state actually stocks with various kinds of fisherman-friendly sport fish, some native, others not so much. So if any of them gets a notion to swim upstream as far as the base of Lower Multnomah Falls, that would probably be a bad place to be a baby caddisfly, and maybe an adult one.

As far as other Gorge endemic species go, there's even a Larch Mountain salamander [doc], though its (still very limited) range extends beyond Larch Mountain. They even made it across the Columbia once, somehow, the northern ones forming a genetically isolated population [d

There's also such a thing as a waterfall specialist plant, like this one discovered in Sierra Leone in 2017. I haven't seen any discussion about similar plants here, but it's entirely possibly nobody has looked for them yet.

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Stuff behind waterfalls

It's a longstanding media trope and particularly a video game one, which has become one man's personal quest The problem in real life being that caves behind waterfalls tend to be a lot wider than the falls (see Ponytail Falls for example), and that's going to attract curious visitors, who will quickly find whatever gold you hid there since the cave never goes back very far. Or maybe those are just the decoy caves, and the real ones are hidden so well that nobody's ever noticed them. Someone on Reddit pointed out one example, a large cave system in Alabama that has an entrance behind a waterfall, though it has several other entrances.

One very weird thing-behind-a-waterfall (and an exception on the natural resource front) is at Eternal Flame Falls, in a suburb of Buffalo, NY. Seems there's a methane seep in a small niche behind a waterfall, and the methane is concentrated enough that it can be set alight. Despite the name, the flame is not 100% eternal; visitors are encouraged to practice good citizenship by bringing a barbecue lighter along to relight the waterfall if it goes out.