900

860

1040

1060

1020

880

1000980

960 940

920mls

nls

mt

_tc

Mss

hbtnts

_e

prt

<gr

_w

nts

cg1nt

cg

pu

ms

<gr

pu_m

hwt

<gu

ms

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nthl

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hbt

nhsnhs

ct1

ct1

ct1

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ct

_sl

<dg

mlsmlt

_tc

ct1

<dg

ct

cg

prt

hwt

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mt

sct

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nhs

mlt

ct

hl nt

psu

hanhs

cg1nts

hwt

ct1

hs

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<gu

ntsmt

ct1

mt

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<gr

ms

_j

cg1

nts

sct ct1

_m

mt

zus

nts hbt

sct

_m

_m

nt

<gr

_w

8732

345.2*

5.8*

20.2

227.9

12

7

117

16.2 2413

510110

460

460

650

189540

690

540

360

139

560

810270

170

50034.9

1050

1100

1000

1200

1150

950

900

850

800

750

700

650

600

550

500

450

400

1050

1100

1000

950

900

850

800

750

700

650

600

550

500

450

400

350

300

Ele

vatio

n (fe

et)

C’

C

Coun

ty H

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5

Map

le L

ake

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ncis

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hrist

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unty

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Stat

e Hw

y 25

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y 55

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ty H

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th F

ork

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er

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se L

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nts

wmt

pu

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wmtcg1

<gr

<gr

ha

ct

ctmt

_e

prs

ct1

hwt nts

Mss

Mss

mlt

prt

_wha

mlt

ct

ct1

prs

nts

cg1

hbt

Agn

sct

ct1

prssct

wmt

nt

Agn

hs

pu

cg wmt

pu

_tc

ct1

ct1

ms

cg1 ms

prt

_m

nt nt

<dg

ct

zus

prt

mt

ha

mt

<gr

ct

hwt

ha

Mss

mlt

Kd

sct hwt

_w

pwt

940

920

900

1060

860

1040

880

10201000 1000

980

960

5711.1

19.912.2

15.6

5.6*

6.1

6*

91

19.5

2618.4 6

7.1

10.3200

130

370

380320

940

186

610

680

300

730

1.879.2

1.78

9

4500

50004

2.6

2.3

1050

1100

1000

1150

950

900

850

800

750

700

650

600

550

500

450

400

1050

1100

1000

1150

950

900

850

800

750

700

650

600

550

500

450

400

350

300

Ele

vatio

n (fe

et)

B’B

Stat

e Hw

y 25

Coun

ty H

wy

39

Coun

ty H

wy

39

Miss

issip

pi R

iverBi

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Long

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ty H

wy

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ticello

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e Hw

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ater

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ty H

wy

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issip

pi R

iver

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mt

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ct1

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zus

ct

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sct ha

<gr

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prs

wmt

nt

cg1

nts

hscghwt

nts

ct1

nt

puprt_mmlt

980 960940

9201000 59

19

7.5

75.9

6.2

29

228

312

250 410

180

232

100

3.4

1000

1800

3.1

2.7

3.9

1050

1000

950

900

850

800

750

700

650

600

1050

1000

950

900

850

800

750

700

650

600

550

500

Ele

vatio

n (fe

et)

A’A

Twin

Lak

e

Miss

issip

pi R

iver

I-94

Stat

e Hw

y24

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gand

Lak

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ty H

wy

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ty H

wy

7

LOCATION DIAGRAM

1000

950

900

850

800

750

700

650

600

550

1050

1000

950

900

850

800

750

700

650

600

550

Ele

vatio

n (fe

et)

Mss

ct1

cg hlmt

psu

cg1

nt

prt

pu

Agn

Cmts

ct

Birch Lake

*aquitard

*aquitard

includes ha, wmt

Aquifers and aquitards grouped by stratigraphy

Quaternary unconsolidated sediment(see Figure 6 in the report for geologic unit correlation)

Quaternary aquitards

Grouped by texture ranging from highest to lowest sand content indicating relative hydraulic conductivity.

Surficial sand and gravel

Buried aquifers and aquitards

Geologic unit code Percent sand

Bedrock Dakota

Jordan

St. Lawrence Formation*

Upper Tunnel City

Wonewoc

Eau Claire Formation*

Mt. Simon

Mesoproterozoic (includes Hinckley, Fond du Lac, and Solor Church)

Precambrian crystalline bedrock (includes Agn, <dg, <gd, <gr, <gu)

_j

_e

_m

_w

_tc

_sl

Kd

Mss

ct

hwt, mt

ct1, nt, prt

hbt, pwt, sct, mlt

hl

>60%

>50% and ≤60%

>40% and ≤50%

>30% and ≤40%

≤30%

Groundwater conditions

Symbols and labels

Land or bedrock surface

General groundwater flow direction

Geologic contact

Approximate equipotential contour; contour interval 20 feet

900

Water table

Tritium age

Darker color in small vertical rectangle (well screen symbol) indicates tritium age of water sampled in well. Lighter color indicates interpreted age of water in aquifer.

Mixed: water is a mixture of recent and vintage waters (greater than 1 TU to less than 8 TU).

Well not sampled for tritium.

Vintage: water entered the ground before 1953 (less than or equal to 1 TU).

Recent: water entered the ground since about 1953 (8 to 15 tritium units [TU]).

CROSS SECTION EXPLANATION

Interpreted tritium age is indicated by background color

Interpreted tritium age is indicated by pattern color

Chloride: if shown, concentration is ≥5 ppm.(* indicates naturally elevated values)

32

Nitrate: if shown, concentration is ≥1 ppm.9.2

Arsenic: if shown, concentration is ≥2 ppb.24

Manganese: if shown, concentration is ≥100 ppb.

Carbon-14 (14C): if shown, estimated groundwater residence time in years.

5000

180

Enhanced-permeability zone

hl*

hbt*

nhs, nts

nt*

ms

mt*

cg

ct*

cg1

ct1*

hs

hwt*

scs

sct*

mls

mlt*

prs

prt*

pwt*

psu

pu

zus

Groundwater moves from an overlying surficial aquifer to a buried aquifer.

Tritium concentrations may be artificially elevated by high capacity pumping.

Groundwater moves from an overlying buried aquifer to an underlying buried aquifer.

Water from the surface moves through a thin layer of overlying fine-grained material to an underlying aquifer.

Groundwater discharges to a surface-water body.

Direction of fault movement, arrows indicate relative movement

Groundwater flowpath is unknown.

Groundwater flows laterally.

)101

)24

)55

)25

)25

)55

94

12

94

Howard Lake

Buffalo

Maple Lake

Annandale

South Haven

Rockford

WaverlyCokato

Montrose

Delano

Albertville

Monticello

Clearwater

45°

94°

94°15'

93°45'

45°15'

B’

A A’

B

C

D

E

G

F

D’

E’

F’

G’

C’

C’C

D’D

E’E

A

B

A’

B’

Symbols

Part B line of cross section shown on this plate

Well used to generate cross section*

A A’

Part B line of cross section shown on Plate 9

D D’

Part A line of cross sectionA A’

N

1 0 1 2 3 4

SCALE 1:300 000

1 0 1 2 4 5 6 7 83 9 KILOMETERS

5 MILES

*Not all wells are displayed in cross section view due to the high density of wells.

1 0 1 2 3 4 5 MILES

1 0 1 2 4 5 6 7 83 9 KILOMETERS

SCALE 1:100 000VERTICAL EXAGGERATION X 50

Hydrogeologic Cross Sections

By John D. Barry

2018

Geologic Atlas of Wright CountyCounty Atlas Series C-30, Part B

Plate 8 of 9Hydrogeologic Cross Sections

A–A’ through C–C’

Minnesota Department of Natural ResourcesCounty Geologic Atlas Program mndnr.gov/groundwatermapping

To accompany the atlas Report and Plates 7 and 9.

Cross Section A–A′

Three areas of coarse-textured sediments (sand and gravel) allow recent tritium-age water to migrate from the land surface to underlying shallow buried sand aquifers. In these areas, elevated chloride and nitrate were present. Elsewhere, loam till (sand, silt, and clay) lessens groundwater recharge and offers a level of protection to underlying aquifers. Aquifers deeper than approximately 100 feet below the land surface had vintage tritium-age signatures. Water collected from two wells in buried sand aquifers had calculated carbon-14 residence times of 1,000 (scs) and 1,800 (zus) years. Groundwater flow, depicted as equipotential lines, is both vertically downward and east toward the regional groundwater discharge zone, the Mississippi River. Local groundwater flow is toward lakes such as Wiegand Lake and Twin Lake and toward small streams.

Cross Section B–B′

Many aquifers are connected along this cross section with no intervening till to impede vertical migration of water. The west and east sides of the cross section have a prevalence of coarse-textured sediments at the land surface that allow recent tritium-age water to migrate from the surface to underlying shallow buried sand aquifers. In the west portion, mixed tritium-age water was found at a depth of approximately 80 feet below the land surface. Vintage tritium-age water was sampled from two wells in Cretaceous deposits (Kd) that are roughly 200 to 250 feet below the land surface. The water from the well near County Highway 2 had a calculated carbon-14 residence time of 5,000 years.

In the central portion of the cross section, more permeable till units and areas of overlapping aquifers allow recent and mixed tritium-age water to migrate to depths of approximately 100 feet below the land surface.

On the east side of the cross section, mixed tritium-age signatures were present to depths 150 to 200 feet below the land surface. This is likely due to coarse sand deposits at the land surface and the higher relative hydraulic conductivity of the intervening till of the Cromwell Formation (ct). In this area recent and mixed tritium-age water was present in aquifers above the Mt. Simon. In the Mt. Simon, vintage tritium-age water had a calculated carbon-14 residence time of 4,500 years. Near Monticello, high-volume groundwater appropriation appears to have brought mixed tritium-age water to depths greater than would be expected without pumping.

Groundwater flow depicted as equipotential lines is both vertically downward and east toward the regional groundwater discharge zone, the Mississippi River. Local groundwater flow is toward lakes such as Clearwater and Long lakes and toward smaller rivers and streams such as the Clearwater River.

Cross Section C–C′

Loam till is the dominant geologic material at the land surface along this cross section. However, near Moose Lake and County Highway 2 coarse-textured deposits allow recent tritium-age water to migrate from the surface to underlying shallow buried sand aquifers. In these locations, aquifers are connected, or have few intervening tills to impede vertical migration of water.

Recharge along the rest of the cross section is more limited, as the loamy till of the Heiberg Member (hbt) has relatively low hydraulic conductivity. Vintage tritium-age water was present on the west side of the line at depths exceeding 150 feet. Water collected from a buried sand aquifer (scs) near Maple Lake had a calculated carbon-14 residence time of 500 years.

East of I-94, recent and mixed tritium-age signatures were common in buried sand aquifers at depths of approximately 150 to 200 feet below the land surface. In general, vintage tritium-age water was present in the bedrock aquifers. Recent tritium-age water was found at depth in a well west of Foster Lake that was inconsistent with the tritium ages determined from surrounding wells; the reason for its occurrence was unclear.

Groundwater flow depicted as equipotential lines is both vertically downward and east toward the regional groundwater discharge zone, the North Fork Crow River. Local groundwater flow is toward lakes such as Maple and Pelican lakes and toward smaller rivers and streams such as the North Fork Crow River.

Note about the vertical exaggerationThe cross sections use a vertical exaggeration 50 times greater than the horizontal scale. The geologic units are otherwise difficult to see at a one-to-one scale.

For comparison, this inset depicts a portion of cross section B–B′ with no vertical exaggeration to illustrate the true thicknesses of the units. The inset location is indicated by the red rectangle near Birch Lake.

This map was compiled and generated in a geographic information system. Digital data products are available from the DNR County Geologic Atlas Program at mndnr.gov/groundwatermapping.

This map was prepared from publicly available information. Every reasonable effort has been made to ensure the accuracy of the factual data on which this map interpretation is based. However, the DNR does not warrant the accuracy, completeness, or any implied uses of these data. Users may wish to verify critical information. Sources include both the references in the report and information on file in the offices of the Minnesota Geological Survey and the DNR. Every effort has been made to ensure the interpretation shown conforms to sound geologic and cartographic principles. This map should not be used to establish legal title, boundaries, or locations of improvements.

Base modified from Minnesota Geological Survey, Wright County Geologic Atlas, Part A, 2013.

Universal Transverse Mercator projection, zone 15N, North American Datum of 1983. North American Vertical Datum of 1988.

500 Lafayette Road St. Paul, MN 55155-4025 888-646-6367 or 651-296-6157 mndnr.gov

This information is available in alternative format on request.

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© 2018, State of Minnesota, Department of Natural Resources and the Regents of the University of Minnesota

Prepared and published with the support of the Minnesota Environment and Natural Resources Trust Fund and the Clean Water, Land and Legacy Amendment