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Where Did the Water Go? Busting 5 Myths About Water Levels on the Great Lakes

Image: Fog on Lake Michigan. Credit: Suze Bonadeo.
Cooler than normal summer water temperatures led to frequent fog events in northern Lake Michigan this summer. Photo by Suze Bonadeo

Much-needed rain in the Great Lakes basin helped water levels recover somewhat this summer. Higher than average precipitation throughout most of the region in July left Lakes Erie and Ontario with above average water levels for this time of year, according to the most recent monthly water level report by the U.S. Army Corps of Engineers (USACE) Detroit District Office.

Despite the rain, the other three Great Lakes remain below their long-term averages. Lakes Michigan and Huron, the hardest hit by extreme low water levels this past year, received the least rain last month and remain 19 inches below their long-term average.

All of the lakes are now leveling off and beginning their normal seasonal decline through late fall and early winter. USACE forecasts Lakes Michigan and Huron to remain lower than normal for the next six months.

The extreme low levels earlier this year left many asking, “Where did the water go?” The answer is that it simply evaporated. The surface of the Great Lakes acts like an enormous evaporating pan under the right conditions. As explained in a previous post, the lack of ice cover in 2011-12 and record-breaking warm temperatures created ideal conditions for high rates of evaporation on Lakes Superior, Huron, and Michigan. These lakes had already been fluctuating below average levels for 15 years. A severe drought prevented the lakes from replenishing themselves, and water levels reached record lows.

Another reason the water levels on Lakes Michigan and Huron are lower than normal is the past dredging and erosion in the St. Clair River that resulted in a 10- to 15-inch (25- to 38-centimeter) lowering of water levels. These historic losses were never offset with mitigation measures. The only dredging that occurs today is to keep rivers at authorized depths for navigation. Recent studies show this is not the cause of low water.

Even though this is well documented by the agencies that have been monitoring water levels, going back to 1918, various theories about possible causes abound, especially online. Some of these theories and misleading facts get repeated so often, they become mythic. As the lakes begin their seasonal decline, a little myth-busting is in order.

Photo: Low water levels on Grand Traverse Bay, Lake Michigan. Credit: Lisa Borre.
Low water levels in November 2012 on Grand Traverse Bay, Lake Michigan. Photo by Lisa Borre.

Myth 1: Water levels are declining because companies are pumping millions of gallons of water from springs every day in northern Michigan, and it’s being bottled up and taken away.

On a recent Water Currents post on lake levels, commenter Bob wrote:

No mention is made about the companies that are pumping millions of gallons of water, “legally”, every day, out of springs in northern Michigan. These springs are connected to the lakes and yes the water is being “bottled up and taken away”.

Although groundwater extraction is an important concern for reasons that I won’t elaborate here, there is really no comparison with the amount of water lost through evaporation. John Lenters, a lake and climate scientist at the University of Nebraska–Lincoln, helped put some of these numbers in perspective in a previous post on the topic. “On average, Lake Superior loses 29 billion gallons of water PER DAY through evaporation,” he told me. His calculation is based on the annual average rate, but he notes that the daily evaporation rate can be ten times higher during the late fall.

The difference between evaporation from the largest of the five lakes and pumping rates in Northern Michigan is roughly a factor of 1,000 or more he says.

Myth 2: Water from the Great Lakes is secretly being shipped to China.

In a comment that was removed from this post due to other offensive language, someone wrote:

THE CHINESE ARE TAKING OUR WATER AND LEAVING US WITH THE [TOILET] WATER!! TANKERS WITH OUR FRESH WATER IN HUGE BLADDER-LIKE TANKS TO PUT INTO THEIR [AQUIFERS] THAT THEY HAVE ABUSED AND ARE NOW DRIED UP!!

Perhaps this is better categorized as a conspiracy theory. Its origins go back to concerns raised when opening the Great Lakes to international shipping in the 1950s. The myth is perpetuated today in the blogosphere and sometimes includes the detail that bladder tanks are being used to transport the water in the holds of ships bound for China.

All ships entering and leaving the Great Lakes must pass through the Great Lakes St. Lawrence Seaway System, where shipping traffic and cargo loads are closely monitored as ships pass through the lock system. In 2012, the Seaway Corporation logged 1,491 downbound transits through the Lake Ontario-Montreal section with a total cargo load of 18.9 million metric tons. According to the Seaway Corporation, traffic headed out the St. Lawrence River in 2012 carried 17,760 metric tons on average.

If water was secretly being shipped, these sea-going freighters would need to be converted over from carrying dry cargo such as grain, coal, and iron ore to be able to carry liquids such as water. Using the example from Lake Superior, even if each ship could carry 2.5 million gallons of water in bladder tanks, it would take more than 10,000 ships a day leaving Lake Superior to equal the amount of water lost to evaporation in one day. This would create quite a traffic jam at the Soo Locks!

Photo: Ship on Lake Erie, Great Lakes. Credit: Lisa Borre.
Ships transiting the Great Lakes have had to lighten loads this past year. Myth-buster: Water is not secretly being shipped to China in bladder tanks. Photo by Lisa Borre

Myth 3: Water is being diverted to the Mississippi River (or through a pipeline to western states).

On a recent post, commenter Peter wrote:

“Global warming causes low lake levels” ya and Santa is warming the north pole. It must not have anything to do with man made things, like a massive new water pipe line going into the southern states…

Water diversions in the Great Lakes basin are regulated by appropriate state, provincial and federal government authorities. The International Joint Commission (IJC) approves and provides regulatory orders for projects that affect levels and flows on the other side of the international border. I already busted this myth in a previous post but will summarize it again here.

Studies show that “the Chicago diversion is more than offset by a diversion into Lake Superior from Canada.” More water evaporates from the Great Lakes than flows over the Niagara Falls every year, according to the IJC. If there were a secret pipeline pumping water from the Great Lakes, it would have to be massive. I think someone might notice a project of this scale.

Myth 4: Just blame it on the weather (or Mother Nature).

Reader Peter also wrote:

Record low rain falls, and a climate that goes through cycles some of them thousands if mot millions of years old, (lo[n]g before man) and its impossible to know what cycle we are in…

It’s true that the weather plays a major role in water level fluctuations. The lakes respond rapidly to changes in weather, with the contrast between this year and last serving as an excellent example. Experts have been quoted blaming the weather for low lake levels in everything from this blog to the New York Times and in NBC News reports, but as described in detail in a previous post about how climate change and variability drive water levels on the Great Lakes, just blaming the weather is not the full story.

What is rarely mentioned is that these weather events, including more frequent droughts, warmer air temperatures, and even extreme weather events such as the flooding in the western portion of the Great Lakes basin this spring, are part of longer-term climate trends. There is no question that lake temperatures are warming and winter ice cover is decreasing. Both are consistent with global trends and are related to climatic factors that affect water levels in the Great Lakes. Given the well-documented trends in the region, it would be difficult to show that human-induced climate change is not having an effect on lake levels. There’s no denying that we humans share some of the blame.

Image: MI-Huron Water Levels 1918-2012. Source: IJC.
Water levels on Lake Michigan-Huron over the historical record (1918-2012). The data show a change after the last extreme drought 15 years ago. Source: International Joint Commission

Myth 5: There’s nothing that can be done.

In response to reader Peter and others, it’s true that there is no simple fix to the problem of extremely low (or high) water levels in the Great Lakes region. Not only is this the largest freshwater system in the world, the supply of water that sustains the lakes is affected by global climate change. A recent report by the IJC states:

Climate change poses new challenges for adapting to fluctuating Great Lakes water levels. Although the future is not certain, increases in temperature and alterations in patterns of precipitation are likely to affect water levels in the Great Lakes-St. Lawrence River system. There is strong evidence that in the future we will likely experience more extreme water levels – both high and low – that are outside the historical range experienced over the past century.

Further complicating matters is the fact that natural variation in the water levels is essential for maintaining a healthy ecosystem. Extended periods of extreme low or high water not only affect shipping and waterfront property, it also impacts sensitive fish and wildlife habitat throughout the region.

Current water control structures at the outlets of Lakes Superior and Ontario do very little in controlling the overall supply of water in the basin. Engineering or other solutions come with a big price tag and have yet to gain acceptance as feasible options.

Short of slowing or reversing global climate trends – something that would require a major societal shift away from fossil fuel dependence, which few people seem to be talking about – an adaptive approach to management of water levels is being promoted. Earlier this month, the International Joint Commission released a report and invited public comment on a proposal to establish an Adaptive Management Plan for the Great Lakes and St. Lawrence River Systems. The deadline for comments is August 31.

The record low water levels this past year provide a glimpse of what the future may hold for some of the greatest lakes on Earth. If this concerns you, read the IJC report, comment on its recommendations, and get involved with this and other Great Lakes restoration efforts aimed at finding solutions.

Lisa Borre is a lake conservationist, freelance writer, and avid sailor. With her husband, she co-founded LakeNet, a world lakes network, and co-wrote a sailing guide called “The Black Sea” based on their voyage around the sea in 2010. A native of the Great Lakes region, she served as coordinator of the Lake Champlain Basin Program in the 1990s. She is now an active member of the Global Lake Ecological Observatory Network.

Comments

  1. Paxrail
    September 23, 4:05 am

    Is glacial rebound also affecting water levels in the Great Lakes? As land slowly, over thousands of years, rises now that the ice sheets are gone, water depths would naturally begin to become more shallow. I saw some documentary or read some research on the matter a few years ago.

    • Lisa Borre
      September 24, 1:00 pm

      Yes, glacial rebound does have a small effect on water levels but it varies within in the Great Lakes region. For more information, see the International Upper Great Lakes Study by the IJC: http://ijc.org/iuglsreport/.

  2. Spanish Fly
    August 23, 8:43 am

    Myth 6: California is being punished through aerosol (chemical spraying) weather modification (causing it to NOT RAIN).

    Geoengineering Whistleblower ~ Ex-Military ~ Kristen Meghan
    http://youtu.be/jHm0XhtDyZA

    BUSTED Pilot Forgets To Turn Off CHEMTRAILS while landing
    https://www.youtube.com/watch?v=O01ZebpBHhU

    http://worldtruth.tv/busted-pilot-forgets-to-turn-off-chemtrails-while-landing/

    Five Chemtrail Planes Spraying In Formation!!!
    https://www.youtube.com/watch?v=8bymRuLR6-M

    Aerospace Worker: “I Installed Chemtrails Devices”
    https://www.youtube.com/watch?v=RnCaE_3hImY#t=75

    Former FBI Chief Admits Chemtrails Are Real – And Then He Is Poisoned And Dies
    https://www.youtube.com/watch?v=9-f-3fWh5mA

    Chemtrails to De-Populatehttps://www.youtube.com/watch?v=XREsFIMX7g4

    HAARP Freq Stepping CAUGHT in Action!!

  3. Mrs. Bryden
    california
    August 3, 8:04 pm

    Listen: We can hear the gigantic sucking sounds from the Great Lakes being used as a bottled water company all the way to California. Did no one consider “cumulative impacts”?

    LISA – While your intentions are lovely, it would be beneficial if you let us discuss this without your constant interference. Not to take it personally, but it’s tiresome when anyone repeatedly discounts all that is pragmatic in favor of ideology and one’s own mythology.

    • Lisa Borre
      August 4, 12:23 pm

      Mrs. Bryden, Thanks for your comment about “cumulative impacts.” A group was recently convened to look at the impacts of climate change, including increased demand for Great Lakes water. The region is expected to become increasingly important for agricultural production in a changing climate. Exporting these water-demanding products from the region will add to the “sucking sound” you hear in California, but like bottled water, it is not currently considered a major factor affecting water levels. Here’s a link to the study led by the University of Wisconsin, which addresses the topic of water demand and lake levels: http://centerforwaterpolicy.wordpress.com/climate-change-and-the-great-lakes/.

      And I’m sorry that you perceive my participation in this dialogue as “interference.” One of the reasons I wrote this blog post was to correct the misperceptions created by online commentaries. I realize that participating in the dialogue runs the risk of offending those who disagree with me, but I care too much about the Great Lakes to sit on the sidelines.

  4. Jenny W
    England
    August 1, 12:19 pm

    I understand your post is specifically about the Great Lakes but when reading it the consequences of water diversion on the Aral Sea came to mind. The Aral Sea was once one of the four largest lakes in the World with an area of 68,000 kilometers squared, by 2007 the sea had declined to just 10% of its original size. It is true that at the moment diversions of water from the Great Lakes are negligible relative to the amount of evaporation which takes place. However, with an expanding population and global warming likely to lead to more arid conditions in the US, pressure on US states surrounding the Great Lakes to divert water to drier parts is increasing. Do you think we’ve learnt from the environmental disaster of the Aral Sea? Or do you perceive water diversion to be a future threat to the Great Lakes as global warming progresses?

  5. John Green
    Fort White, FL
    July 29, 7:20 pm

    Your answer to the question someone posed regarding the effect Yellowstone’s magma chamber had on lake levels reminded me of an article I once read about the 1964 Alaskan earthquake causing disruptions in the Yellowstone hydrothermal system. I, too, thought how unlikely that two such things seperated by many miles could interact. Just food for thought.

  6. Tim Rth
    July 4, 9:14 am

    Water is actually being shipped to china. This is not a myth. Its net even a secret. So much product comes from China and very little goes TO china. What do you think those ships do on the return trip? Anyone who ships anything can tell you that shipping to China is cheap because there are so many liners without a payload for the trip back. They do ship water to china on these vessels. They dont pay them well to do it either. Its no secret. Go to the shipyards and hear the grumbling. Dont beleive these websites or me. Go watch, listen and learn for yourselves.

    • Lisa Borre
      July 8, 12:39 pm

      Tim, This post debunks myths about the causes of water level fluctuations on the Great Lakes, including the one about “shipping water to China.” I have already shown that it is not possible for this to affect water levels, given the current amount of shipping traffic out of the Great Lakes.

  7. josh
    earth usa
    June 15, 4:17 am

    Evap and nestle is pumping water out along with othersl this water is going to China. Blue gold is be bought up, sold and controled. The bushs have theirs allready. China is having a water crisis in the north and is going to start a huge project to get water from the south. This may harm the souths water and other countries such as India. Have you done your recon? The pumping should be happening behind fence and property lines.

  8. Colin
    Pennsylvania
    June 7, 7:52 pm

    Hi Lisa, I have to say that I do not buy the whole global warming is causing the Great Lakes to decline. I do not deny that climate change, human or not, effects the lake levels, but to say that they are doomed to an inevitable decline I think is a simplistic view. If you were to draw a trend line through the above graph you would not see a overall decline that would be indicative of a long term trend. The lakes were overflowing in the 80s and most of the 90s and plunged in 98. These are big bodies of water and have not been able to recover. Even after the drought the trend is not nessisary downward but are just stuck in the down position. Back in 2007 they said Superior was a disappearing lake, but today it is above average. The lakes seem to go through long trends that takes a monumental drought or wet period to change. The other theory that the lack of ice is causing it to me is not true. If the winters are mild they typically have more precipitation and less lack effect would occur since the temperature difference between the lake temperature and the air would not be so extreme. It seems that when we get warm falls and then short cold snaps that the lakes lose a lot. Perhaps most interesting is that Lake Ontario which freezes the least has not had these problems. I guess my point is to say that this is climate change alone is pretty narrow in scope. Also to respond to every change in lake fluctuation seems foolish as well. One of the reasons they dredged the st Clair river was that the lakes were causing property damage from high levels and everyone thought the lakes could handle it. Now we have this problem and let’s say we take extraordinary measures and the levels come back. You will have people complaining because their cottages flooded out. I am not saying I know any answers or that nothing should be done, but it should be considered. Are these issues considered in these debates?

    • Lisa Borre
      June 11, 1:55 pm

      Colin, Thanks for your comments. I’m not claiming that the Great Lakes are “doomed to an inevitable decline” due to climate change. The purpose of this post was to bust myths regarding other factors and conspiracy theories about what was causing water levels to reach record lows last year.

      You are right to note that the figure from the IJC report is not showing a declining trend but a period of lower than normal water levels since 1998. Some scientists describe this as a “step-change,” something I wrote about in another post: Warming Lakes: Climate Change and Variability Drive Low Water Levels on the Great Lakes. In that post, I include a link to NOAA’s water level dashboard where you can see how the current conditions compare, going back to 1918. The big question is whether the previous 15-year period was just an anomaly or whether it is an indication of what the future holds in a warming climate.

      Your are also right to mention the role of major droughts or wet periods that lead to extreme highs and lows. In this and other posts on the topic, I note that there is still the possibility that lake levels will reach extreme high levels in a changing climate, mainly due to the increased likelihood of extreme events and other predictions based on climate models. If the lakes were fluctuating according to their natural cycles, they should have already reached higher than normal levels seen in the 1980s and 1990s.

      Only time will tell if the lakes will reach record high levels again, but to your question about whether this is being considered in the dialogue about what to do, if anything, the answer is “yes.” Historic dredging, current conditions and climate predictions were all part of the considerations in a recent review of water level regulations in the International Upper Great Lakes Study by the IJC. I encourage you to read the report, which does not recommend that extraordinary measures be taken.

      Regarding your comment about the role of ice cover, you may want to read a more recent post on this topic: “Ice Cover Affects Lake Levels in Surprising Ways.” You mention Lake Ontario as one of the reasons that you don’t think the lack of ice cover is a factor; however, Lake Ontario’s water levels are regulated to some degree by a manmade water control structure at its outlet. Lake Superior also has a water control structure at its outlet.

      The conditions over this past winter actually provide further confirmation about how water temperatures, ice cover and evaporation affect lake levels. We should all be happy that lake levels are recovering from the record lows last year. This is especially true given the latest predictions about major climate events on the horizon. According to NOAA’s Climate Prediction Center (CPC), “there is a greater than 65 percent chance of El Niño conditions developing later this year, which could have significant impacts on temperature and precipitation patterns around the world.” The last strong El Niño was in 1997, the start of the 15-year period with lower than normal water levels in the upper Great Lakes.

      The important point is that if you agree that the climate is changing, there is no way that this will not affect water levels on the Great Lakes. I certainly don’t claim to know what the future holds, but if the previous 15 years is any indication, we should all be deeply concerned about how climate change is affecting the Great Lakes.

  9. Stephanie
    Wyoming
    May 9, 11:07 am

    Stainless steel water bottles folks….. stainless steel. …. stop buying water and plastics…… that simple. If everyone would do this we would see a dramatic change.

  10. Show-Me Mike
    United States
    May 6, 11:31 am

    If all 6.5 billion people in the world drank 6 16oz bottles of great lakes water a day for one year, it would lower the lakes’ level by 1 inch. Do the math.
    6,500,000,000 people and a combined lake surface area of 94,250 sq miles. I don’t think people stealing/bottling the water is the problem.

  11. Noel Calizo
    United States
    April 29, 6:40 pm

    Lisa,

    Thanks for your time on bringing us to these thoughts. I would like to see how you came to this conclusion. You’re saying that
    Government and business are not packaging enough water to drain the lakes? the government would never take an essentially free commodity and find ways to sell it back to us? https://www.google.com/search?q=warehouse+of+bottled+water&safe=off&es_sm=122&source=lnms&tbm=isch&sa=X&ei=KilgU7HLBde2yASvz4CwBQ&ved=0CAcQ_AUoAg&biw=1920&bih=918#facrc=_&imgrc=0PZE7QFlwARUeM%253A%3BtkBAA3oTN2e6NM%3Bhttps%253A%252F%252Fwww.meted.ucar.edu%252Fbroadcastmet%252Fwxrx%252Fmedia%252Fgraphics%252Ffema_water13758.jpg%3Bhttps%253A%252F%252Fwww.meted.ucar.edu%252Fsearch%252Fmodule_images.php%253FcurrentPage%253D13%2526module_id%253D507%3B640%3B480 warehouses like these exist across america. they can be stacked 6ft high. This is just bottled water. what about other foods and beverages? I think you are wrong. if water is evaporated it will cycle back to earth. In this case it is not.

  12. Michel Desjardins
    montreal quebec
    April 2, 2:15 pm

    you should read the national geographic vol 172 no 1 july 1987

    thank god the level is going down

  13. Eve
    USA
    March 26, 1:10 am

    Sooooo…you are trying to say the water isn’t bottled up and sold? Sorry but that has been going on a long time and yes it is well known that our water is being bought and used in other countries…not just at home.

    • Lisa Borre
      March 26, 10:02 am

      Eve, I’m not saying that water isn’t bottled up and sold outside the basin, just that this is not the cause of water level fluctuations on the Great Lakes. Now out-of-date studies show that “bottled water” imported into the Great Lakes watershed is more than what is exported, or at best it’s a wash. These studies need to be updated, but the point is that the bottled water volume is minimal compared to evaporation and historical dredging and diversions. In a previous post on the topic, I make the point that groundwater extraction is an important concern for the hydrology of inland lakes and wetlands and maintaining the base flow in streams flowing into the Great Lakes.

  14. Jack
    USA
    March 14, 1:58 am

    Lisa, thank you for being a voice of reason regarding the insane conspiracy theory that China is stealing water from the Great Lakes through a pipeline traversing the western states and Mexico to the Pacific where it is loaded into bladders that are then towed to China in “bladder trains” that are up to 6 miles long. Even though no one has ever seen this pipeline or these bladder trains, there are those who are absolutely convinced that they exist and this myth is propagated across the internet without a shred of evidence to back it up.
    ~Jack

  15. Rhiannon
    Ohio
    February 28, 12:18 pm

    We visit Old Mission Peninsula every year and my husband grew up spending summers there. Summer 2013 was definitely the lowest he and I remember, so it’s nice to see our memories correlating with the chart–and it’s good to know the science behind it.

    You mentioned that the increased evaporation rates are partly due to the lakes not freezing over for the winter. Is it logical to anticipate a higher water lever in Lake Michigan this summer due to the polar vortexes and complete freeze-over of the lake? Or will one frozen winter not be enough to make an impact quite yet?

    • Lisa Borre
      February 28, 6:57 pm

      Rhiannon, the cold weather, ice cover and heavy snowfall this winter are good for lake levels. Experts are predicting that water levels will recover further this spring and summer, but it make take another cold, wet winter for Lakes Michigan and Huron to return to their long-term average. Winters like this one are becoming more rare, and given climate change trends, this is a concern for the long-term situation with water levels. If the lakes were fluctuating as they have in the past, they should have already gone through an above average cycle. You may also be interested in this post, especially the comments section: Ice Cover Affects Lake Levels in Surprising Ways.

  16. Sacha
    NJ
    February 25, 7:58 pm

    I have to ask what you say to people now that they have admitted to the fact that China is taking the water right out of the Great Lakes? We know the procedure for any ship leaving, but they aren’t hiding it! They are ALLOWED to take our water.

    I have a radio show, come on and share your view, because it just doesn’t add up.

    • Lisa Borre
      February 26, 10:06 am

      Sacha, I’m confident that the numbers don’t add up to support your view that shipping water to China is affecting water levels on the Great Lakes. If your listeners are interested in my views on this topic, I suggest they read this blog and post their comments and questions here. Thanks for your interest in the Great Lakes.

  17. Mac Parsons
    Connecticut
    February 14, 1:04 pm

    Dear Lisa,

    Is there any volcanic influence on The Great Lakes? Granted, the Yellowstone magma chamber is at least three full states away from The Lakes, but is there any possible link?

    On evaporation: Here in the Northeast, we’ve been through our share of hot sticky summers. Yet, starting in The ’80s, we never had an accumulation of mold in our books. Makes one wonder.

    • Lisa Borre
      February 15, 5:04 pm

      Thanks for your questions, Mac. I am not aware of, nor can I imagine any possible link between the Yellowstone magma chamber and Great Lakes water levels. So the answer to your second question is “no.” I asked John Lenters, who studies lake levels and is now at LimnoTech, an environmental consulting firm, about your questions, and the only volcanic link he could come up with is Mt. Pinatubo, which erupted in 1991. The ash from this eruption had a cooling influence on the U.S. in the summer of 1992, and this could have led to cooler lake temperatures and lower evaporation rates that year, he says. Regarding your observation about the lack of accumulation of mold in books in CT since the 1980s, I’m sorry I can’t provide any further insight. Good luck sorting out that mystery!

  18. Becky
    Fort Collins, CO
    February 13, 5:07 pm

    Wow, your article has been very informative, but even more informative are your responses to others’ comments!

    My question is about evaporation trends. There was a study performed on a western reservoir (can’t remember the source), but it basically showed that increasing the reservoir’s capacity to a certain volume would essentially increase the evaporation to a point where the capacity increase would not be beneficial. So, my question is, do you think that as lake levels continue to decline, they will reach a point where evaporation could eventually become a smaller factor? I’m already wondering if the evaporation could start seeing a decreasing trend anyway (to conserve the water and energy budgets), but just wondering if there have been any studies linking evaporation trends to the volume of water for the Great Lakes.

    • Lisa Borre
      February 15, 4:48 pm

      Becky, Thanks for your comment and question. Because I don’t know the reservoir you’re referring to, I’m just guessing that to increase its capacity would require increasing its surface area, too. In terms of the relative importance of evaporation, it is the surface area of the water body that is most important. If I understand correctly, you are wondering if there would be a reduction in evaporation due to a decrease in lake surface area with lower water levels. The Great Lakes are so large in terms of both their surface area and total water volume that a change in water level would have minimal effect on evaporation rates because the percent change in lake area would be so small, according to John Lenters, a researcher studying evaporation on the Great Lakes who is now at LimnoTech, an environmental consulting firm. “More important would be the effect of lower water levels on the outflow through connecting channels (e.g., the St. Marys River, St. Clair River, etc.). The percent change in outflow (for a given drop in water level) would be a lot more than the percent change in evaporative flux,” he said. For more on evaporation studies on the Great Lakes, you may be interested in this more recent post: Ice Cover Affects Lake Levels in Surprising Ways.

  19. Dan
    Pt. Elgin On
    February 2, 5:41 am

    Has there been any study done on the amount of water from storms which originate in the Gulf of Mexico? Has it been more, less or stable as a trend?

  20. Robert black
    United States
    February 1, 7:04 am

    Does this include the new Canadian Power Project @ Niagara Power Station? For years the US power project at lewison has used the max amount of water allocated. The canadians just finished a new diversion tunnel (last 5 years) and began taking the share they were entitled to from the beginning of the lewison project? I Feel that it might be having an effect. I grew up on the banks of
    lake Erie between Buffalo and Erie PA. I feel the lake is still down even though the report says it’s up. It is no where near the depth it was back in the mid 80′s and early 90′s. I spent every nice summer day playing in half full of water caves, now the water is 2 ft. below the cave floor. ?

  21. Vailhem
    United States
    January 29, 6:41 pm

    Two words: biochar & graphene.

    …and, luckily, graphene can be made from biochar. Biochar helps to cut the amount of water needed. It locks the carbon pulled out of the atmosphere into a molecularly stable form that keeps it out of the atmosphere for ‘at least a century’ … thus helping to reduce or even reverse global warming due to ghg’s to begin with.

    It increase carbon sequestration by the soil up to and even over it’s weight by 3x (1lb of biochar added to the soil will help the life in the soil pull an additional 2lbs out of the air simply because the biochar was there). It builds soil organic carbon which helps soil retain rain water so less needs to be added to crops… thus pulled from other places to be added to them. It gives water time to trickle down into aquifers vs rushing off. It holds onto resources so that less need to be added, as well so that less resources are flushed into the surrounding ecosystem… both cutting costs for the farmer as well costs to the surrounding environment.

    During its production process, energy is released in the form of hydrogen and syngas that can be used for all sorts of purposes…. including desalination of salt water…

    And, better still, you can use the carbon that makes up biochar as a feedstock for graphene production… which, in turn, is the ‘perfect’ water filter… allowing a very low energy input in such that water can be pumped through graphene sheets under small amounts of pressure, the non-water elements in it will stay inside the graphene pipes while clean fresh absolutely pure H2O will ‘sweat’ out the sides… reducing the costs for reverse osmosis by orders of magnitude. ….

    Not only can this help to cut the amount of global warming happening, the amount of water needed to be pulled from the lakes (and other water sources) to feed out crops, many of which are grown to fuel our ghg-spewing SUVs… but it can also rebuild the aquifers and watersheds that drain into the lakes to begin with… so that, it doesn’t just limit it, it helps to refill them. And, if that doesn’t happen fast enough… we can use the fuels produced during biochar production to power the machinery necessary to convert said biochar into the graphene needed to then use the energy to pump salt water through the graphene and convert it into freshwater to… refill the lakes from the oceans to which they drain.

    Did I mention it increases plant yields?

  22. Mark
    United States
    January 27, 6:13 pm

    One of the reasons the “Secret pipeline” to the West conspiracy theory doesn’t work, is the great lakes are at a much lower elevation than the parched western cities. So you’d need a tremendous amount of secret energy plants to pump it all that way.

    • Lisa Borre
      January 29, 12:09 pm

      Good point, Mark!

  23. Barbara buhrow
    Riverview FL
    December 19, 2013, 1:47 am

    “Not only is this the largest freshwater system in the world” Having lived in Brasil, I find it difficult to believe that the Great Lakes watershed is larger than that of the Amazon. Can you speak to this?

    • Lisa Borre
      December 19, 2013, 10:51 pm

      Thanks for your question, Barbara. First, let me clarify that the statement about the “largest freshwater system in the world” was not referring to a comparison of watershed area. The designation is commonly cited in reference to the tremendous volume of surface freshwater supply in the Great Lakes basin. According to the USEPA Fact Sheet and other sources, the Great Lakes represent “21 percent of the world’s surface freshwater supply.”

      You are absolutely right that the Amazon watershed is larger than the Great Lakes basin in surface area. It is also significant in terms of freshwater supply, but the total volume of water is less. I did a quick search on Wikipedia to find that the size of the Amazon watershed is approximately 7 million square kilometers (2.7 million square miles), which is almost ten times larger than the Great Lakes watershed at 764,564 square kilometers (295,200 square miles). However, the total volume of water of the Amazon river in a year is about 6,591 cubic kilometers (1,581 cubic miles) compared to a volume of 22,500 cubic kilometers (5,398 cubic miles) in the five Great Lakes.

      The reason for the volume difference is obvious because the lakes store more water than flowing rivers. I should bring in the example of Lake Baikal in Siberia because this one lake goes toe to toe in terms of volume with all five of the Great Lakes combined. Likewise, when comparing rivers to rivers, the average discharge of water from the Amazon is larger than the next seven largest rivers combined.

  24. Barbara buhrow
    Riverview, FL
    December 19, 2013, 1:42 am

    I grew up around Cleveland, mostly within a mile of the shore of Lake Erie. I also lived several years in Brasil so I find it hard to e the statement

  25. Chris forton
    MICHIGAN
    December 18, 2013, 5:41 pm

    Lisa, I find it a bit weird you had the time to respond to apart every post except for Bill. Your third “myth,” actually isn’t a myth at all, it’s fact. Stop being a puppet for your check. Call it like it is. A loophole in the 2006 Great Lakes Compact allows the water to be called a product and sold off outside the basin. So, Lisa, what is your response to that? I doubt I will get a response. Can’t dispute FACTS

    • Lisa Borre
      December 19, 2013, 11:56 pm

      Chris, This post is intended to debunk myths about the causes of lake level fluctuations. I felt no need to respond to Bill’s comment because he basically agreed that water bottling operations (actually Myth #1 not #3) are not the “sole” cause of water level fluctuations. Myth #3 has to do with water diversions, specifically a climate change denier’s myth about a secret pipeline sending water to the western or southern states. Since you asked for my response, I will say that I don’t agree that legal loopholes or secret pipelines are what’s causing lake level fluctuations.

  26. Penny Pepperell
    Georgian Bay
    October 28, 2013, 5:05 pm

    I’m a fan. I’ve been writing about Georgian Bay/Great Lakes water levels and ecological matters for years now. I’ve just started a blog about nature, science and politics in the Great Lakes and Georgian Bay. You can visit at thebufflehead.org. Cheers Penny Pepperell

  27. Bill
    California
    October 12, 2013, 7:26 pm

    Regarding myth #3. It is not entirely a myth. Semantics play a key role in this so called myth. China has indeed been removing water from the Great lakes area through bottled water product agreements with certain global corporations for years and there has been nothing “secret” about it. There have been several battling pieces of legislation over access to Great lake water for decades, and as usual, especially when it comes to water, if you follow the money trail you will find the truth. This may not be the sole cause of lowering water levels but it is also not a myth.

  28. Casandra
    September 20, 2013, 11:01 am

    It is simple: as the climate changes, air temperatures rise and precipitation patterns change, the rate of surface evaporation from lakes and other bodies of inland water will grow. Ultimately , this will radically alter the topography of surrounding land, turning lake towns into brush towns.

    This article was helpful and well written. Another document I recommend folks read is called “The Great Waves of Change” written by Marshall Vian Summers. This document pulls together the converging trends of climate, economy and conflict into a cohesive picture of what is coming and how we can act for the purpose of mitigation and personal preparation. Highly recommended. http://www.greatwavesofchange.org

  29. Will Juntunen
    Muskegon, Michigan
    September 1, 2013, 12:54 pm

    I am happy to see the St. Clair River dredging being addressed as an outflow of water, with evaporation being pointed out as the prime culprit. It is amazing the number of professionals who are working on the puzzle of the Great Lakes. Allow me to share this event on Great Lakes Brownfields and photography at the Muskegon Museum of Art:

    Evening with Lloyd Degrane
    Wednesday, September 11

    5:30 pm

    Photographer Lloyd Degrane has partnered with the Alliance for the Great Lakes to document the interaction of the Great Lakes and brown fields. Degrane will take the stage at the Muskegon Museum of Art to discuss his portfolio of Great Lakes images. He will be joined by Laurel Berman, an Environmental Health Scientist specialising in toxic substances, who will discuss Degrane’s images from a scientific context. An afterglow and popup exhibition will follow at 7:00 PM, located in the dining room of Hennessy’s Irish Pub. For more information, call 231-714-8130. Hosted by the Alliance for the Great Lakes. Free and open to the public.

    http://www.muskegonartmuseum.org/event-calendar/details/793-evening-with-lloyd-degrane

  30. Matt K
    St Louis
    August 28, 2013, 6:15 pm

    How about the 2.1 billion gallons per day of water that is pumped out of Lake Michigan for Chicagoland communities? That number if my math is correct is about 10% of the evaporation rate. Are water conservation efforts in the area being taken seriously to control the siphoning of the lake from the people who rely on the lake for their water supply?
    http://news.medill.northwestern.edu/chicago/news.aspx?id=221928

    • Lisa Borre
      August 29, 2013, 6:27 am

      Matt, Thanks for the link to this interesting article about water supply in Chicago. The 2.1 billion gallons per day you mention is what is referred to in this post as the “Chicago diversion” or the amount of water Chicago is allowed to draw from the lake. The reason this is considered a diversion is that the water is taken from the lake but discharged outside the Great Lakes Basin to the Mississippi watershed. This is part of what is included in the figure of historical losses due to dredging and diversions and is not a number that is likely to increase or decrease anytime soon, as stated in the article you provided. You’re absolutely right about the need to take water conservation efforts seriously in the Chicago area because of the restrictions on diverting water from the Great Lakes outside the basin.

  31. jennifer michaels
    fruitport mi
    August 28, 2013, 12:36 pm

    Lisa, I didn’t see fracking water extraction addressed in your otherwise very thorough article. Wouldn’t this use of water have a greater impact than extraction for bottling? I imagine sealing off this contaminated water removes it from the cycle. Also has agricultural extraction of groundwater increased in general? The summer of ’12 was so hot and dry here I saw a lot of irrigation on crops.

    • Lisa Borre
      August 29, 2013, 7:07 am

      Jennifer, Thanks for the concerns you raise. I didn’t focus on groundwater extraction from any sources because groundwater is not considered as significant in calculating what is known as the “net basin supply” of water available to the Great Lakes themselves. The IJC defines net basin supply as: “The net amount of water entering one of the Great Lakes, comprised as the precipitation onto the lake minus evaporation from the lake, plus groundwater and runoff from its local basin. The net basin supply does not include inflow from another Great Lake.” Groundwater is more important for maintaining the base flow of streams flowing into the lake, and in this way, more slowly replenishing the lakes over time.

      The concerns you raise about fracking are important ones, and anything that permanently removes or seals off water from flowing into the Great Lakes will affect the net basin supply. With extraction for water bottling, updated information is needed about the relationship to water exported from the region versus the balance of water imported or used in the region, especially since bottled water use has increased so much.

      Groundwater that is extracted for use in the basin (in bottles, for agriculture or otherwise) is not considered a loss because it is assumed that it will find its way back into the hydrologic cycle eventually. The increased agricultural irrigation you mention might be a concern for groundwater supply, but assuming it is used in the basin, it would not contribute directly to lower lake levels.

  32. Psalmon
    August 26, 2013, 9:54 am

    “There is no question that lake temperatures are warming…”

    2013 temps have been average to below average according to NOAA. http://coastwatch.glerl.noaa.gov/statistic/

    Until the last week Superior has been at record low temps if you care to look at all the graphs into the 90s

    Please check the data before making pronouncements that support your conclusions.

    • Lisa Borre
      August 27, 2013, 4:40 pm

      Although summer lake temperatures have been cooler this year than in recent years, if you look at the long-term trends, the lakes are warming. This is true even though some years summer lake temperatures are average or cooler than average.

      A study by NASA Jet Propulsion Laboratory found that in the last 25 years, the world’s largest lakes have been steadily warming, some by as much as 4°F (2.2°C). In comparison with other lakes, Lake Superior is one of the most rapidly warming lakes in the world. These findings are backed up by similar study conducted by European scientists. These global assessment was summarized in a previous post: http://newswatch.nationalgeographic.com/2012/10/05/warming-lakes-barometers-of-climate-change/.

      I also wrote about how warming lake temperatures, loss of ice cover and increased evaporation, particularly on Lake Superior, affect the Great Lakes in a previous post: http://newswatch.nationalgeographic.com/2012/11/20/climate-change-and-variability-drive-low-water-levels-on-the-great-lakes/.

      Studies of Lake Superior by Jay Austin at the Large Lakes Observatory at the University of MN-Duluth, has found that summer temperatures on Lake Superior are warming rapidly. His website states: (1) air and water temperatures are increasing quickly (about 1 degree Celsius, or ~2F, every decade), wind speeds are increasing, and the date of the spring overturn is becoming earlier (about 1/2 day per year). For more information visit: http://www.d.umn.edu/~jaustin/ICE.html.

  33. Colin Dobell
    Georgian Bay
    August 23, 2013, 1:52 pm

    Boy was this article needed. We are just completing a campaign to register 20,000 members to our free online community “http://www.stopthedrop.ca” (this pilot is focused on Georgian Bay – our next rollouts will expand to other Great Lake regions). As the Exec. Director, I have canvassed all around Georgian Bay, and I can confirm your 5 myths are those I have heard from folks most. The other ones we hear: “Americans are stealing our water”; “The Bruce Power nuclear plant is sucking it up”; and my favourite: “There’s an 18ft diameter pipe taking water from Michigan down to Kansas”.

    • Lisa Borre
      August 24, 2013, 5:22 am

      Colin, Thanks for the information about your campaign and for sharing some of the other myths out there. Good luck with your campaign to stop the drop!

  34. tom emery
    east tawas, michigan
    August 23, 2013, 9:25 am

    Interesting discussion, I am not aware that the dredging issue was ever proven to have an effect. In the late 1980′s, long after it was completed, we had record high water levels. It appears that our current situation is due to evaporation and lack of replenishment.

    I found your article while looking for information differentiating the coastal flooding along the oceans from the situation on the Great Lakes. Without an icecap in our basin, it seems that further decline is inevitable, absent global cooling.

    By the way, Mr. Conn – Lake Huron, the North Channel and Georgian Bay – our side of our one lake is not too shabby.

    • Lisa Borre
      August 23, 2013, 1:33 pm

      Tom, the dredging operations were shown to have an effect due to continued erosion for several decades after dredging was completed, but studies show it has now stabilized. The issue you raised about an ice cap in the basin reminded me of another “myth” I’ve read on the internet: How can the lakes be declining when sea level is rising? The answer to that one is so obvious, as you have pointed out, that it needs no further elaboration. I grew up in the part of the Great Lakes where Mr. Conn is from and first visited your part of the “lake” by boat in the late 1960s. You’re right, it’s not too shabby at all.

  35. Gary Conn
    Grand Haven, Lake Michigan, Michigan
    August 22, 2013, 9:35 pm

    State of Michigan Government Internet Links

    Department of Environmental Quality manages all water in Michigan.

    DEQ homepage http://michigan.gov/deq

    DEQ on Twitter https://twitter.com/michiganDEQ

    Coastal Management http://www.mi.gov/coastalmanagement

    Water Use, Levels & Diversion: Ennbridge Oil Spill; Boundary Waters Treaty 1909; Chicago Diversion Decree (Sewage Canal)
    http://michigan.gov/deq/0,1607,7-135-3313_3677_3704—,00.html

    Along The Shore: Public Trust Doctrine in Michigan
    http://www.michigan.gov/documents/deq/deq-lwm-wetlands-alongtheshore_339898_7.pdf

    Brochure describes Public Trust Doctrine.

    Public Trust Doctrine in Michigan obligates the state to protect all waters and to preserve the public right to boat, hunt, fish and traverse the shoreline.

    Michigan has the longest freshwater coastline in the world.

    Gary

  36. Harold Glutzenbaum
    Montreal
    August 22, 2013, 6:21 pm

    The long term geological cause of the lower levels of the Great Lakes is mainly the rebound of the land masses which were under glaciers that receded about 10,000 years ago. The short term is mainly the weather which fluctuates and causes the lakes to fluctuate. Droughts and low levels have been seen before and the inverse also. Much ado about nothing and what’s new?

    • Lisa Borre
      August 23, 2013, 2:07 pm

      Harold, I’m glad you raised the topic of how the land in the basin is adjusting as it recovers from the retreat of glaciers. Without the weight of the ice, the land surface is slowly rising, but as you probably know, not all parts of the basin are adjusting at the same rate. As explained in the IJC’s International Upper Great Lakes Study (2009), “The land surface is slowly rising, particularly on the north shore of Lakes Superior and Huron (Georgian Bay) and subsiding in other parts of the system, most notably on south western shores of Lakes Superior and Michigan relative to their outlets.” This does play a role in lake levels on a geological time scale, especially in Lakes Superior, Huron and Michigan.

      You’re also right that droughts and low lake levels have been seen before. It is also true that the lakes will continue to fluctuate, but it’s too simplistic to just blame it on the weather. The climate warming we have experienced in the last five decades is unprecedented when compared to post-glacial period you mention. Both rebound and climate change are more gradual trends compared with the immediate effects of weather. The issue is not whether there are droughts or not, but the increased frequency of these extreme events due to human-induced climate change. In addition to factors that affect water levels (warming water temperatures, loss of ice cover and increased evaporation), climate change affects the overall health of the ecosystem. What’s new? Climate trends that should concern anyone who cares about the Great Lakes.

  37. npirani
    Houston, TX
    August 22, 2013, 11:42 am

    Is there a way to get a original/print version of this article? Or is this an online blog post only?

    Thank you in advance! I plan on taking the pledge!

    • Lisa Borre
      August 23, 2013, 2:09 pm

      Thanks for your interest in the article. It is only available online.

  38. Suzanne Lossing
    Michigan!
    August 21, 2013, 11:53 am

    You diverted the answer for Myth 1 by comparing it to evaporation. Yes evaporation a very serious concern -but I want a valid answer on does groundwater diversion have an effect on lake levels? What are the water tables? Yes, evaporation causes a higher loss (Lake Superior alone regulates the temperatures), but does water diversion, such as Nestle’s bottle water (out of the watershed and on the shelves – and the water consumed to process all the plastic bottles) reduce the water tables for the Great Lakes? If so, in what areas the most? Side note-I’ve seen Bottled Water from Nestle in stores in Kentucky–not sure if is it Great Lakes Water or not.

    • Lisa Borre
      August 21, 2013, 12:39 pm

      Suzanne, I addressed the bottled water issue in detail in the commentary on a previous post which is why I didn’t go into it in detail here: http://newswatch.nationalgeographic.com/2012/11/20/climate-change-and-variability-drive-low-water-levels-on-the-great-lakes/. The short answer is that groundwater extraction for water bottling is more of a concern for the aquifers and inland lakes, rivers and streams than it is for water levels on the Great Lakes themselves. Here’s the answer I gave to a question very similar to yours:

      “…You may be interested in this 2000 report on the Protection of Waters of the Great Lakes: http://www.ijc.org/php/publications/html/finalreport.html#3. Although these data are more than ten years old, the report looks at the impact of bottled water. At that time, about 14 times more bottled water was being imported than exported from the Great Lakes Basin. The net effect of imports and exports doesn’t address the point you make about impacts on individual aquifers, but this is the reason the report concludes that “bottled water appears to have no effect on water levels in the Great Lakes Basin as a whole.”

      In my reply to Bob, I provided information about the volume of water lost through evaporation to illustrate its significance to net basin supply in comparison to bottled water. The original post explains in more detail that the impact of evaporation is no longer based on estimates. Researchers are now measuring (rather than estimating) evaporation on all five of the Great Lakes. Their measurements and observations confirm the significance of evaporation and help explain some (not all) of the complex interactions among factors that affect water levels.”

  39. Gary Conn
    Grand Haven, Lake Michigan, Michigan
    August 21, 2013, 6:11 am

    The Water.

    Thank you; images of carp in The Great Lakes terrify us.

    The town on Lake Michigan is on Grand River. The river is 11% of the Lake Michigan drain basin.

    Of course, Michigan State and local authorities carefully monitor the lake and river for pollutants. However, upstream residential buildup and farm runoff waste spill fertilizer and manure into Grand River and Lake Michigan.

    In this way, water quality is forever lost, wildlife habitat is finally destroyed and the aquatic life can be killed.

    Alternatively, here’s my NGS YourShot photo gallery: See the natural beauty of Lake Michigan as it really is!

    http://yourshot.nationalgeographic.com/profile/18688

    Gary

  40. Gary Conn
    Grand Haven, Lake Michigan, Michigan
    August 20, 2013, 7:18 pm

    My home is Lake Michigan, the World’s Most Beautiful Lake.

    Yes we have issues; encroachment, habitat loss, pollution, use, over use, and abuse.

    My idea? Government should make Lake Michigan a National Park; a World Heritage Nature Reserve; a UN Water and Wildlife Sanctuary. Feedback!

    Another question: Why no mention about invasive species Asian Carp entering Lake Michigan biology via the Chicago diversion sewage canal? Gary

  41. joe Barrett
    North Tonawanda, NY
    August 20, 2013, 3:03 pm

    Here’s a story for National Geographic to cover, The Price of Stopping the Ice. The true cause and effect of the ice boom on Lake Erie as told by Joe Barrett. Google me. or visit http://www.bantheboom.com The Lower Great Lakes are dying and need your help. THX, JBB

  42. James
    Ontario
    August 20, 2013, 2:43 pm

    The picture at the end of point 2 is a Canadian flagged vessel that sailed as the Canadian Olympic and has now been renamed the Algoma Olympic. This vessel is not SOLAS class and does not leave home trade waters. Also it is a self unloader designed for carrying bulk cargoes such as coal or iron ore, not liquid cargoes. I work in the shipping industry and would be happy to make myself available for non company specific comments if you would like.

    Interesting read, thanks.

    • Lisa Borre
      August 20, 2013, 11:14 pm

      Thanks for your comment about shipping, James. The photo caption does not identify the ship as ocean-going, but your point is well-taken. The image was just meant to draw attention to the impact low water levels have had on Great Lakes shipping this past year, in general, and to give readers a sense of the size of ships on the Great Lakes. As you point out, most ships are carrying bulk cargoes, not liquid, and therefore would not be equipped to secretly ship water. I’m glad to have the details you provide of this particular ship because it happened to be one that passed me while sailing on Lake Erie in 2004.

  43. Jessica Robinson
    United States
    August 20, 2013, 2:04 pm

    This was worth the read and well written. I love how Lisa specifically addresses readers and their comments. Many of us have seen comments like these all too often and Lisa directly responded to them. Love it.

    • Lisa Borre
      August 20, 2013, 11:42 pm

      Thanks for reading, Jessica.

  44. Wally
    August 20, 2013, 11:14 am

    You stated that “All water diversions in the Great Lakes basin are regulated by the International Joint Commission (IJC) under the auspices of the Boundary Waters Treaty of 1909.” This is mostly incorrect. The IJC does not regulate water diversions, unless they affect the levels and flows on the other side of the border, and to the best of my knowledge, no diversion has been considered to affect the levels and flows on either side of the border (and, consequently, the IJC’s arbitration clauses have never been invoked). Even the Illinois Diversion through the Chicago River is governed by the U.S. Supreme Court and not the IJC (of particular note there–Lake Michigan is entirely within the U.S., and therefore not considered to be controlled by the Boundary Waters Treaty).

    Diversions are primarily managed by the individual States and Provinces pursuant to the Great Lakes-St. Lawrence Sustainable Water Resources Agreement and the Great Lakes-St. Lawrence Water Resources Compact in recent years (and diversions are outright prohibited by both agreements, with a few near-basin exceptions) , and under other State and Federal laws in past years.

    • Lisa Borre
      August 20, 2013, 1:48 pm

      Wally, thanks for pointing out the error regarding the IJC’s authorities. I meant to say that water levels (not diversions) are regulated by the IJC, and this has been corrected in the post. The information you provided regarding the IJC in the first paragraph is basically correct, but since you raised the topic, I contacted John Nevin at the IJC to clarify further. Here’s what he had to say:

      “The IJC approves and provides ongoing regulatory orders for projects that affect levels and flows on the other side. Examples of this are the structures at Sault Ste. Marie and the dam between Cornwall Ontario and Massena, NY. The Chicago Diversion predates the Boundary Waters Treaty. Moreover, the governments can agree to projects through exchange of notes and not involve the IJC if they so choose. In addition, since Michigan and Huron are effectively one lake, a diversion from Lake Michigan is a diversion from Lake Huron.” For more on the diversion, here’s a piece he wrote on the topic: http://biotech.law.lsu.edu/cases/environment/ChicagoDiversionHistoryMarch5.pdf.

      Thanks for the additional detail in the second paragraph of your comment about how water diversions are handled, which is largely correct. “The bottom line is that water levels are under the auspices of the IJC only to the extent that structures we have authorized affect flows in connecting channels from one lake to the next,” Nevin said.