# The Great Salt Lake is Shrinking **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [March 10, 2016, 12:52pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536 "2016-03-10T12:52:57Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [March 15, 2016, 6:53pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/21 "2016-03-15T18:53:46Z")
> [@TokyoBayer](#): > > I’m trying to understand your logic here, which seems perplexing. You seem to be saying that because there are fluctuations in the lake level and that the current level is within this historic and estimated prehistoric levels that the current historical record-breaking low levels must not be because of the actual significant decrease in the inflow. > > As of December, last year, the northern part of the lake is at the lowest point in the 160 years of record keeping and the southern part (which is separated by a railroad causeway) is within a foot of the record low. > > You seem to accept the general science behind the obvious equation that water in minus evaporation produces either a surplus for the year, with a net increase in the volume of the lake or a net decrease. > > Yet, because the levels don’t exceed estimated prehistoric records, then you reject the science behind the equation without providing an alternative hypothesis for the recent historic lows. Do you also reject the idea that the tremendous increase in the size of the lake in the 80s when there were unusually high snow falls and the subsequent increase of the inflow? Or do you just kick out the data you don’t like? > > The point which you are continuing to ignore is that the scientists are utilizing actual data. They’re not simply squinting at a graph of the lake fluctuations and saying if they’re normal or not, which is what it seems you’re doing, they are also looking at the volume of inflow and the level of lake. > > The level of the lake is completely dependent on the inflow and evaporation, both of which are known or can be calculated and because of the decrease in inflow, the lake is getting lower. It is completely meaningless to say that there were prehistorical periods where the lake was lower. The question is how much is the lake decreasing because of the amount of water we are diverting for consumption. The measured or calculated that and have an answer. > > If you have an alternative scientific principle which explains the lake level other than inflow and evaporation, then please let us know. > > The difference with the Arial Sea is the degree of diversion, with it have a far higher percent of water diverted. What the scientist are saying for the GSL is that we need to watch out for the future, because if we continue to increase the amount of water diverted, the lake will continue to decrease in size. Look, I do have an earth sciences background (although admittedly not in hydrology, beyond a couple of undergrad classes a long time ago) so it’s not like I’m just being argumentative in some sort of folksy anti-intellectual way. What I think _might_ be going on here is the all too common situation where you come up with a very reasonable-sounding model that seems to work very well for explaining the empirical observations in a very specific set of circumstances, but doesn’t really hold up if you try to broaden the scope. The model they’ve come up with here _seems_ to work if you only look at recorded time, but I find it hard to imagine that it works for all the prehistoric time when there were no water diversions and yet the variation in lake level looks exactly the same. And you keep saying “actual scientific data” as if it’s some unimpeachable gospel. What they have are some limited measurements and assumptions they’re using to try to interpolate to the actual data they want re: inflow, diversions, evaporation, etc. I say “I don’t dispute” the measurements and assumptions they’ve made in that I think they’re perfectly reasonable ones, but having a perfectly reasonable-seeming model is no guarantee against being wrong. Onto the nitty-gritty, you say “historic lows” but they’re really not. Firstly, saying the north half of the lake is at historic lows is pretty misleading given that it’s only been a separate entity for a few decades. With overall lake levels, they were still much lower back in the early 1960’s, and of course have been about as low or lower dozens times in the past 800 years. You mention the high lake levels in the 1980’s: of course those were due to climate and higher inflows. My “alternate theory” is that they’ve overestimated the effects of diversions relative to natural inflow and evaporation. The high water interval in the 1980’s is maybe the best illustration of that. Looking at the prehistoric data (and the one previous high-water interval in the 1860’s) there’s been about 1-2 high water intervals per century for the past 800 years. The 1980’s high interval looks completely normal compared to those. If diversions were really having a major effect, I would expect it to be at least near the low end. Sure, an alternate explanation is that maybe the extra inflow during the 1980’s was unusually high compared to the prehistoric high-water intervals so lake levels would have been even higher were it not for the diversions, but we don’t have good inflow data for the earlier ones so who knows. FWIW, knowing a little about the recent climate history of the region, I don’t think there’s any reason to think the 1980’s were an unprecedentedly wet time. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 15, 2016, 8:00pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/22 "2016-03-15T20:00:26Z")
> [@](#): > > Look, I do have an earth sciences background (although admittedly not in hydrology, beyond a couple of undergrad classes a long time ago) so it’s not like I’m just being argumentative in some sort of folksy anti-intellectual way. What I think might be going on here is the all too common situation where you come up with a very reasonable-sounding model that seems to work very well for explaining the empirical observations in a very specific set of circumstances, but doesn’t really hold up if you try to broaden the scope. The model they’ve come up with here seems to work if you only look at recorded time, but I find it hard to imagine that it works for all the prehistoric time when there were no water diversions and yet the variation in lake level looks exactly the same. Uhh, guys – in “Prehistoric time” the lake was MUCH bigger. Lake Bonneville (prior to 14,000 BP) was huge, with the structures still visible and called “The Benches” being the beaches of the Lake, Posters put out in the mid-1980s during the floods predicted the Return of Lake Bonneville, and showed the water rising to the level of the Angel Moroni on the Salt Lake Temple. Clearly the lake levels change with time. I’m surprised to see that 12,000 years BP the lake was actually smaller than the present Great Salt Lake (so my naive understanding that the GSL is the still-shrinking remnant of Bonneville is incorrect). The question is whether the current fall is mainly due to human activity, and it seems to me the answer to that has to be “yes” – where else would the water be going? Human activity draining runoff its different watersheds and diverting it to places where it can evaporate, rather than run into the GSL would seem much more probable that any naturall,-developing alternate routes for the water, which should otherwise all drain into the Salt Lake Basin. It’s not a question of “Was the Salt Lake Level Changing Before Man?” We know that it did, and likely would have continued to change in response to random natural events. The question is “Are the actions of people hastening the decline?” and I suspect the answer is “Yes”. > **[Lake Bonneville](https://en.wikipedia.org/wiki/Lake_Bonneville)** > > Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperatures. The lake covered much of what is now western Utah and at its highest level extended into present-day Idaho and Nevada. Many other hydrographically closed basins in the Great Basin contained expanded lakes during the Late Pleistocene, including Lake Laho... ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [March 15, 2016, 9:05pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/23 "2016-03-15T21:05:32Z")
> [@CalMeacham](#): > > Uhh, guys – in “Prehistoric time” the lake was MUCH bigger. Lake Bonneville (prior to 14,000 BP) was huge, with the structures still visible and called “The Benches” being the beaches of the Lake, Posters put out in the mid-1980s during the floods predicted the Return of Lake Bonneville, and showed the water rising to the level of the Angel Moroni on the Salt Lake Temple. > > Clearly the lake levels change with time. I’m surprised to see that 12,000 years BP the lake was actually smaller than the present Great Salt Lake (so my naive understanding that the GSL is the still-shrinking remnant of Bonneville is incorrect). > > The question is whether the current fall is mainly due to human activity, and it seems to me the answer to that has to be “yes” – where else would the water be going? Human activity draining runoff its different watersheds and diverting it to places where it can evaporate, rather than run into the GSL would seem much more probable that any naturall,-developing alternate routes for the water, which should otherwise all drain into the Salt Lake Basin. > > It’s not a question of “Was the Salt Lake Level Changing Before Man?” We know that it did, and likely would have continued to change in response to random natural events. The question is “Are the actions of people hastening the decline?” and I suspect the answer is “Yes”. > > [Lake Bonneville - Wikipedia](https://en.wikipedia.org/wiki/Lake_Bonneville) Lake Bonneville dried up (and drained via spectacular floods) very quickly at the end of the Pleistocene. It reached the size of the modern GSL well over 10,000 years ago. Since then, the evaporation and inflow rates have been more or less in equilibrium so, while there’s been huge short term variations, averaged over time the lake hasn’t been growing or shrinking. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [March 16, 2016, 1:29am UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/24 "2016-03-16T01:29:18Z")
I’ve got more later, but a question for you: How specifically are they determining the lake levels prior to 1847? ---
**Author:** ![kopek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kopek/32/337_2.png) [@kopek](https://boards.straightdope.com/u/kopek)\ **Post date:** [March 16, 2016, 1:37am UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/25 "2016-03-16T01:37:44Z")
I’ve followed this since SaltAir II closed in the 70s. Famous for being the site of the film “Carnival of Souls” it was a pretty fantastic place. (In the odd things happen department – when SaltAir III was built to get closer to the then current shoreline, it flooded) ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [March 16, 2016, 3:16am UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/26 "2016-03-16T03:16:45Z")
> [@TokyoBayer](#): > > I’ve got more later, but a question for you: How specifically are they determining the lake levels prior to 1847? The major line of evidence that the lake has continually undergone the high/low cycles since the last Lake Bonneville period is through lake bed coring stratigraphy and paleoshorelines. The maximum and minimum Holocene levels of the lake have long been known, as well as that it’s gone through many expansions and contractions. The tree ring study I keep harping on studied the tree rings and ages from several areas around the lake that are occasionally inundated, which is interesting because it gives a much more precise idea of the timing and magnitude of the most recent high/low cycles. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [March 17, 2016, 2:58pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/27 "2016-03-17T14:58:44Z")
> [@GreasyJack](#): > > Look, I do have an earth sciences background (although admittedly not in hydrology, beyond a couple of undergrad classes a long time ago) so it’s not like I’m just being argumentative in some sort of folksy anti-intellectual way. No, it looks like you are argumentative without rigorous logic. > [@](#): > > What I think _might_ be going on here is the all too common situation where you come up with a very reasonable-sounding model that seems to work very well for explaining the empirical observations in a very specific set of circumstances, but doesn’t really hold up if you try to broaden the scope. The model they’ve come up with here _seems_ to work if you only look at recorded time, but I find it hard to imagine that it works for all the prehistoric time when there were no water diversions and yet the variation in lake level looks exactly the same. You haven’t pointed to anything which accounts for what the lake would look like without the diversion and you are seriously underestimating its effects. I’ll repeat the quote again from the study. > [@](#): > > The 39% decrease in river inflow to the lake is based on a 10‐year average (2003‐2012). This calculation accounts for the importation of Colorado River water into the basin. The 39% decrease due to depletions is calculated based on total depletions (corrected for Colorado R. imports) of 1,451,000 acre‐feet (Utah DWR) and current river inflow to the lake of 2,303,000 acre‐feet (Mohammed, I.N. and D.G. Tarboton, 2012). Thirty nine percent is not a trivial amount and by all accounts should easily overwhelm any possible effect of some change in the rate of evaporation of any possible temperature differences in the same time period. All you are saying is that prehistorically, there were swings in the water level, so we can’t possible know anything. That’s simply wrong. They are measuring the inflow of water and the water levels and have been doing this for years, enough so that they can get a reasonable estimate. If you have a cite where the estimates of the prehistoric inflows and lake levels are seriously out of sync then it would help your argument. In you opinion, how much of a difference should one expect if the inflow is reduced by 39%? Less than 5%? Less than 10%? Less than 15%? Less than 20%? Less than 25%? > [@](#): > > Onto the nitty-gritty, you say “historic lows” but they’re really not. Firstly, saying the north half of the lake is at historic lows is pretty misleading given that it’s only been a separate entity for a few decades. With overall lake levels, they were still much lower back in the early 1960’s, and of course have been about as low or lower dozens times in the past 800 years. I never knew that almost 60 years is a “few” decades. Learn new things all the time, I guess. I also wasn’t aware that a foot is “much,” and since water no longer flowing through the breach in the causeway, that the overall level would be a third less than that, so we’re within 8" of the historic low overall. And again, what has happened over the past 800 years means nothing because we didn’t have the data we have now. You keep harping on the fact that there were droughts before, but we didn’t know with the precision of what we know now. > [@](#): > > You mention the high lake levels in the 1980’s: of course those were due to climate and higher inflows. My “alternate theory” is that they’ve overestimated the effects of diversions relative to natural inflow and evaporation. The high water interval in the 1980’s is maybe the best illustration of that. Looking at the prehistoric data (and the one previous high-water interval in the 1860’s) there’s been about 1-2 high water intervals per century for the past 800 years. The 1980’s high interval looks completely normal compared to those. If diversions were really having a major effect, I would expect it to be at least near the low end. Sure, an alternate explanation is that maybe the extra inflow during the 1980’s was unusually high compared to the prehistoric high-water intervals so lake levels would have been even higher were it not for the diversions, but we don’t have good inflow data for the earlier ones so who knows. FWIW, knowing a little about the recent climate history of the region, I don’t think there’s any reason to think the 1980’s were an unprecedentedly wet time. And this is why I can’t take you very seriously. I lived in Salt Lake for most of my life until I moved to Japan in 1990, and the relationship between the snow pack and the lake level is not contested by any serious scientist. You obviously are [uninformed](https://www.ksl.com/?sid=25219479). > [@](#): > > SALT LAKE CITY — Memorial Day weekend marks the 30th anniversary of a massive flood that turned State Street in downtown Salt Lake City into a river. > > The 1981-1982 water year had broken records, and officials had been concerned since at least Sept. 1982 that come May, there would be more water than the city could handle. > > There were mudslides in Big and Little Cottonwood canyons in fall 1982, and flooding creeks damaged 300 homes, roads and bridges. Gov. Scott Matheson declared a state of emergency but was denied federal aid. > > The autumnal floods foreshadowed something bigger, as a mild January and February paved the way for a record-breaking March. Levees and dikes were constructed in an effort to keep the Jordan River from overflowing as efforts were made to keep Utah Lake at normal levels. > > April brought even worse weather, as high moisture levels mixed with winds of up to 100 mph to do millions of dollars’ worth of damage along the Wasatch Front. Cracks in the ground near the Capitol caused roads to slump and be closed. > > **Water levels in the Great Salt Lake rose so much that the newly opened Saltair III, built eight feet above the lake’s usual level, was rendered useless, its floors below water level.** I’ve helpfully bolded the part which demonstrates the relationship between water coming into the Great Salt Lake and the water level. As you see, since the lake lacks an outlet, when there are massive amounts of water coming in, the lake can only rise more. Likewise, when not as much water comes in, the water level goes down. As only a certain amount of water is diverted, when there is flooding, as happened in the early 80s, the excess is going to go straight into the lake. From your quote, “FWIW, knowing a little about the recent climate history of the region, I don’t think there’s any reason to think the 1980’s were an unprecedentedly wet time.” I would rewrite it as "knowing [del]a[/del] little about the recent climate history of the region. . . > [@GreasyJack](#): > > At the risk of sounding like some sort of shrinkage-truther . . . Well, yes you do. ---
**Author:** ![Jennshark](https://avatars.discourse-cdn.com/v4/letter/j/8e8cbc/32.png) [@Jennshark](https://boards.straightdope.com/u/Jennshark)\ **Post date:** [March 17, 2016, 4:45pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/28 "2016-03-17T16:45:26Z")
Native Utahn here (and escapee to the East Coast). How’s Antelope Island doing? I would assume there’s more of it visible if the water level is dropping? ---
**Author:** ![Jennshark](https://avatars.discourse-cdn.com/v4/letter/j/8e8cbc/32.png) [@Jennshark](https://boards.straightdope.com/u/Jennshark)\ **Post date:** [March 17, 2016, 4:49pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/29 "2016-03-17T16:49:20Z")
> [@GreasyJack](#): > > The major line of evidence that the lake has continually undergone the high/low cycles since the last Lake Bonneville period is through lake bed coring stratigraphy and paleoshorelines. The maximum and minimum Holocene levels of the lake have long been known, as well as that it’s gone through many expansions and contractions. The tree ring study I keep harping on studied the tree rings and ages from several areas around the lake that are occasionally inundated, which is interesting because it gives a much more precise idea of the timing and magnitude of the most recent high/low cycles. I can’t seem to find the right search keywords, so maybe you can clarify my memory. Lake Bonneville broke through a barrier in Southeast Idaho and left behind Utah Lake, Great Salt Lake and became a version of Bear Lake? ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [March 17, 2016, 10:02pm UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/30 "2016-03-17T22:02:00Z")
> [@TokyoBayer](#): > > You haven’t pointed to anything which accounts for what the lake would look like without the diversion and you are seriously underestimating its effects. > > I’ll repeat the quote again from the study.Thirty nine percent is not a trivial amount and by all accounts should easily overwhelm any possible effect of some change in the rate of evaporation of any possible temperature differences in the same time period. They estimate that 39% of the current inflow is being diverted, but keep in mind that the diversion volume is more or less fixed, but the total inflow volume isn’t. I find the 39% figure completely plausible for where we are now, at the nadir of a dry cycle, but during wetter years with higher inflow the diversion percentage is going to be much, much lower. > [@TokyoBayer](#): > > All you are saying is that prehistorically, there were swings in the water level, so we can’t possible know anything. That’s simply wrong. They are measuring the inflow of water and the water levels and have been doing this for years, enough so that they can get a reasonable estimate. > > If you have a cite where the estimates of the prehistoric inflows and lake levels are seriously out of sync then it would help your argument. If we’re just talking about the past 800 years, we don’t have precise data for the regional micro-climate but we’ve got a very good idea of what the global climate has been doing. We see the lake levels responding to the Little Ice Age, for example. Since then, we’ve seen both high and low lake levels in excess of both the historical minimums and maximums that don’t seem to correspond to anything major, climatically speaking. > [@TokyoBayer](#): > > In you opinion, how much of a difference should one expect if the inflow is reduced by 39%? Less than 5%? Less than 10%? Less than 15%? Less than 20%? Less than 25%? Probably much less than you’d think. The evaporation rate declines drastically as the surface area shrinks and salinity increases. > [@TokyoBayer](#): > > I never knew that almost 60 years is a “few” decades. Learn new things all the time, I guess. > > I also wasn’t aware that a foot is “much,” and since water no longer flowing through the breach in the causeway, that the overall level would be a third less than that, so we’re within 8" of the historic low overall. If we’re talking about 17 decades of recorded history and 80 decades of prehistoric history, yeah, 6 decades is a few decades. And, yeah, when you’re talking about a lake level that’s only varying by about 10 feet in either direction, a foot or two is significant. (Although admittedly I just looked at the current level and it is about two feet lower than I thought it was.) > [@TokyoBayer](#): > > And again, what has happened over the past 800 years means nothing because we didn’t have the data we have now. You keep harping on the fact that there were droughts before, but we didn’t know with the precision of what we know now. They’re claiming that the current conditions are a departure from the previous normal conditions, so the lines of evidence we have about what those previous conditions were are absolutely relevant, even if our data for those conditions are less complete. > [@TokyoBayer](#): > > And this is why I can’t take you very seriously. I lived in Salt Lake for most of my life until I moved to Japan in 1990, and the relationship between the snow pack and the lake level is not contested by any serious scientist. I am not even remotely contesting that either. My whole point is that the feedback interaction between inflow and evaporation is the driver of lake level. The major driver of inflow is snowpack and the major drivers of evaporation are climate and lake size/salinity. The water diversions are certainly _a_ factor, but I’m simply not entirely sold on the idea that it’s the decisive factor it’s being made out to be here. > [@TokyoBayer](#): > > You obviously are [uninformed](https://www.ksl.com/?sid=25219479).I’ve helpfully bolded the part which demonstrates the relationship between water coming into the Great Salt Lake and the water level. > > As you see, since the lake lacks an outlet, when there are massive amounts of water coming in, the lake can only rise more. Likewise, when not as much water comes in, the water level goes down. > > As only a certain amount of water is diverted, when there is flooding, as happened in the early 80s, the excess is going to go straight into the lake. > > From your quote, “FWIW, knowing a little about the recent climate history of the region, I don’t think there’s any reason to think the 1980’s were an unprecedentedly wet time.” I would rewrite it as "knowing [del]a[/del] little about the recent climate history of the region. . . > > Well, yes you do. Sorry, by “recent climate” I mean recent geologically speaking. That period in the 1980’s were of course wet compared to the preceding and succeeding decades, but we’ve seen wet periods a few times a century going back to the Pleistocene, so a wet period by itself is not unusual. What I’m arguing is that if the record-high lake levels would have been _even higher_ were it not for the diversions, then the 1980’s wet period must have been an unprecedentedly wet one. Which is certainly a possibility, but I think it’s more likely that it was just a normal one and the diversions weren’t very significant compared to the drastically elevated inflow volume. ---
**Author:** ![GreenElf](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@GreenElf](https://boards.straightdope.com/u/GreenElf)\ **Post date:** [March 18, 2016, 3:24am UTC](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536/31 "2016-03-18T03:24:19Z")
It will eventually be known as the Great Salt Lick. [Previous page](https://boards.straightdope.com/t/the-great-salt-lake-is-shrinking/748536.md?page=1)