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  • HDT Team

Q&A with Freshwater's Carrie Jennings

Updated: Jan 4, 2023

A highlight of Back to Basics will be the keynote address from Dr. Carrie Jennings, research and policy director with Freshwater. In addition to her expertise, Dr. Jennings has both academic and public service experience and is an active water enthusiast. Her talk, “The Long History of Water in the Northern Lakes Region,” will paint a picture of how the water we use today came to be and how to best protect it. For more information about the 17th Annual Back to Basics, please go here.

What sparked your interest in geology? Had you always planned to become a geologist?


My plan when my clarinet teacher drove me from Ohio to Northwestern in Illinois for an audition was to become a professional musician. I wasn’t accepted to study with the prestigious clarinetist of the Chicago Symphony Orchestra but NU wrote me a nice letter saying I could come to school there anyway. The first two years were fully dedicated to distribution requirements and I stumbled on a class called The Origin of Mountains and was hooked. Most geologists find the field this way, accidentally. Not sure I could cut it, I vowed to myself to stay with it until I flunked out. I ended up with a PhD (after some shaky grades in Physical Chemistry).


Did you come across surprising information about Minnesota geology (in general or in our area in particular) when you worked on the County Geologic Atlas program?


Every day of mapping the geology of Minnesota involved gathering clues and solving little mysteries to build the picture of what happened in the past. So much of the evidence is missing so you have to rely on incomplete information. I loved the process and sometimes a puzzle piece would finally snap into place after years, completing the story. I think that what I am most known for is developing the idea that our ice lobes were the outlet glaciers of fast-moving ice streams, like those you hear about these days in Greenland and Antarctica. They don’t advance when it’s cold, they are actually the mechanism by which ice sheets are drawn down as climate warms.



I think the other big idea was correcting the idea of how boulders form. We like to think that glaciers are just plucking away at the bedrock and then rivers round rocks after the fact. In fact, extremely large, perfectly round and polished boulders emerge from the rotten rock—saprolite--developed over 100,000s of year of chemical weathering. These corestones were released from the surrounding grus [coarse-grained rock fragments] and clay as glacier and their meltwater streams simply brushed away the grit.


Can you tell us a little bit about your organization, Freshwater, and the goals you are working towards?


I take the statement on our homepage to heart: WE TRANSLATE SCIENCE INTO POLICY AND ACTION TO PRESERVE OUR FRESHWATER RESOURCES. We work on both surface water and groundwater, and both quantity and quality. We also work on both the natural and the built water environment. I prioritize my research in areas where it can inform policy and where that policy can move the needle. If policy solutions are out of reach, we work with community leaders and doers to inform and multiply our impact.


What do you consider is the biggest threat to the State of Minnesota’s groundwater?


Once groundwater is contaminated it is impossibly expensive to clean it up in most cases. This also means that less clean water is available for the multiplicity of uses that we put it to, not to mention the connection it intrinsically has to our surface water features. Our groundwater is very old in some cases and not being replenished at the rate we are using it. We need to protect and preserve it for the best and highest purposes. The widespread contamination of our aquifers in agricultural areas with pesticides and nitrate and in populated areas by our personal care products, pharmaceuticals, household products not to mention industrial waste is a HUGE problem. Nothing really goes away and sometimes chemicals transform and interact in ways we don’t anticipate. My best council is to use as few chemicals as possible in your day-to-day lives and we will all be the better for it.


How concerned should we be about PFAS or other “forever chemicals” in our water supplies?


Parts of Minnesota are ground zero for PFAS contamination of groundwater. The landfills that received waste from 3M have large plumes of contamination impacting a lot of the east metro. Lower concentrations of these chemicals are everywhere but concentrated around landfills, grocery composting sites, areas where fire-fighting foam was used at airports and for training and sometimes even forest-fire suppression. The most important thing for us to do is to stop using them. They were designed to be slippery and impossible to break down—and they do that well. They persist and are apparently in everyone’s bloodstream. The Minnesota Department of Health’s limits are very conservative and based on the amount that a breast-fed infant might be exposed to. See their website for more information and recommendations.


What do you wish people understood about geology as it relates to water?


I wish that people understood how it is all ONE water. Surface water and groundwater are connected and surface water is just the visible expression of the groundwater. The water in the atmosphere is also a critical part. We do it by draining wetlands, digging ditches, controlling lake levels but also in more subtle ways by changing the vegetative cover which is one of the main ways that water gets from the ground and back to the atmosphere and in profound ways by changing the climate. That boring water cycle diagram? Take another look. There is no part of the water cycle that we have not disrupted in the last 150 years.



Minnesota in 2123

How do you think the geology of Minnesota will look different in 100 years?


Gravity does not like a hole or a hill and will work to fill in depressions and wear down hills. That is, in the absence of new forces that churn up ground (glaciers), make depressions (meteor impacts, dissolution of rock, glaciers), or push up mountains (plate tectonics). So here in the stable midcontinent of Minnesota, until and if there is another ice age, we will become more…subtle. The youngest parts of the landscape are the most active now, with precipitation-driven landslides decreasing slopes along rivers and lake, and loose sediment blowing or washing away. We’ve accelerated this great leveling by stripping vegetation from parts of the landscape. The only exception to the leveling is that rivers will continue to work their way farther up into undrained, lake- and wetland-dotted parts of the landscape, draining them. In certain part of the state, namely the Minnesota River watershed and the St. Louis River watershed, there is a big difference in elevation from the headwaters areas to the outlet (big for a Minnesotan). That means that the tributaries in these watersheds will begin to look more like the southeastern part of the state where rivers have been on this course for longer (not, driftless, but drift-ish—it was glaciated previously but long enough ago for river valleys to dominate the landscape.)


If you could go back in time to witness any geologic era, which one would you choose?


The atmosphere was very different early in the life of the planet and so was the way that atmospheric and dissolved chemicals in the ocean circulated. Somehow this led to the conditions for the earth to be completely covered in ice—a Snowball Earth. However that flip-flopped with the complete loss of ice. I don’t know what vantage point I would need in order to observe these Ice-House-Green-House fluctuations beginning in the Cryogenian (700 million years ago), but I have a hard time envisioning them. So it would be great to witness (with commentary). If it was safer to stand in Brazil during the Permo-Carboniferous, that was when ice sheets covering Gondwanaland 300 mya (million years ago) created outlet glaciers into a sea in the Parana Basin. They would have looked much like our ice lobes as they flowed out of a massive ice sheet covering Africa and Antarctica when all three of those continents were part of the super continent.


What action do you recommend the average property owner takes to protect groundwater? Does local government have a role to play?


Reduce, reuse, recycle works for water too. It is not just the water at your tap that you should think about reducing but water used for the large-scale industrial and agricultural practices. Products take a lot of water to make.


You can start by calculating your water footprint. Then I’d say try to restore the way water wants to be on your land by doing the following:

  • Let it soak in where it falls.

  • Keep native vegetation as much as possible.

  • Capture roof and driveway runoff and let it soak in.

  • If you are on septic, and even if you are not, never use the drain to dispose of anything except wastewater.

  • Keep your wastewater stream as clean as if you were going to drink it again because you are. We can’t stop using our prescriptions and shampoo but use the mildest and least amount possible. Don’t believe in magical cleansers, especially if they don’t tell you what is in them.

  • Reuse roof water by storing in rainbarrels (or rain pillows!); use water more than once whenever practical.

  • Minimize your use of lawn chemicals, driveway sealants and other things you don’t want in your drinking water. Even laundry soap can be simple without a lot of brighteners, bleaches and doo-dads.

Keep your wastewater stream as clean as if you were going to drink it again because you are.

Local governments supply water to cities and have to meet drinking water standards. They should be urged to participate in voluntary sustainability planning efforts to make sure they aren’t selling out future generations for economic gain.


Much of the Pine River area is dominated by sandy outwash plains. How do these geological landforms interact with ground and surface waters? What should be our primary concerns in protecting these resources?


The water is all one system, and this is especially visible in a sand plain. Like sand on a beach, water that wets the surface of the Pineland Sands will immediately sink in before the next wave approaches. Anything happening on the surface gets to the water table in hours to days: chemicals deliberately applied or spilled. Similarly the water table responds very quickly to changes in precipitation. There are no mysterious delays like with Devils Lake in North Dakota. Flash drought=low lakes and brown grass. The speed at which things on the surface show up in the ground and then re-emerge in cold water streams is your biggest asset and biggest risk. You will bounce back from drought quickly but prolonged drought will likely begin to blow the sand away and change ecosystems. It is best to keep the sand covered in vegetation as close to original as possible, not speed up the movement of water by pumping it hard and allow the water ample time underground to cool to our average temperature—for at least a season or two!


Same questions as above about geological landforms' interactions with ground and surface waters, but for the Karst geology of the Driftless area--Happy Dancing Turtle has a hub location in Winona.


My name for southeastern Minnesota is Drift-ish. It was glaciated, just not the last time around. It was ice-free long enough for river process to dominate the expression of the landscape, all but erasing the effects of glaciation. (SW Wisconsin is truly “driftless.")


This part of the state, where bedrock hosting fractures and caverns can be close to the surface, is equally if not more vulnerable to rapid infiltration of surface contaminants. There are very high levels of agricultural chemicals in some areas so get your water tested and treat it if it is showing contamination. Test it yearly when you change your fire alarm battery because it is worsening with the limited changes in our agricultural practices. This area is less prone to drought and has higher average annual rainfall but mega rains are eroding stream banks. Minimizing tile drainage or slowing water down as it moves across the landscape so that not all of the rain gets to the river at once will help the rivers and allow groundwater to be replenished.


Dr. Jennings' keynote will be free and open to the public starting at 8:45 am on Saturday, February 11 at Pine River-Backus School. Several workshops being offered that day also have a water theme. Check out all the Back to Basics information here.




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