University Place Wednesday Nite at the Lab  Viruses in Groundwater Kenneth Bradbury  August 1,2012 UP749 CC >> Welcome, everyone, to Wednesday Nite at the Lab. I'm Tom Zinnen. I work here at the UW Madison Biotechnology Center. I also work for UW Extension Cooperative Extension, and on behalf of those folks and our other sponsors, Wisconsin Public Television, Wisconsin Alumni Association, and the Science Alliance here at UW Madison, thanks for coming to Wednesday Nite at the Lab. We do this every Wednesday night, 50 times a year. Tonight it's my pleasure to be able to introduce to you Ken Bradbury. He received his PhD in geology from UW Madison in 1982, and he's been a research hydrogeologist and professor with the Wisconsin Geological and Natural History Survey, which is also part of UW Extension Cooperative Extension, since that time. He serves as a program leader of water and environmental programs for the survey, and his current research interests include groundwater flow and fractured media, aquitard hydrogeology, groundwater recharge processes, wellhead protection, and the hydrogeology of glacial deposits. Ken is the author of numerous scientific papers and reports. He's a fellow in the Geological Society of America, and he has chaired the National Research Council's Committee on Water Resource Research for the US Geological Survey. 

And he is a former member of the National Research Council's Water Science and Technology Board. In 2007, Ken undertook six weeks of research and teaching in South Africa and Zimbabwe supported by the Fulbright Senior Specialist Program. Tonight, he's going to talk to us about something much closer to home, and that is viruses found in water deep below the ground. I'm a plant virologist so I won't know much about this, but it's pretty fascinating to think there are viruses, especially human viruses, hundreds of feet deep in the water that we like to drink. So I'm very much looking forward to Ken's talk. Please join me in welcoming Ken to Wednesday Nite at the Lab. [APPLAUSE] >> Thank you, Tom, and thanks to all of you for inviting me here. As Tom said, I'm a geologist and specifically a hydrogeologist, and it's a little daunting to give a talk in a biotechnology center and talk about viruses because I'm not a virus export but I work on viruses in groundwater. But I'm more on the geology side. But I hope to give you a summary of research that we're working on that really is pretty fascinating and we think is pretty important here. 

So, what I'm going to talk about, really my talk has three parts. First of all, human viruses, what they are and why we care, why you should care. Then a little bit about groundwater. Rocks, fractures, and water wells, where your groundwater comes from. By the way, if any of you drink water, you're drinking groundwater around here because that's where all our water is coming from. All our water is coming out of wells in Madison. And then, finally, viruses. Why are they showing up in deep wells in Madison here, and how do we find out about those? So, first of all, viruses in the news, again in a biotechnology center there's probably a lot of people here that know a lot about viruses, but the most common way we hear about them these days is people get sick on cruise ships from something called norovirus. This is a human enteric virus, meaning it's carried in the human gut. It's excreted. 

It makes people sick. Diarrhea, what's called the flu, gastrointestinal illness. It can be pretty uncomfortable and even fatal to people with weakened immune systems, for example. Of course, viruses aren't the only pathogen we see in wastewater. And just so everyone's on the same page here, we have things called bacteria, and then bacteria and then protozoa which are both single-celled things. Protozoa are a little bit more complicated than bacteria. And then we have viruses which are basically little hunks of genetic material that aren't really alive. They require some sort of host. And the viruses that I'm going to talk about require a human host. They're human viruses. 

Waterborne disease outbreaks are pretty important. As you can see here, from 1970 to 2002 there were at least 700 outbreaks of gastrointestinal illnesses associated with infectious agents in water. 60% of those are attributed to groundwater, and many of those are thought to be caused by a virus. Often they don't know what caused them, but viruses are often thought of. And there have been some pretty famous cases of groundwater-borne diseases. Here in Ohio, South Bass Island, 1400 people sick. Missouri, Walkerton and Ontario was a very famous case where several people died from E coil in the city well. There was a very important case here in Wisconsin a few years ago in Door County where norovirus was found in a restaurant well. At least 229 of the patrons became ill and some of the employees became ill and 6 people were hospitalized. That restaurant had to be shut down for a while. 

They found that the viruses were actually coming from the restaurant's septic system into the restaurant's own well. So these things happen close to home. Now, as a hydrogeologist, what do we know about viruses? As a hydrogeologist, I worry about things being transported by flowing groundwater in the subsurface. And we think of things as either a chemical, which is a concentration, something being dissolved in water, but viruses are not like that. Viruses are actually a particle. So in geology we talk about things called colloids, which are very, very small particles, less than .2 nanometers or microns in diameter. And you can see that a common colloid which might be something like a piece of clay is in that range. Bacteria are about .2 to 20 microns, but viruses are much, much smaller than that. They're in the nanometer range where a nanometer is one-billionth of a meter. So they're tiny, tiny things. 

For comparison, a human hair is 50 to 100 microns, and a fracture in rock, so I'm going to get to how do we move these through rock, rock fractures are a micron up to maybe a millimeter. So much, much faster. So I think of a virus, this little tiny thing being like a ping pong ball going through that door if we're underground looking for a little fracture. So viruses can move in the subsurface. Now, why do we care about this? Well, I care because we worry about drinking water, and drinking water in Wisconsin, unless we happen to be next to Lake Michigan or Green Bay, everybody's using groundwater and water is coming out of wells. And so this is a map of municipal wells in Wisconsin. Of course, most of them are clustered around Madison or the bigger cities, but then there are a lot of smaller communities that just have one or two municipal wells. And you may not know this but currently 60 of these systems do not disinfect in any way. They don't chlorinate or do any other treatment. The water is just used as raw water out of the ground and served out to people. 

Now, in Madison here the water utility adds chlorine to kill viruses and bacteria, and many of the other large communities do that, but not everybody does. And that, as you'll see, is something we're concerned about. How does water get to a well? This is sort of a cartoon of a typical cross-section through the land. We have a well here, and wells usually have an open interval toward their base. I'll talk a little more specifically about the Madison wells in a minute, but water comes in down there and is produced in the well, and it comes from somewhere. In Wisconsin it doesn't come from very far away. It doesn't come from Canada. It doesn't come from back when the Earth was pure. It comes from fairly nearby. In fact, here in Madison we've mapped out the capture zones for various wells, and so this is part of Madison. 

Here's the Isthmus here and Lake Mendota, Lake Monona, and these odd shapes are shapes around the various municipal wells in Madison. And so the red areas are where water gets to the well within five years, the tan is 50 years, and the gray are 100-year travel times from the surface to the well as predicted by a groundwater flow model. Now, as you'll see, our virus data doesn't really agree with this, and that's part of the issue here. So the goal of our research has been to look at the occurrence of human viruses in the Mount Simon aquifer, which is the sandstone aquifer that is used around here, and see if viruses are there and how they move. Now, a surprise for hydrogeologists, a few years ago we were doing a sort of related project. The viruses were not really supposed to be part of the project. And we proposed to find out, I had a colleague who knew how to sample for viruses and test water for viruses, and we said as long as we're doing this project, let's look for viruses in the groundwater. And he said we can do that, but that's a waste of time. You'll never find any; no one ever has. Viruses don't live that long, they don't go that deep, and they've never been found that deep. 

So we thought, well, that's what research is all about, isn't it? We try new things. So we did not expect to find any viruses because the travel times were much longer. We thought our model said it should be tens to hundreds of years to get to these wells, and the virus lifetime or before they disintegrate were thought to be two years. And so it was a surprise because we found viruses in every well we sampled. And these are deep wells. These are not just shallow water table wells. These are 800 to 1,000 feet deep. So that's pretty deep. And then they're in rock. They're not just in sand and gravel or very shallow materials. 

So these raised some important questions such as where do the viruses come from, how do they reach the wells, and how can they get down there so rapidly? So these are the questions we've been looking at for the last few years, and to do this, the first thing we did was a lot more sampling. And before I get to that, I want to give a little background on Wisconsin geology for those of you who don't know too much about it. We have both bedrock and glacial aquifers here. An aquifer is a geologic formation that carries economical and useful quantities of water. Our bedrock, this is a map of the bedrock of the state, and don't worry about all the colors. They all represent different sorts of rock. This green is up in northern Wisconsin are crystalline rocks like granite that don't really produce a lot of water. But down here we have these tan and gray rocks are sandstones and dolomites that are quite porous, and those make great aquifers. And above those rocks we have glacial deposits. Now, around 100,000 years ago or more we had glaciers that covered much of the state, as you know, and those left deposits of sand and gravel and clay which can form shallow aquifers. 

So we have an interesting geologic history. If we focus in on Dane County, this is a map of the glacial deposits in Dane County. So the colors represent different sorts of sand and gravel and clay left by the glacier. You can see this dashed line I've just added. This represents the boundary of what's called the driftless area. And out here toward Blue Mounds we have different topography, a lot more rugged topography. That's because that area was not glaciated. East of that line, the other two-thirds of the county has more subtle topography, and it's covered by glacial deposits. Now, if we have a cross-section from the Capitol to out to, say, Blue Mounds State Park and we cut through the Earth and look at a cross-section along that line and we greatly simplify things, it would look something like this. So this out in the west would be Blue Mounds, and this would be Madison and part of Lake Mendota would be there. 

And so we have this thick layer of sandstone under our feet here. This is called the Mount Simon sandstone. It's about 800 feet thick, and it's a great aquifer. But we never see it. None of you probably have ever seen it in Dane County because it's never at the surface. It's always underground. Below that we have granite. Above it we have a thin shale called the Eau Claire shale that I'll talk more about. And above that we have sandstones and dolomites that you may see in road cuts or outcrops. Now, I've shown one city well here. 

The city wells or the high capacity wells around here are drilled down into this deep sandstone. Groundwater moves through all these formations, moves up and down and sideways as shown by these arrows. It moves to the wells. It moves to the lakes. And we also have shallow wells like the well I have at my house that are completed up in these shallower units. And then we have a water table that's given by the dashed line that intersects the lakes, and then as you move west to Blue Mounds it would be farther to the water. That's the place you would first hit water if you drilled a well or dug a hole. I said you can't see the aquifer in Dane County, but if you want to see what it looks like, you could go to the Dells and ride the ducks. Do the boat ride. So this is Cambrian sandstone that's along the Wisconsin River in the Wisconsin Dells, and you can see that that formation covers about two-thirds of Wisconsin. 

It's a wonderful aquifer. Really I will say one of the best in the world. It's because it's thick, it's porous, and it produces really great quality water. And so what you see here in Madison extends to other parts of Wisconsin. And if we look at that aquifer with a microscope, you can see why it's such a good, this is actually some samples from one of the Madison wells. This is a picture through a binocular microscope, and you can see how nicely rounded and uniform the sand grains are. And then here's another picture of a rock quarry. Even though we call this a rock, sometimes it falls apart like beach sand. So it's an excellent, excellent aquifer. You can imagine water moving through that very well. 

In contrast, this is a picture of the Eau Claire shale, and you can see that it doesn't look very porous. In fact, it only has some fractures and cracks in it, but overall it's a shale. It's a very low permeability material. So that tends to separate the lower and the upper aquifer, and that's part of our story here too. >> What's an aquitard? >> Aquitard, well, great question, sir. So, an aquitard, and that Eau Claire shale is an aquitard, is a geologic formation that doesn't let a lot of water go through it. It lets a little bit. So it's something like a clay or a shale that's very impermeable or low permeability compared to a sand. Now, so this is kind of a cut-out view of Dane County based on a computer simulation. So you can see Lake Mendota here and the Yahara chain of lakes, some of the topography, and then we cut through the ground so we have these upper geologic units. 

That red is that Eau Claire shale. This is just to show how thin it is. And then the orange is the deep sandstone there. And then away from that, some of these other things are wells and then surface water bodies just to give you an idea of where that shale is. Now, when we sample, we've been sampling municipal wells. And one of the people in audience, Chris Gellis this is Chris here, he's a graduate student who next week is going to be defending his PhD on this project and has done a lot of work with us. This was his site, Madison well 7 out on the east side. If you drive around Madison, you occasionally see a little well house like this, and inside there will be a big pump, and that's pumping the water up from that aquifer and out into the city. And there's no treatment going on other than they do add the chlorine, but there's no water treatment plant. That's one of the great things about groundwater. 

We don't need to do very much treatment. It's interesting to know, and you probably can't read this, but this is a plaque in this well house that thanks President Roosevelt who was president when this was built back in 1938. And that's just an example of how old some of our infrastructure is here. So this is a well that's coming on 80 years old or so, and an example of the kind and sort of leaky infrastructure we're having in cities these days. Now, when we sample for viruses, we sample by filtering the water, and we sample out of the output pipes from the pump at the well house. So this is just some of our sampling equipment and filters that we hook into the line and then filter the viruses out of the water. And so when we're doing our study we collect samples monthly prior to chlorination because we don't want to kill of the viruses before we sample them, and then they're sent up to a laboratory up at Marshfield that my colleague Mark Borchardt has with the Agricultural Research Service. They do this RT-PCR detection for enterovirus, rotavirus, hepatitis, norovirus, adenovirus, and some other ones, all human viruses. They look for the genetic material, they try to speciate the virus if they can, and then they also look for infectivity, meaning is the virus actually viable, can it reproduce. We also did some work with isotopes of water to try to look for water sources. 

I won't have time tonight to really go into that very much. That's another technique that we used. Now, a little more about, specifically, the Madison wells. We really have two kinds of wells here in Madison, and just again to review the geology. These are cross-sections very simplified through the geology. So here at the surface we have some glacial materials, we have a shallow bedrock aquifer, we have this shale aquitard, we have this deep sandstone, and then we have the crystalline rock or granite underneath. A typical well might be 800 or 900 feet deep. So they drill a hole down here, down to the bottom, and then they put a steel casing in, and that casing is cemented into the rock. Below that casing, the hole is just open and it just stands open in the rock and they pump the water out. Some of the older wells, this is typical of the newer wells, some of the older wells have shallow casings, and because they didn't think they needed to case that deep back in the old days and so they're open both above and below this shale, this aquitard. 

And that has some consequences that I'll talk about in a minute. So there are really two kinds of wells here. We have a water table that's near the surface, but we also have this dashed line which is called the potentiometric surface. That represents the water level in the deep aquifer, and it's below the water table because of pumping. Pumping in the city has lowered this pressure surface, and that means the water is going to tend to want to move downward to this aquifer. And it would take viruses with it if they were there. So, these wells, here's, again, this well with this shallow casing. We call that a cross-connecting well because it's connecting these two aquifers. And what that means is when we pump the well, pump water out, water can come into the well in the upper aquifer and in the lower aquifer, and it flows up the pipe and out. And that's how the well is supposed to work. 

The problem is when you turn that well off, then there's a potential for water to actually run into the pipe, down the well, and out into the aquifer here. And we think that happens in some of the wells, and that's something that I think a lot of the water utility people didn't really realize years ago when they were drilling these wells that this could happen. So, our sampling program, now Madison has something on the order of 20 wells that they're using now. We didn't sample all of them because this virus sampling is rather expensive, but we did try to get a good cross-section across the city. And so here's a map of Madison, and each of these little triangles is one of the city wells, and they're all red because every one is red that we found viruses in. And I want you to remember how far apart these are. We found viruses on each side of Lake Mendota, really miles apart, and so one of the thoughts people had is maybe there was some sort of a spill or a contamination event that put these viruses into the ground. Well, that's not consistent with finding them over the whole metropolitan area here. All right? Now, we didn't have enough money in our project to sample all these wells repeatedly, so we focused on six. Six wells where we knew we had viruses, and we had three that were of this cross-connecting kind and three that were deeply cased. 

And you can see where they are here. And, again, Chris, who's in the audience, did all his work here up at well 7. We've sampled other wells, and again notice that they're fairly far apart. So what did we find? We sample these in 2007 to 2009. We sampled them every month, more or less. And we also sampled Lake Mendota, and we also sampled sewage because we had an inkling that where would the virus come from? Human waste. Where do you find a lot of human waste? In the sewer. Where are there a lot of sewers? Everywhere. So where would you find a ubiquitous source of viruses? The sewer system seemed like a logical thing to look at. So these are some of the overall results. 

So every one of those six wells we found viruses a number of times but not every time we sampled. And so for the wells were positive about 50% of the samples, actually 46.6%. And we measure viruses in what are called genomic copies per liter, or GC per liter. And you can see the concentrations are rather low, and a maximum of about six copies per liter and a mean of about .6. And you can have something less than one here because we're averaging over large volumes of water. In contrast, look at the sewers here. We had millions, 38 million copies per liter. The sewers are loaded, loaded with viruses. With a mean of two million viruses per liter. So lots and lots of viruses. 

And we had an idea that maybe the lakes had something to do with this, so we sampled the lakes. And sometimes you do get a lot of viruses in the lakes. In fact, they were 82% of the time positive. So don't drink lake water while you're swimming. Now, a little bit about, as hydrogeologists we worry about the weather too. What was the weather doing during our sampling period? So this is a chart of time from January of 2007 to May of 2009 on the X axis here. Precipitation by these blue lines. And then this was cumulative precipitation And this was air temperature. Now, I'm just doing this to show that there were a couple of periods here we had really, really a lot of rain. One of these was in August of 2007, and that's when we had all the flooding and the Lake Delton failed and Spring Green got flooded. 

And then if you remember back in May-June of 2008, that was the big flood but we also had a lot of flooding back in August. So we had these two periods of a lot of rain and flooding. So lots of groundwater recharge then. And we think there's a link between virus detections and lots of precipitation events. Here are some of the overall results all summed together. And I'll explain this graph. Again, going through time here, in the upper part of this is just the overall percentage of positive wells. Remember, we're sampling six wells, and so every sampling event has got a point here. And sometimes we missed a well, but generally we have six wells. And so this is how many of those wells were positives. 

And so you can see that the beginning of our study we were running 80% one month and then it dropped down to 40%, went up to 80%, and then for a while it went down. At one point we had no positive wells out of the six. But we see this trend up and down. We also see kind of the same trend in this concentration in sewage. Now, this is a logarithmic scale so it's a little bit distorted, but you can see that there's sort of a parallelism in the peaks here between the wells and the sewage. And then we also see viruses in Lake Mendota, although it's kind of hard to draw a lot of conclusions because we couldn't sample in the winter because the lake's frozen, and the lake samples turn out to be a lot more problematic. But we do see some coincidence of concentration in the sewage and detections in the wells. Keep in mind, this is a place where the original idea is we would never find any viruses. So we're finding viruses a lot of the time. Now, let's look at individual wells. 

So, you probably can't read that, but just to remind you that these wells are spread out quite a bit. We got through time and we can see that these are actually concentrations now, and each of these lines is a different well. Well 7, well 11, well 12, well 13, 19, and 30. Now, these three wells are the deeply cased wells which should be better protected from contamination. And these upper three wells are the cross-connected. But you see there's not a lot of difference, for one thing, and you can also see that we have some parallelism in the peaks, not 100% of the time, but peaks when we find viruses. And they kind of line up with the times when we had a lot of precipitation. Again, I think the coincidence of these peaks in wells that are miles apart suggests a regional, this is a regional thing, not just something that's related to an individual well or some kind of a spill. So, we're kind of working with that idea now. Now, here's some of the most interesting work, I think. 

Now, I know this is sort of complicated and you don't need to be able to read all of it. Just look at the colors. What we've got here is a chart. Each column of the chart represents a different sampling date. We had 26 sampling dates all together. This upper part represents sewage. This is wells and this is lakes. And then each of these rows represents a different virus, and the viruses are color coded. So, although only probably those of you in the first row can read this, this says A41. That's adenovirus 41, adenovirus 31 and so forth. 

But just look at the colors, all right? And what we start to see is that there's correlations between the sewage and the wells. >> Where do you get the sewage? >> We sample the sewage, good question, Tom. The sewage is sampled at the Nine Springs Sewage Treatment Plant. So we collected from their influent line there. And they were kind enough to give us bottles of sewage to get analyzed. >> [INAUDIBLE] >> Excuse me? >> Who asked the question? >> Oh, I'm sorry. It sounded like it came from Tom. Good question, sir. >> Thanks, Tom. >> All right, good. 

So we see some coincidence. Let me show you what I mean by here. Let's look at the A2 here. If we think of the sewage as a source and we're sampling sewage every month, we see a bunch of kind of yellow here, and then we don't see any more. Let's look at the wells. Here we see a bunch of yellow, we see a little more yellow, but usually most of it drops out. Here's some echovirus 3. We see a red here. We see a red here. We go down here, we see a red, a green, and a black. 

We see sort of this combination of these three viruses, red, green, black, don't worry what they are, and we down here we see the same combination, red, green, black, and that's the first time we've seen it during this sampling period. Here's another one. We look over here and we see, this is the E30. No E30 and suddenly we hit it here in the sewage. By golly, we hit it in the wells at the same time. So here the viruses are being, I think and our group thinks, a temporal tracer. We can speciate these viruses, we can detect them at very low levels, and they're acting as a time tracer telling us that's what's happening with the sewage is showing up in the wells and showing up rapidly. It's showing within weeks, not a hundred years. And that leads us to think that there's some very rapid transport going on. More rapid than most hydrogeologists like me had predicted in the past. 

So this is, I think, some pretty interesting stuff. Now, why do we think it's the sewers? I had never thought a lot about sewers in the past, maybe you haven't either, and we started thinking about sewers. First of all, you've got to realize that there are sewers everywhere. Now, what I've shown here is a map, these are the regional sewers that connect to the Nine Springs Sewage Treatment Plant which is down here. So these are the main lines, but each of those main lines has all these laterals that are under every street and connect to every single house and building. So there are thousands, literally thousands, of miles of sewers. And when people look at sewers and they run, say, a television camera through there, they look like this. They're full of cracks and leaks. But they usually see the water leaking in, and that's because if these sewers are below the water table there is a reason for water to leak in. But, of course, you can't see water leaking out. 

There wouldn't be any signal for that. The fact is, though, that a lot of these sewers are up to a hundred years old. Some of them are still made of clay pipes. More recent ones, of course, are better and they're made of steel or PVC or something like that. But when you think of all the things that can happen to a sewer over a hundred years, tree roots growing through it, people digging into it, land, earth shifting and cracking it, we know that they leak quite a bit. And so it's a good, and we know the sewage is loaded with viruses, so, again, it seems like that's a good potential source. So, how do we get the viruses down there? Well, can we do it with our common groundwater flow equations? And I'm not going to go into what those equations are, but what we've got to do is we've got to get the viruses from the sewer pipe, we've got to get them down through this upper sandstone aquifer, through this aquitard, and then over to the well and out the well. And can we do it within the survival time? Well, we can if we really push all our parameters, things like hydroconductivity and porosity. We can do it but it's hard. It's a little bit outside the box. 

So, if we can't do it with traditional porous media flow very easily, what other transport possibilities are there? Well, how could you get these things down there faster than through traditional porous media flow? Well, are there fractures in the rock that are going to be super highways for the water to move through? Are there going to be these, what we call, erosional or stratigraphic windows? That is, holes in the aquitard where it was eroded away or wasn't deposited. That would let the water through. These cross-connecting wells are a potential way, and we know there are some of those there. Or maybe the well, the municipal well itself is leaking and it's poorly sealed and it's old and has breaches in that steel casing, maybe that's a way. So these are the things we're working on, and we can't answer all these questions yet. We have some ideas. And Chris Gellis, who's in the second row here, has been working on some of this for his PhD. So he's been working out by well 7 on the east side, and we have an experimental design there where not only are we sampling water from this deep municipal well but we've also put in some shallow monitoring wells in these upper units to try to look for viruses in this upper aquifer because prior to this work we've only been really sampling these wells, and so we had no proof that they're actually out there. Well, now, because of the Chris' work and then other work we're doing, we know that they are out here. This would be the sewer up here as the potential source of the viruses. 

 And one of the things that you can do when you have a good graduate student is have them do a lot of work. [LAUGHTER] And, fortunately, we have access to some very sophisticated tools, and one of the things that we do, and that Chris did here, is a lot of geophysical work, which means we lower some special sensing tools into boreholes, and they go down through the well and they measure various properties of the rocks and the water in that borehole. And one of the things we're really looking for is fractures in the rock. Now, keep in mind a little context here. Hydrogeologists worry about fractures all the time but not usually in sandstone. We're talking about sandstone here. Sandstone is thought to be a really great porous, uniform thing, and fractures don't really matter. We worry about fractures in granite or limestone, something that's a little less porous. But here we're starting to worry about fractures in sandstone. One of the neat logs we have is what's called an optical borehole image log, which is this line here. 

And let me show you a little more what that looks like. This is actually a digital camera that goes down the well and takes a 360-degree digital image of the inside of the well, and then it shows things like this, which is a horizontal fracture, and here is a dipping fracture. And let me show you a little more of that. So we blow that up, so this is an unwrapped image of the inside of a well, and then here the computer has reconstructed that image to look like a core. This is not really a core. It's a 360-degree image of the inside of that well. We see an image like that, how do we get that? Well, that's the image of a very steeply dipping fracture. And so we can assemble that and then we have abilities now to visualize that, and so you can see how that fracture might intersect with the well. So it's a dipping fracture. This is the kind of fracture that could transport viruses. 

We don't know that for sure, of course, but we know that fractures are present which is something that we didn't really know before. So, here's Chris in the field, and he developed a tool to put down the well called a straddle packer sampler or tester. And you probably can't see it very well, but this device, here's his test well, this device has two inflatable rubber bladders on it at a couple feet apart here that inflate when they're underground, and they isolate a little part in the middle so it allows you to pull water in or measure things about the water just in that interval. So you can go down a well that has an open borehole and then measure things down the way. And particularly, you can measure the properties of various fractures, and so when Chris did that, and this is a figure from a recent paper that he did, he went down and he found that there were a number of fractures, and he's only shown the most important ones here, but these fractures are intersecting this borehole. And most of them are horizontal or near horizontal, but we did have this one high angle or near vertical fracture that could potentially be taking water deeper. Now, we weren't able to see it below this Eau Claire formation because this well didn't go deeper than that. So it's only projected it might go down that deep, but I think the important thing is we know there are fractures there. Chris has done a lot of work looking at the connectivity of these and so forth. And we know that there are viruses in some of these fractures. 

So that's one potential way to get the viruses down there. And he's wrapping up his PhD, but we have a grant to keep doing this sort of work at other wells. So, some of the take-home messages are that this groundwater from these deep confined bedrock aquifers which we usually assume to be protected from surface contamination is showing things up because we're seeing viruses in these deep wells. I want to emphasize that this isn't just a Madison problem. We happen to be looking at it in Madison, but we think this is probably typical of most urbanized areas that have bedrock aquifers. We found viruses in every one of the wells we tested. We think the leaky sewers are a potential virus source, and we're seeing that the transport to the wells is much more rapid than we would predict with standard groundwater models and assumptions, suggesting that we have to think about flow through these discrete features like fractures to explain the transport and the virus occurrence. Now, back to the big question, who cares? Do viruses matter? And so this is an important question, but we have some answers. Consider that, again, my colleague Mark Borchardt, who was up at the Marshfield Clinic at the time, did a very detailed and careful look at 14 Wisconsin communities using untreated water. Now, these are a little different because they were rural communities that had shallower wells. 

He found viruses in wells in every one of those systems. So we knew the people there were drinking untreated water that had viruses in it, and because of his association with Marshfield Clinic, they were able to look at the health records from those people. And they did a lot of epidemiological work and concluded that about 15% of their annual gastrointestinal illness was attributed to using this untreated water. >> Can you translate gastrointestinal illness? >> That means your diarrhea and vomiting and uncomfortableness. And most of us have at least one or two bouts of that a year, and people say, well, I must have eaten something bad or I got too tired or whatever. Mark's got some pretty good evidence that 15% of that, which is, as I understand it in the healthcare field, that's a huge number. To be able to attribute that much illness to one particular cause, that's a huge number. 15% is coming from drinking untreated water. >> But that's only in communities using untreated water. >> That's in communities using untreated water, right. 

But that gets us to the next question: should we treat the water? So, should communities be required to disinfect the water? So, following our studies in 2009 we reported our work to the DNR, and they decided to require all communities that have public water supplies, public water utilities, to disinfect their water using chlorine as the most common, although there are some other ways, UV light and so forth can be used. And, actually, the DNR had public hearings and put that rule into effect. But last year our legislature decided they didn't like that rule, and so they actually voted to make it illegal to require disinfection. And I went to the public hearings to hear all the arguments about that, and the reasons given by people were it cost too much, it made the water taste funny, and the most common was, well, it was a local control issue and they didn't want someone in Madison telling them what to do. And, interestingly enough, they talked about the cost of treatment but not the cost of illness, which I thought was interesting. But that's for another venue, I suppose. Anyway, so right now there is no requirement that water be disinfected from public drinking water. And I think a lot of people assume that when they go somewhere the water is treated. There's also no requirement they test for viruses. So you're kind of taking your chances. 

And we found a lot of the utility managers didn't understand the difference between viruses and coliform bacteria, for example, because they're different. So, implications. We know now that viruses can be commonly present in deep bedrock water supply wells like we have here in southern Wisconsin. We would recommend that communities that use drinking water for a source should do some sort of treatment, chlorination or other disinfection, to deactivate those viruses. We also know that a single sample doesn't tell you whether you have viruses or not. We've done this time series kind of sampling. And the virus occurrence varies a lot from time to time. It seems to be related to weather events. And so you need a more extensive kind of sampling than just a grab sample once a year to tell whether your well has viruses in it. We know that untreated sewage contains a lot of viruses. 

That's probably not a big surprise. But we need to start thinking about that as a source of groundwater contamination, and it's something that I don't think a lot of hydrogeologists have paid enough attention to. And, finally, more on the research side, because we can look at these serotypes or these virus types and we can speciate the viruses and we can measure them in such small quantities, they represent a potential really interesting tracing tool for us to look at groundwater flow patterns, groundwater flow to wells, and other hydrogeologic studies. So I think it gives us an interesting arena for future research. We do have some publications on this, and I know you're not going to copy all that down, but we published some of this stuff. I want to acknowledge a lot of our cooperators and coworkers. This is not just a one person thing. There are many people. Here's Chris Gellis. He's currently, next week, defending his PhD. 

In the second row here. We had help particularly from my colleagues at the State Geological Survey and also from Mark Borchardt, Susan Spencer at the USDA ARS lab in Marshfield that do all the virus analyses. And I want to also acknowledge the Madison Water Utility which was very helpful in allowing access and continues to be allowing access to their wells, and the Madison Metropolitan Sewage District lets us have sewage samples. And then funding from the Wisconsin DNR and also the US Environmental Protection Agency has given us a large grant from their STAR grant program. And I will stop there and take any questions you may have. [APPLAUSE]