Availability of Ground Water 

in Lyon County, Minnesota

IM »U I

GEOLOGICAL SURVEY 

CIRCULAR 444

PREPARED IN COOPERATION WITH THE DIVISION OF WATERS, MINNESOTA DEPARTMENT OF CONSERVATION 

AND THE MARSHALL MUtsliriPAl IITIIITIF<; MAPSHAII
Availability of Ground Water 

in Lyon County, Minnesota

By Harry G. Rodis

Prepared in cooperation with the Division of Waters, Minnesota Department of Conservation 

and the Marshall Municipal Utilities, Marshall, Minn.

GEOLOGICAL SURVEY CIRCULAR 444

Washington, 0. C. 

196?
United States Department of the Interior

STEW ART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

Free on application to the U.S. Geological Survey, Washington 25, D. C.
CONTENTS

Page Page

Abstract..-.--.........___-____ 1 Availability of ground water ___ ..... 4

Introduction....- ..._......_-_.___ 1 Discussion.. ...................... 5

Geologic conditions.................. 1 Conclusions......................... 6

Ground-water conditions ............ 4 References cited ...» _______ _____ 7

ILLUSTRATIONS

Page 

Figure 1. Ground -water-map of Lyon County ..... _____ _ _ _________________ _.- 3

TABLES

Page 

Table 1. Description of geologic units and their water-bearing characteristics____________ 2

2. Description of selected water wells in Lyon County... . .__.._______._ ___ 6

HI
Availability of Ground 

in Lyon County, Minnesota

By Harry G. Rodis

ABSTRACT

Lyon County is in southwestern Minnesota, about 150 miles 

southwest of Minneapolis and St. Paul. The basement rocks 

in the area consist of granite and quartzite of Precambrian 

age. These materials are in turn overlain by shale and sandstone of Cretaceous age, glacial drift of Pleistocene age, and 

alluvium of Recent age. Ground water is available primarily 

from aquifers in Pleistocene and Cretaceous strata from 

depths ranging from 15 to 500 feet below the land surface.

The county is divided into areas of ground-water availability based on the quality and quantity of ground water 

available from the different geologic units. The glacial drift 

which covers all of the area, yields very hard water from 

sands and gravels occurring in melt-water channel deposits 

or as small, isolated melt-water bodies. Wells in the drift 

commonly yield from 2 to 30 gpm (gallons per minute), but 

sustained yields of as much as 500 gpm are obtained in areas 

where thick melt-water channel deposits occur. Cretaceous 

strata underlie about two-thirds of the county and yield water 

from poorly consolidated sandstone. The water ranges in 

hardness from soft to very hard and is sometimes high in 

chloride content. Wells in Cretaceous strata commonly yield 

from 2 to 7 gpm; however, in areas where the sandstone is in 

contact with" the underlying weathered granite, sustained 

yields of as much as 75 gpm are obtained. The geographic 

and stratigraphic distribution of the geologic units suggests 

that additional water supplies may be available from Pleistocene and Cretaceous strata in areas not yet fully explored.

INTRODUCTION

Ground .water in Lyon County, Minn., is 

available in widely varying quantities from 

several geologic units. This circular summarizes the availability of ground water and 

briefly describes the geologic source and 

quality; its purpose is to present this information to residents and drillers of the area. 

The study was made by the U.S. Geological 

Survey as part of an investigation of the 

ground-water resources of Lyon County in 

cooperation with the Division of Waters, Minnesota Department of Conservation. The investigation was made under the direct supervision of Robert Schneider, district geologist 

of the Ground Water Branch of the U.S. Geological Survey.

Much of the information, in this report is 

based on records of more than 2,500 wells 

collected from well owners and drillers during the summer field seasons of 1956 58. 

Detailed information on individual aquifers in 

the area was obtained from drillers' logs, by 

mapping of surficial glacial deposits, and by 

test drilling supervised by the Geological 

Survey. Determinations of hardness and 

chloride content of water samples were made 

in the field, and some were verified later by 

laboratory analysis.

Lyon County is in southwestern Minnesota, 

about 150 miles southwest of Minneapolis and 

St. Paul in the drainage basin of the Minnesota 

River. The county is approximately rectangular, about 30 miles from north to south and 

24 miles from east to west. It may be divided 

into two distinct topographic units: the southwestern part which lies on the northeast slope 

of the Coteau des Prairies, an elongate highland extending northwestward through South 

Dakota, Minnesota, and Iowa (Fenneman, 1938, 

p. 573); and the northeastern part, which is a 

gently rolling prairie. The southwestern part 

is well drained and is characterized by a 

moderately dissected drift topography, whereas the northeastern part is a flat, poorly 

drained drift plain.

GEOLOGIC CONDITIONS

The geographic and stratigraphic distribution of the major geologic units in Lyon County 

is illustrated on the accompanying map (fig. 1) 

and are described briefly in table 1. The 

basement rocks consist largely of Precambrian granite and quartzite, the quartzite occurring only in the extreme southwestern part 

of the area. In most places the granite is 

deeply weathered and is covered by a thin
AVAILABILITY OF GROUND WATER IN LYON COUNTY, MINNESOTA

Table 1. Description of geologic units and their water-bering characteristics

System

Quaternary

Cretaceous

Precambrian

Series

Recent

Pleistocene

Upper 

Cretaceous

(?)

Approximate 

thickness 

(feet)

0-20(?)

10-550 +

0-450+

(?)

Description

Alluvium made up mostly of 

silt, sand, and gravel, generally restricted to stream 

valleys .

Glacial drift , mostly till made 

up of unsorted mixture of 

clay, silt, sand, gravel, and 

boulders; contains sorted 

and bedded out wash deposits of sand and gravel deposited in channels and 

lake basins; till contains 

small lenses and irregularly shaped bodies of silt, 

sand, and gravel.

Shale, soft, dark -bluish-gray 

contains thin zones of interbedded sandstone, siltstone, and lignite; sandstone is fine grained and 

loosely consolidated and 

generally occurs in beds 

less than 2 ft thick.

Quartzite, hard, compact, 

pink, fractured.

Granite, pink, red, and gray, 

coarse-grained, biotitics; 

weathered and creviced at 

the top.

Water -bearing 

characteristics

Not an important aquifer because of its limited thickness and areal extent.

Outwash sand and gravel 

yields small to large supplies of water, the amount 

depending on the thickness, 

extent, and permeability of 

the deposits. Till is relatively impermeable; small 

to moderate amounts of 

very hard water are obtained from small bodies 

of silt, sand, or gravel in 

the till.

Sandstone usually yields 

small amounts of water. 

Shale, silt stone, and 

lignite are virtually impermeable.

Virtually impermeable;. may 

yield a little water from 

creviced zones.

Virtually impermeable; may 

yield a little water from 

weathered and creviced 

zone.

regolith, consisting in part of weathered materials transported and reworked during Cretaceous time.

The Precambrian rocks are overlain in 

places by flat-lying Upper Cretaceous strata 

composed largely of thick sections of soft 

dark-bluish-gray shale but including thin beds 

of loosely consolidated sandstone. The strata 

were deposited in a basin whose axis bisects 

the county from northwest to southeast. They 

are more than 450 feet thick near the center 

of the basin and gradually pinch out against 

its flanks.

Glacial drift, deposited during successive 

advances and retreats of the Pleistocene ice 

sheets, overlies the Precambrian and Cretaceous rocks. The drift, which consists largely 

of till, ranges in thickness from about 10 feet 

in the north and northeast to about 550 feet in 

the southwest.

The most prominent surficial glacial deposits in the county are 5 northwestwardtrending end moraines, 2 of which are associated with, and parallel to,relatively extensive 

.belts of outwash. The intervening areas are 

flat to slightly rolling ground moraine. In the
1

Index map 

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PIPESTONE 

COUNTY I

Base modified from general highway map 

of the Minnesota Department of Highways
AVAILABILITY OF GROUND WATER IN LYON COUNTY, MINNESOTA

southwest, where the drift is very thick as a 

result of multiple glaciation, buried meltwater channel deposits having no obvious topographic expression probably occur at depth 

(Schneider and Rodis, 1959, p. 1671).

GROUND-WATER CONDITIONS

The principal sources of ground water in 

Lyon County are the permeable deposits of sand 

and gravel in the glacial drift and the sandstones of Cretaceous age (table 1). Although 

water is locally obtained from Recent alluvium 

and Precambrian rocks, these materials are 

not dependable sources of water.

Water in the glacial drift may occur under 

artesian or water-table conditions. The water 

is usually very hard and low in chloride, and 

contains large amounts, 2 to 6 ppm (parts per 

million) of iron. In most places wells in the 

drift yield 2 to 30 gpm (gallons per minute); 

however, where melt-water channel deposits 

occur, sustained yields of as much as 500 gpm 

are obtained. In the northern and northeastern parts of the county where the drift is thin, 

static water levels in the drift range from 5 

to 20 feet below the land surface. Where the 

drift is thicker, as in the southwest, static 

water levels generally range from 30 to 150 

feet below the land surface.

Water in the Cretaceous sandstone occurs 

under artesian conditions and is commonly 

softer, lower in iron (0 to 2 ppm), but higher 

in chloride content, than the water in the 

glacial drift. Because the Cretaceous aquifers 

have low coefficients of permeability and are 

relatively thin, they commonly yield only 2 to 

7 gpm to wells. However, where they are in 

contact with the underlying regolith and the 

weathered granite, yields as high as 75 gpm 

are sometimes obtained. Static water levels 

of wells in Cretaceous strata generally range 

from 20 to 70 feet below the land surface. 

There are some flowing wells in the central 

part of the county, however.

AVAILABILITY OF GROUND WATER

Division of the county into areas of groundwater availability (fig. 1) is based on the 

amount and the quality of ground water available at various depths from the different geologic units. These areas are described as 

follows:

AREA A

[Glacial drift is underlain by Cretaceous strata]

Most wells obtain water from Cretaceous 

sandstone at depths of about 100 to 300 feet; 

some tap the overlying glacial drift at depths 

of 15 to 75 feet. A few wells obtain small 

amounts of water from the underlying weathered granite. Yields from Cretaceous sandstone generally range from 2 to 7 gpm.

Where water is obtained from the drift, 

wells yield from 2 to 30 gpm; higher yields, 

as much as 500 gpm, can be obtained where 

the drift contains melt-water channel deposits. 

Known melt-water deposits are outlined on 

the map. The water from the glacial drift 

usually is very hard ( > 500 ppm) but is low in 

chloride content ( < 50 ppm).

AREA AI

9

Water from the Cretaceous sandstone is 

hard (120 to 500 ppm) and is high in chloride 

content (500 to >2,000 ppm).

AREA A 2

Water from" the Cretaceous sandstone 

ranges from soft (< 60 ppm) to hard, and its 

chloride content commonly is moderately 

high (50 to 500 ppm).

AREA B

[Glacial drift is underlain by Cretaceous strata or Precambrian 

granite]

Most wells obtain water from the glacial 

drift at depths of about 15 to 125 feet. In 

some places, however, water is obtained from 

Cretaceous sandstone at depths of 100 to 180 

feet, and from the weathered granite at depths 

of 40 to 250 feet.

Wells in the drift may yield 2 to 30 gpm. 

Sustained yields of 75 gpm have been obtained 

where the drift contains melt-water deposits. 

The water is commonly very hard but is low 

in chloride content.

Wells in the Cretaceous sandstone and in 

the weathered granite normally yield 2 to 7
DISCUSSION

gpm. The water ranges from moderately hard 

(60 to 120 ppm) to very hard and, in places, 

is moderately high in chloride content.

AREA C

[Glacial drift is underlain by Cretaceous strata]

Very hard water is obtained from the glacial 

drift at depths of about 15 to 80 feet and from 

Cretaceous sandstone at depths of about 40 to 

120 feet. In places, moderately hard or hard 

water in smaller quantities is obtained from 

Cretaceous sandstone at depths of 220 to 280 

feet. The weathered granite is of little importance as a water source.

Well sin the drift and in the shallow aquifers 

of Cretaceous age yield about 2 to 45 gpm, but 

yields from the deeper Cretaceous aquifers 

are generally less than 7 gpm. Higher yields 

may be obtained from melt-water channel 

deposits in the drift.

AREA D

[Glacial drift is underlain by Cretaceous strata]

Most wells obtain water from Cretaceous 

strata at 1 of 3 horizons: 40 to 120 feet, 240 

to 280 feet, and 325 to 425 feet. Water is obtained also from the overlying glacial drift at 

depths of about 15 to 175 feet. A few wells 

obtain water from the weathered granite.

Wells tapping shallow aquifers of Cretaceous 

age (40 to 120 feet) generally yield 2 to 20 gpm. 

Commonly the water is hard to very hard, but 

it is low in chloride content. Wells in the 

deeper Cretaceous aquifers (240 to 280 feet 

and 325 to 425 feet) normally yield 2 to 7 gpm. 

The water is soft to hard and commonly is 

moderately high in chloride content. Where 

Cretaceous aquifers are in contact with the 

underlying regolith or the weathered granite, 

sustained yields of as much as 75 gpm have 

been obtained. Several flowing wells in the 

southwestern half of the area yield as much 

as about 2 gpm from the deeper Cretaceous 

aquifers.

Water in the drift is very hard but is low in 

chloride content. Yields commonly range 

from 2 to 30 gpm. Sustained yields of as much 

as 500 gpm have been obtained in places where

the drift contains 

deposits.

thick melt-water channel

AREA £

[Glacial drift is underlain by Cretaceous strata or by Precamtman 

quartzite or granite]

Most wells obtain water from the glacial 

drift at depths ranging from 15 to 450 feet, 

although the majority of the drift wells are 

less than 250 feet deep. Water in the glacial 

drift is very hard but low in chloride; yields 

of wells in drift commonly range from 2 to 

30 gpm. A few wells obtain small amounts of 

water from the weathered granite or from 

quartzite at depths greater than 450 feet.

AREA EL

[Glacial drift is underlain by Cretaceous strata]

Near the northeast border of this area, 

wells 200 to 500 feet deep yield 2 to 7 gpm 

from Cretaceous aquifers. The water from 

the Cretaceous strata is moderately hard to 

hard but is low in chloride content.

AREA Eg

[Glacial drift is underlain by Cretaceous strata]

In this area flowing wells yield about 30 to 

150 gpm from Cretaceous strata at depths 

from 225 to 300 feet; the water is very hard 

but is low in chloride content.

AREA E8

[Glacial drift is underlain by Precambrian quartzite or granite]

A few wells obtain small amounts of water 

from the quartzite.

DISCUSSION

The density of well information of which 

the map areas are based averages about 3 

wells per square mile. Selected well information is shown on table 2; data on additional 

wells are on file at the U.S. Geological Survey, 

St. Paul, Minn.
AVAILABILITY OF GROUND WATER IN LYON COUNTY. MINNESOTA

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Countywide differences in the geologic 

source of ground wate*r are shown by areas 

A, B, C, D, and E; differences in the quality of 

water from a particular source are indicated 

by subscripts, as area A^ and area A 2 (Rodis 

and Schneider, 1960). In areas £and E ground 

water is obtained from the glacial drift, 

whereas in areas A and D it is obtained primarily from the Cretaceous strata. In -area C 

the glacial -drift and Cretaceous strata are 

equally important as water sources. It should 

be noted, however, that where surficial meltwater channel deposits cross areas A, C, and 

D, these drift deposits may be the principal 

source of ground water.

The distribution of geologic units in the 

county suggests that additional water supplies 

may be available from strata not yet fully 

explored. Test drilling of surficial meltwater deposits near Marshall, in area D, has 

shown that they are not necessarily confined 

to the area beneath the surficial melt-water 

channel, but may extend 1 mile or more beyond its limits (Schneider and Rodis, 1959, 

p. 1671. Even though test drilling of these deposits was confined to a small area, it is probable that similar subsurface conditions exist 

in other parts of the same channel in areas 

C and D as well as in the melt-water channel 

that crosses area A. As was mentioned 

earlier, buried melt-water channel deposits 

probably occur in area Bt but considerable 

drilling would be necessary to determine their 

extent.

Although Cretaceous rocks underlie much of 

area E, water, supplies from these strata are 

obtained by only a few wells along the northeast margin and in area E2 . Inasmuch as 

multiple areally extensive aquifers are present in Cretaceous strata throughout areas A> 

C, and D and adjacent parts of £lt it is likely 

that they occur also in the Cretaceous strata 

underlying area £ .

CONCLUSIONS

Ground water in quantities adequate for 

domestic use and moderate-scale municipal 

and industrial use is available from deposits 

of sand and gravel associated with two 'surficial melt-water channels in northeastern 

Lyon Coomty and in buried melt-water channels 

in the southwest. Because of the sinuous shape 

of these deposits, any large ground-water
REFERENCES CITED

development should be preceded by an adequate 

program of test drilling and test pumping.

Supplies of ground water adequate for domestic and small municipal or industrial 

needs are available from small, isolated deposits of sand and gravel in the glacial till. 

These deposits are more numerous in the 

thick drift of the southwest than they are in 

the thin drift of the north and northeast.

Small quantities of ground water, adequate 

only for domestic supply, are available from 

the thin sandstone of Cretaceous age in the 

northern and northeastern parts of the county. 

It is likely that small supplies may be available also from Cretaceous aquifers at depth 

in the southeastern and south-central parts 

of the county.

Although water from Cretaceous aquifers 

is generally softer and lower in iron content 

than that from the glacial drift, supplies are 

small and adequate only for domestic use. 

Where larger supplies are needed, as for expanding municipal water systems and industrial developments, adequate amounts of water 

may locally be obtained from the thicker more 

permeable aquifers in the glacial drift.

REFERENCES CITED

Fenneman, N. M., 1938, Physiography of eastern United States: New York, McGraw-Hill 

Book Co., 714 p.

Leverett, Frank, 1932, Quaternary geology of 

Minnesota and parts of adjacent States: U.S. 

Geol. Survey Prof. Paper 161, 149 p.

Rodis, H. G., and Schneider, Robert, 1960, Occurrence of ground water of low hardness 

and high chloride content in northeastern 

Lyon County, Minnesota: U.S. Geol. Survey 

Circ. 423, 2 p.

Schneider, Robert, and Rodis, H. G., 1959, 

Aquifers in melt-water channels along the 

southwest flank of the De.s Moines lobe, 

Lyon County, southwestern Minnesota [abs.]: 

Geol. Soc. America Bull., v. 70, no. 12, 

p. 1671.

INT.DUP.,D.C.61- 91835