# Colorado River Historic High Water Level Within The Grand Canyon



## GCPBA (Oct 22, 2009)

Colorado River Historic High Water Level Within The Grand Canyon

This report was commissioned by GCPBA for the benefit of the private boater. John Vrymoed, author of the report, is a registered civil and geotechnical engineer in California, now retired. He is a published author on topics related to earthquake engineering and dam performance, has served on a panel of experts for the U.S. Army Corps of Engineers, and has given presentations at various conferences.

Synopsis: The purpose of this report is to define the Colorado River's high water level's location and thereby assist the private boater in recognizing the extent of the disputed boundary between Grand Canyon National Park and the Hualapai tribal lands. The Colorado River historic high water level within the Grand Canyon is determined to be 80 feet above a base flow of 8,000 cfs between Lees Ferry and the confluence of the Little Colorado River, and 100 feet above the base flow from there to the Grand Wash Cliffs.

Read the full report here: Colorado River Historic High Water Mark Report

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## mikepart (Jul 7, 2009)

Holy crap! Do you really think that you can define the historic high water mark by modeling out a flood with a return period of over 3 million years!


I'm no lawyer, but 1.13 million cfs is a theoretical paleo-flood that has never been observed by any human in historical times. The author uses the geologic age of the Grand Canyon as a justification for using his determination of the "historic peak flow".


To be clear, paleo-flood studies referenced in this piece of non-peer reviewed, very shady grey literature have documented some big floods in the Colorado River, but nothing close to what this guy is calling the historic peak flow; the flows he is using are so unlikely that they are derived by extending a model millions of years past the available data.


Please don't anyone take this document as sound legal advice that you can go where you want as long as you stay withing 100 ft of elevation from the river level.


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## john vrymoed (Aug 22, 2014)

“_Holy crap! Do you really think that you can define the historic high water mark by modeling out a flood with a return period of over 3 million years_!” Absolutely! Yes! These kinds of engineering studies are done all the time – you’re just seeing one applied to the Colorado River thru the Grand Canyon. Engineers put men on the moon, made the Library of Congress available on a microchip, allow you drive from Paris to London, provide for magnetic resonance imaging, etc. All decades ago! The foregoing more justifiably elicit a “Holy Crap.” 

More to the point. Apparently the report was skimmed - understandable as it is long and perhaps a little tedious to read. Very quickly: A probable maximum flood is not a paleo flood. PMF studies are routinely carried out and are based on data provided by the National Weather Service. They do not extend data to millions years. Yes, it is easy to confuse length of time with probability as most people do. 

Paleo flood studies are well recognized as reliable. They extend our knowledge of historic events neither seen nor recorded. “_Observed by any human in historical times_” - in the case of observed and recorded data at Lee’s Ferry, this would be about 100 years – the blink of an eye in relation to the GC’s age. The 100ft elevation is not based on a flood of 1.13 million acre feet. 

“_I'm no lawyer_” - as such, it is also understandable that it may be difficult to discern what constitutes legal advice. The report is an engineering, not a legal study. The report states the 3 options available. 1) Pay the Hualapai for camping on the left side; 2) Camp solely on the right side, and; 3) Camp on the left side and stay below the high water mark per the NPS instruction. Locating the high water mark simply better defines option #3 – the NPS does not provide a location. These three options are well known. The report does not recommend one option over the other - it is difficult to understand how this could be construed as legal advice. 

Don’t agree with the GCPBA’s commissioned report? A little hesitant re option #3? Then use options #1 or #2 or come up with your own analysis or guess re the historic high water level’s location.


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## john vrymoed (Aug 22, 2014)

Oops, that 1.13 million cfs - not acre feet.


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## GeoRon (Jun 24, 2015)

Let's see what type of response results from: 

Attempts to define the high water mark on the left bank is yet again another attempt by the whiteman to take away land from the redman.


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## mikepart (Jul 7, 2009)

"More to the point. Apparently the report was skimmed - understandable as it is long and perhaps a little tedious to read. Very quickly: A probable maximum flood is not a paleo flood. PMF studies are routinely carried out and are based on data provided by the National Weather Service. They do not extend data to millions years. Yes, it is easy to confuse length of time with probability as most people do."


I read the entire report and I did not find it difficult to read or understand. I did find your justification (or lack of justification) for using these ridiculous flows unconvincing. You provide no justification whatsoever that the PMF corresponds to a discharge associated the "high water mark" in question. The only reference that you provide to explain what defines a high water mark is Wikipedia.


TO BE CLEAR: I have no problem with the synthesis you performed on existing work. I have no problem with the concept that the discharge levels provided roughly correspond to the elevations above base flow that you have indicated. My problem is with the determination that a flow of 860,000 cfs corresponds to what was intended as the "high water mark." 



Engineers and hydrologists can do great work when provided with a clear definition of of the problem or question at hand. Unfortunately, "high water mark" is not a clearly defined measurement or concept. As such, I have heard of two types of high water marks: ordinary high water marks and historic high water marks. Roughly, an ordinary high water mark is one that can reasonably be expected to occur on an ordinary year. Ordinary high water marks are often defined by changes in vegetation and other observable features. I am, admittedly, less clear on what defines a historic high water mark, but the term historic seems to point to a high water mark that was observed at some point during recorded history. Regardless, there is no precedent that I know of to use the probable maximum flood as a benchmark for determining any high water mark used to resolve boundary disputes.


I did not misunderstand the difference between return period and probability. These flows that you reference have a return period over 3 million years (Figure 3). So the probability of water reaching your high water mark in a given year is 1:3,000,000. Yep, p=0.00000033. Pretty darn unlikely. On page 10, you use the geologic age of the Grand Canyon (6-70 million years) as justification that these flows have probably happened in the past, but here is another way of looking at it: The species _****_ _sapiens_ is believed to be around 350,000-200,000 years old. Using the older number, that gives us a probability of 0.12 (roughly 1 in 9) that these flows occurred when humans existed as a species. Now considering that humans first arrived in North America between 15,500 and 13,500 years ago, we have a probability of 0.0052 (roughly 1 in 200) that a flood of this magnitude occurred when humans inhabited this continent.


Hey, I like boating and I like access, but I don't like it when someone uses technical knowledge to create an illusion of accuracy to serve their own interests. Do you really think that when the boundary of the reservation was determined to be the left bank of the river, that the original authors of that document intended the bank to be determined by such an unlikely flood event so that anglo Americans can recreate through the river corridor?


Having dealt with tribal access issues a little bit previously, I can say that what often really screws things up is when some white boys come in and say that they actually don't have rights to the land. 



How is this anything more than another attempt to encroach on the sovereignty of this little bit if land set aside for the tribe by trying to use an outlandish high water mark to serve your own agenda?


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## mikepart (Jul 7, 2009)

"The 100ft elevation is not based on a flood of 1.13 million acre feet."


Oh, oh, sorry. 860,000 cfs. Still ridiculous.


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## caverdan (Aug 27, 2004)

mikepart said:


> "The 100ft elevation is not based on a flood of 1.13 million acre feet."
> 
> 
> Oh, oh, sorry. 860,000 cfs. Still ridiculous.


I wonder if they are basing it on dam breakage??? 

Now THAT would be a flood.....


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## waterdude (Apr 20, 2017)

Does the rain follow the plow, here? This seems to be the real question, as conjuring doubt that a legacy land policy is inaccurate and thus we should reassess the ownership distinction to indigenous peoples, do not change the facts of the matter. It rather seems like a hamfisted effort to create controversy for the sake of securing more river access, which to me is entirely unethical. Troubling to me most, which is what someone else pointed out quite succinctly, is the cherry-picking of literature to create a new series of conclusion, without going through a robust peer review. Because, let's say for example you submit to top-tier journal....well, they will solicit reviews from an expert panel of hydrologists and affiliated experts, whom will challenge you on basis of assertion, evidence, and available literature. The fact that the author of this report chimed in here to attack others on a who questioned the validity of the conclusions, only irritates me further because I myself have published in WRR and don't appreciate the implication that technical knowledge is above reproach...regardless of whether it came from a retired expert or not. 

Paleohydrology is also tricky business; involving a delicate mix of hydrodynamics, sedimentology, fluvial geomorphology, as well as a touch cosmogenic nuclide analysis to get right. The relationship between high water marks to infer discharge also tends to fall apart on longer timescales because the river is both downcutting and the bathymetry is changing. Sure, it works on a flood that just happened to figure out what the peak flow was, but beyond that the resolution is poor. Let us not also forget the glaciation/deglaciation cycles, and that the last only occurred tens of thousands of years ago. In light of that, using recurrence intervals is a disingenuous approach since it is only as robust as the length of record (i.e. datapoints), therefore extending that into the distant, dynamic past borders on the absurd. We need not look further than the literature on the historical glacial lake outbursts, to wonder if in fact a discharge near 1 million CFS is even possible in the Grand Canyon. 

Another major gripe I have is the avoidance in using a robust model to estimate runoff using drainage area and precipitation, particularly when BoR uses VIC to create these estimates for PMF using a ton of available data (met, hydro, ET, soil moisture/thickness, etc). Where is that analysis? As talking about a model, then making a huge assumption about drainage area + precipitation = runoff is dubious at best, and here in the 21 century we use supercomputers to perform that kind of work. But Riverware or MODSIM can do a decent job as well. But the point here is the complexity of surface water modeling tools is high, and there is reason for that. 

In any case, I'm not going to indulge in a debate, because that's a pointless exercise particularly here. Rather I want to point out that just because something is "long" or appears "tedious" to read doesn't means its entirely factual or robust, and we should approach all new information with a healthy bit of skepticism....perhaps more so if it comes from those with skin in the game like the GCPBA, as we don't need to conjure evidence to make River Access Great Again.


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## mikepart (Jul 7, 2009)

waterdude said:


> In any case, I'm not going to indulge in a debate, because that's a pointless exercise particularly here. Rather I want to point out that just because something is "long" or appears "tedious" to read doesn't means its entirely factual or robust, and we should approach all new information with a healthy bit of skepticism....perhaps more so if it comes from those with skin in the game like the GCPBA, as we don't need to conjure evidence to make River Access Great Again.



I agree, but you don't need to read very far into this report to see the true absurdity of it. Regardless of how you calculate it, no one ever intended any estimation of the largest possible flood for a drainage to be used to determine where a body of water is used as a boundary.


If this guys logic holds true, boundaries all over the country would be changed.


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