.... .

RESOURCES

Wapello County

Open File Report 79-90 WRD

Compiled by PATRICIA M. WITINOK

GROUND-WATER RESOURCES OF WAPELLO COUNTY

Introduction

Approximately 56 percent of the residents of Wapello County rely on ground water as the source of their drinking water. It is estimated that the use of ground water in the county currently approaches 2.52 billion gallons per year. For comparison, this amount would provide each resident with 150 gallons of water a day during the year. Actually, few if any households use this much water, and the rather large annual per capita use reflects the greater water requirements of the county's industries, agribusinesses, and municipalities.

The users of ground water in the county draw their supplies from several dif­ferent geologic sources. Several factors must be considered in determining the availability of ground water and the adequacy of a supply source:

distribution - having water where it is needed,

accessibility - affects the costs for drilling wells and pumping water,

yield - relates to the magnitude of the supply that can be sustained,

quality - determines for what purposes the water can be used.

In terms of these factors, there are few locations in Wapello County where the availability of ground water is not limited to some degree. The most common limitation is poor water quality, that is, highly mineralized ground water. Secondary limitations are generally related to poor distribution, small yields from some sources, and poor accessibility due to the great depths to adequate sources.

Occurrence of Ground Water in Wapello County

The occurrence of ground water is influenced by geology -- the position and thickness of the rock units, their ability to store and transmit water, and their physical and chemical make-up. Geologic units that store and transmit water and yield appreciable amounts to wells are called aquifers. The best aquifers are usually composed of unconsolidated sand and gravel, porous sandstone, and porous or fractured limestone and dolostone. Other units with materials such as clay and silt, shale, siltstone, and mudstone yield little or no water to wells. These impermeable units are called aqui­cludes or aquitards and commonly separate one aquifer unit from another.

In Wapello County there are four principal aquifers from which users obtain water supplies. The loose, unconsolidated materials near the land surface comprise the surficial aquifer. Below this there are three major rock aquifers -- the Mississippian, the Devonian, and the Cambro-Ordiv.i ci an aquifers. ::figure 1 shows the geologic relations of these beneath the county. Each of the -aquifers has its own set of geologic, hydrologic, and water quality characteristics which determine the amount and potability (suitability for drinking) of water it will yield.

1

Surficial Aquifers

Unconsolidated deposits at the land surface are comprised of mixtures of clay, silt, sand, gravel, and assorted boulders. Water-yielding potential of the surficial deposits is greatest in units composed mostly of sand and/or gravel. Three types of surficial aquifers are used: the alluvial aquifer, the drift aquifer, and the buried channel aquifer.

The alluvial aquifer consists mainly of the sand and gravel transported and deposited by modern streams and makes up the floodplains and terraces in majoi valleys. Alluvial deposits are shallow, generally less than 50-60 feet and thus may be easily contaminated by the infiltration of surface water.

The drift aquifer is the thick layer of clay to boulder size material deposited over the bedrock by glacial ice which invaded the county at least twice in the last two million years. The composition of the glacial drift varies con­siderably and in many places does not yield much water. There are, however, lenses of beds of sand and gravel within the drift which are _ thick and wide­spread enough to serve as dependable water sources. These lenses are difficult to locate because they are irregular in shape and buried within the drift de­posits. Usually one or two sand layers can be found in most places that will yield minimum water supplies for domestic wells.

The buried channel aquifer consists of stream alluvium of partially filled valleys that existed before the glacial period. The valleys were overridden by the glaciers and are now buried under glacial and recent alluvial deposits.

The distribution, yields, and water quality characteristics for the surficial aquifers are summarized in Figures 2, 9, and 13. An indication of accessibility can be obtained by comparing the elevations of the top (the land surface) and the bottom (the bedrock surface) of the surficial deposits from Figures 4 and 5. The thickness of the glacial drift and the depth of the buried channels are determined by subtracting the elevations at selected locations.

Rock Aquifers

Below the surficial materials is a thick sequence of layered rocks formed from deposits of rivers and shallow seas that have covered the state within the last 600 million years. The geologic map (Figure 3) shows the geologic units which form the top of this rock sequence. These rocks are Pennsylvanian in age and are mainly shales. Although the Pennsylvanian rocks usually act as an aquiclude, there are locally sandstone layers (particularly in the central area near Ottumwa and west central areas of the county) which supply small yields to domestic wells. The thickness of the Pennsylvanian rocks varies from about 150' in the vicinity of Ottumwa to 0 to 10' in the western part of the county.

Underlying the Pennsylvanian aquiclude is a series of older rocks, parts of which form the three major rock aquifers in Wapello County. This sequence and the water-bearing characteristics of the aquifers and aquicludes are shown in Table 1.

2

·W ')

KEY

~Glacial Drift

~Shale ~j Limestone l ;:·;~,:_'~~'. J i sandstone

.. .... .. .-....... --it· ..... - ....... ·- .... - .~ ..... . ....... ...,__ ---- - -- .. . ...... .

Figure 1

BLOCK DIAGRAM SHOWING THE GEOLOGY OF WAPELLO COUNTY

. . .. .. ... . .... , ..... . , ...... ,... .... .

r

Examples of the sequence of rock units encountered in drilling existing wells at various locations in Wapello County are indexed and illustrated in Figures 7 and 8. The geologic unit that supplies ground water and the amount of water yielded to the well are shown next to each of the well logs.

The accessibility of ground water in the rock aquifers depends first on the depth to the aquifer. The deeper a well must be, the greater the cost for well construction and pumping. The depths to and thicknesses of units at specific sites will vary somewhat because of irregularities in the elevation of the land surface and in the elevation of the tops of the underlying rock units. Estimates of depths and thicknesses can be made by comparing Figure 4 with the maps of aquifer elevations in Figures 10, 11 and 12. The range in depth below land surface to the top of the county's principal bedrock aquifers is given for each township in Figure 6.

The second factor which affects accessibility is the level to which the water will rise in the well (the static water level). Since water in the rock aquifers is under artesian pressure the water rises in the well once it pene­trates the aquifer. This rise in water level can reduce the cost of pumping. Average static water levels in Wapello County wells are shown in Figures 10, 11 and 12.

Average yields and water quality characteristics throughout the county for each of the aquifers are also summarized in the maps in Figures 10, 11, 12, 13, 14 and 15.

4

Tab 1 e 1

GEOLOGIC ANO HYOROGEOLOGIC UN ITS IN WAP ELLO COUNTY

Water-Bearing Age Rock Unit Description Thickne ss Range* Hydrogeol ogic Unit Characteristics

Alluvium Sand, gravel, si lt and c lay Fair to large yields (25 to JOO gpm)

Qua ternary Gl acial drift I Predominantly ti 11 conta ining 0- 250 ( feet) Surficia l a qui fer Low y ields (undifferentiated) I seat tered irregular bodies of ( less than IO gpm)

I sand and gravel

Buried channel Sand, gravel, silt and clay Small to large yields deposits

Pennsyl vania n Des Moines Series Shale; sandstones; most l y 0- 150 Aquic l ude Low yields only from thin limestone and sandstone

Meramec Series Sandy l imes tone

Mississ ippian Osage Serie s Limestone and dol ostone cherty; sha le 150- 450 Mi ssissippian aquifer Fair to low y ields

Ki nderhook Series

I Limestone , ooli tic, and dolostone, cherty

Maple Mill Sha l e

Sheffield Formation Shale; limestone in 450 - 650 Devonian aqu iclude Does not yield water lower part

Devonian Lime Creek Formatior

Cedar Va 11 ey Li me-Stone Limestone and doloston~;

contain s evaporites (gypsum) 650- 1000 Devonian aquifer Fair to low y ields Wapsipinicon in so uthern half of Iowa

Formation

Maquoketa Format ion Shale and dolostone Maquoketa Aquiclude Does not yield water

Galena Formation Do l os tone and chert Minor aq uife r Low yields

Decorah Formati on- L imes tone, dolostone and Ordovician Platteville Forma- thin shale inc ludes san d- 1000- 1800 Aq ui cl ude Does not yield water

ti on stone in SE Iowa

St. Peter Sa ndstone Sandstone Cambri an - Ordovician Fair yields aquifer

Prairie du Chien Oolostone, sandy and High yields Formation cherty (ove r 500 gpm)

Jordan Sands tone Sand s tone - - - - - - -

St. Lawrence Dolostone Cambrian Formation 1800 Aquitard Low yields

Franconia Sandstone and Shale Sandstone

Dresbach Group Sands tone Dresbach aquifer High to low yields

Precambrian Und iff eren ti a ted Coarse sandstones: Base of ground- Not known to yield crystalline rocks water reservoir water

* includes approximate depth to formation

5

Z .

r-­i-:

I

~--- ----' j i ia.~

0

Figure 2

SURFICIAL MATERIALS

R.15 w. R.14 w. R.13 W R.12 w.

·-1·-·-r·--1--+--r----1-!.lp.~--+-*+--+-+-+---t-+----+----r-==t--t---·41 ~f--+-7-[]~-~-L(+-+---+--~~-+=-c±--+----+r-+-t-+--t--r--.

---+--- --- ---t--: DIUotL0HH4

d --- . .

___ l __ ._ . ..,

....... ~-+~-+CJ'-+-~+-~+-~

L-·- _L__L __ _ R.15 w. R. 14 w.

~ Alluvium

'I I Glacial Drift

[IJJTI Buried Channels

R.13 W.

6

... ..._. ""° Rl2W.

z . C\J r--i-:

Figure 3

GEOLOGIC MAP

c R.15 w. R.14 w. R.13 w. R.12 w. !"' ~~ ·-·., ---,- i

[]--~~

z z If) If) ,.._ ,._ t-= t-=

' I ' ' --- -!'----- -- ---,--' 0.MLOMEM

i.U

z z N N ,.._ ,.._ t-= t-=

j_ ___ ---- ----- --- --- --- --- --,...--' i I

i j i ITT .. ......ANO

CJ z z ,._ ,.._ t-= t-=

i . i ! - J_j ' I

' I ' i __ L. __ L ____ ' L-·- ___ L._. ... ..,_.

""'° R.15 w. R.14 w. R.13 w. R.12 w.

LJ Pennsylvanian

f$&11Ji?fiJ Mississippian - Upper Part

7

:z:: C\I ,._ .,._:

:z::

Figure 4

ELEVATION OF LAND SURFACE IN FEET ABOVE MEAN SEA LEVEL

Rl5 W. R.14 w

R.15 w. R.14 w

600-700

700-800

8

R.13 w

R.13 w

f;;;;;;; ;1 800-900

-!!:§ff@ : 900-1000

R.12 w.

DU..,_. . ._ R.12 w.

-----;

:z::

z ,..., ,._ I-'

z (\J ,._ I-'

Figure 5

ELEVATION OF BEDROCK SURFACE IN FEET ABOVE MEAN SEA LEVEL

R.15 w.

R.15 w.

f0:rnsHtl Below 600

r -- 1- 600-700

R.14 w.

R. 14 w.

R.13 w.

R.13 w

9

R. l2W. ":-7-;-•• ;-;-;- • -;-; ..,.

: : : : : : : : : : : ~

·--R.12 W.

700-800

Over 800

z (\J ,._ I-'

Figure 6

RANGE IN DEPTH TO WAPELLO COUNTY 1 S PRINCIPAL ROCK AQUIFERS

R. 15 w \- - -- - ·- -- ·-

I i BEDROCK

0- 100

z MISSISSI PPIAN

100- 300 t<) ,.._ OE VON IAN I-' 600 - 900

CAMBRO- ORDOV ICIAN

lB00 - 2000

I

BEDROCK

0- 200

NISSISSIPPIAN

z 100- 300 C\J DEVONIAN ,.._ I-' 600- 900

CAMBRO -ORDOVICIAN

IB00- 2000

BEDROCK 50- 300

MISSISSIPPIAN z !00 - 300 ,.._

DEVON IAN I-' 700-1000

CAMBRO- ORDOV IC IAN

1900- 2100

R. 14 W R. 13 w _] _________ ____ ____________ _

BEDROCK BEDROCK

0- 100 0-100

MISSISSIPPIAN MISSISSIPPIAN

100- 200 100- 300

OE VON I AN

700 - 900

CAMBRO-ORDOVIC IAN

lB00-2000

BEDROCK

0- 100

MISSISSIPPIAN

100- 300

DEVONIAN

500- 900

CAMBRO - OROOV ICIAN

1700- 2000

BEDROCK

50 - 250

MISSISSIPPIAN

100- 300

DEVON IAN

500 - 900

CAMBRO- ORDOVIC IAN

1750-2000

DEVON IAN

700-900

CAMBRO-ORDOV IC I AN

1700- 1900

BEDROCK

0- 100

MISSISSIPPIAN

100-300

DEVONIAN

500 - 900

CAr1BRO - ORDOVIC IAN

1700- 2000

BEDROCK

0- 100

MISSISSIPPIAN

100- 200

DEVON IAN

500 - 90D

CAMBRO- OROOVIC IAN

1750- 2000

'-- ·- ·- ·- ·-·- ·- ·- ·- ·- -- -- ·- ·- ·- ·- - ·- ·- · - ·- ·- ·- ·-· - ·- ·- ·- ·- ·- ·- ·- ·- ·-

R. 15 W R. 14 W R. 13 w

10

R. 12 W.

--- ---------- - --- ~

BEDROCK

0- 100

Ml SS I SS I PP IAN

50 - 200

DEVON IAN

700 - 900

CAMBRO -ORDOV IC I AN

1700- 1900

BEDROCK

0-1 00

MISSISSIPPIAN

!00- 200

DEVONIAN

500-900

CAMBRO - ORDOVICJAN

1700-1900

BEDROCK

0- 100

MISSISSIPPIAN

100- 200

DEVONIAN

500-900

CAMBRO-ORDOV IC I AN

1700- 1900

R. 12 w

I

- ·- ·J

z C\J ,.._ f-

z ,.._

~

z: I') .

l'-1-'

z: C\J ,._ I-'

R.15 w.

i----- ---- --1 j i

Figure 7

INDEX MAP FOR TYPICAL WELLS IN WAPELLO COUNTY

R.14 w.

' I I I

R.13 w.

--- - ---- ----:----- --- ---

• OU.LOl«M

R.12 W.

--, i

I i ___ ...j

I i

i11..~ ........ .,

~Cj~L_-J_--i---J.~-l--~-+~-l---+--+~+---t--t~t--plllllf~ft--j-J---t'0'--+---1---+----'

L I I I , - ·-'---

R.15 w. R. 14 w. R.13 w. R.12 w.

11

z: I') ,._ I-'

z: C\J l'-1-'

z: ,._ I-'

0

500

t-w w LL

z _J _J w 1000 3 LL 0

I f-Cl.. w 0

1500

2000

Figure 8

TYPICAL WELLS IN WAPELLO COUNTY

Jack Hartman

~p

D~~ y =I+

® Earl

Glenn

Y=7

V.R. Robertson

Op

Rex Dickey

fill:p a~M

y = 10

® L.A. Bill

Garrison Boyd __ Op NS

bo ~~~~ Qp

-_-_:-p

y =12 Y=6

Dr. R.R. Pearson

Y=IO

EXPLANATION

~ Glacial Drift

~Shale

~ Limestone-Dolostone

[] Sand-Sandstone

~Chert

~ Gypsum-Anhydrite

12

0 Water Producing Unit

Y Yield in gal/min

NS No Sample

Op Quaternary-Pleistocene

P Pennsylvanian

M Mississippian

D Devonian

O Ordovician

.f Cambrian

®

y = 3000 :t

Figure 9 SURFICIAL AQUIFERS

Water Levels

Water levels in the ·surficial aquifers are difficult to analyze, water rises to different levels in wells drilled into alluvial, buried-channel, and drift aquifers. The water table in the drift aquifer generally slopes from high land areas toward the streams and, changes noticeably throughout the year. Levels in drift and buried-channel aquifers respond rapidly to recharge from precipitation. Water levels in the alluvial aquifer fluctuate somewhat in the same way as those in the drift and buried-channel aquifers; however, the main influence on the alluvial aquifer is the stage (level) of the associated streams. Water levels will be high during periods of high stream stage and low during the low-stage periods.

Water levels in the drift aquifers commonly are from 10 to 50 feet below the land surface, and those in the buried-channel aquifers have been reported to be as low as 175 feet below the land surface. The water levels in allu­vial wells are from 4 to 20 feet below the flood-plain surface and the depth to the water surface will be accordingly deeper in wells located on terrace surfaces.

Water yields to wells in gallons per minute

LJ Below 20

L~~~~J 20-100

1 ·;1;·1:;·::,'::*·;:,:~:.-1 100-500

13

Figure 10

MISSISSIPPI~N AQUIFER

~..,-l.-l-~~j__j-+~~&-·~7f7(;ft-l+-r--t-t-+-A:-~ z .. ... ""

'=-'--lc~~,.!=~4-,il"{;,..£,,,c_+-'-+-+--±:~~~~-+---t---: ~

Rl5W Rl3W RS2W.

Elevation of Mississippian Aquifer in feet above mean sea level

...

lllO. ....... ll 13"' 11-H i I l ..... 11!

71"";_- ,, ·" '{.._ \ i [[LL il !'... '

~r ; "'' - I"-. \. l l iii""

i... i'\ !VI'\, -....;., 'l.. I ! "'-: J ,, ~ ~I 1'' -...J ; ,_

f 7 J' -~ '- I ~- ~ ' J .

(i' O> k"' ~Li 1'. 'Ci_ I 1\ "' ' , . r

!f-t--' N ... "" · ~ ;)

' I ' O"i

"">--

~ \JI.... ! .......... ti ']' i l"N.~

' r7. ~ I i \ 1 ~ ; I

i\ I ; . f<-V\. i.....

I .: " t~ tr n-T·-i1 -~

"' I . ! I 11 · : ! ~ · ,_

' : :_/i !/ 1 : -......_ IJ

'f'J1 ~ -

"" 'I

......

"' '"' \

;

I ~ ..... ':c' rr::. i

I

; \

R.IZ'lll

,, I I .,,.,, I

;

l ""'~ l

"' ~ I I ,, .... I

1_.....,,. 't / I

; I

(I I I 0 I

I

'-,- '\ I

I "1 I I

v r ~ -: -~ ; IL ~--~ L I ;/(J: i ,...__ ,___ : __J__J_ _J

~

Rl5W R.M'lll Rl3W Rt2W.

Water levels in wells in feet above mean sea level

Upper-Part

n- R.IZW

'; . 1 ~ .<.'- ..... ·, : r R.14 ·-111-r ·--R.-13_•_ ....... -4-~-~~~

I I I I ; I l~~ I i 111 il

: i ' ' _ i I i "'- . -;::.._ i\ n; I ' I I ~ ' ' .I :: I l'-1\, i I I--

I . I i I/,"\: I "'- ~ )'.. ! ~ 1- ~·~,,._.+-+-,~---+--+-+-+-,f-+-+-'--.....p.~~-+--+-+-: f / I y -\.._ I "' '

I \ ! /' 1\.... 1 , i... f"<.-1 z ::~-1 1 i I ~~ ~ 1 ~r 1 I ~>: ... :J~ i I

J I '"'-'..!<''\. '- I

OT I ; I z ' ' I I I '/' /'. ~ , ....,._ I : T"'-' 1 ;-. : x:: :·:·:t i I

i ----"\ ~ -+-- I ; \_ Li--.~.._l'--"~-_,_.;... __ ~1-_,__._i _._1 _"-'-~' -~~~' · _LL_ n , l

Rl!SW ....... R. 13W lllZW-

Water yields to wells in gallons per minute

% .. ... ...

~~~~~f ;c+..+-4"-+-~~~~~ z

~µ+:.;.~!-+-+--+e--h:~P:::i:-1 ~

R.14W Rl3W Rl2.W.

Dissolved solids content in milli­grams per liter (mg/l)*

""

z .. ... ...

% ~ ...

LJl selow 20

1·;~!;{i't i;f1;;~i!i; l [ 20-so

- 500-1000 . ' ;

c===:=JGreater than . ----- ~ 2500

1000-2500

*Other water quality data in Figure 13

14

MISSISSIPPIAN AQUIFER

IU4W. IU3W n- lll2W

'l I

~ i \ n' _ I

' J I ~-,. i

: ! I T I ' - ; l --

z , I

~ I "'-"'

R.tS. R.HW R.13W fl r2 • .

Water yields to wells in gallons per minute

Lower Part

.1 I I z ;

:!' ... !

15

k.!--h~~~~_,;..,,.,..:._L-!-l-_;_-f--t-l~""'P~7-t-t-t-~ ~ L.,-=J..-+-~+---+-L-+-+::~"'+-~+-t-1--t-T--t-,--,;~~~ ...

R.15W R.HW R.13 w. RS2W.

Dissolved solids content in milli­grams per liter (mg/l)*

jr: . +j 1000-2500

I 1·2500-5000

*Other water quality data in Figure 14

Figure 11

DEVONIAN AQUIFER

~,.,.....J.---+-f-'-+-+-\+-P"l~~-~~-+--t-t-i---;-t-t---t-::.t::~ z

~~=-f::'....L-l---l-\-1---!~Q:i:"'l'---l--+-t-r-t---t-t-+:rf---t-t-! ~

R. 15 W. R13W R'2W.

Elevation of Devonian Aquifer in feet above mean sea level

Water yields to wells in gallons per minute

...

16

' I 111

lll4.

: I "'~ I j

~ : I ,rv, I ! I I ·~~ ' I '

J'll3W

: i..... v ; '"""" n lJ J.Ll l :rt I I(,-..._ I ' U..

n- R.12W.

. , i I l I :Z: .( .. -I\ o-; .. i

.---.... I.I ; I I

I I f'\. I

: \ I I i ..... I " :.. -+-+--+---+-t-t--+-+--t.2;--:1"~" :N z : ~ _,.) i 1 I [~1-== ~ 1 ~ ~ ,!_»- I JI'{).... : I/ I'"'

: ;

!

v f ; ; ' ,,r y "'l-7i""'*--+-+-+,...,_f-IJ-+--t--r-h1 u__,_ _ 1 1..:..L_ H- H-"ni:..r.:i_;r..: >.:11 1L-lll,~',1....-1-'--'=":....i--+--+-r-+--:! : ! I i : . I

I : r ,_:_

--

R.15 w RMW JU3W

Water levels in wells in feet above mean sea level

R"'W ...... RJ3 W n- Jl 12 •

-\.: II' l.l~Fi! ' -...; i i I . ]

z .. .. ...

.. .. ...

z ;;: ...

:"- !IrL I i\ : I~ I I i ..... l I , ..... !"- ' j ! : -· 1~: j

Lr "~ ru !Hl : -: f ' f( ! 1..... i ' ; : \ ' /' I \.. i i.,._

' ~ _,.) r ~· d-'

"--11'"1 ! I I ! r r-.. ' I I

'.) I : I I .,r """' ._

u__ +t -1-H-~ Jr\ I Tl : ! i ' I

ir:- I I I ' I I i

f I I _.L I ~ ; ; i : I

~ - : :V 1 '!'-- ! ..:.. i : r. f9j]_L_l_L I L

R.15 w RMW.

l I I

Gl"= i\ :;-~ i ' I'\... I I ;

'-.- I )'._ I

~ :-- I/ ! : I : ['\ ! : ........ - : 1'l I

; ~"! I i Li I I I I

I I : lJ J ' I r,_:_ . J

l\r i I I !

1 - ' . I I ......,

l L I I I l I i I ' I I

I

~ l'-c- 1 L __;

R.I! W Rl2.W_

z N .. ...

z ;:: ...

Dissolved solids content in milligrams per liter (mg/1 )*

*Other water quality data in Figure 15

Figure 12

CAMBRO-ORDOVICIAN (JORDAN) AQUIFER

II.Ill• 11.14. - 12"00 ll 13 w n-- ..

--\:-, .... .. .. ....

! : ! !

. if

:'

"" ...._

-

L,.r

I

i 'l. ~i;i !

r 1'. I\ ~ i ........ ... qi-

"' I'\. i i I\.. [..d"\! --...,..... T

. ..,.....,, i I( i -\...! i ~

I: : ll. ~

z .. .... ....

: .!""<- [..J j ! I I f'..'...'il ~ I .'...._. ~ I I 111 1'.. :

'.) \. i .,r V\.. ...... , I ' i..~ rr ,,

: ·~i I ~ ~ I (}. I I I -: ! _l.... !\.. ' I I

"'-- rV :'\..'i--.. - I ;:: ....

Rl2 II<

,. ,., l i i \ Cii I I I i

I I

·' I/ i ' !'\. I I

: f"'< 1 i : !--";.._, '1 I I/ I

' .r : ''-- ! i - ll '(J,

I I

! I I,.. l ' L T I

; \ 1\ / i i I -;-"" ~: :.__ I N \. I N~W ~ I I i ) ~· !"--:--. - : i _i__: _J

R. 15 w. R.l:SW -ll 12 w. R 14 II<

Elevation of Jordan aquifer in feet above sea level

z ~ \ ;······•iL ... ,; \. ·.,,. i .••••. :\········ >········•> ·~ ~ · ~ .. ;; 0 :;~; · ,~~:' z ~ . "'-- \ ......... :;, ... 'J ko.· ·L \ r • ••··•· <>+ .:::: :•c•l/:.\ \ -J· •·• ·•·••· ·<'""""'• ~

: i .... ·. '• ,,,),,:;'::: ~· •: .' .·•· .•:· ···\ .. : "" [":••:• •:,::·:: ~.... ·•·•·•••••·· :•• : .. :·."·.: ....... ·.\' 'E .•. ·.·.; ... • ;....····~····.···.·. ·' L I !\;':) (: ... :•· •'•'•·•·• ·. l.•.•:. f ' ·l'.::.' ::•:,:, .•· · .. ~'!:'• : ·· ...• . · ...... .. -

Rl!I• R ... 11< R.13W Rr2W.-

Water yields to wells in gallons per minute

1 . - - r 500-1000

)(~·J.i~t~i~I~ 'more than 1000

11QO

z iii ... ...

z .. .. ....

17

11.111• R.1211<

,... I /';"""

! ~

'( i I I I i I

,___....._~-~-'..-k. I : '\'.

~ ·~ - I i L .J I i I L_:......Jl--L.:::.L..:SC>L_J.._,_

R. 15 W. R .... Rl:SW. -11.12•

Water levels in wells in feet above mean sea level

R.~W. ...... w. Rl3 • Rl2W.

i Z I I t!

i ....

l

I

z ;:: ....

n-'-\r I -~I ,-,, i .,

z .. .... ....

z ;:: ....

: " i I fl l ii A I i : '"" - I i i ur-c ! \ ;, I I I

I !VT\. I l ~ j I jjJ : - I ,..; t"\• I : '->-r-. i I "" i I L , ,, ~9'. i .----{ JI i : f I( i '- ' I ' f"\. I I

' ' ' I"-.~ I : N ' : \ ' I I

' ,;f'-- !) i ! ~ · : ~'i ' I .!.-- .J'- : I r"' ' I I I/ I I i) I I .,r' ""'

..... , I ' v I ' I ;

f-- -1- I -1 ... 11 L i ! :-- - ·l -I

' I I ! ,,

' i:lT ' I \ ,..-.! I .....! I

: I I I -'- : ' i : (' .L I I i i 1- -, !"' / ~ ' i i ' ! I : I I - : ' I I I : '\'.. l i ~l-J ~ .

L I I i ) , L I r-- ,_, L _ __i __ LL _J

R."W R. MW R.1311< Rl2W.

z .. .. ....

.. ....

....

z ;:: ...

Dissolved solids content in milligrams per liter (mg/l)*

-u 1000-1500

*Other water quality data in Figure 15

Table 2

SIGNIFICANCE OF MINERAL CONSTITUENTS AND PHYSICAL PROPERTIES OF WATER

To . the user, the quality of ground water is as important as the amount of water that an aquifer will yield. As ground water moves through soil and rock materials, it dissolves some of the minerals which, in turn, affect water quality. In addition to mineral content, bacterial and chemical con­tamination may be introduced through poorly constructed wells and seepage from other pollution sources.

Recommended standards for common water constituents are described in the table above. These are rationally accepted as guidelines for acceptable drinking water supplies. Limits for uses other than drinking often differ from these. For instance, water that is unacceptable for drinking and household use may be completely satisfactory for industrial cooling.

From analyses of ground water averages (A) and ranges (R) of values in milli­grams per liter (mg/l) for several mineral constituents are summarized in Figures 13, 14 and 15 for the 4 major aquifers in Wapello County. Recommended concentrations for some constituents are often exceeded without obvious ill effects, although the water may be unpalatable. Water quality analyses for individual wells should be obtained to determine if concentrations of consti­tuents that affect health are exceeded.

18

~ ~'--b"""':"'"'=.r==~c::-t':'~-t--:--~r-t--t' "" ~-+-+-~+--'--'-+-+-~[!>oo.,~-+-+--r

R.15 W. R 14 W. R. 13W

Figure 13 CHEMICAL CHARACTER OF GROUND WATER

Rl2W.

Surficial Aquifers

~

, I 1

z Hj::n ~

""

I I I .

I ~ .~~

~~ ~~ ::i -~ ;! i] r ],f

103 36 40

77-1 50 24 - 61 13-88

108 31 11

84 - 1113 20-41 ll - 28

" JI 45

55- 135 17 -49 3.5 - 133

:i g-Qd"

-~!".

Drift Aquifer

506 74

304-739 11-393

A 11UYia1 Aqu i fl!~r

195 169

218- 390 22-287

Surled Channel Aquifer

"' " )05-673 .l-140

1.7 0. 4

0 . 5-7.S 0.2-0.7

11 .4

3.5-17 0-LO

7.8 .2

.5 -36 o-.6

547

357-982

551

440 - 726

501

Jll-6 76

406

292-625

395

304 -525

The alluvial and drift aquifers yield good quality water. The dissolved solids content is high, but is acceptable for drinking pur­poses if no other water is available. Water from buried channel aquifers has a lower dissolved solids concentration. Water tem­peratures average 54°F(12.0°C) and the range of temperatures is from 48°F to 58°F (9.0°C to 14.5°C).

Mississippian Aquifer Upper Part

R.12W

104 32 43 472 91 4 . 5 0. 4

66-156 19-50 8.8-118 322-802 5.8- 240 O.S-24 0-1.8

299 92 125 281 1100 s.s .8

537

345-737

1950

"' 315-545

1130

197-54 7 47-124 33-214 44-434 750- 1590 2-22 . J-1.6 1420-2 740 723-1560

61 31 404 608 587 22 2.1 1400 281

54-69 25-37 275-513 471-736 400-710 20-25 .9-J.S 1060-1490 240-JZ4

327 76 679 284 2160 68 1.4 3620 1130

154-490 54- 99 474-1080 212- JSO 1500-2850 27-186 1.2-2.4 2710- 4880 605-1520

~ l=:''--b"""',.;.._,.r=:::p.,;-:-+."d---+-~4--i""..t-+-+-~""""':--'-+-t--+--1 ~ ~-t--:t---=:+:-+---1-t-+-7"~~:---r~...t-+-+-t-r----.lii~±---i ""

Fair water quality is available in the upper part of the Mississippian aquifer, which is

""

Rl5W. R.HW Rl3W

more highly mineralized than that typically found in the surficial aquifers and is usually very hard. Except for along the northern bor­der, the dissolved solids content is high, par­ticularly in the south western portion of the county. For most of the county, sulfate concen­trations exceed recommended standards. Average water temperature is 55°F (13°C) and the range of temperatures is from 51°F to 60°F (10.5°C to 15. 5°C).

19

Figure 14

Mississippian Aquifer

Lower Part

n- R.12 ..

'; NT1 ~ .... ~ !\ I "' ;;- .. l I . i ; ...

"" I i "

~ R.~W. R.MW. R.DW.

1 '""'\:~; ~r--t\-.--~l.......,.......,......-r-r~~""--Fi""irr--......... ..-4-~~~

~.1 ~,...,\,-.+--+i'..~-+-+-~1 4-r-....._+--!__._~-Y-'t+--'==l:-+-4--+-+='-+--+-~ z: ! l,1 _ I' I j ~

~ i ~IV"~"--·~_._~l-!--l-4!-+-~~_,,,,_~ff-L+1-+--t>.,&-r-t-+~ ! .. i'.. __,h ; !"-.. -...._

~ I I i f : ~ I I

I

: i l'i ; i ~" "' .. I ..i i I I ...

'"' : 111 ; j

E I I i I

; ' ·- I

L I I z

' I I 1 ;::

'"' ~ I L ' _J

R15W R.MW -Rl2W. Rl3W

"' I iii I E

I I I I ~ g~l"l ~~

~~ ]M i~ ~ -

~~ ~~ ~~· g~ a ; ol'-

102 52 718 459 1340 169 2.6 2710 469

35-193 15- 107 451-994 266- 595 920-1660 19-365 .S-6 2220-3250 148-891

354 36 38 371 295 86 1500 1040

299-410 24 - 48 28- 47 322-420 8- 582 9-162 1190-1800 849- 1230

78 38 276 592 354 57 l.6 1110 355

38-128 19-68 143-489 465-754 260-560 . 5-150 .5-2.5 879- 1480 176- 581

Water in the lower part of the Mississippian aquifer is generally of poorer quality than found in the upper part. Throughout the county the water is exceptionally hard and with the exception of the extreme northeast corner and along the Des Moines River from Eddyville to Ottumwa, greatly exceeds recom­mended values for sulfate content. Total dissolved solids are extremely high and flour­ide content is generally a bit high. Average water temperature is 55°F (13°C), and the range of temperature from 51°F to 60°F (10.5°C to 15.5°C).

20

Ffgure lS

CHEMICAL CHARACTER OF GROUND WATER

Devonian Aquifer

lllHW R.13W 11- Rl2W

., I ' 1r- I\ l I

z _ I : .. I '

... ... i '~ I : " tP !\ n

~ i f"1\. I ! l.f-, i ! - I~! I _J I "-;. i '!._ I 1 ! ~ ,.,- --+~---r'ilU LJA In ,-...._ v I ; : fl I I( --r i:. I ; LL ' "'- : : : : \ 1 /' : ..... ."5.' : i 1'1 : z

N : ~ _) j : N.~l I ~" ..

:: 1 L.-lJ'- : 1 1 r~ : 1 1 v 1 1 ::

v I i i '-SA\.... I ' I/ / I i ~ ' ;_H_L:__. ~ ~ r ... i : ' : I I I i T : I , ! ; I ' ~ I! . : ! ' I -, ' -' ....... i

: i I . I I ! I I I' i I i I I z

:: ~ --. r'li ~- . I I ' I : t 1 1 "" ' '1!1 !L i ~t-! , , , r · ,- · ·-J 1 ' , .._ _ - , L • _ _,__._.__.__1.... _j_L..LL_ __i_l_~_ - ·-- __, . -- _J

R. 15 W. R. ~W R. l,W R.12 • .

NO DATA

For the Devonian aquifei in this county, which is not a potable water source, there is no imme­diate data available, but from data extrapo~ lation of nearby counties, the water quality is found to be very poor. The water is highly mineralized with sulfate, sodium, iron and manganese and has a very high content of dissolved solids, most likely in excess of 10,000 mg/l . Water temperatures are higher than that from the Mississippian aquifers sources averaging 600F (ls.soc) and with a temperature range of S40F to 640F (12.ooc to 18.00C). ·

Cambra-Ordovician Aquifer

;: '----=+-~---+--'---L.;.-;_:::i;~ ......... .-+-+-+-+----+--t-,-=="i.::±-~ ~

Rl5W R. MW R.13W lll12 •.

I I I e

I I I I ~~M

~-~~ ~

0

~~ ii ~~ ~ ~~q> OU a ~ ; Jl -~ ;'!-

106 so 202 304 552 52 1.2 1180 470

98- 116 46-54 192- 211 283-337 520-600 38-60 1.0-1.S 1120- 1240 452-510

84 34 267 198 476 124 1.7 1160 349

78 -92 26- 41 247-283 ZSJ - 317 455-500 100- 148 1.0- 2. 2 1100- 1220 322 - 388

This deep aquifer yields water of relatively good quality compared to the other rock aquifers. However, the water is noticeably hard and .exceeds recommended standards for sulfates and dissolved solids. Water temperatures are higher than other rock aquifer sources averaging 72°F (22°C) and with a temperature range from 68°F to 76°F (20.0°C to 24.S°C).

21

RECOMMENDATIONS FOR PRIVATE WATER WELLS

Contracting for Well Construction

To protect your investment and guarantee satisfactory well completion, it is a good idea to have a written agreement with the well driller. The agreement should specify in detail:

size of well, casing specifications, and types of screen and well seal

methods of eliminating surface and subsurface contamination

disinfection procedures to be used

type of well development if necessary

test pumping procedure to be used

date for completion

itemized cost list including charges for drilling per foot, for materials per unit, and for other operations such as developing and test pumping

guarantee of materials, workmanship, and that all work will comply with current recommended methods

liability insurance for owner and driller

Well Location

A well should be located where it will be least subject to contamination from nearby sources of pollution. The Iowa State Department of Health recommends minimum distances between a new well and pollution sources, such as cesspools (150 ft.), septic tanks (50 ft.), and barnyards (50-100 ft. and downslope from well). Greater distances should be provided where possible.

The well location should not be subject to flooding or surface water contamina~ tion. Select a well-drained site, extend the well casing a few feet above the ground, and mound earth around it. Diversion terraces or ditches may be necessary on slopes above a well to divert surface runoff around the well site.

In the construction of all wells care should be taken to seal or grout the area between the well bore and the well casing (the annulus) as appropriate so that surface water and other pollutants cannot seep into the well and con­taminate the aquifer.

Locate a well where it will be accessible for maintenance, inspection, and re­pairs. If a pump house is located some distance from major buildings and wired separately for power, continued use of the water supply will be jeapordized by fire . in major buildings.

22

Water Treatment

Water taken from a private well should ideally be tested every six months. The University Hygienic Laboratory will do tests for coliform bacteria, nitrate, iron, hardness, and iron bacteria in drinking water for private individuals. Special bottles must be used for collecting and sending water samples to the laboratory. A sample kit can be obtained by writing to the University Hygienic Laboratory, Un. of Iowa, Oakdale Campus, Iowa City, Iowa 52242. Indicate whether your water has been treated with chlorine, iodine, or bromine; for different sample bottles must be used for treated and untreated water. The charge for the bacterial test is $3.00; for iron hardness and nitrate, it is $3.00; and for iron bacteria, $5.00. If your well is determined to be unsafe, advice for correcting the problem can be obtained from your county or state Department of Health. Several certified private l·aboratories also run water analyses.

Shock chlorination is recommended following the construction and installation of a well and distribution system and anytime these areopened for repairs or remodeling a strong chlorine solution is placed in the well and complete distribution system to kill nuisance and disease-causing organisms. If the first shock chlorination does not rid the water supply of bacteria it should be repeated, if this does not solve the problem the well should be abandoned or the water should be continuously disinfected with proper chlorination equipment.

Since most of the ground waters in Wapello County are mineralized, water softening and iron removal equipment may make water more palatable and pleasant to use. Softened water contains increased sodium; contact your physician be­fore using a softener if you are on a sodium-restricted diet. Chlorination followed by filtration will remove most forms of iron and iron bacteria. Iron bacteria has no adverse effect on health but will plug wells, water lines, and equipment and cause tastes and odors. Iron removal equipment can be used if problems persist.

Well Abandonment

Wells taken out of service provide easy access for pollution to enter aquifers supplying water to other wells in the vicinity. Unprotected wells may also cause personal injury. Proper abandonment procedures should be followed to restore the natural conditions that existed before well construction and prevent any future contamination. Permanent abandonment requires careful sealing. The well should be filled with concrete, cement grout, or sealing clays throughout its entire length. Before dug or bored wells are filled at least the top 10 feet of lining should be removed so surface waters will not penetrate the subsurface through a porous lining or follow cracks in or around the lining. The site should be completely filled and mounded with compacted earth.

ABANDONED WELLS SHOULD NEVER BE USED FOR DISPOSAL OR SEWAGE OR OTHER WASTES.

23

SOURCES OF ADDITIONAL INFORMATION

In planning the development of a groundwater supply or contracting for the drilling of a new well, additional information is often required. This section lists several types and sources of information.

State Agencies

Iowa Department of Natural Resources Environmental Protection Division Wallace Building Des Moines, IA 50319-0034

(515)-281-8666

(Pollution problems, public drinking water, wastewater treatment, water quality, assistance to local communities, protection of surface and underground reservoirs, allocates water use, permits water use of 25,000 or more gallons per day)

Environmental Protection Division Regional Office No. 6 117 N. 2nd Avenue Washington, IA 52343

(319) 653-2135

(Municipal water supplies and waste water treatment routine sanitary inspections, local pollution problems, assistance to communities)

Energy and Geological Resources Division Geological Survey Bureau 123 North Capitol Street Iowa City, IA 52242

(319) 335-1575

(Geologic and groundwater data repository, consultant for well problems, well forecasing, hydrogeologic research, and related services)

Iowa Department of Public Health Lucas Building Des Moines, IA 50319

(515) 281-4942

(Promotes public health hygiene and sanitation; programs of health education, quality of health care)

University of Iowa Hygienic Laboratory University of Iowa Oakdale Campus Iowa City, IA 52242

(Water analyses)

Cooperative Extension Service Iowa State University Ames, IA 50011

(Advice on water system design and maintenance)

(319) 335-4500

(515) 294-4569

Well Drillers and Contractors

The listing provided here was drawn from an Iowa Geological Survey mailing list and yellow pages of major towns in phone books. These selected are within an approximate radius of 50 miles of Wapello County. For a state­wide listing contact either the Iowa Water Well Drillers Association, 4350 Hopewell Ave., Bettendorf, Iowa 51712, (319) 355-7528 or the Iowa Geological Survey.

Bailey Well Co. 203 East Main New London, IA 52645

Bruinekool Well Co. Oskaloosa, IA 52577

Detrick Well Co. R.R. #1 New London, IA 52645

Kramer Well Co. Mt. Pleasant, IA 52641

Lyon Well Co. Sal em, IA 52649

Schlicher Bros. Well Hwy 34 West Fairfield, IA 52556

Brooks Well and Pump Co. R.R. 2 Kn ox vi ll e , IA

Bruinekool Well Co. Pella, IA 50219

Verwers Well Co. Sully, IA 50251

Snook Well Co. R.R. 1 Promise City, IA 52583

Campbell Well 701 South Columbia Bloomfield, IA

Doyle· Van de Krol Sully, IA 50251

Neal Lyon Well Co. Salem, IA 52649

25

Topographic Maps (Available from the Iowa Geological Survey)

R.15W. R. t<4W A. 13 W

Map Title Date Scale Contour Interva 1

(Published)

Eddyville 1968-(76-1)* 1:24,000 10'

Avery 1968-(76-1) 1:24,000 10 1

Blakesburg 19.68-(76-1) 1:24,000 10 1

Kirkville 1968-(76-1) 1:24,000 10 I

Ch ill icothe 1968-(76-1) 1:24,000 10 1

Blakesburg NE 1968-(76-1) 1:24,000 10 1

Ottumwa North 1956 1:24,000 10 1

Ottumwa South 1956 1:24,000 10'

Farson 1956 1:24,000 10'

Agency 1956 1:24,000 10 I

Eldon 1965 1:24,000 10' (Preliminary)

Ottumwa NW 1:24,000 10'

Ottumwa NE 1:24,000 10 I

Packwood NW 1:24,000 10'

Packwood SE 1:24,000 10'

*Map photoinspected 1976- no major culture or drainage changes observed

- ------ -- ----- ·-- -.-'··--~---.. ---- - ·-· -- ~ ..... -~------- --------

26

Useful Reference Materials

Coble, R.W., and Roberts, J.V., 1971, The water resources of Southeast Iowa, Iowa Geological Survey, Water Atlas No. 4.

Horick, P.J., and Steinhilber, W.L., 1973, Mississippian aquifer of Iowa, Iowa Geological Survey, Misc. Map Series No. 3.

Horick, P.J., and Steinhilber, W.L., 1978, Jordan aquifer of Iowa, Iowa Geological Survey, Misc. Map Series No. 6.

Iowa State Department of Health, 1971, Sanitary standards for water wells, State Department of Health, Environmental En~ineering Service.

Van Eck, O.J, 1971, Optimal well plugging procedures, Iowa Geological Survey, Public Information Circular No. 1.

Van Eck, O.J, 1978, Plugging procedures for domestic wells, Iowa Geological Survey, Public Information Circular No . 11.

27