South-Central Minnesota Groundwater Monitoring of the Mt

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer

James A. Berg and Scott R. Pearson Minnesota Department of Natural Resources Ecological and Water Resources Division St. Paul, Minnesota

November 2012 Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative Commission on Minnesota Resources (LCCMR).

This is the final project report of Result 2 of the LCCMR project titled “South-Central Ground- water Monitoring and County Geologic Atlases” (M.L. 2008 Chap. 367, Sec. 2 Subd. 4 (h)).

Authors James A. Berg Scott R. Pearson

Contributors and Reviewers Jeanette Leete Neil Cunningham Bob Tipping Tony Runkel John Mossler

Last version: Version 3.1, June 2011 Current version: Version 3.2, November 2012 (text update)

If you have questions or would like additional information, please contact James Berg at 651-259-5680.

Minnesota Department of Natural Resources 500 Layfayette Road North | Saint Paul, MN 55155-4040 | www.dnr.state.mn.us | 651-296-6157 Toll free 888-MINNDNR | TTY 651-296-5484

This report is available in additional formats upon request, and online at www.dnr.state.mn.us Contents

Abstract...... 6

Introduction and Purpose...... 7

Geology of South-Central Minnesota...... 8

Investigation Methods...... 9 Site selection Drilling methods and well construction Aquifer interval selection for monitoring Geophysical well logging Well development Groundwater sample collection Specific capacity procedures and results Continuous water level measurements

Thickness of the Mt. Simon Aquifer Near the Western Subcrop...... 13

Groundwater Movement and Potentiometric Surface - Mt. Simon Aquifer...... 13

Geochemistry...... 14 Groundwater Residence Time Stable isotopes, 18O and deuterium Source water temperature and mixing Evaporation of source water Major ions Trace elements

Hydrogeology Illustrated by Cross Sections and Hydrographs from Observation Well Nests...... 18 Cross section A-A’ and Severence Lake WMA hydrograph Cross section B-B’ and Sibley County landfill property hydrograph Cross section C-C’ and Norwegian Grove WMA hydrograph Cross section D-D’ and Peterson unit hydrograph Cross section E-E’ and Courtland West/Nicollet Bay hydrographs Cross section F-F’ and Helget-Braulick WMA hydrograph Cross section G-G’ and Bergdahl WMA hydrograph Cross section H-H’ and Case WMA hydrograph Cross section I-I’ and Madelia WMA hydrograph Cross section J-J ‘and Long Lake WA hydrograph Cross section K-K’ and Exceder WMA hydrograph Cross section L-L’ and Rooney Run WMA hydrograph

Paleohydrology and recharge estimates...... 22 Southern area recharge Northern area recharge 2009 Groundwater Appropriation...... 23 Southern area appropriation Northern area appropriation

Conclusions...... 24

References...... 25

Attachments Section

Tables...... 27 1: Well summary 2: Specific capacity and water level data summary 3: Field sample collection and handling 4: Residence time indicators, stable isotopes, and selected trace elements 5: Selected anion and cation data

Figures...... 33 1: Mt. Simon observation well nest locations 2: Cambrian and older stratigraphy in study area 3: County and state Paleozoic bedrock map 4: Mt. Simon Sandstone thickness 5: Mt. Simon potentiometric surface and groundwater flow directions 6: Cross section Z-Z’, Mt. Simon potentiometric surface 7: Carbon-14 residence time data from the shallower aquifers at each observation well nest 8: Mt. Simon carbon-14 residence time, potentiometric surface, and groundwater flow directions 9: Stable isotope data compared with North American meteoric line 10: Ternary diagram-relative abundances of major cations and anions 11: Mt. Simon sulfate concentrations (mg/l), and groundwater flow directions 12: Mt. Simon chloride concentrations (mg/l), and groundwater flow directions 13: Mt. Simon arsenic concentrations (mg/l), and groundwater flow directions 14: Precipitation departure from normal October 2009-September 2010 15a: Cross section A-A’ 15b: Severance Lake WMA hydrograph 16a: Cross section B-B’ 16b: Sibley County landfill hydrograph 17a: Cross section C-C’ 17b: Norwegian Grove WMA hydrograph 18a: Cross section D-D’ 18b: Peterson Unit hydrograph 19a: Cross section E-E’ 19b: Courtland West Unit hydrograph 19c: Nicollet Bay Unit hydrograph 20a: Cross section F-F’

4 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 20b: Helget Braulick WMA hydrograph 21a: Cross section G-G’ 21b: Bergdahl WMA hydrograph 22a: Cross section H-H’ 22b: Case WMA hydrograph 23a: Cross section I-I’ 23b: Madelia WMA hydrograph 24a: Cross section J-J’ 24b: Long Lake WA hydrograph 25a: Cross section K-K’ 25b: Exceder WMA hydrograph 26a: Cross section L-L’ 26b: Rooney Run WMA hydrograph 27: Mt. Simon recharge interpretation 28: Generalized cross section Z-Z’ and geochemical data 29: Cross section Z-Z’, Mt. Simon recharge and discharge 30: Mt. Simon observation well nest locations and 2009 groundwater appropriation

Appendix A: Geological/Geophysical Logs and Well Construction Diagrams...... 77 Geological Log Legend Severance Lake WMA Rooney Run WMA Swan Lake WMA - Peterson Unit Norwegian Grove WMA Swan Lake WMA - Nicollet Bay Unit Madelia WMA Long Lake WA Lake Hanska WA Helget Braulick WMA Exceder WMA Swan Lake WMA - Courtland West Unit Case WMA Bergdahl WMA Sibley County Landfill

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 5 Abstract

The deepest bedrock aquifer of south central/southeastern Minnesota, including the Minneapolis/St. Paul metro area, is the thick (50 to 200 feet) Cambrian sandstone Mt. Simon aquifer. It supplies all or some of the water used by over one million Minnesotans. The few water level measurements available from this aquifer in the Mankato and Minneapolis/St. Paul metro area indicate declining water levels in areas where water is being withdrawn for municipal and industrial use. To better understand the recharge dynamics of the Mt. Simon aquifer the western and northern edge of the Mt. Simon aquifer, where it is not overlain by relatively impermeable Paleozoic shale formations, was considered the most likely area for aquifer recharge. This edge of the Mt. Simon aquifer was investigated and characterized through observation well installations, water level monitoring, groundwater chemical analysis, and aquifer capacity testing to help determine recharge pathways and sustainable limits for this aquifer. Most data collected for this study are derived from the wells installed at 14 locations by contracted drilling companies.

The combination of chemical residence time indictors, continuous water level data from nested well locations, and a general knowledge of the regional hydrostratigraphy, show an aquifer with a very slow recharge rate from a large source area located south of the Minnesota River and a smaller source area located in the northern portion of the study area. The younger 14C residence time values of Mt. Simon groundwater (7,000-8,000 years) from this project roughly correspond to a time after the last ice sheet had receded from southern Minnesota suggesting groundwater in the Mt. Simon aquifer in this region began as precipitation that infiltrated during the post-glacial period.The stable isotope data of oxygen and hydrogen support this conclusion. A recharge estimate of the Mt. Simon aquifer south of the Min- nesota River based on these minimum residence time data suggests a recharge rate of approximately 0.49 cm/yr. The resulting 1.2 billion gallons/year of recharge from the southern source area is less than the amount of groundwater used from the most recent year for which data are available (2009). The results of this project suggest that Mt. Simon aquifer groundwater use in the study area, for the most recent period (2009), may be more than the replacement rate along the Mt. Simon subcrop. Continued monitoring of the observation wells in this region should help determine if more water is used than is being replaced by recharge.

A major accomplishment of this project is the creation of a network of observation well nests along the western margin of this aquifer system. Long term water level data and geochemistry from these wells will enable future hydrologists to evaluate the local and regional effects of Mt. Simon groundwater pumping in the region.

6 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Introduction and Purpose

The 2008 and 2009 legislatures allocated funding from the Environment and Natural Resources Trust Fund for an aquifer investigation, mapping, and monitoring project in south-central and east-central Minnesota (Figure 1). The 2008/2009 allocations provide $4,295,000 for a 4-year project. The allocation is being shared by the Department of Natural Resources (DNR, $2,769,000) and the Minnesota Geological Survey (MGS, $1,526,000) to evaluate the Mt. Simon aquifer and produce geologic atlases. The purpose of this report is to compile, summarize, and interpret data collected from the first phase of the DNR portion of this project as required by the statute (ML 2008, Chap. 367, Sec. 2, Subd. 4 (h)). A report summarizing the sec- ond phase of the project west and northwest of the Twin Cities Metropolitan area is scheduled for comple- tion June 30, 2012.

The deepest bedrock aquifer of south central/southeastern Minnesota, including the Minneapolis/St. Paul metro area, is the thick (50 to 200 feet) Cambrian sandstone Mt. Simon aquifer. It supplies all or some of the water used by over one million Minnesotans. The few water level measurements available from this aquifer in the Mankato and Minneapolis/St. Paul metro area indicate declining water levels in some parts of these areas where water is being withdrawn for municipal and commercial use. While efforts currently are underway through other agency and additional Minnesota Department of Natural Resources projects to locally map and understand these depressed Mt. Simon water level areas, we believed a project to regionally understand the recharge dynamics of the Mt. Simon aquifer was needed. The western and northern edge of the Mt. Simon aquifer (Figure 1), where it is not overlain by relatively impermeable Paleozoic shale formations, was considered the most likely area for aquifer recharge. This edge of the Mt. Simon aquifer also was investigated and characterized through observation well installations, water level monitoring, groundwater chemical analysis, and aquifer capacity testing to help determine recharge pathways and sustainable limits for this aquifer. These data will help determine aquifer recharge characteristics and potential limita- tions for future use.

Most data collected for this study are derived from well nests (two or more observation wells completed at the same location but at different depths) installed at 14 locations by contracted drilling companies. A total of 13 Mt. Simon Sandstone wells and 15 wells in other geologic units were drilled; one Mt. Simon sandstone well was sealed following drilling. Staff from the DNR Ecological and Water Resource Division coordinated the installation of these wells, which are known among groundwater professionals as observation wells. Drilling in the northern portion of the investigation area (Phase 2) began in the fall of 2009 to complete well nests at an additional 10 locations. The wells are completed in the Mt. Simon aquifer and shallower aquifers on public property in the project area to depths of 70 feet to 718 feet (Table 1). The wells were sampled for chemical constituents such as tritium and carbon-14 that will help determine the residence time or age of the groundwater in this aquifer and overlying aquifers. The wells were also instru- mented with equipment to continuously record groundwater levels.

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 7 Geology of South-Central Minnesota

The focus of this investigation was the Cambrian Mt. Simon Sandstone (Figure 2) which is located at the base of a thick sequence of marine Paleozoic carbonate, shale, and sandstone formations that underlie central and southeastern Minnesota in a broad structural basin known as the Hollandale embayment (Figure 3). The Mt. Simon Sandstone is generally a medium to coarse-grained quartzose sandstone (Mossler, 2008). The Mt. Simon formation cuttings observed from drill holes for this project generally indicated the unit is dominated by thick beds of gray and white silty, very fine to medium-grained quartzose to feldspathic sandstones with thin white-grey and light green shale beds. The basal portion of the Mt. Simon Sandstone has somewhat thicker shale beds and coarse yellowish quartz grains ranging from very coarse sand to medium pebble size.

Various Precambrian rocks underlie the Mt. Simon Sandstone due to a complicated geologic history prior to the deposition of the Paleozoic rocks. These older underlying rocks include Middle Protero- zoic sedimentary rocks, such as the Hinckley Sandstone and the Fond du Lac Formation, Early Pro- terozoic igneous and metamorphic rocks, and in some southern areas, the Lower Proterozoic Sioux Quartzite. None of these underlying rocks have desirable aquifer properties for most purposes. There- fore, the Mt. Simon Sandstone is the deepest bedrock aquifer in the region. Furthermore, along the western edge of the Hollandale embayment (Figure 3), the Mt. Simon aquifer is commonly the only aquifer available for large capacity (i.e., municipal and industrial) use.

Following the deposition of sand and other sediments that would become the Mt. Simon Sandstone and overlying formations, there was a long period of exposure and non-deposition of rock materials. During the Late Cretaceous period marine and non-marine sedimentary rocks (mostly shale and sandstone) were deposited along the western edge of the Hollandale embayment in south-central Min- nesota. During this period a shallow epicontinental (inland) sea covered the western interior of North America. Relatively thick sections of these types are rocks are common in the southern portion of the investigation area.

Following another long period of exposure and non-deposition of rock materials after the Cretaceous period, the region was affected by repeated continental glaciations during the Quaternary period. These glaciations deposited thick alternating layers of glacial outwash (sand and gravel), glacial till (dense mixture of silt, sand, and clay), and other types of deposits. Thus the depositional history for most of southeastern and south-central Minnesota has left a legacy of both bedrock and glacial aquifer systems.

8 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Investigation Methods

Site Selection The wells for this investigation were drilled on public land to help ensure the longevity of these monitoring locations. With the exception of one location, all the wells are on state land managed by the Department of Natural Resources, on either wildlife management areas (WMAs) or at water access (WA) locations. One well site in Sibley County is owned by the county. At that location special access permission for that location was obtained from the County Board of Commissioners.

Site locations were chosen in suspected recharge areas for the Mt. Simon aquifer near the western edge of the Hollandale embayment at location where the Mt. Simon Sandstone was likely to be the uppermost bedrock to be found beneath the surficial glacial deposits or Cretaceous shale and sandstone. A shallow and deep well were drilled at most locations to provide data on the vertical hydraulic head gradients, changes in groundwater chemistry, and residence time with depth. These sites were spaced as evenly as possible across the recharge area given the existing distribution of public land in the region. The well nest locations are typically near existing roads and parking lots for easy access and to minimize disturbance of undeveloped parts of these properties.

Drilling Methods and Well Construction Two different kinds of drilling methods were used to install wells for this project (Table 1). Mud rotary (MR) is a commonly used and widely available method for drilling and completing water wells. Typically a hollow tricone drilling bit is attached to hollow drilling rods that are turned by the drilling rig. During the drilling process, a drilling mud mixture is pumped through the interior of the hollow rod and bit assembly which pushes the ground rock and sediment upward through the annular space between the drilling rods and the larger diameter borehole to the surface. The drilling mud flows into an open tank at the surface and is subsequently recirculated back down the inside of the drill bit/rod assembly to the bottom of the borehole. The advantage of this method is that it is relatively fast and inexpensive. The disadvantage of this method is that the ground-up bits of rock and sediment (also known as “cuttings”) that the driller and geologist use to identify drilling progress become difficult or impossible to identify below a depth of several hundred feet because of mixing and mechanical degra- dation of the cuttings on their way to the surface.

Another type of drilling method called dual rotary/ reverse circulation (DR/RC) was used in selected areas. During DR/RC drilling, the drill cuttings are returned to surface inside the rods. Reverse circulation is achieved by pumping air down the outer tube of the rods with a large compressor. The dif- ferential pressure at the drill bit creates suction that pulls the water and cuttings up the “inner tube” which is inside the rod. Once the water and cuttings reach the surface, the cuttings move through a sample hose and are collected in a sample pail. DR/RC drilling produces discrete and easily identifi- able rock chips from all depths and is therefore ideal for drilling in unknown areas where the geologist does not know exactly what to expect at depth. DR/RC drilling is slower and more expensive than mud rotary.

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 9 Aquifer Interval Selection for Monitoring Methods for well construction were somewhat different for boreholes drilled with the two methods. For the dual rotary holes, an 8- inch or 10-inch diameter temporary steel surface casing was driven simultaneously during drilling to the base of the unconsolidated or poorly consolidated Quaternary and Cretaceous layers. Once solid bedrock was reached, the remainder of the hole was drilled without casing because the hole was unlikely to collapse. Drilling continued until Precambrian bedrock was encountered beneath the Mt. Simon Sandstone. A geophysical log of the hole was then made by geologists from the Minnesota Geological Survey at which time the depth of the permanent 4-inch diameter casing was determined based on the gamma log characteristics of the Mt. Simon Sandstone. The relatively shale-free portions of the formation were typically left as open hole. The casing was then constructed by the drilling crew and grouted in place and the temporary casing was removed. The advantage of this procedure was that the depth of the permanent casing could be chosen based on the cuttings and the geophysical log ensuring that the open-hole portion of the well was in the correct depth range such as the most transmissive portion of the Mt. Simon sandstone.

Drilling with the mud rotary method followed a different sequence. A seven-inch diameter borehole was drilled into the top of the Mt. Simon Sandstone and a four-inch steel casing was grouted in place. Once the grout had set, the drilling crew would drill inside the four-inch casing with a smaller drill bit and rod assembly until they had drilled through the Mt. Simon Sandstone into the underlying Pre- cambrian bedrock. The depth at which the Mt. Simon is encountered is estimated by reference to logs of nearby wells and careful observation of changes in the cuttings that come to the surface with the drilling mud. The main disadvantage of this method is that if the top of the Mt. Simon Sandstone is misidentified, the base of the permanent casing might not be placed at an ideal depth.

Once the deep Mt. Simon well aquifer was completed and logged with geophysical tools, the aquifer for the shallower well in the nest was chosen based on gamma log and cuttings characteristics. These shallow wells were completed in the discontinuous sand and sandstone layers of the Quaternary and Cretaceous units at a relatively wide range of depths. In general, we were seeking the shallowest aquifer that might be used for domestic or larger capacity purposes.

Geophysical Well Logging Well logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole. The geologic log is a compilation visual description and interpretations of samples brought to the surface. The geophysical well log is a record of formation physical properties with electrically powered instruments. The main geophysical log types collected for this project include passive nuclear measurements (natural gamma rays) and resistivity. After the borehole has been completed, but before the permanent casing has been grouted in the borehole, the logging tool (or probe) is lowered into the open wellbore on a wire connected to the surface. Once lowered to the bottom of the hole, measurements are taken as the probe is withdrawn from the wellbore. Measurements are recorded continuously while the probe is moving.

10 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Gamma ray logging is a method of measuring naturally occurring gamma radiation to characterize the rock or sediment in a borehole. Different types of rock emit different amounts and spectra of natural gamma radiation (Driscoll, 1986). Shale and clay usually emit more gamma rays than other sedimentary rocks, such as sandstone, or sand and gravel because radioactive potassium, uranium, and thorium are common components in their clay content. This difference in radioactivity between clay-rich and non-clay-rich formations allows the geologist to distinguish between shale and sandstone/carbonate rocks and fine or coarse grain glacial sediments with the natural gamma log.

Resistivity is a property of all materials which represents how strongly a material opposes the flow of electric current. This log is recorded in boreholes containing electrically conductive fluid (drilling mud or water). Sand and sandstone tend to be insulators (high resistivity); clay and shale tend to be conduc- tors (low resistivity). Similar to the gamma log, this difference in resistivity between shale (or clay-rich sediments) and sandstones/carbonate rocks (or non-clay-rich sediments) allows the geologist to distinguish between the two general categories of sediments or sedimentary rocks using the resistivity log.

Generalized versions of the gamma logs completed by the staff of the Minnesota Geological Survey (MGS) are shown with the lithologic logs for each of the project well nests in Appendix A. The lithologic descriptions on each of these logs are summarized from MGS interpretations of cuttings. De- tailed copies of these logs can be obtained from the MGS.

Well Development After the borehole is drilled and the permanent well casing is grouted in the well, the well is purged for one to two hours to remove sediment that may have accumulated at the base of the well. This well development procedure is designed to ensure that all or most of the open hole portion of the well is unclogged and water level measurements from the well are representative of water levels in the aquifer at that location.

Groundwater Sample Collection Protocols commonly employed for the collection of groundwater samples generally require the re- moval of much of the standing water in the borehole prior to the collection of groundwater samples. This is done so that the sample represents fresh groundwater and is representative of the resource. Removing groundwater from a well can be completed through the use of many mechanical methods; including bailers, air injection and pumping. An electric submersible well pump was selected for this project because it is capable of removing hundreds of gallons of water from depths greater than 150 feet in a relatively short period of time time in preparation for groundwater sampling. In addition, well performance testing information was collected during the same field event.Therefore, the collection of water samples was organized to complete two tasks; the collection of groundwater samples and a short duration well performance test.

To accomplish these two tasks, a submersible water well pump was temporarily installed and operated by a State-certified water well contractor. An electric generator was used to provide power to the pump and a combination of piping and flexible hose were installed to deliver the groundwater to the surface. During the course of the field sampling events two different pumps were used. The first pump had a

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 11 capacity of eight gallons per minute which proved too low to pump out the required volumes of water at an acceptable rate. This pump was replaced by a pump capable of producing pumping rates of 25 gallons per minute. Table 2 presents the basic information collected during these procedures.

Groundwater was pumped through a hose from the flow meter to a clean, white five gallon bucket that allowed field observations of color and odor. The bucket was also used as a flow through chamber into which the probes of several instruments were suspended. Sequential measurements of temperature, pH and specific conductance were made. The wells were pumped until constant values of pH, temperature and specific conductance were observed. The groundwater sample was collected after the values of these parameters remained stable and at least one well volume of water had been removed from the well.

The sampling consisted of filling prepared and labeled containers with groundwater from the hose discharge at the stabilization bucket. The carbon-14 (14C) sample size was approximately 30 gallons and required special handling and containers. Analytes and sampling protocol are summarized in Table 3. Samples were sent to the University of Minnesota Hydrochemistry Laboratory (U of M) and the Uni- versity of Waterloo Laboratory (Waterloo).

Specific Capacity Procedures and Results A specific capacity test provides an estimate of the potential yield from a water well. Specific capacity can be calculated from the results of a short duration pumping test. Specific capacity is the pumping rate (gallons per minute) divided by the measured drawdown (feet) and is reported in units of gallons per minute per foot of drawdown (gpm/ft). In Minnesota’s principal aquifers, the observed specific capacities (Minnesota DNR, 2004) range from less than 1.0 gpm/ft. to values greater than 100 gpm/ ft. Specific capacities for the Mt. Simon- Hinckley wells typically range from 1 to 33 gpm/ft; specific capacities for glacial drift wells show greater variability from less than 1 to greater than 50 gpm/ft. As shown in Table 2, the observed specific capacities for the Mt. Simon wells ranged from 13 gpm/ft at Exceder WMA to less than 1 gpm/ft at Helget-Braulick WMA.

The depths to groundwater were measured from dedicated measuring points located at the top of the well casings. For this project the measuring points elevations were measured using engineering grade global positioning systems (GPS) that use the Minnesota Department of Transportation Continuously Operating Reference Station (CORS) network. The measuring point at each well is on the north side of the top of the four-inch diameter steel well casing (top of casing or TOC). Groundwater depth measurements were collected before, during and after pumping using electronic tapes and electronic pressure transducer instruments.

A flow meter was used to measure rate and a flow totalizer was used to measure total water discharge in gallons. The flow rate from the well was controlled with the well head check valve. At the start of each pumping test the valve was opened to allow the full pumping rate. Some of the wells were pumped at rates lower than the capacity of the pump to maintain water levels above the pump intake. Graphs of changes in the water level and water temperatures over time (hydrographs) are included in Appendix B. DNR observation well 83012 and Flandrau State Park campground well were not accessible for water level instrumentation and are not represented in Appendix B with a hydrograph. These two wells were, however, sampled for groundwater chemical analysis.

12 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Continuous Water Level Measurements Unattended continuous water level measurements can be made with pressure transducers – instruments that respond to changes in pressure created by the water column above the instrument. A data logger can record the measurements taken by a pressure transducer at specific intervals set by the user. Improvements in technology over the last decade have resulted in combined data logger and pressure transducer units that are about the size of a small flashlight.

Sealed data logger/pressure transducer units were submerged in each well to a depth of 20 to 25 feet below the water surface. Sealed units record changes in total pressure including barometric pressure. To discriminate changes in pressure readings that are related to barometric pressure change from real water level changes, a record of barometric pressure must also be made. Three data logger/barometer units were deployed across the study area for this purpose. All of the instruments were programmed to collect and store hourly readings.

Data are stored in the data logger until downloaded during quarterly site visit occurs. Communication cables connected to the instruments are accessible from the top of each well. At each location, the data are downloaded from the instruments, and a water level measurement is taken with a measuring tape. Following data downloads, computer software calibrates the data stream to the actual measurements and adjusts for changes in barometric pressure.

Thickness of the Mt. Simon Sandstone Near the Western Subcrop

One of the objectives of the project was to better define the physical boundaries of the Mt. Simon Sandstone in the study area to help with future water resource evaluations. With the exception of the well at the Nicollet Bay unit, all the Mt. Simon aquifer wells drilled for this project penetrated to the base of the formation. Most existing wells in this area (Figure 4) provide a minimum thickness value since most of the wells are domestic and are only drilled into the top of the aquifer to provide relatively small quantities of water.

Across the study area thicknesses of the Mt. Simon Sandstone increase toward the east over a short distance with the exception of an apparently broad and thin (0-50 feet) area in eastern Brown county. East of the western formation edge, the Mt. Simon Sandstone is commonly 200 feet thick or greater (Mossler, 1992).

Groundwater Movement and Potentiometric Surface – Mt. Simon Aquifer

A key aspect of understanding the hydrogeology of any area is to develop a basic understanding of the groundwater flow pathways. Aquifers and systems of aquifers are rarely static or unchangeable. Water is usually moving into the aquifers (recharge), through the aquifers, and out of the aquifers (discharge) in complicated but definable patterns. Three primary types of data are used by investigators to understand these relationships: chemical data from collected samples, aquifer test data gathered by pumping wells under controlled conditions, and static (non-pumping) data measured from wells and surface water bodies. Static water-level data and potentiometric surfaces are the primary focus of this section.

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 13 A potentiometric surface is defined as “a surface that represents the level to which water will rise in a tightly cased well (Fetter, 1988). The potentiometric surface of a confined aquifer (aquifer under pressure) occurs above the top of an aquifer where an overlying confining (low-permeability) layer exists. Static (non-pumping) water-level data from the County Well Index and measurements by personnel from the Department of Natural Resources were plotted and contoured to create the potentiometric contour map (Figure 5). Additional wells in fractured Precambrian crystalline aquifers beyond the extent of the Mt. Simon aquifer are included to show the hydraulic head conditions near the boundary of the aquifer. The contour lines illustrate the potentiometric surface much like the contour lines of a topographic map represent a visual model of the ground surface. The potentiometric surface is generally not the physical top of the water table, but is a representation of the potential energy that is available to move the groundwater in a confined aquifer. Low-elevation areas on the potentiometric surface that could be above the coincident surface-water bodies may indicate discharge areas; when combined with other information sources, high-elevation areas on the potentiometric surface can be identified as important recharge areas. Groundwater moves from higher to lower potentiometric elevations perpendicular to the potentiometric elevation contours (flow directions shown as arrows).

Groundwater flow pathways from recharge areas through the aquifer to discharge locations operate on a wide continuum of depth, distance, and time. Flow into, through, and out of shallow aquifers can occur relatively quickly in days or weeks over short distances of less than a mile, whereas flow through deeper aquifers across dozens of miles may take centuries or millennia.

Figure 5 shows northeasterly groundwater flow directions toward the Minnesota River in the southern portion of the study area. In the northern portion of the study area flow is southeasterly in Sibley County and then diverges toward the Minnesota River in Nicollet County at a very low gradient. On Figure 5 and Figure 6 (cross section Z-Z’) the potentiometric contours bend toward the Minnesota River indicating that it is a discharge feature for the Mt. Simon aquifer. Even though the potentiometric contours indicate discharge to the Minnesota River, the previously mentioned low gradient in the northern portion of the study area could indicate low flow to the river.

Geochemistry

All the wells constructed for this project and two additional wells in the area were sampled for analysis of common ions, trace constituents, residence time indicators (tritium and 14C), and stable isotopes (18O and deuterium). The results of all these analyses (Tables 4 and 5) assist in the interpretation of the recharge characteristics of the Mt. Simon aquifer.

Groundwater Residence Time Two residence time indicators were used in this project: tritium and carbon-14 (14C). Residence time is the approximate time that has elapsed from when the water infiltrated the land surface to when it was pumped from the aquifer for these investigations. In general, short residence time suggests high recharge rates or short travel paths, whereas long residence time suggests low recharge rates or long travel paths.

14 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Tritium (3H) is a naturally occurring isotope of hydrogen. Concentrations of this isotope in the atmosphere were greatly increased from 1953 through 1963 by above ground detonation of hydrogen bombs (Alexander and Alexander, 1989). This isotope decays at a known rate, with a half-life of 12.43 years. Groundwater samples with concentrations of tritium equal to or greater than 10 tritium units (TU) are considered recent water (mostly recharged in the past 60 years). Concentrations equal to or less than 1 TU are considered vintage water (recharged prior to 1953). Concentrations between these two limits are considered a mixture of recent and vintage water and are referred to as mixed water.

The carbon-14 (14C) isotope, which also occurs naturally, has a much longer half-life than tritium (5730 years). Carbon-14 is used to estimate groundwater residence in a time span from about 100 years to 40,000 years (Alexander and Alexander, 1989).

With one exception, none of the groundwater samples contained detectable tritium concentrations (Table 4) and therefore, the residence time for these samples is greater than approximately 60 years. This is consistent with the generally greater depths of the sampled aquifers and general lack of thick surficial sand and gravel in the study area. The one mixed tritium sample was from the shallow well at the Long Lake WA that was screened in a sand and gravel aquifer at a depth of 128 feet.

Figure 7 shows the distribution of 14C residence time values from the shallow wells constructed for this project. These values represent data from aquifers with a wide depth range (70 to 444 feet). This map, therefore, is not intended to show any regional trends or tendencies but is shown to illustrate the wide range of values in these settings. These values are more interesting in comparison to the values discussed below and shown in Figure 8 from the underlying Mt. Simon aquifer.

Figure 8 shows the distribution of 14C residence time values from the Mt. Simon aquifer wells constructed for this project, two additional Mt. Simon aquifer wells sampled for this project, and Mt. Simon aquifer data from other studies (Lively and others, 1992; Alexander, personal communication). Values in the southern portion of the study area range from 7,000–8,000 years in central Watonwan County to 30,000 years near the Minnesota River following a pattern of increasing age away from central Waton- wan County. The youngest values (8,000–10,000 years) in the northern portion of the study area occur in northeastern Sibley County and also increase in age toward the Minnesota River to the south and east.

The younger 14C residence time values (7,000–8,000 years) roughly correspond to a time not only after the last ice sheet had receded from southern Minnesota, but also after the time when the modern day Minnesota River Valley (Glacial River Warren) ceased to be the main discharge route for the glacial melt water (9,500 years) that was stored in Glacial Lake Agassiz (Wright, 1987). These 14C values and the unique glacial history of the region suggest groundwater in the Mt. Simon aquifer in this region began as precipitation that infiltrated during the post-glacial period. The stable isotope data described in the following section provided important corroborating evidence for this conclusion.

Stable Isotopes, 18O and Deuterium All groundwater samples collected from the study area were analyzed for stable isotopes of oxygen and hydrogen, the two atoms found in water. Analysis of the results provides an additional tool for character- izing the area groundwater. Isotopes of a particular element have the same number of protons but different numbers of neutrons. Stable isotopes are not involved in any natural radioactive decay. They are used to understand water sources or the processes affecting them (Kendall, 2003). Commonly used isotopes

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 15 for these purposes include oxygen isotopes 16O and 18O and hydrogen isotopes 1H and 2H. The heavy hydrogen (2H) is called deuterium. The mass differences between 16O and 18O or 1H and 2H result in water molecules that evaporate or condense at different rates. Thus the concentrations of these isotopes in water changes (fractionates) during evaporation and precipitation, resulting in different 16O/18O and 1H/2H ratios in rain, snow, rivers, and lakes. The values are expressed as del2H and del18O. The ab- breviation “del” denotes the relative difference from standard mean ocean water and express the relative abundance or the rarer heavy isotopes, del2H and del18O. These values from precipitation water generally plot close to a straight line known as the meteoric water line (Figure 9). The departure of 18O and 2H values from the meteoric water line can indicate evaporation or mixing of water from different sources.

Figure 9 shows a plot of del18O and del2H values from groundwater samples collected in the study area compared to the meteoric water line. Three types of information regarding the origin and history of these water samples can be interpreted from this graph: relative atmospheric temperature during source water precipitation, relative mixing of water from cold and warm sources, and evaporation of source water.

Source Water Temperature and Mixing For the samples that plot along the same slope as the meteoric water line, the samples more depleted in heavy isotopes (samples that plot closer to the bottom left of the graph) suggest water that precipitated from a colder atmosphere (Siegel, 1989). Person et al (2007) provided a compilation of paleohydrologi- cal studies of groundwater systems in North America that were affected by the advance and retreat of the Laurentide ice sheet. He concluded that the range of del18O groundwater values from cold ice or snow melt sources ranges from del -25 to -9. Most values of groundwater samples from south central Minnesota ranged from approximately del -8 to del -10 suggesting a mixture of glacial meltwater and a larger component of post-glacial precipitation. The data are consistent with the younger 14C ages dates (7,000 to 8,000 years) from the post-glacial and post River Warren era as discussed previously.

It is also significant to note that many of the older14 C values in this area are in the range of the last glacial advance in the upper Midwest (12,000 to 24,000 years BP) but the del18O values are just slightly within the range of water from ice melt sources (del-25 to del-9). This apparent discrepancy suggests that these waters are from mixed sources and time periods, indicating a combination of much younger and much older water. Recognizing that all groundwater is a mixture, Mt. Simon 14C residence time values greater than 9,000 or 10,000 years may represent a minimum age in these areas.

Fractionation of Source Water and Evaporative Signatures Deuterium (2H) is an isotope of hydrogen consisting of a proton and a neutron, whereas hydrogen (1H) consists of a proton. Deuterium, therefore, has approximately twice the mass of common hydrogen. Similarly, oxygen-18 (18O) has more mass than the more common oxygen-16 (16O). Fractionation occurs because of these mass differences. Molecules of water with the more common hydrogen and oxygen are lighter and more readily evaporated, leaving the remaining water more concentrated in the heavier isotopes. As a result, lake water typically shows an evaporative signature (a higher concentration of the heavier isotopes than precipitation). Water that directly infiltrates the ground is not fraction- ated in this manner, so it has a meteoric signature (higher concentration of the lighter, more prevalent isotopes). The effect of this type of fractionation is that isotopic values from samples with an evaporative signature will plot along a line with a slope less than the slope of the meteoric water line.

16 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer On Figure 9 the evaporated types of samples are shown on the right upper portion of the graph (Peter- son unit, Helget Braulick WMA, and the Nicollet Bay unit). These three samples, from buried sand and gravel aquifers, show evidence of water that infiltrated from lakes or wetlands.

The majority of samples plotted in the center portion of the graph along the meteoric water line (Figure 9) suggest sources from post ice-age precipitation (normal rain and snow meltwater) that infiltrated directly into the subsurface and did not reside for long periods in lakes or similar water bodies.

Major Ions Some evidence of distinct source water types and mixing of these waters can be understood by considering the relative abundances of some common cations and anions as ion concentrations plotted as percentages from area groundwater samples. Figure 10 shows the relative abundances of these common ions plotted on a ternary plot. Table 5 also shows the concentrations of these constituents in mg/l. The most common type of water in this area has Ca and Mg (Ca+Mg) as the predominant cation. There is a fairly even distribution between waters containing bicarbonate as the primary anion and waters containing sulfate as the predominant anion. The bicarbonate type of water is common in glacial aquifers of the upper Midwest (Freeze and Cherry, 1979, p. 284) and is derived from dissolution of calcite and dolomite minerals in soil and glacial sediments by infiltrating precipitation. Higher sulfate concentrations in the Mt. Simon aquifer tend to occur in the southern and western portions of the study area (Fig- ure 11) where infiltrating water has passed through Cretaceous sandstone and shale layers that contain sulfate minerals such as gypsum and anhydrite.

The data from a few samples plotted on the lower right corner of the cation ternary plot show that some Na/K waters are also present in the area. These Na/K type waters (Mt. Simon aquifer: Norwegian Grove and Flandreau; Sioux Quartzite: Courtland West) may have a partial deep bedrock origin. Other evidence of deep isolated groundwater or upwelling from deep crystalline bedrock sources is suggested by some elevated chloride values of samples collected near the Minnesota River Valley (Figure 12). El- evated chloride values at the Helget Braulick and Peterson unit sites should be dismissed since samples from these wells probably contain some chloride from the chloride disinfectant that was added to these wells during the well construction process.

Trace Elements Analysis of groundwater samples for a suite of trace element constituents reveal exceedences of drinking water standards for boron (one sample) and arsenic (five samples). A boron concentration of 1,910 ug/l (ppb) was measured in water from the Lake Hanska well that was completed in a Cretaceous sandstone aquifer. The Minnesota Department of Health (MDH) health risk limit (HRL) for this element is 600 ug/l. This elevated value is not typical of concentrations measured in the rest of the samples which otherwise ranged from 74 to 497 ug/l (Table 4). The reason for the elevated concentration of boron is unknown; however, the most negative 18O value (del -10.27) of all the samples collected in the study area was also detected in the sample from this well which suggests that this aquifer is relatively stag- nant and isolated.

Arsenic concentrations that exceeded the federal drinking water standard of 10 ug/l were detected in samples collected from five wells, three from buried sand and gravel aquifers and two from the Mt. Simon aquifer (Table 4 and Figure 13). Two of the exceedences (Nicollet Bay unit and Helget-Braulick WMA) from buried sand and gravel aquifers also contained water from sources with an evaporative

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 17 surface water signature (discussed in the fractionation of source water section). Arsenic in groundwater tends to come from disseminated mineral sources in glacial till (MDH, 2001; Erickson and Barnes, 2005). Arsenic can be released from these minerals into solution by oxygenated water. Infiltrated lake water could be a possible source of oxygenated water resulting in the elevated arsenic concentrations found in these samples.

Two of the elevated arsenic samples were collected from the Mt. Simon aquifer wells at the Peterson unit and the Nicollet Bay unit. Both of these wells are near Swan Lake in Nicollet County, the apparent source of water with an evaporative signature sampled at the shallow Nicollet Bay unit well. Elevated arsenic values in the Mt. Simon aquifer may be also due to mobilization of arsenic by oxygenated lake water that has infiltrated through multiple interconnected layers of glacial sand and till.

Hydrogeology Illustrated by Cross Sections and Hydrographs from Observation Well Nests

A set of 12 geologic cross sections were created for this report to provide location-specific represen- tations of the stratigraphy and geologic structure for each well nest and to provide a hydrogeologic context for the hydrograph and geochemical data. The cross sections were constructed by projecting lithologic, stratigraphic, and well construction information onto the line of each cross section (Figure 3) from within a one kilometer zone on either side of the cross section.

Water level data were plotted to create hydrographs illustrating water elevation changes over time. Hydrographs provide a method of representing large amounts of data from one or more wells. The water elevation hydrographs are provided for each corresponding cross section. Each hydrograph dis- plays the water levels recorded in two wells nested at the same site, the Mt. Simon aquifer well (blue) and the shallower depth well (red). Nested wells are located at the same site within a few feet of each other. On several hydrographs the difference in water elevation is large enough to require the use of a secondary axis. The shallower well information is set on the secondary axis and the corresponding units are indicated on the right side of the hydrograph.

Seasonal high and low water level cycles are apparent on most hydrographs. These are yearly cycles where groundwater levels decline during the summer months and increase during the winter and spring. In many cases both nested wells follow similar trends. Average cumulative precipitation increased throughout the period of record for the water level data (Figure 14). A corresponding rise of water levels throughout 2010 is apparent from the hydrographs at several sites and is consistent with the cumulative increases in rainfall for the region compared to normal. Considering the relatively long residence times typical of most aquifers that were sampled for this study most of these water level fluctuations are not caused by rapid infiltration of precipitation (recharge) but a pressure response to the increased volume and weight of additional groundwater in the overlying water table aquifer and shallow buried aquifers (Maliva et al, 2011).

18 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer The hydrograph data of the nested observation wells, shown on Figures 15b through 26b, show two general patterns of vertical gradients: downward and upward. Most of the hydrograph comparisons show a downward gradient. A downward gradient exists where the groundwater elevation in the shallower well is higher than the groundwater elevation in the deeper well. This condition indicates that groundwater will move downward, if a flow pathway is available. Within this group of downward gradient hydrograph pairs most of the hydrographs follow identical although offset patterns (Sibley County Landfill, Peterson Unit, Bergdahl WMA, Case WMA, Madelia WMA, Exceder WMA, and Rooney Run WMA). These identical patterns strongly suggest that fluctuations within both the shallow and Mt. Simon aquifer well pairs are due to pressure effects of changes in the overlying water weight of the water table aquifer. A smaller group of downward gradient nests (Severance Lake WMA, Nicol- let Bay Unit, and Helget Braulick WMA) show shallow aquifer hydrograph patterns that are different from the Mt. Simon aquifer hydrograph pattern suggesting local pumping or surficial influences in the shallow aquifer.

The Courtland West Unit (Figure 19b), Long Lake WA (Figure 24b), and possibly Norwegian Grove WMA (Figure 17b) sites demonstrate locations where upward groundwater movement is apparently occurring. At these locations the groundwater elevation from the shallower well is lower than the deeper bedrock groundwater elevations indicating an upward gradient condition. An upward gradient suggests that groundwater from the deeper bedrock will move upward if a flow pathway is available. Upward gradient maybe due to local pumping influences or proximity to major discharge zones such as the Minnesota River.

Cross Section A-A’ and Severence Lake WMA Hydrograph (Figures 15a and b) The Severence Lake WMA is located in northern Sibley County near the subcrop (eastern edge) of the Mt. Simon Sandstone. The shallow well was completed in a buried sand and gravel aquifer that appears to be part of a stack of interspersed and hydraulically connected sand bodies. The hydrograph from this well shows several feet of variation throughout 2010 with low water levels occurring during summer and early fall (high water use period). Water levels recovered beginning late fall and continued through early spring. A similar but more muted pattern is apparent for the Mt. Simon aquifer, suggesting no connection or a very minor connection to the summer pumping that is occurring in the area.

Cross Section B-B’ and Sibley County Landfill Property (Figures 16a and b) The well nest on the Sibley County landfill property in central Sibley County is located near the City of Gaylord. The Gaylord city wells and some domestic wells completed in the same buried sand aquifer as the shallow well are shown northwest of the well nest. The stratigraphy and geochemistry shown on Cross section B-B’ (Figure 16a) suggest a direct hydraulic connection between the buried sand and gravel aquifer in which the shallow well is completed and the Mt. Simon aquifer. The well nest hydrographs (Figure 16b) show a downward gradient from the buried sand and gravel aquifer. The area stratigraphy, long residence times, and identical water level hydrograph trends suggest that the water level fluctuations are a pressure response to changes in the weight of water in the overlying water table aquifer.

Cross Section C-C’ and Norwegian Grove WMA Hydrograph (Figures 17a and b) The Norwegian Grove WMA well nest in northern Nicollet County is located at the eastern edge of the Mt. Simon subcrop. The cross section (Figure 17a) shows the shallow well is completed in a stack of interspersed, and hydraulically connected sand bodies and a nearly direct connection of these buried

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 19 sand aquifers to the underlying Mt. Simon aquifer. The hydrographs (Figure 17b) shows a very slight upward gradient from the Mt. Simon to the buried sand and gravel aquifer. The hydraulic connection between the two aquifers, however, may not be very extensive since there is a large difference in groundwater residence time (4,000 years in the shallow aquifer versus 20,000 years in the Mt. Simon aquifer) and aquifer chloride/sodium concentrations.

Cross Section D-D’ and Peterson Unit Hydrograph (Figures 18a and b) The Peterson Unit well nest in central Nicollet County is located near the eastern edge of the Mt. Simon Sandstone subcrop. The aquifer hydrographs (Figure 18a) shows very little fluctuation in water levels (approximately one foot). The buried sand aquifer water levels are about eight feet higher than those of the Mt. Simon aquifer. These water level data and the 14C residence time of 22,000 year of the Mt. Simon aquifer suggest that these aquifers are not directly connected and are both relatively isolated.

Cross Section E-E’ and Courtland West/Nicollet Bay unit hydrographs (Figures 19a, b and c) The geologic setting of two well nests (Courtland West unit and Nicollet Bay unit) in south central Nicollet County and an existing well that was sampled (Flandreau State Park) in eastern Brown County, is shown on this cross section. An upward gradient exists at the Courtland West site, east of the Minnesota River, which may result in upward groundwater flow direction due to the proximity of the river. Upward gradients are commonly found near major rivers where groundwater discharges to the al- luvial aquifer from underlying aquifers locally. West of the Minnesota River a similar upward gradient is suggested by a 14C residence time of 30,000 years and high sodium-chloride concentrations (Table 5 and Figure 12). These chemical characteristics suggest old, isolated groundwater from the underlying crystalline bedrock is moving upward through the thin Mt. Simon aquifer to the base of the Minnesota River alluvium.

At the Nicollet Bay unit location at the east side of the cross section the shallow well is shown completed in a stacked complex of buried sand and gravel aquifers. The graph of stable isotope values (Figure 9) shows that the sample from this well contains some water that had an evaporative signature from a surface water source. The detectable tritium concentration from this sample is also good evidence of focused recharge at this location. The relatively constant water level elevation shown in the hydrograph from this well (Figure 19c) and these chemical characteristics suggest a strong hydraulic connection to a stable surface water source such as Swan Lake. The hydrograph of the Mt. Simon aquifer well at this location appears to show some influence from local pumping possibly from the wells shown on the cross section west of the Nicollet Bay well nest.

Cross Section F-F’ and Helget-Braulick WMA hydrograph (Figures 20a and b) The Helget-Braulick WMA well nest is located in central Brown County near the western edge of the Mt. Simon Sandstone subcrop. The shallow well, completed in a buried sand and gravel aquifer, contained some groundwater tht had an evaporative signature from a surface water source (Figure 9). A very short 14C residence value (500 years) is consistent with this stable isotope data. In addition, the shallow well hydrograph trend follows the precipitation trend of higher than average rainfall during the summer of 2010, also suggesting a hydraulic connection and pressure response to the additional water at or near the surface. The muted but similar hydrograph pattern of the Mt. Simon aquifer well hydrograph is probably a pressure response.

20 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Cross Section G-G’ and Bergdahl WMA hydrograph (Figure 21a and b) The Bergdahl WMA well nest of northeastern Watonwan County and a shallower well completed in Cretaceous sandstone at the SE Lake Hanska WA are shown on this cross section. The deeper well that was planned for the Lake Hanska site was not built since no Mt. Simon Sandstone was found at this site during drilling. Both hydrographs in the Bergdahl WMA well nest show for 2010 a rising pressure response corresponding to a cumulative increase in precipitation in the area.

Cross Section H-H’ and Case WMA hydrograph (Figures 22a and b) The Case WMA well nest located in eastern Watonwan County and an irrigation well that was sampled for this project are shown on this cross section. Some of the youngest Mt. Simon aquifer groundwater in the area was collected from the irrigation well which is located at the eastern edge of the Mt. Simon Sandstone subcrop. The 14C residence time of 7,000 years from this well is actually younger than groundwater that was sampled from the shallower buried sand and gravel aquifer at the Case WMA well nest. This irrigation well sample also contained elevated concentrations of sulfate indicating migration through the overlying sulfate mineral rich Cretaceous sandstone and shale. Both hydrographs at the Case WMA well nest show an approximate 4.5 foot pressure response rise in water levels throughout 2010 which corresponds to a cumulative increase in precipitation in the area.

Cross Section I-I’ and Madelia WMA hydrograph (Figures 23a and b) The Madelia WMA well nest located in eastern Watonwan County is shown on the eastern side of this cross section. The Mt. Simon aquifer sample from this location also had one of the youngest 14C residence time values, suggesting a closer proximity to the eastern edge of the Mt. Simon sandstone subcrop than is suggested by this cross section or Figure 4. Both hydrographs at the Madelia WMA well nest show an approximate 4.5 foot pressure response rise in water levels throughout 2010 corresponding to a cumulative increase in precipitation in the area.

Cross Section J-J’ and Long Lake WA hydrograph (Figures 24a and b) The Long Lake WA well nest located in south central Watonwan County is shown on the western side of this cross section possibly near the center of the Mt. Simon Sandstone subcrop. Similar to the sites described on cross sections H-H’ and I-I’, the 14C residence time value of the Mt. Simon aquifer at this location is among the youngest (8,000 years). Elevated sulfate concentrations indicate groundwater migration through the overlying Cretaceous sandstone and shale.

The shallow well was completed in a buried sand and gravel aquifer just above the Cretaceous sandstone and shale. The gradient between the shallow aquifer and the Mt. Simon aquifer is upward (lower hydraulic head in the shallow aquifer compared to the deeper aquifer) possibly due to intensive pumping of the shallow buried aquifers from domestic wells surrounding Long Lake. The approximate 1.5 to 2.5 foot rise of water levels in both wells throughout 2010 corresponds to a cumulative increase in precipitation in the area.

Cross Section K-K’ and Exceder WMA hydrograph (Figures 25a and b) The Exceder WMA well nest, located in north central Martin County, is shown near the center of this cross section. The approximate two-foot pressure response rise of water levels in both wells throughout 2010 corresponds to a cumulative increase in precipitation in the area.

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 21 Cross Section L-L’ and Rooney Run WMA hydrograph (Figures 26a and b) The bedrock geology of the Rooney Run area is relatively unknown. The top of the Mt. Simon Sand- stone at the DNR observation well site was deeper than the top of the Mt. Simon Sandstone at wells drilled in the Welcome area (Figure 26a). Therefore, a fault is shown on cross section L-L’ northwest of Welcome to account for this elevation difference. Southwick (2002) also shows a fault in this area described as an “Inferred fault, mapped beneath the Sioux Quartzite or Paleozoic strata.” The hydrographs of the buried sand and gravel and Mt. Simon wells show very little fluctuation during 2010 and are difficult to interpret without a longer period of record.

Paleohydrology and Recharge Estimates

Data and interpretations generated by this project provide some basis for a general estimate of groundwater recharge through overlying glacial sediments and Cretaceous formations to the Mt. Simon Sand- stone subcrop in south central Minnesota. In addition to improving understanding of the aquifer boundaries, thickness, permeability, and extent of overlying confining units, basic data have been generated regarding the residence time of groundwater in the Mt. Simon aquifer and its source water characteristics.

The 7,000-8,000 year residence time of Mt. Simon aquifer groundwater in the region (see Figure 27, Watonwan County and adjoining areas and northern Sibley County near the City of Arlington) and development of post-glacial drainage conditions in the Minnesota River Valley at approximately 9,000 years BP (before present) suggests the current flow conditions toward the valley and slow recharge of the aquifer began at approximately that time. Prior to that time the much larger volume of water flowing through the valley as glacial River Warren would have created higher head conditions in that area and a lower gradient that would have inhibited flow toward the valley in the Mt. Simon and overlying aquifers. Siegel (1989) suggests that flow in the Mt. Simon aquifer during the glacial maximum (16,000-14,000 years BP) was easterly toward the ancestral Mississippi River.

A conceptual model of recharge to the Mt. Simon subcrop is based on geochemical data shown on the generalized cross section Z-Z’ (Figure 28) which extends from the Long Lake WA site in southwestern Watonwan County to the North Star WMA observation well in the Minnesota River Valley. This cross section is drawn perpendicular to the potentiometric contours of the Mt. Simon aquifer (Figure 8) and is meant to represent a flow path from the recharge areas southwest of the Minnesota River to the Min- nesota discharge area.

On cross section Z-Z’ 14C residence times are younger in areas to the southwest in the Mt. Simon aquifer and overlying aquifers. Higher sulfate concentrations in the Mt. Simon aquifer in the southwest indicate downward groundwater flow through the overlying Cretaceous formations. Slightly higher chloride concentrations have been detected in wells closer to the discharge area suggesting some upward migration of older water from Precambrian crystalline bedrock. Finally, the least negative (warmer) del 18O values are found in Mt. Simon wells on the left portion (upgradient) of the cross section and in the shallower wells, whereas the more negative del 18O values (colder) were found in wells on the right (downgradient) portion of the cross section.

22 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Southern Area Recharge A conceptual recharge model based on this information is shown in Figure 29. The groundwater residence times of most of the Mt. Simon wells are assumed to be an average value of age-stratified water in the well. Actual values from discrete intervals within the wells might vary from top to bottom. There- fore, an assumed 5,000 year value contour was placed near the top of the Mt. Simon aquifer for the wells in the “post-glacial recharge” area. The depth to the top of this contour in this area ranges from approximately 350 to 450 feet. Assuming an average depth of 400 feet (12,192 cm), an average porosity of the material overlying the Mt. Simon at 20 %, the amount of recharge moving downward to the top of the Mt. Simon aquifer would be approximately 0.49 cm/year. The area labeled “post-glacial recharge” (Figure 27) is approximately 960 square km. The volume of recharge across this area would be approximately 4.7 million cubic meters/year or about 1.2 billion gallons/year.

Northern Area Recharge A similar recharge estimate of the Mt. Simon aquifer for the eastern portions of Nicollet and Sibley Counties (area north and west of the Minnesota River) is more difficult since only a small portion of the area west of the City of Arlington and the Severance Lake WMA is shown as post-glacial recharge (Figure 27). In most of this area 14C residence time values are approximately three times older than the youngest values southwest of the Minnesota River. In general, groundwater recharge of the Mt. Simon in the northern portion of this region (north and west of the Minnesota River) is probably lower than in the southern part of this region (south of the Minnesota River).

2009 Groundwater Appropriation

Southern Area Appropriation For this appropriation discussion the southern area is defined as a triangular area that extends from the southernmost well nest (Rooney Run WMA) to Mankato and along the Minnesota River to New Ulm (Figure 30). Mt. Simon aquifer groundwater in the southern area is currently used by permitted (large capacity) municipal wells, agricultural processing wells, and irrigation wells (DNR web page). The DNR 2009 reported use data indicate approximately 2.2 billion gallons were pumped out of the Mt. Simon aquifer in this area. However, the actual volume pumped from just the Mt. Simon aquifer is less since some of the older municipal wells in the area are also open to overlying aquifers. The Mt. Simon aquifer annual pumped volume, therefore, may be more than the recharge described in the previous section. Permitted volumes (volume of water that the users are allowed to pump) for appropriators in this area are approximately 4.7 billion gallons per year.

Northern Area Appropriation The northern area is defined as the eastern parts of Nicollet and Sibley Counties. Mt. Simon groundwater in the northern area is currently used by permitted (large capacity) municipal wells, agricultural processing wells, and crop irrigation wells, and golf course irrigation wells (DNR web page). The DNR 2009 reported use data indicate approximately 1.1 billion gallons were pumped out of the Mt. Simon aquifer in this area. As in the southern area, the actual volume pumped from just the Mt. Simon aquifer is less since some of the older municipal wells in the area are also open to overlying aquifers. Permitted volumes for appropriators in this area are approximately 1.9 billion gallons per year.

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 23 Conclusions

The results of this project suggest that Mt. Simon aquifer groundwater use in the study area, for the most recent period (2009), may be more than the replacement rate along the Mt. Simon Sandstone subcrop. Continued monitoring of the observation wells in this region should help determine if more water is being used compared to recharge. A major accomplishment of this project is the creation of a network of observation well nests along the western margin of the Mt. Simon Sandstone that is considered an important recharge area for the aquifer. Long term water level and geochemistry data from these wells will enable future hydrologists to evaluate the local and regional effects of Mt. Simon aquifer groundwater pumping in the region. In addition, this project demonstrated the value of continuous, nested water level measurements, groundwater chemistry, and residence time data in constructing conceptual models of groundwater flow and recharge.

24 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer References

Alexander, S.C., and Alexander, E.C., Jr., 1989, Residence times of Minnesota groundwaters: Minnesota Academy of Sciences Journal, v. 55, no.1, p. 48-52.

Alexander, S.C., personal communication, e-mail correspondence received May 26, 2009 containing 14C and general chemistry information from wells in southeastern Minnesota.

Anderson, Julia R, 2010, Bedrock geology, Plate 2 of Geologic Atlas in Blue Earth County, Minnesota: Minnesota Geological Survey County Geologic Atlas C-26 (in progress), scale 1:100,000.

Chandler, Val. W. and Mossler, John H., 2009, Bedrock Geology, Plate 2 of Geologic Atlas in Mcleod County, Minnesota: Minnesota Geological Survey County Geologic Atlas Geologic Atlas of McLeod County, C-20, 6 pls., scale 1:100,000.

Driscoll, Fletcher G., 1986, Groundwater and wells (2d ed.): St. Paul, Minnesota, Johnson Screens, 1089 p.

Erickson, M.L., and Barnes, R.J., 2005, Glacial sediment causing regional-scale elevated arsenic in drinking water: Ground Water, November-December, v. 43, no. 6, p. 796–805.

Fetter, C.W., 1988, Applied hydrogeology (2d ed.): Columbus, Ohio, Merrill, 592 p.

Freeze, R. Allan, and Cherry, John A., 1979, Groundwater, Englewood Cliffs, NJ, Prentice Hall, Inc., 604 p.

Jirsa, Mark A. and others, 2011, Geologic Map of Minnesota Bedrock Geology, Minnesota Geological Survey State Map Series S-21, scale 1:500,000.

Kendall, C. and Doctor, D., 2003, Stable isotope applications in Hydrologic studies, Holland, H.D. and Turekian, K.K., editors, chap. 11 of v. 5, Surface and ground water, weathering, and soils, in Treatise on geochemistry: Amsterdam, The Netherlands, Elsevier, Inc., p. 319-364.

Lively, Richard S. et al, 1992, Radium in the Mt. Simon-Hinckley aquifer, east-central and southeastern Minnesota, Information Circular 36, Minnesota Geological Survey, 58 p.

Maliva, Robert G. et al, 2011, Confined aquifer loading: Implications for groundwater management, Groundwater, May-June 2011, vol. 49, No. 3, p. 302-304.

Minnesota Department of Health, 2001, Minnesota arsenic study (MARS): St. Paul, Minnesota Department of Health, 3 p.

Minnesota Department of Natural Resources, 2004, Selected aquifer parameters for groundwater provinces – Groundwater Provinces web page, accessed at < http://www.dnr.state.mn.us/groundwater/ provinces/data.html>.

Minnesota Department of Natural Resources, Water use – Water Appropriations Permit Program web page, accessed at .

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 25 Mossler, J.H., 1992, Sedimentary rocks of Dresbachian age (Late Cambrian), Hollandale embayment, southeastern Minnesota: Minnesota Geological Survey Report of Investigations 40, 71 p.

Mossler, J.H., 2008, Paleozoic stratigraphic nomenclature for Minnesota: Minnesota Geological Survey Report of Investigations 65, 76 p., 1 pl.

Mossler, J.H., and V.W. Chandler, 2009, Bedrock geology, Plate 2 in Geologic Atlas of Carver County, Minnesota: Minnesota Geological Survey County Atlas C-21, 5 pls., scale 1:100,000.

Mossler, J.H., and V.W. Chandler, 2010, Bedrock geology, Plate 2 in Geologic Atlas of Sibley County, Minnesota: Minnesota Geological Survey County Geologic Atlas C-24 (in progress).

Mossler, J.H., and V.W. Chandler, 2010, Bedrock geology, Plate 2 in Geologic Atlas of Nicollet County, Minnesota: Minnesota Geological Survey County Geologic Atlas C-25 (in progress).

Person, M., J. McIntosh, V. Bense, and V. H. Remenda, 2007, Pleistocene hydrology of North America: The role of ice sheets in reorganizing groundwater flow systems, Rev. Geophys., 45, RG3007, doi:10. 1029/2006RG000206.

Siegel, D.I., 1989, Geochemistry of the Cambrian-Ordovician aquifer system in the northern Midwest, United States: U.S. Geological Survey Professional Paper 1405-D, 76 p.

Southwick, D.L., 2002, M-121 Geologic map of pre-Cretaceous bedrock in southwest Minnesota. Minnesota Geological Survey map series M-121, scale 1:250,000

Wright, H. E., 1987, Quaternary History of Minnesota in Geology of Minnesota, Minnesota Geological Survey, University of Minnesota, St. Paul, Minnesota p. 515-548.

26 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Tables

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 27 152.37 36.67 88.32 152.71 40.31 144.23 156.12 28.10 126.73 163.92 48.65 126.90 108.21 38.62 68.12 108.87 55.30 69.06 145.60 3.52 81.95 157.07 sealed 75.24 water (ft) 26.23 32.59 Depth to Depth 40.10 32.69 245-253 119-129 272-280 390-537 415-479 458-630 215-223 109-119 420-430 390-545 495-648 460-575 195-205 197-206 434-444 356-463 495-672 640-718 188-198 155-164 222-232 410-519 sealed 497-680 interval (ft) interval 65.5-70.5 118-128 screened 267-282 373-547 Depths of Depths or hole open 978.349 1000.712 1008.182 978.378 996.857 1008.529 991.497 1064.408 993.974 991.333 1063.842 993.624 992.493 1039.160 1201.381 992.730 1038.803 1201.236 988.448 1003.582 1174.086 988.370 1004.161 1174.015 (ft above msl) above (ft 1019.371 1129.249 elevation 1019.757 1129.111 Ground 980.876 1002.757 1009.977 Simon sandstone = CambrianCMTS Mt. =quartzite Precambrian Sioux PMSX 981.188 999.802 1010.648 993.752 1067.303 996.049 993.467 1067.011 995.742 994.935 1041.967 1204.317 996.321 1041.922 1203.873 990.761 1009.414 1176.966 990.669 1004.311 1176.856 (ft above msl) above (ft 1021.900 1131.731 elevation 1021.947 1131.407 Top casing 4923015.735 4883267.280 4947369.955 4923018.885 4883267.002 4947369.756 4911106.35 4870090.087 4932926.352 4911110.024 4870093.555 4932926.374 4905567.941 4871989.969 4843427.544 4905565.047 4871991.533 4843431.030 4902804.578 4885218.599 4851322.787 4902807.503 4885215.946 4851318.450 Northing 4896564.977 4862852.802 UTM 4896564.649 4862854.602 405655.564 388504.074 410696.317 405653.717 388508.699 410698.789 397937.852 382101.235 405888.095 397939.24 382101.048 405883.249 392095.445 389453.682 366705.458 392095.616 389450.77 366704.522 400936.287 374743.738 372700.159 400938.203 374745.213 372699.859 Easting 369438.015 365174.415 UTM 369435.816 365169.986 547 260 129 280 537 479 630 223 120 430 545 648 575 202 206 444 463 672 718 198 164 232 519 316 680 Depth 70.5 128 282 Table - 1 Well Summary DR/RC QBAA = Quaternary buried aquifer QBAA = Quaternary KRET sandstone = Cretaceous MR MR DR/RC DR/RC MR DR/RC MR MR MR DR/RC MR MR* MR MR MR DR/RC MR MR MR MR MR DR/RC MR MR Method RS MR Drilling DR/RC CMTS QBAA QBAA QBAA CMTS CMTS CMTS QBAA KRET QBAA CMTS CMTS CMTS QBAA QBAA QBAA PMSX CMTS CMTS QBAA KRET KRET CMTS CMTS CMTS Formation QBAA QBAA CMTS Long Lake Norwegian Grove Norwegian Bergdahl Severance Lake Severance Norwegian Grove Norwegian Bergdahl Severance Lake Severance Peterson Madelia Sibley Co. LF Co. Sibley Peterson Madelia Sibley Co. LF Co. Sibley Courtland WestCourtland Case Rooney Run Rooney Courtland WestCourtland Case Rooney Run Rooney Nicollet Bay Lake HanskaLake Exceder Exceder Nicollet Bay Lake HanskaLake Exceder Exceder Site Name Site Heget BraulickHeget Long Lake Heget BraulickHeget Brown Watonwan MR = mud rotary MR DR/RC = dual rotary/reverse circulation DR/RC = dual rotary/reverse Nicollet Watonwan Sibley Nicollet Watonwan Sibley Nicollet Watonwan Sibley Nicollet Watonwan Sibley Nicollet Watonwan Martin Nicollet Watonwan Martin Nicollet Brown Martin Nicollet Brown Martin County Brown Watonwan 768259 770427 770445 760690 770443 770444 760691 770442 770450 760688 770441 770449 760689 770440 768262 760686 771161 768261 760687 771163 768264 760692 768139 768263 760651 768125 Unique 768260 770439 MN 08012 83023 Drilling methods: 52008 83022 72003 52007 83021 72002 52006 83020 72001 52005 83019 72000 52004 83018 46009 52003 83017 46008 52002 08014 46007 52001 sealed 46006 OB# 08013 83024 DNR

28 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 3.1 3.6 5.7 2.8 na 8.0 5.5 na 7.0 0.3 4.8 28.0 1.1 1.9 5.0 0.367 1.3 9.2 0.036 1.2 6.5 4.2 13.1 (gpm/drawdown) 2.6 2.2 capacity 11.8 6.7 Specific 0.0075 5.1 2.66 7.2 1.22 8.7 na 0.88 4.7 na 1.18 90.2 0.6 0.30 22.8 12.6 1.69 32.0 12.5 0.86 63 16.7 1.22 4.8 1.8 (feet) 8.27 11.3 drawdown 0.69 3.8 Water level 186.25 5.3 27 8.2 26 7.0 25 3 7.1 26 900 8.2 26 3 8.4 26 24 8.5 11.7 17 7.9 2 20 8.0 20 23 rate (gpm) rate 21.2 25 pumping 8.1 26 Average 1.4 627 326 1610 834 930 450 310 1040 14400 880 536 171 590 944 1270 970 337 1070 620 230 967 1240 250 1503 (gallons) 1200 586 volume 320 1887 Pumped 126 90 23 40 62 120 38 150 44 40 16 107 20 57 70 36 53 114 29 65 78 103 48 156 13 64 (minutes) 57 23 Pumping 39 74 886.670 1037.903 837.812 1016.581 829.777 1001.867 na 828.626 984.722 1025.87 828.808 964.307 1005.084 869.309 957.770 1136.197 868.792 995.950 1134.813 921.197 981.237 1113.766 866.468 844.240 1100.476 (ft above msl) 832.940 1099.031 elevation 886.365 1098.917 Static water 109.65 29.40 155.94 50.43 163.69 40.10 na 152.25 57.20 8.89 152.38 38.45 4.33 126.74 42.03 68.12 126.95 25.95 69.06 88.78 40.71 63.20 144.18 146.52 76.38 casing (ft) 157.73 32.70 from top from 108.57 32.49 Depth to static water Table Specific 2 - Capacity Summary Data Level and Water PMSX KRET QBAA CMTS CMTS QBAA CMTS QBAA CMTS CMTS CMTS QBAA KRET QBAA CMTS QBAA CMTS QBAA CMTS QBAA CMTS KRET CMTS QBAA CMTS Formation CMTS QBAA QBAA CMTS Courtland West Madelia Peterson Madelia Peterson Case Flandrau SP Norwegian Grove Case 83012 Norwegian Grove Bergdahl Lake Hanska Sibley Co. LF Bergdahl Rooney Run Sibley Co. LF Heget Braulick Rooney Run Severance Lake Heget Braulick Exceder Severance Lake Nicollet Bay Exceder Site name Nicollet Bay Long Lake Courtland West Long Lake CMTS = Cambrian Mt. Simon Cambrian = Mt. sandstone CMTS quartzite Precambrian = Sioux PMSX Nicollet Watonwan Nicollet Watonwan Nicollet Watonwan Brown Nicollet Watonwan Watonwan Nicollet Watonwan Brown Sibley Watonwan Martin Sibley Brown Martin Sibley Brown Martin Sibley Nicollet Martin County Nicollet Watonwan Nicollet Watonwan 768261 760688 770450 760689 770449 760686 405338 770445 760687 132275 770444 760690 760692 770441 760691 771161 770440 768260 771163 770443 768259 768139 770442 768264 768125 unique 768263 770439 MN 768262 770427 10/13/2009 10/15/2009 10/9/2009 10/15/2009 10/9/2009 10/15/2009 10/26/2009 10/9/2009 10/15/2009 11/24/2009 10/8/2009 10/14/2009 10/28/2009 10/8/2009 10/15/2009 10/26/2009 10/8/2009 10/14/2009 10/26/2009 10/7/2009 10/14/2009 10/16/2009 10/7/2009 10/14/2009 10/16/2009 sampled 10/14/2009 10/15/2009 Date 10/9/2009 10/15/2009 QBAA = Quaternary buried aquifer buried Quaternary = QBAA KRET = Cretaceous sandstone Cretaceous = KRET

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 29 duplicate no no no no yes yes no Storage none 1 for every 20 1 for every **** 20 1 for every **** none none none 1 for every 20 1 for every **** Field blank Field 1 for every 20 1 for every none none 1 for every 20 1 for every 20 1 for every 1 for every 20 1 for every 1 for every 20 1 for every Field duplicate Field 2-3 weeks years 24-48 hours long long 2-3 weeks 2-3 weeks Shelf life yes ifYes, not analyzed onsite no no no yes yes Refrigeration 3 OH to pH 4 5 drops HNO 15N NH 8.5 no no no no 1 drop HCl 6N Preservative no no yes yes no yes yes Filter yes * yes * yes ** no yes * Rinse NO NO Table 3 FieldTable Sample Collection and Handling Details Head space yes yes yes yes NO yes yes Sample 15 ml, Fisherbrand BLUE cap container 500 ml, HDPE 60 ml, HDPE 50 ml, Argos BLACK *** 15 ml, Sarstedt cap RED 500 ml, plastic 30 gallon barrel Lab Waterloo U of M U of M onsite U of M Waterloo U of M Parameter Tritium 18O, Deuterium Cations Anions Trace constituents Alkalinity 14C *Rinse the bottleonce FILTERED with sample prior to water collectingthe sample.Rinsing means fill the bottlesample with (FILTERED water if sample is filtered) and thenthe pour contents out theover cap. ** Rinse the bottle three times sample with prior to water collecting the sample. Fill bottle submerged capwith in hand. Sealbottle submergedensuring no remnant bubbles. *** Fill 50 ml anion bottleunless filtering is difficult. very Bottle mustat be least 1/3 full. **** Use DIfrom water small bottle for fieldblanks (NOT THECARBOY). Pour into DI water the back of thethe syringe plunger is when removed. Fill bottles throughfilter.

30 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer O 18 -9.95 -4.84 -9.36 -10.27 -9.59 -9.04 -8.56 -8.65 -9.18 -6.39 -8.23 -9.19 -9.85 -7.45 -9.39 -9.11 -9.75 -8.64 -9.88 -10.09 -8.31 -9.70 -9.28 -9.81 -8.88 -7.72 -9.15 -9.66 -9.07 Deuterium Stable isotopes**** -68.61 -40.89 -66.38 -68.69 -66.42 -63.67 -63.42 -64.82 -65.18 -50.23 -60.05 -65.96 -69.97 -56.77 -67.30 -65.92 -67.46 -61.71 -66.69 -67.27 -58.81 -69.42 -66.70 -72.7 -61.30 -54.04 -58.41 -65.90 -65.65 Tritium*** <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 2.9 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 CMTS = Cambrian Mt. Simon Cambrian = Mt. Sandstone CMTS PMSX = Precambrian Sioux Quartzite Precambrian = Sioux PMSX C (years) 14 Residence time indicators 30,000 Recent 10,000 11,000 20,000 4,000 13,000 4,000 7,000 500 22,000 8,000 13,000 8,000 20,000 11,000 17,000 8,000 8,000 18,000 2,600 10,000 10,000 NA 5,000 2,300 7,000 18,000 9,000 B 89 114 213 1910 497 183 361 452 244 376 89 260 173 322 225 272 336 464 335 344 295 193 241 571 192 74 357 152 317 Trace elements** As 0.19 14.3 0.1 0.13 1.93 5.11 0.29 1.75 0.37 41.2 22.8 10.3 0.37 1.37 0.13 0.44 2.41 1.67 3.78 0.36 5.27 0.61 1.88 0.23 0.42 1.45 0.21 44.2 0.26 QBAA = Quaternary buried aquifer buried Quaternary = QBAA KRET = Cretaceous sandstone Cretaceous = KRET Date sampled 10/26/2009 10/14/2009 10/15/2009 10/28/2009 10/8/2009 10/15/2009 10/14/2009 10/9/2009 10/15/2009 10/14/2009 10/9/2009 10/14/2009 10/16/2009 10/9/2009 10/15/2009 10/16/2009 10/8/2009 10/15/2009 10/26/2009 10/8/2009 10/15/2009 10/26/2009 10/7/2009 10/9/2009 10/7/2009 10/9/2009 11/24/2009 10/14/2009 10/15/2009 Depth (ft) Depth 200 198 672 164 540 120 284 260 648 70.5 545 129 680 223 479 231 575 547 444 430 128 718 630 463 280 202 484 474 209 Formation CMTS QBAA Kret CMTS QBAA CMTS QBAA CMTS QBAA CMTS QBAA CMTS QBAA CMTS KRET CMTS CMTS QBAA QBAA QBAA CMTS CMTS PMSX QBAA QBAA CMTS CMTS QBAA CMTS **** delta values reported in units values delta reported **** per thousand relative to standard thousand to relative per NA = not analyzed not = NA County Brown Nicollet Brown Nicollet Watonwan Brown Nicollet Watonwan Brown Nicollet Watonwan Martin Nicollet Watonwan Martin Sibley Watonwan Martin Sibley Watonwan Martin Sibley Nicollet Sibley Nicollet Watonwan Nicollet Watonwan Watonwan Table 4 Residence time indicators, stable isotopes, and selected trace elements Site name Flandrau State Park Lake Hanska WMA Norwegian Grove WMA Madelia WMA Helget-Braulick WMA Norwegian Grove WMA Madelia WMA Helget-Braulick WMA Peterson Unit* Bergdahl WMA Exceder WMA Peterson Unit* Bergdahl WMA Exceder WMA Sibley Co Landfill Long Lake WA Rooney Run WMA Sibley Co Landfill Long Lake WA Rooney Run WMA Severance Lake WMA Courtland West Unit* Severance Lake WMA Courtland West Unit* Darrin Bocock Nicollet Bay Unit* Case WMA Nicollet Bay Unit* Case WMA MN unique 00405338 00760692 00770444 00760688 00768259 00770445 00760689 00768260 00770449 00760690 00768125 00770450 00760691 00768139 00770440 00770427 00771161 00770441 00770439 00771163 00770442 00768261 00770443 00768262 00132275 00768263 00760686 00768264 00760687 *part of Swan Lake Swan of WMA*part ** ug/l (parts per billion) per (parts ug/l ** *** tritium units (TU), < means < tritium detected not units (TU), ***

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 31 Mn 0.074 0.215 0.304 0.143 0.192 0.256 0.274 0.210 0.0185 0.429 0.126 0.311 0.141 0.838 0.165 0.191 0.0925 0.203 0.114 0.271 0.197 0.1126 0.203 0.313 0.1134 0.891 0.218 1.037 0.388 2.92 1.68 2.55 3.44 2.30 2.90 3.18 0.780 1.91 2.92 2.02 2.12 3.81 0.920 4.26 5.91 3.52 1.28 3.62 1.18 0.246 3.72 1.05 2.06 3.90 Fe 1.30 3.25 2.21 0.012 27.1 5.49 5.62 7.64 6.25 4.67 5.71 4.88 5.25 5.49 4.96 5.85 5.49 5.77 8.70 10.38 7.79 8.71 12.4 6.77 4.93 6.71 5.21 6.92 9.50 4.24 K 10.02 6.62 5.64 73.3 131 68.7 75.0 70.1 33.0 170 82.2 22.1 53.4 54.4 45.1 95.1 65.6 49.0 150 48.7 52.3 22.3 45.3 53.2 31.4 39.9 57.4 77.6 64.4 8.27 Na 203 77.3 Cations mg/l 77.6 39.5 60.9 66.4 38.7 51.9 58.1 63.3 60.9 35.3 44.4 57.5 66.3 45.5 58.4 55.8 36.7 106.5 95.8 65.8 42.7 84.9 43.6 35.8 71.2 117 40.1 36.6 Mg 22.0 212 93.5 8.62 210 90.5 172 192 198 208 112 126 186 227 108.7 190 150 86.9 168 269.4 150 96.0 255 111 109 219 363 104.6 123 Ca 47.2 167 64 171 47 68 124 35 43 49 37 3044 52 42 42 54 55 245 46 33 71 911 139 15 290 81 31 293 69 Cl/Br 291 0.067 0.054 0.059 0.042 0.053 0.057 0.028 0.078 0.043 0.015 0.016 0.043 0.042 0.060 0.049 0.033 0.249 0.013 0.037 0.041 0.038 0.056 0.043 0.062 0.052 0.048 0.073 0.016 Br 0.450 586 29.8 433 544 45.1 475 388 705 615 99.1 181 435 523 206 493 320 162 481 751 31.4 191 665 51.7 175 544 1114 131.7 63.6 SO4 239 Anions mg/l Anions 11.2 3.43 10.1 1.98 3.59 7.04 0.99 3.36 2.10 0.56 48.7 2.25 1.75 2.5 2.67 1.83 60.9 0.60 1.21 2.93 34.6 7.77 0.65 18.0 4.21 1.49 21.4 1.10 Cl 130.9 10/15/2009 10/8/2009 10/9/2009 10/14/2009 10/8/2009 10/26/2009 10/15/2009 10/9/2009 10/26/2009 10/15/2009 10/9/2009 10/16/2009 10/15/2009 10/9/2009 10/16/2009 10/15/2009 10/8/2009 10/14/2009 11/24/2009 10/14/2009 10/14/2009 10/15/2009 10/7/2009 10/14/2009 10/28/2009 10/15/2009 10/7/2009 10/9/2009 Date sampled 10/26/2009 CMTS = Cambrian Mt. Simon Cambrian = Mt. sandstone CMTS quartzite Precambrian = Sioux PMSX Table 5 Selected anion and cation data 479 430 463 129 575 718 648 223 444 120 545 231 672 260 680 209 540 70.5 484 198 284 128 280 474 164 547 630 202 Depth (ft) Depth 200 CMTS QBAA PMSX QBAA CMTS CMTS CMTS QBAA QBAA QBAA CMTS KRET CMTS QBAA CMTS QBAA CMTS QBAA CMTS QBAA CMTS QBAA QBAA CMTS KRET CMTS CMTS QBAA Formation CMTS Watonwan Sibley Nicollet Watonwan Sibley Martin Watonwan Nicollet Martin Watonwan Nicollet Martin Watonwan Nicollet Martin Watonwan Nicollet Brown Watonwan Nicollet Brown Watonwan Sibley Nicollet Brown Watonwan Sibley Nicollet County Brown QBAA = Quaternary buried aquifer buried Quaternary = QBAA sandstone Cretaceous = KRET Bergdahl WMA Sibley Co Landfill Courtland West Unit* Bergdahl WMA Sibley Co Landfill Rooney Run WMA Madelia WMA Peterson Unit* Rooney Run WMA Madelia WMA Peterson Unit* Exceder WMA Case WMA Norwegian Grove WMA Exceder WMA Case WMA Norwegian Grove WMA Helget-Braulick WMA Darrin Bocock Nicollet Bay Unit* Helget-Braulick WMA Long Lake WA Severance Lake WMA Nicollet Bay Unit* Lake Hanska WA Long Lake WA Severance Lake WMA Courtland West Unit* Site name Flandrau State Park 00760691 00770441 00768261 00760690 00770440 00771163 00760689 00770450 00771161 00760688 00770449 00768139 00760687 00770445 00768125 00760686 00770444 00768260 00132275 00768264 00768259 00770439 00770443 00768263 00760692 00770427 00770442 00768262 MN unique 00405338 *part of Swan Lake Swan of WMA*part

32 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figures

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 33 !

Isanti

St. Cloud !P ! Sherburne ! !

! Wright Anoka

! Phase 2 area Hennepin (funded 2009) ! ! Minneapolis !P St. Paul !P McLeod !

! Sibley

Phase 1 area ! (funded 2008) Nicollet ! ! ! Brown ! Mankato !P

! ! well nest location

! ! Regional west boundaries Eau Claire Formation (shale) ! Watonwan Mt. Simon Sandstone

Figure 1 Mt. Simon observation well nest locations Jackson Martin

34 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer

Figure 2 Cambrian and older stratigraphy in study area (Modified from Mossler 2008)

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 35 !

! !

!! !

! !

Clr

County Atlas units State map units Cj Paleozoic bedrock Paleozoic bedrock Cmu Carver McLeod Op St. Peter Sandstone, Osp Upper Ordovician, Ou Cj Prairie du Chien Group, Op and Oo Middle and Upper Ordovician, Omu Severence Lake WMA Jordan Sandstone, Cj Lower Ordovician, Ol ! Csl Renville (includes Op and Oo) St. Lawrence Fm, Csl Phf Op Upper Cambrian, Cu Tunnel City Gp (Lone Rock Fm), Clr (includes Cj, Csl, and Clr) A Cm Wonewoc Sandstone, Cw Clr Middle and Upper Cambrian, Cmu Eau Claire Fm, Ce (includes Cm, Ce, and Cw) Op B Cw Csl Sibley Mt. Simon Sandstone, Cm Scott Samples wells Cm Sibley Co property ! Precambrian bedrock # Existing water supply wells Csl Ol Hinckley Sandstone ! New well nests for this project and/or Fond du Lac Formation, Phf Ce Regional west boundary Ce C Ce Cw Sioux Quartzite, Ps (dashed where uncertain) Cm Norwegian Grove WMA Csl Regional west boundary Cm ! (dashed where uncertain) Cm C' Redwood Csl D Cw Clr

Peterson unit Nicollet ! Le Sueur D E Ce ' Op Cj Courtland West unit # Ps !

Flandreau State Park ! E' Ol Brown Ce Nicollet Bay unit F Helget-Braulick WMA ! Cu Os F' Cj Os Cw Csl Os H SE Hanska WA G! Clr G' ! Study area location in Hollandale Oo embayment (modified from Siegel 1989) irrigation Bergdahl WMA Cj Cmu # Blue Earth Os I Case WMA Cottonwood ! Watonwan I Csl ! ' H' Os Madelia WMA J' Oo J ! Cj Long Lake WA Cu Osp

K' Omu K ! Exceder WMA L Ol

Rooney Run WMA ! Jackson Omu Martin Faribault

Figure 3 Ou Cmu County and state Paleozoic bedrock map

L '

36 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer !

! !

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!!! ! ! ! Carver !

! 200 McLeod !

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0 !! 5 Mt. Simon wells Cottonwood H' Watonwan !! I' ! Existing water supply wells

J' ! New well nests for this project

J !! Regional west boundary Cm

1 Contour interval = 50 feet 0 0

! ! ! ' ! K

K !! L

! ! ! Jackson Martin Faribault

!! ! ! ! Figure 4 Mt. Simon Sandstone thickness ! L '

!! !

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 37 ! !! ! !

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Carver McLeod

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0 ! 0 ! 2 ! 1

Jackson Martin Faribault

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0 ! ! ! ! 0 Figure 5 Mt. Simon potentiometric surface ! and groundwater flow directions

! !

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South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 39 5000 280 QBAA

18000 438 QBAA Sibley

4000 Nicollet 253 QBAA

2300 8000 205 223 QBAA QBAA

0 198 500 QBAA 70.5 QBAA

Estimated residence Brown 11000 time in years (carbon-14) 164 KRET 33 - 100 8000 Watonwan 129 101 - 1000 QBAA 1001 - 10000

10001 - 25000

25001 - 60000 9000 206 2600 QBAA 8000 (residence time, years) 4000 121 206 (well depth, feet) 119 QBAA QBAA (aquifer code) QBAA

Regional west boundary Ce Blue Earth Regional west boundary Cm

11000 Martin 232 KRET

8000 Figure 7 444 QBAA Carbon-14 residence time data from the shallower aquifers at each observation well nest

40 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 10000 5 2 8 900 8000 30000 20000 Sibley 20000 17000

850 20000 Nicollet

20000

22000

0 30000 85

18000 Z' 30000

13000

8 20000 1 00 0 0 9 8 Brown 0 0 5 0 0

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1 05 0 7000 Estimated residence time in years (carbon-14)*

33 - 100 10000 7000 101 - 1000

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Z -9.85 - delta 18O value Martin

13000 Regional west boundary Ce

0 Regional west boundary Cm 0 2 1

* With addtional data from Richard Lively (MGS), 10000 Scott Alexander and Calvin Alexander (U of M)

1 1

Figure 8 Mt. Simon carbon-14 residence time, potentiometric surface and groundwater flow directions

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 41 -4 -5 -6 Evaporated water fromsurfacesource s QBAA - Quaternary buried aquifer QBAA - Cretaceous sandstone KRET CMTS - Cambrian Mt. Simon sandstone - Precambrian Sioux quartzite PMSX Linear(N AmericanPrecipData) -7 O 18 -8 del data compared with North American meteoricline -9 isotope 10 - fromdirect Figure 9 Stable Water infiltration ofprecipitation 11 - 12 -

30 40 50 60 70 80 90

------

H del 2

42 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ) C 3 a O lci N u ( m e t ( a C r it a ) N + + M l) a C ( " g n e e id " si r o # u l m h " C # ( "#" M + " " " " g ) # ) 4 O # S # ( e t " a "" ! lf u S # # " # # # " " Mg SO4 #"

"! #" #" """"" # #" # ! # " " " "## " # # #" " """# "" ##" " #"" " # " " " # # " # ##"

Ca Na + K HCO3 Cl + NO3

Aquifer # QBAA - Quaternary buried aquifer " CMTS - Cambrian Mt. Simon sandstone " KRET - Cretaceous sandstone ! PMSX - Precambrian Sioux quartzite

Figure 10 Ternary diagram - relative abundances of major cations and anions

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 43 !

131.7 !

151 150 !!

! 45.1 ! 88 !

Sibley 162 !

Nicollet

181 ! 36.1 328 !

239 ! 175 ! Z'

191 96.7 ! !

90 ! Brown

586 ! Watonwan

751 !

523 ! 388 !

1114 !

Blue Earth Z

493 ! Martin Regional west boundary Ce Regional west boundary Cm 475 !

Figure 11 Mt. Simon sulfate concentrations (mg/l), and groundwater flow directions

44 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer !

21.4 !

1.94 2.01 !!

! 3.59 ! 6.08 !

Sibley 60.9 !

Nicollet

48.7* ! 17.5 440 !

130.9 ! 18.0 ! Z'

34.6* 28.4 ! !

5.50 ! Brown

11.2 ! Watonwan

1.21 !

1.75 ! 0.99 !

1.49 !

Blue Earth * Samples appear to contain added chloride from well construction disinfectants Z

2.67 Martin ! Regional west boundary Ce

Regional west boundary Cm

7.04 !

Figure 12 Mt. Simon chloride concentrations (mg/l) and groundwater flow directions

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 45 1.88 !

2.41 !

Sibley

1.93 !

Nicollet

22.8 !

0.19 ! 44.2 ! Z' 0.29 !

Brown

0.13 ! Watonwan

0.21 !

0.1 ! 0.37 !

1.67 !

Blue Earth Z

0.37 ! Martin Regional west boundary Ce Regional west boundary Cm

0.61 !

Figure 13 Mt. Simon arsenic concentrations (ug/l) and groundwater flow directions

46 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer

Figure 14 Precipitation departure from normal October 2009 – September 2010

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 47 ' A - ! A '

! n ! A

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48 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figure 15b Figure 15b WMA Lake Severance Hydrograph

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 49 ' B - B

n o i a c t 6 1 s e

e r s u o g r i ! C F ! ' B

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50 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figure 16b Figure 16b Sibley Landfill County Hydrograph

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 51 ' C - C

n o i a c t 7 1 s e

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52 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figure 17b Figure 17b WMA Grove Norwegian Hydrograph

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 53 ' D - D

n o i a ' c t 8 D 1

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54 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figure 18b Figure 18b Peterson Unit Hydrograph

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 55

0 6 8 9 0 2 0 0

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56 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Figure 19b Figure 19b Unit West Courtland Hydrograph

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 57 Figure 19c Figure 19c Nicollet Bay Unit Hydrograph

58 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ' ' F F -

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South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 59 Figure 20b Figure 20b WMA Braulick Helget Hydrograph

60 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ' G - m G F

c n ' a o l

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South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 61 Figure 21b Figure 21b WMA Bergdahl Hydrograph

62 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ! ! ! ! ! ! ' H ' H - ! H

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South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 63 Figure 22b Figure 22b WMA Case Hydrograph

64 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ' I - I

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a n d i x l e l

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p i r t e l c r v a

* a e e n

e V a e n i s h

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t e n d P e f r

n c o 0

a C e 0 l s ) 0 r p 5 a m y e

s a ,

s ) e n m m i a t

p 4 1 6 4 3 7 0 0 e

) m - ! c

m l

* e n / 4 9 4 0 6 1 0 0 l p , e ) o g ! p I

! d h

O i

- m 1 8 4 8 2 1 0 0 W

8 s n l / e e 1 ! e t ( C

r g p

r a a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o f t e m l l C r 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5

I b l e u o 4 1 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0

d 1 m C S g

1 n 1 1 ( ( ( ( u ) l s m t e e f ( n o i t a v e l E n

n e s i

5 0

0 1 4 c a u

s c r . 3 l

0 8 . q l l i 9 l 7 - 5 2 e n e

2 9 6 0 6 7 0 0

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 65 Figure 23b Figure 23b Madelia WMA Hydrograph

66 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer J ' ! - J '

J n o i a

c t p

4 G 2 ! s e

t !

e i

r C

u l

o e g r

i n

F C

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a l

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r n e

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s f

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X e l

m 0 m * i a A 5 o 9 e

f 3 n

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o 0 e s n W t 7

s t u 7 o a i d e 0 o t w 0

k n a ! d a r c e 7 ! e ! ! s a ! a L e t 2 !

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e ! l

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c 0 i m 1

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n 1 1 - 8 i e a ! t n i l n l a c o

s t t e l s ) y e r p r e a c f m

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s a , a

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c m l * e n /

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s c r . 3 1 1 4 5 5 6 6 7 7 8 8 9 9

0 0 2 l

8 . q l l i 9

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2 9 6 0 6 7 0 0

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 67 Figure 24b Figure 24b WA Long Lake Hydrograph

68 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ' K ! - ' K

K n o ! i

! n 5 5 8 0 5 4 0 0 c t 5 a !

s e

4 5 4 8 2 2 0 0 u ! e ! ! r r T s u o g r i ! ! ! F C ! l ! v e a r g / d n a s

l a c i

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t 8 1 1 4 1 2 1 0 M 0 0 6 !

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E 0 0 ! 5

7 0 8 3 , . 6 ! . 9 3 9 2 4 - 1 ! ) e c r u s o

r e

a 5 2 9 1 7 1 0 0 w !

c e a f r s u X

0 a

m ! = o

r f n

r o i e t t ) a a l l r i w c k

t e ( o d g r e

s t g t e a a n r n

i x o e l l l e p a

m a l i c i v a a s t d e a c l

y i r t e g s e r c

m e n o V s a i r s n b i a m t ! a n c ! t c o e

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b l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e u o 4

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1 1 4 5 5 6 6 7 7 8 8 9 9 0 0 2 2 e

e 1 1

s i

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) l s m t e e f ( n o i t a v e l E 0 1 4 c a u

s c r . 3 l

0 8 . q l l i 9 l 7 - 5 2 e n e

2 9 6 0 6 7 0 0

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 69 Figure 25b Figure 25b Exceder WMA Hydrograph

70 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer ' L - L

n o i a c t 6 2 s e

e r ' s u L o g r i

m ! C F

! l ! C

s 1 3 6 0 4 7 0

0 E

3 3 3 1 2 1 0 0 S ! !

n 8 8 0 7 1 2 0 0

o !

i e l

S *

. e 4 5 6 9 9 1 0 0 t

s h !

4 5 9 0 6 7 0 0 M o s ! s t u d o n c e s a a

t d

8 7 0 4 4 7 0 0 a C

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0 !

e 0 4 3 1 3 7 0 0

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s r

t 7 8 1 7 0 1 0 0 u n A !

e l s o

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d 0 1 a a l 1 0 0 n 0 w

7 s e g 5

4 0 u 7 7

5 , . 0 0 R . 7 0 = c e 0 9

a 7 4 - 1 f y n 1 r e 6 o i ! 1 n t s u 1

o 7 a a r

! o 0 e 0 m 0 8

R g 0 0 o 8 5 r g . 1 0 f . 1 ,

a 9 r 2 6 - 8 x e t e a

l w

a d c

c k i

e ! 6 5 4 8 2 1 0 0 t t o r r ! a

e r e o V n p i l ! l v a a e

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m t

v e

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a t s ! ! e ! r n n f s g

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l c e a l e s ) r r p c i a P m a l y e g !

s a ,

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e p e

) L m - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c

m l * e n 0 5 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 /

l p , e ) o g 1 1 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 2

p I

h d

1 1

1 1 1 i

m - ) l s m t e e f ( n o i t a v e l E W

8 s n l / e e 1 e t ( C

r g p

r a a o f t e l m l C r

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s c r . 3 l

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South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 71 Figure 26b Figure 26b WMA Run Rooney Hydrograph

72 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 10000 -9.28 Post-glacial 8000 30000 recharge

20000

17000 -9.75 20000 Sibley

20000 Nicollet -9.59

20000

22000 -8.23

30000

18000 Z' -9.66

30000 13000 -8.56 Mixed post-glacial

Brown recharge 20000 and older water Watonwan 20000 -9.39

7000 Estimated residence -9.15 time in years (carbon-14)

33 - 100 Post-glacial 10000 -9.36 101 - 1000 recharge 7000 -9.18 1001 - 10000

10001 - 25000 8000 25001 - 60000 -8.64 Blue Earth

Z -9.85 - delta 18O value

Martin Mt. Simon groundwater flow 13000 -9.85 directions

Regional west boundary Ce

10000 Regional west boundary Cm -9.70

Figure 27 Mt. Simon recharge interpretation

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 73 n o r i t a r t S v a

r h ' A t l l r Z s e d M e o b e w W o N

c t y e l l a V

r e v i R

a t o s e n n i M e e l t a f l l s e s u

s C y r

l l d s / / 0 m S g g n 0 F c

0 m m a ,

o e ' 0 7 8 r i w 3 9 2 Z a e l - n C

p o Z

u u W a o n r E g o

i y t i c t C

l s e e n s n a

u s t e n T n o a o o r t d m c i s

l d S

n d . t a c a i M S z e 8 i l m 2

s t a e r e e h r e n

c l u n l o e g e i e e e t t w

F G g a a f f O O l l A 8 8 u u l s 1 1 s s M

l l l s l l C y r / /

e e

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d d 0 l d l

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c l i l e s l

I i

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e l

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a a l

n f . i t g ( c l o

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g 0 e 5 3 6 . m n , 6

8 o 2 6 - 8 t s

d d n e t s a a i s t u n e l e o r a e c e f f s h a i

t d d e n r n U C a Z

74 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer n o ' r i t a Z r t S v a

r h A t l l r s e M e o

w o W N

y e l l a V

r e v i R

a t e o s e n n i M g r a

s c h Z m S - s i F

c Z d e o

n s d a

l r e

o n a

n i C

y a u

c t

W 0 o a

r 0

e E

g 0

, s e g

y 0 r t 3 i s a C s

r h l o e

e c r

n ,

d e n d C l r s u n

T o n

n s a e 9

) d o t d 2 m l i

e n s i m d d

i a e d d

r s e l S

e n l u

b a

a . a r i g t , e i c i y s t t c a a l n e F M

i a g ( c l

n l

l g - e t

w s

A o

M p

W d

e s h r

a x

a i

e y e d

g 0

m c t

r 0

, e e 0 j 2 o B r

r a a

i a t

y a

0 d

d 0

0 l

, l e 0 1 e M

w f

o A y M t i C W

e s a C * s l l e w

n o i t a g i

r e r I g r

e r

a i s c e

a c k

l o m r ) a

g d

- c J i e

t h . b t

s p r e S

o n i f l m

o P a t a t y t e y s i m c r C

d n n a i t a r s b s e

u e m n n o n

o l e o c a l t n m e e i s r g i d S w P s (

r n . t a A a M S W

0 k e

0 s

a r

, L a

2 g

o 0

L 0

0 ,

5 e n o t s

d d n e t s a a i s t u n e l e o r a e c e f f s h a i

t d d e n r n U C a Z

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 75 !

! !

!! !

! !

Mayer Lester Prairie New Germany

Victoria

Waconia Biscay

Danube ' Olivia Plato A Bird Island well nest location Buffalo Lake Norwood Hector Brownton Glencoe Cologne Stew art Carver Young America McLeod Groundwater appropriation 2009 Ham burg (million gallons/year) Unconsolidated Mt. Simon and combinations Severence Lake WMA sand and gravel ! Green Isle Renville New Auburn 0.0 - 20.0 0.0 - 20.0 A 20.1 - 40.0 20.1 - 40.0 Belle Plaine B Arlington 40.1 - 60.0 40.1 - 60.0 Sibley Gaylord Scott Morton Redwood F alls 60.1 - 80.0 60.1 - 80.0 ! Franklin Fairfax Sibley Co property Winthrop Henderson 80.1 - 100.0 80.1 - 100.0 Gibbon

C 100.1 - 857.5 100.1 - 1370.1 Le Sueur Norwegian Grove WMA B ! ' Lafayette C' RegMiorgnanal west boundaries Redwood Le C enter Eau Claire Formation (shale) D Clem ents Le Sueur Mt. Simon Sandstone

Evan Peterson unit Nicollet ! D Saint Peter Cleveland E '

Sleepy Eye New Ulm Courtland West unit ! Cobden Kasota Courtland Brown ! E' Nicollet Bay unit Nicollet Springfield F Sanborn ! F Helget-Braulick WMA ' Madison Lake Elysian

North Mankato Hanska

Skyline Eagle Lake H G SE Hanska WA Mankato ! Janesville Com frey Bergdahl WMA G' Lake Crystal ! La Salle Saint Clair Darfur

Madelia Blue Earth I Case WMA Good Thunder Pemberton ! Cottonwood Madelia WMA Vernon C enter Waseca Watonwan ! H' Saint James

Butterfield J' Mountain Lake Waldorf Bingham Lake Long Lake WA Mapleton J ! Lewisville Amboy

Windom Odin

Ormsby K' Minnesota Lake Exceder WMA K ! Trum an L

Winnebago Delavan Easton Trimont Rooney Run WMA ! Wells Jackson Martin Northrop Granada Faribault Figure 30 Welcom e Mt. Simon observation well nest locations and 2009 groundwater appropriation

Sherburn Fairmont (millions of gallBoluen Esar/thyear) Alpha L '

Jackson Walters

Dunnell Frost

Bricelyn

76 South-Central MinnesotaCeylon Groundwater Monitoring of the Mt. Simon Aquifer Kiester Appendix A

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 77 Geological Log Legend

Geological Log Legend

Lithologic Description Lithologic Symbol Top Soil

Till

Lake Deposit

Outwash

Sandstone

Sandstone and shale

Shale

Quartzite

Igneous or metamorphic bedrock

78 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Severance Lake WMA

County Sibley

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

770442 MN Unique 770443 0 1000 Topsoil Till (multiple sources with outwash) Grout Grout

Water 100 level 900

Outwash Water 4 Inch level casing

Till (multiple sources with outwash)

200 800

Outwash - Undifferentiated 4 Inch Casing

Well screen 300 700 Lake deposit

400 Eau Claire Formation 600

Mount Simon Sandstone

500 500

Open Hole

600 400 Hinckley Sandstone

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 79 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Rooney Run WMA

County Martin

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

771163 MN Unique 771161 0 1200 Topsoil

Till - New Ulm Formation Grout Grout

Water Water level Outwash (NW source) level 100 1100 Till (NW source)

Lake deposits (NW source)

Till (NW source)

200 1000 4-inch casing

300 900 4 inch casing Lake deposits - undifferentiated

400 800

Outwash (NE Rainy source) Well Wonewoc Sandstone (Upper Screen Cambrian)

500 700

Eau Claire Formation (Middle to Upper Cambrian)

Mount Simon Sandstone (Middle Cambrian)

600 600

Pre-Mount Simon saprolith (?) Open hole 700 500 Granitic rock? (Neoarchean)

80 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Swan Lake WMA Peterson Unit

County Nicollet

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

770449 MN Unique 770450 0 Topsoil

Till - Des Moines Lobe (high Grout Grout shale member)

900 100 4-inch casing

Outwash - Des Moines Lobe (moderate shale member)

Till - Des Moines Lobe Water Water (moderate shale member) level level

800 4 inch 200 casing Outwash Well screen Unnamed formation (Lower to Upper Cretaceous, Albian to Cenomanian)

700 300

Eau Claire Formation

Mt. Simon sandstone

600 400

Open hole 500 500

Unnamed granite/gneiss (Archean)

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 81 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Norwegian Grove WMA

County Nicollet

Nested Well Construction

Depth Elevation Lithology 0 Gamma 150

770444 MN Unique 770445 0 Topsoil

Till - Des Moines Lobe (high Grout Grout shale member)

Outwash - Traverse des Sioux Formation (Rainy lobe) 900

100

4-inch casing Till - Traverse des Sioux Formation (Rainy lobe) Water Water level level Outwash - Traverse des 800 Sioux 10 inch Till - Traverse des Sioux casing 200 4 inch Outwash (NW source) casing

Till (NW source)

Outwash (NW source) Well screen Lake deposits 700 Outwash (NW source)

300 Lake deposits - Undiff.

Outwash - Undifferentiated

Eau Claire Formation

Mt. Simon sandstone

600

400

Open hole 500

500

Fond du Lac Formation

82 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Swan Lake WMA - Nicollet Bay Unit

County Nicollet

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

768263 MN Unique 768264 0 Topsoil

Till - Des Moines Lobe Grout Grout

Outwash - Des Moines Lobe

900 4-inch 100 casing

8 inch casing Water Outwash - Undifferentiated level Water level

800 Outwash (NW source) Well 200 4 inch screen Lake Deposits - casing Undifferentiated

Wonewoc Sandstone 700 300 Eau Claire Formation

Mount Simon Sandstone 600 400

Open hole 500 500 Stabilizer pack

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 83 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Madelia WMA

County Watonwan

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

760689 MN Unique 760688 0 Top soil

Lake Deposits - Glacial Lake Grout Grout Minnesota Water Water level Till - Des Moines Lobe level 1000 4-inch Outwash casing

Till - late or pre Wisconsin? 100 Dakota Formation Well screen

900

200

4-inch Tunnel City Group casing 800

300

Wonewoc Sandstone

700 Eau Claire Formation

400

600 Mt. Simon Sandstone

500

500 Open hole

600

Igneous or metamorphic bedrock?

84 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Long Lake WA

County Watowan

Nested Well Construction

Depth Elevation Lithology 0 Gamma 100

770427 MN Unique 770439 0 Topsoil

Till - Des Moines Lobe (low Grout Grout 1100 shale member) Water Water Till - Des Moines Lobe level level (moderate shale member) 4-inch casing Outwash - Unnamed carbonate-rich formation (northwest source) 100

Well 1000 Dakota Formation screen (Cretaceous, Cenomanian) shale and sandstone

4 inch 200 casing

900

Unnamed unit (Cretaceous?, Albian/Cenomanian) shale 300 and sandstone

800

Mount Simon Sandstone (Middle Cambrian)

400

700

Open hole

500

Saprolith (pre-Mount Simon; 600 Middle Cambrian?) Granite/gneiss (Neoarchean/Mesoarchean)

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 85 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Lake Hanska WA

County Brown

Nested Well Construction

Depth Elevation Lithology 0 Gamma 600

760651 MN Unique 760692

Water 0 1000 Top soil level outwash

Till - Des Moines Lobe Grout Surface seal

Outwash - Des Moines Lobe

Till - Des Moines Lobe

Dakota Formation Sandstone 4 inch and Shale casing

100 900

Well screen

Undifferentiated Cretaceous Grout Shale and sandstone 200 800

300 700 Mount Simon sandstone?

Igneous or metamorphic bedrock

86 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Helget Braulick WMA

County Brown

Nested Well Construction

Depth Elevation Lithology 0 Gamma 100

768259 MN Unique 768260 0 Topsoil

Till - Des Moines Lobe (high shale member) Grout 1000 Grout Water level

Water 4-inch level casing

Outwash (NW source) Well Till (NW source) Screen

Till and outwash undiff.

Dakota Formation sandstone 100 and shale

900

4 inch casing

Undifferentiated Cretaceous sandstone and shale

200

800

Mt. Simon sandstone

Fort Ridgely Granite Well screen

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 87 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Exceder WMA

County Martin

Nested Well Construction

Depth Elevation Lithology 0 Gamma 200

768125 MN Unique 768139 0 Top soil

Till - Des Moines Lobe (low Grout Grout shale member)

Till (NW source) 1100 Water Outwash (NW source) level Water level 100 Till (NW source) 4-inch casing Till or lake deposit - Undiff.

Dakota Formation (Upper Cretaceous) 1000

200

Well Screen 4 inch casing 900

300

Tunnel City Group, Lone Rock Formation

800 Wonewoc Sandstone

400

700

500 Eau Claire Formation

Mount Simon Sandstone

600 Open 600 hole

500

88 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Swan Lake WMA - Courtland West Unit

County Nicollet

Nested Well Construction

Depth Elevation Lithology 0 Gamma 400

768261 MN Unique 768262 0 Topsoil

Till - Des Moines Lobe Grout Grout

900 4-inch 100 casing Water level Water level

Till (nw source)

Lacustrine Deposits - pre Wisc.

Outwash - pre Wisc. 8 inch Till - pre Wisc. casing 800 200 4 inch Well Outwash - pre Wisc. casing screen

Dakota Formation - Cretaceous

Cretaceous Deposits

Wonewoc Sandstone

Sioux Quartzite

700 300

600 400 Open hole

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 89 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Case WMA

County Watonwan

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

760687 MN Unique 760686 0 Top soil

Lake Deposits Grout Grout 1000 Water level Water level Outwash - Des Moines Lobe

Till - undiff. 100 4-inch Till (NW source) casing

ice contact - Unnamed 900 Till (NE source)

Lake deposits - Undiff. 200 Well screen Tunnel City Group 800

Birkmose Member 300 Wonewoc Sandstone

700

Eau Claire Formation

400

600

Mt. Simon sandstone

500

Open hole 600

400

Rhyolite

90 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer Geological / Geophysical Logs and Well Construction Diagrams

Site Name Bergdahl WMA

County Watonwan

Nested Well Construction

Depth Elevation Lithology 0 Gamma 350

760691 MN Unique 760690 0 Lake Deposits - Glacial Lake Minnesota

Till - Des Moines Lobe (high Grout Grout shale member) Water Water level level 4-inch casing Till - Des Moines Lobe (low shale member)

100 900 Outwash - Des Moines or Rainy Lobe? Well Till & outwash - ice contact screen deposits Des Moines or Rainy Lobe?

Till - Browerville Formation

200 800 4-inch Till - Unamed low to casing moderate carbonate (Rainy source)

Eau Claire Formation

Mt. Simon sandstone 300 700

400 600

Open hole

Granite/Gniess

South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer 91 Geological / Geophysical Logs and Well Construction Diagrams

Site Name Sibley County Landfill

County Sibley

Nested Well Construction

Depth Elevation Lithology 0 Gamma 250

770440 MN Unique 770441 0 Top Soil

Till - New Ulm Formation Grout Grout

900 100

Lake deposits - Undiff. Water Water level level Till - Traverse des Sioux Fm

Till - Browerville Formation 800 200 4-inch casing 4 inch casing Till - Unnamed carbonate- rich formation (northwest source) 700 300

Outwash - Undifferentiated

Outwash - Unnamed low to moderate carbonate formation (northeast Rainy 600 source) 400 Lake deposit - Undifferentiated Well Screen Outwash - Undifferentiated

Lake deposit - Undifferentiated 500 500 Mount Simon Sandstone (Middle Cambrian) Open hole

Fond du Lac (?) 400 Mesoproterozoic 600 First boring (270298 sealed)

92 South-Central Minnesota Groundwater Monitoring of the Mt. Simon Aquifer