Effect of the Cedar River on the Quality of the 

Ground-Water Supply for Cedar Rapids, Iowa

By PETER M. SCHULMEYER__________________

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 94-4211

Prepared in cooperation with the 

CITY OF CEDAR RAPIDS, IOWA

Iowa City, Iowa 

1995
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

GORDON P. EATON, Director

For additional information write to:

District Chief

U.S. Geological Survey

P.O. Box 1230

Iowa City, Iowa 52240

Copies of this report can be 

purchased from:

U.S. Geological Survey 

Earth Science Information Center 

Open-File Reports Section 

Box25286, MS 517 

Denver Federal Center 

Denver, Colorado 80225
CONTENTS

Abstract........................................................................................^

Introduction ..............................................................................................................................................................................1

Purpose andScope..........................................................................................................................................................2

Acknowledgments..........................................................................................................................................................2

Description of Study Area ........................................................................................................................................................2

Location and Physical Setting........................................................................................................................................2

Geology and Hydrology .................................................................................................................................................4

Municipal Well Fields................................................................................................................................................... 10

Intensive-Study Site...................................................................................................................................................... 10

Data Collection and Results ...................................................................................................................................................17

Cedar River Discharge and Stage................................................................................................................................. 18

Ground-Water Levels.................................................................................................................................................... 19

Selected In-Situ Water-Quality Properties and Constituents ....................................................................................... 19

Specific Conductance .........................................................................................................................................19

pH.......................................................................................................................................................................20

Temperature ........................................................................................................................................................20

Dissolved Oxygen...............................................................................................................................................21

Microscopic Particulate Analysis.................................................................................................................................21

Effect of the Cedar River on Selected Water-Quality Properties and Constituents of the Alluvial Aquifer..........................24

Specific Conductance ...................................................................................................................................................29

pH ...............................................................

Temperature..................................................................................................................................................................31

Dissolved Oxygen.........................................................................................................................................................33

Assessment of Relative Risk of Alluvial Aquifer to Contamination by Pathogens ..............................................................36

Summary ................................................................................................................................................................................39

References Cited.....................................................................................................................................................................41

FIGURES

1. Map showing location of study area, City of Cedar Rapids, Iowa..................................................................................3

2-5. Lithologic section:

2. A-A' in the Cedar Rapids West Well Field................................................................................................................5

3. B-B' in the Cedar Rapids East Well Field................................................................................................................6

4. C-C' in the Cedar Rapids Seminole Well Field........................................................................................................7

5. D-D' in the Cedar Rapids Seminole Well Field ......................................................................................................8

6-7. Maps showing:

6. Location of municipal wells and traces of lithologic sections A-A' and B-B' in the Cedar Rapids East and

West Well Fields...................................................................................................................................................... 11

7. Location of municipal wells and traces of lithologic sections C-C' and D-D' in Cedar Rapids Seminole

Well Field................................................................................................................................................................12

8. Diagram of intensive study site in vicinity of Cedar Rapids municipal well Seminole 10........................................... 17

9. Daily mean discharge of the Cedar River at Cedar Rapids and collection dates of samples for microscopic

paniculate analysis, October 1992 through January 1994............................................................................................. 18

10-20. Graphs showing:

10. Water levels in the Cedar River, Cedar Rapids municipal well Seminole 10, and observation wells CRM-3

and CRM-4, February 1, 1993, through January 31, 1994......................................................................................20

11. Specific conductance and discharge for the Cedar River at Cedar Rapids gaging station from February 20

through April 29 and June 25 through August 30, 1993.........................................................................................29

Contents III
FIGURES-Continued

12. pH and discharge of the Cedar River at Cedar Rapids gaging station from February 20 through

April 29, 1993.........................................................................................................................................................30

13. Dissolved oxygen and discharge of the Cedar River at Cedar Rapids gaging station from February 20

through April 30 and June 25 through August 30, 1993 ........................................................................................ 31

14. Specific conductance of water from the Cedar River, observation well CRM-4, and Cedar Rapids 

municipal well Seminole 10, and estimated traveltimes of water from the river to observation well 

CRM-4 and municipal well Seminole 10, February 1, 1993, through January 31, 1994.......................................32

15. Specific conductance of water from the Cedar River, observation well CRM-3, and the municipal watertreatment plant, February 1, 1993, through January 31, 1994................................................................................ 33

16. pH of water from the Cedar River, observation wells CRM-3 and CRM-4, and Cedar Rapids municipal

well Seminole 10 , February 1, 1993, through January 31, 1994........................................................................... 34

17. Temperature of water from the Cedar River, observation well CRM-4, and Cedar Rapids municipal well 

Seminole 10, and estimated traveltimes of water from the river to observation well CRM-4 and municipal 

well Seminole 10, February 1, 1993, through January 31, 1994............................................................................ 35

18. Temperature of water from the Cedar River, observation well CRM-3, and the municipal water-treatment 

plant, and estimated traveltimes of water from the river to observation well CRM-3, February 1, 1993, 

through January 31, 1994 ....................................................................................................................................... 36

19. Concentrations of dissolved oxygen in water from the Cedar River, observation well CRM-4, and Cedar 

Rapids municipal well Seminole 10, and estimated traveltimes for water from the river to observation 

well CRM-4 and municipal well Seminole 10, February 1, 1993, through January 31, 1994...............................37

20. Concentrations of dissolved oxygen in water from the Cedar River, observation well CRM-3, and the Cedar

Rapids municipal water-treatment plant, February 1, 1993, through January 31, 1994......................................... 37

TABLES

1. Hydraulic properties for alluvial aquifer into which Cedar Rapids municipal wells are completed............................ 10

2. Construction information for municipal water wells, test holes, and observation wells in the vicinity of

Cedar Rapids, Iowa....................................................................................................................................................... 13

3. Results of microscopic particulate analysis for primary indicators in water from study area, December 1992

through November 1993 ...............................................................................................................................................22

4. Results of microscopic particulate analysis for secondary indicators in water from study area, December 1992

through November 1993 ...............................................................................................................................................25

5. Results of microscopic particulate analysis for selected water-quality properties and selected secondary

indicators in water from study area, December 1992 through November 1993........................................................... 27

6. Risk of surface-water contamination as determined by microscopic particulate analysis of water in the study

area, December 1992 through November 1993 ............................................................................................................ 38

7. Filtration efficiency calculated as a log-reduction rate between the Cedar River and selected municipal wells

and the Cedar Rapids municipal water-treatment plant, December 1992 through November 1993 ............................ 40

8. Mean daily water levels in the Cedar River at the surface-water monitoring site, February 1, 1993, through

January 31, 1994........................................................................................................................................................... 43

9. Mean daily water levels in observation well CRM-4, February 1, 1993, through January 31, 1994...........................44

10. Mean daily water levels in municipal well Seminole 10, February 1, 1993, through January 31, 1994......................45

11. Mean daily water levels in observation well CRM-3, February 1, 1993, through January 31, 1994...........................46

12. Water-level measurements for observation wells CRM-3, CRM-4, and CRM-6, February 1993 through

January 1994................................................................................................................................................................. 47

13. Mean daily specific conductance of water from the Cedar River, surface-water monitoring site, February 1, 1993, 

through January 31, 1994..............................................................................................................................................48

14. Mean daily specific conductance of water from observation well CRM-4, February 1, 1993, through

January 31, 1994........................................................................................................................................................... 49

15. Mean daily specific conductance of water from municipal well Seminole 10, February 1,1993, through

January 31, 1994........................................................................................................................................................... 50

16. Mean daily specific conductance of water from observation well CRM-3, February 1, 1993, through

January 31, 1994........................................................................................................................................................... 51

IV Effect of the Cedar River on the Quality of tha Ground-Water Supply for Cedar Rapids, Iowa
TABLES Continued

17. Mean daily specific conductance of water from the Cedar Rapids municipal water-treatment plant,

February 1, 1993, through January 31, 1994 ................................................................................................................52

18. Mean daily pH of water from the Cedar River, surface-water monitoring site, February 1, 1993, through

January 31, 1994 ...........................................................................................................................................................53

19. Mean daily pH of water from observation well CRM-4, February 1, 1993, through January 31, 1994....................... 54

20. Mean daily pH of water from municipal well Seminole 10, February 1, 1993, through January 31, 1994.................55

21. Mean daily pH of water from observation well CRM-3, February 1, 1993, through January 31, 1994.......................56

22. Mean daily pH of water from the Cedar Rapids municipal water-treatment plant, February 1, 1993,

through January 31, 1994...............................................................................................;..............................................57

23. Mean daily temperature of water from the Cedar River, surface-water monitoring site, February 1, 1993,

through January 31, 1994..............................................................................................................................................58

24. Mean daily temperature of water from observation well CRM-4, February 1, 1993, through January 31, 1994 ........ 59

25. Mean daily temperature of water from municipal well Seminole 10, February 1, 1993, through January 31, 1994... 60

26. Mean daily temperature of water from observation well CRM-3, February 1, 1993, through January 31, 1994 ........ 61

27. Mean daily temperature of water from the Cedar Rapids municipal water-treatment plant, February 1, 1993,

through January 31, 1994.............................................................................................................................................. 62

28. Mean daily concentration of dissolved oxygen in water from the Cedar River, surface-water monitoring

site, February 1, 1993, through January 31, 1994.........................................................................................................63

29. Mean daily concentrations of dissolved oxygen in water from observation well CRM-4, February 1, 1993,

through January 31, 1994..............................................................................................................................................64

30. Mean daily concentration of dissolved oxygen in water from municipal well Seminole 10, February 1, 1993,

through January 31, 1994..............................................................................................................................................65

31. Mean daily concentrations of dissolved oxygen in water from observation well CRM-3, February 1, 1993,

through January 31, 1994.............................................................................................................................................. 66

32. Mean daily concentrations of dissolved oxygen in water from the Cedar Rapids municipal water-treatment

plant, February 1, 1993, through January 31, 1994 ......................................................................................................67

33. Numerical range of each primary bio-indicator counted per 100 gallons of water....................................................... 68

34. Relative surface-water risk factors associated with scoring of primary bio-indicators present during microscopic

paniculate analysis of water from study area................................................................................................................ 68

CONVERSION FACTORS, ABBREVIATIONS, AND VERTICAL DATUM

Multiply

inch (in.) 

foot (ft) 

mile (mi)

By

25.4 

0.3048 

1.609

To obtain

millimeter 

meter 

kilometer

square mile (mi 2 ) 2.590 square kilometer

gallon (gal) 3.785 liter

million gallons (Mgal) 3,785 cubic meter

million gallons per day (Mgal/d) 3,785 cubic meter per day

gallon per minute (gal/min) 0.00006309 cubic meter per second

foot per day (ft/d) 0.3048 meter per day

foot squared per day (ft2/d) 0.09290 meter squared per day

cubic foot per second (ft3/d) 0.02832 cubic meter per second

gallon per day per foot [(gal/d)/ft] 0.01242 cubic meter per day per meter

gallon per minute per foot [(gal/min)/ft)______0.2070________liter per second per meter

Temperature in degrees Fahrenheint (°F) may be converted to degrees Celsius (°C) as

follows:

degree Fahrenheit (°F) °C = (°F-32)/1.8 degree Celsius (°C)

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 

1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the firstorder level nets of both the United States and Canada, formerly called Sea Level Datum of 

1929.

Contents
Effect of the Cedar River on the Quality of the 

Ground-Water Supply for Cedar Rapids, Iowa

By Peter M. Schulmeyer

Abstract

The Surface Water Treatment Rule under 

the 1986 Amendment to the Safe Drinking Water 

Act requires that public-water supplies be 

evaluated for susceptibility to surface-water 

effects. The alluvial aquifer adjacent to the Cedar 

River is evaluated for biogenic material and 

monitored for selected water-quality properties 

and constituents to determine the effect of surface 

water on the water supply for the City of Cedar 

Rapids, Iowa. Results from monitoring of 

selected water-quality properties and constituents 

showed an inverse relation to river stage or 

discharge. Water-quality properties and 

constituents of the alluvial aquifer changed as 

water flowed from the river to the municipal well 

as a result of drawdown. The values of specific 

conductance, pH, temperature, and dissolved 

oxygen at observation well CRM-4 and municipal 

well Seminole 10 generally follow the trends of 

values for the Cedar River. Values at observation 

well CRM-3 and the municipal water-treatment 

plant showed very little correlation with values 

from the river. The traveltime of water through 

the aquifer could be an indication of the susceptibility of the alluvial aquifer to surface-water 

effects..Estimated traveltimes from the Cedar 

River to municipal well Seminole 10 ranged from 

7 to 17 days.

Above-normal streamflow and precipitation 

during the study could have increased the effect 

the river had on the alluvial aquifer and on the 

possibility of contamination by a pathogen. 

Microscopic particulate analysis of 29 samples 

found no Giardia cysts or Crytosporidium oocysts

in water collected from municipal wells. Data also 

indicate that the aquifer is filtering out large 

numbers of algae, diatoms, rotifers, and nematodes as well as filtering out Cryptosporidium, 

Giardia, and other protozoa. The number of algae, 

diatoms, rotifers, protozoa, and vegetative debris 

for selected municipal wells tested showed at 

least a reduction to 1 per 1,000 of the number 

found in the river. A relative risk factor and a 

log-reduction rate were determined for the aquifer 

in the vicinity of selected wells. One municipal 

well had a high-risk factor, three other wells had a 

moderate-risk factor, and four wells had a 

low-risk factor. The filtering efficiency of the 

aquifer is equivalent to a 3 log-reduction rate or 

99.99-percent reduction in particulates.

INTRODUCTION

Enactment of the 1986 Amendment to the Safe 

Drinking Water Act prompted a new regulation for 

public-water systems that use surface water or ground 

water that is directly affected by surface water and is 

referred to as "ground water under the direct influence 

of surface water (GWUDI)." This regulation, called 

the Surface Water Treatment Rule (SWTR) (U.S. 

Environmental Protection Agency, 1989), declares that 

States have primary responsibility for identifying 

GWUDI's and their risk pertaining to waterborne 

diseases such as giardiasis (Vasconcelos and Harris, 

1992) or cryptosporidiosis. From January 1991 to 

December 1992 seven outbreaks of such diseases were 

caused by protozoan origin, as reported by Morbidity 

and Mortality Weekly Report (Last, 1994). Four 

outbreaks were caused by Giardia with 123 cases 

reported, and three outbreaks were caused by 

Cryptosporidium with 3,551 cases reported (Last,

Introduction 1
1994). Both Giardia and Cryptosporidium are protozoan parasites that can reside in the digestive tracks of 

vertebrates. These parasites may pass into surface 

water from the fecal material of animals or by surfacewater runoff washing this material into streams or 

pools. Ground water can become contaminated if these 

parasites move with the surface water into a 

ground-water flow system.

Alluvial aquifers adjacent to large streams are 

an important source of ground water for many 

municipalities as a source of drinking water. The 

alluvial aquifer adjacent to the Cedar River, used by 

Cedar Rapids, Iowa, as a source of water supply, has 

tentatively been evaluated as GWUDI. GWUDI is 

defined as any water beneath the surface of the ground 

with either a significant occurrence of insects, other 

microorganisms, algae, organic debris, or largediameter pathogens such as Giardia lamblia, or 

significant and relatively rapid changes in waterquality properties such as specific conductance, pH, 

temperature, or turbidity that closely correlate to 

climatological or surface-water conditions (U.S. 

Environmental Protection Agency, 1989). A cooperative study between the City of Cedar Rapids, Iowa, 

and the U.S. Geological Survey (USGS) was undertaken to quantify the effect of the Cedar River on 

water quality of the adjacent alluvial aquifer. Results 

of this study will aid in an improved understanding of 

surface-water effects on ground water in alluvial 

systems.

Determining the effect that the Cedar River has 

on the alluvial aquifer required a review of departmental and public-water-system records; inspection of 

wells and their construction records; and an evaluation 

of the water source, which involved microscopic 

particulate analysis (MPA) and monitoring of selected 

water-quality properties and constituents. The MPA 

evaluates ground-water samples for surface-water 

indicators such as Giardia, coccidia, diatoms, algae, 

insects, rotifers, vegetative debris, amorphous debris, 

pollen, spores, nematodes, crustaceans, amoeba, and 

protozoa. Evaluation of selected water-quality properties and constituents involves measuring the 

specific conductance, pH, temperature, and dissolved 

oxygen in the alluvial aquifer and the Cedar River. If 

similar changes occur in the alluvial aquifer adjacent 

to the Cedar River, this could indicate that the ground 

water is directly affected by surface water and, 

therefore, is GWUDI.

Purpose and Scope

This report describes the hydrologic and 

biogenic information collected from December 1992 

through January 1994 to determine the effect of 

surface water from the Cedar River on water quality in 

the adjacent alluvial aquifer. Selected water-quality 

properties and constituents (specific conductance, pH, 

temperature, and dissolved oxygen) of the Cedar River 

were compared with those measured in the alluvial 

aquifer and the Cedar Rapids municipal watertreatment plant, and the biogenic particulates in 

samples collected from the Cedar River were compared with samples collected from selected municipal 

wells in the alluvial aquifer and the water system as a 

whole.

Acknowledgments

The assistance of city officials and other personnel of the City of Cedar Rapids in well drilling, sample 

and data collection, and providing well information is 

here acknowledged and appreciated.

DESCRIPTION OF STUDY AREA

Location and Physical Setting

The study area is located in northwest Cedar 

Rapids, along the Cedar River in Linn County, eastcentral Iowa (fig. 1). The study area encompasses the 

East, Seminole, and West Well Fields that supply 

water to the City. There is a well-developed stream 

pattern that drains into the Cedar River, the largest 

tributary of the Iowa River. The river flows in a 

northwest-to-southeast direction through the study 

area (fig. 1). Approximately 1 mi southeast of the East 

Well Field is a low-head dam (fig. 1). This is used for 

flood control, to generate hydroelectric power, and to 

maintain river stage to provide a source of additional 

recharge to-the well fields, especially during periods of 

below-normal streamflow.

The Cedar River drainage basin upstream of the 

gage at Cedar Rapids has a surface area of 6,510 mi2. 

Land use in the Cedar River Basin is predominantly 

agricultural (81 percent), with the major crops being 

corn and soybeans (U.S. Department of Agriculture, 

1976). Annual precipitation ranges from 30 to 36 in., 

and seasonal temperatures vary from summer highs of

2 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Cedar River 

Basin

42°OV

41°59'

Base from U.S. Geological Survey digital data, 

124,000,1983 

Universal Transverse Mercator projection, zone 15

2 KILOMETERS

EXPLANATION

Streamflow-gaging station 

Municipal well

Figure 1 . Location of study area, city of Cedar Rapids, Iowa.

Description of Study Area 3
100 °F to winter lows of -18 °F (Iowa Department of 

Environmental Quality, 1976).

The City of Cedar Rapids had a population of 

108,751 in 1990 and has a steadily increasing demand 

for water (Bob Glass, City of Cedar Rapids Water 

Department, oral commun., 1994). There are 53 municipal wells that provide water for public and industrial 

needs. Pumpage from municipal wells was 8,487 Mgal 

in 1980, 9,118 Mgal in 1990, and 10,385 Mgal in 

1992; the reporting period is from July 1 of the previous year through June 30 of the reporting year (Bob 

Glass, City of Cedar Rapids Water Department, oral 

commun., 1994).

Geology and Hydrology

Carbonate rock of Silurian and Devonian age 

comprise the bedrock aquifer, which is the most 

widely used aquifer in Linn County for industrial and 

domestic supply (Hansen, 1970). Overlying the bedrock is a layer of unconsolidated glacial till, loess, and 

alluvium. The thickness of this layer is variable, with a 

maximum thickness of 86 ft in the study area as interpreted from seismic refraction information. The alluvial deposits that underlie the flood plain and terraces 

of the Cedar River form the principal alluvial aquifer 

in the county. For a more detailed discussion of the 

geology of the area refer to Hansen (1970) and Prior 

(1991).

The Cedar River is a meandering stream that has 

cut into the bedrock surface, exposing steep valley 

walls in the study area. The flood plain is approximately 3,500 ft wide near the Seminole Well Field 

and narrows to 1,200 ft near the West Well Field. The 

fluvial deposits in the study area show typical pointbar sedimentation. Tabular deposits of alluvial material commonly have resulted from the lateral migration of the channel across the flood plain. Deposits of 

this type typically have an upward diminution of grain 

size (Reading, 1978). Driller's logs for most of the 

53 municipal wells confirm this upward fining of 

material in the alluvial aquifer. Coarse-grained sand 

and gravel are found at the base of the alluvium. These 

grade into coarse- to fine-grained sand in the middle of 

the unit, with fine-grained sand, silt, and clay near the 

top. Cobbles and boulders are most prevalent at the 

East Well Field as noted in drillers logs.

Lithologic sections for the alluvial aquifer were 

developed using drillers logs (figs. 2, 3, 4, and 5) and 

show a typical vertical succession of grain size from

coarse sand and gravel at the base of the section to fine 

sand, silt, and clay at the top. Coarse sand and gravel 

are the most permeable of the materials present in the 

alluvial aquifer and, where they are thick, can provide 

the greatest potential for large yields of water (Hansen, 

1970).

The alluvial aquifer is hydraulically connected 

to the Cedar River, bedrock, and upland areas in the 

study area. Recharge to the alluvial aquifer occurs as 

infiltration of precipitation, seepage from adjacent 

aquifers, and from the river when the stage is higher 

than the ground-water level (Wahl and Bunker, 1986). 

Normally, the alluvial aquifer receives enough 

recharge to maintain the water table above the stage of 

the river (Hansen, 1970). When the river stage is lower 

than the water table, the aquifer discharges into the 

river. The Cedar River can receive as much as 

80 percent of its annual discharge from ground-water 

contribution (Squillace, Liszewski, and Thurman, 

1993).

Alluvial aquifers can have large transmissivities 

and hydraulic conductivities, which makes them very 

desirable for water supplies because large amounts of 

water can be withdrawn. Hansen (1970) reported a 

maximum transmissivity of 150,000 (gal/d)/ft for a 

storage coefficient of 0.1 for the alluvial aquifer of the 

East and West Well Fields. The hydraulic conductivity 

for sand and gravel generally ranges from 2.8 to 

2,834 ft/d (Freeze and Cherry, 1979). Single-well hydraulic tests performed on the alluvial aquifer south of 

Cedar Rapids produced results ranging from 2.0 to 

174.0 ft/d (Paul Squillace, USGS, written commun., 

1994).

Specific capacity depends on both the hydraulic 

characteristics of the aquifer and construction of the 

well. Specific capacities for municipal wells, reported 

by the City of Cedar Rapids, are presented in table 1. 

Using a modified Theis equation, transmissivity can be 

calculated using the specific capacity of a well (Heath, 

1987). Transmissivities for the alluvial aquifer in the 

vicinity of municipal well locations were calculated 

using this method and range from 1,543 to 19,240 f^/d 

(table 1). Hydraulic conductivities at each well location (table 1) were calculated by dividing the transmissivity by the thickness of saturated material and 

range from 21.3 to 315.2 ft/d.

Fifteen wells are completed in a portion of the 

alluvial aquifer that has a transmissivity greater than 

10,000 ft2/d. All of the wells are set close to the river. 

Except for municipal wells Seminole 9 and 10, West 9,

4 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapida, Iowa
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EXPLANATION

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7 S J_ Municipal well Name and number

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EXPLANATION

 Approximate lithologic contact

lo"0 J_ Municipal well Name and number 

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Seminole 

10

Figures. Lithologic section D-D'in Cedar Rapids Semonole Well Field.
Table 1. Hydraulic properties for alluvial aquifer in which Cedar Rapids municipal wells are completed

[(gal/min)/ft, gallons per minute per foot of drawdown; ft2/d, foot squared per day; ft/d, foot per day; NR, no record]

Well name 

and number 

(figs. 6-7)

East 1

East 2

East3

East 4

East5

East 6

EastS

East 9

East 10

East 11

East 12

East 13

East 14

East 15

East 16

East 17

East 18

East 19

East 20

West 1

West 2

West3

West 4

West5

West 6

West?

WestS

Specific 

capacity 

[(gal/min) 

/ft]

21.1

23.7

42.9

51.3

45.7

29.4

14.2

28.5

26.1

29.2

50.9

39.1

32.2

75.0

74.2

100.0

96.5

62.2

97.0

75.0

25.0

12.6

17.8

NR

39.5

31.3

24.1

Transmissivity 

(ft2/d)

2,706

3,153

6,156

7,362

6,558

4,006

1,738

3,884

3,472

3,979

7,304

5,439

4,388

11,467

11,345

15,770

14,754

9,148

17,650

11,467

3,326

1,543

2,283

NR

5,597

4,354

3,206

Hydraulic 

conductivity 

(ft/d)

38.7

43.8

85.5

102.3

91.7

57.2

25.0

58.0

51.8

70.4

119.7

89.2

67.5

171.1

164.4

267.3

250.1

160.5

315.2

179.2

46.1

21.3

33.1

NR

78.9

84.5

51.9

Well name and 

number 

(figs. 6-7)

West 9

West 10

West 1 1

Seminole 1

Seminole 2

Seminole 3

Seminole 4

Seminole 5

Seminole 6

Seminole 7

Seminole 8

Seminole 9

Seminole 10

Seminole 1 1

Seminole 12

Seminole 13

Seminole 14

Seminole 15

Seminole 16

Seminole 17

Seminole 18

Seminole 19

Seminole 20

Seminole 21

Seminole 22

Seminole 23

Specific 

capacity 

[(gal/min) 

/ft]

122.0

63.6

67.0

17.8

60.0

68.6

53.1

83.3

62.2

84.2

39.9

60.0

61.7

42.0

31.2

53.8

25.4

43.5

24.8

73.1

NR

NR

NR

NR

NR

NR

Transmissivity 

(ft2/d)

19,240

9,354

10,244

2,793

10,537

12,482

9,325

15,157

10,923

15,320

6,877

10,537

10,836

6,027

4,251

7,913

3,374

6,242

3,296

11,177

NR

NR

NR

NR

NR

NR

Hydraulic 

conductivity 

(ft/d)

305.4

139.6

155.2

43.7

195.5

198.4

169.9

236.8

178.8

242.8

120.0

183.3

158.0

97.2

73.3

129.7

57.2

100.7

50.7

192.7

NR

NR

NR

NR

NR

NR

Description of Study Area 9
and East 20, these well are partially completed in a 

gravel lens of the alluvial aquifer (figs. 2, 3, and 5).

The Cedar River is the largest source of recharge available to the alluvial aquifer, and the rate of 

this recharge is dependent on the hydraulic conductivity of the aquifer, the hydraulic gradient between the 

river and the aquifer, and the infiltration capacity of 

the riverbed materials (Hansen, 1970). The withdrawal 

of water from a well constructed in the alluvial aquifer 

causes a depression of the water table surrounding the 

well called a "cone of depression." The withdrawal 

establishes a hydraulic gradient between the hydraulic 

head in the aquifer and the hydraulic head in the well, 

which causes water to flow from the surrounding aquifer towards the well. With large hydraulic conductivities and transmissivities (table 1), large volumes of 

water can move through the aquifer to the wells; for 

example, 37.1 Mgal/d was obtained on May 21, 1994, 

from the alluvial aquifer by the Cedar Rapids municipal wells (Bob Glass, City of Cedar Rapids Water 

Department, oral commun., 1994).

Municipal Well Fields

The City of Cedar Rapids has three well fields in 

operation along the Cedar River (figs. 1, 6, and 7). 

There are a total of 53 municipal wells (table 2), with 

19 wells in the East Well Field, 11 in the West Well 

Field, and 23 in Seminole Well Field. Seminole wells 

17 through 23 were not in use during the study. The 

well fields are located in the flood plain of the Cedar 

River, and the ground surface at some municipal well 

locations is inundated during river flood stage. The 

wells are installed in the alluvium at varying distances 

from the river (table 2) and drilled to the top of the 

bedrock. Well depths range from 40 to about 72 ft.

All municipal wells are of similar construction. 

A 42- or 52-in. diameter hole was drilled with a rotary 

auger. A 30-in. diameter casing was installed with a 

10- to 20-ft stainless-steel screen that has 0.08- to 

0.10-in. slots. Screens for all municipal wells are set 

close to or on top of the bedrock. Gravel was used to 

fill the annular space around the screen area. The 

remainder of the annular space was sealed with clay, 

such as bentonite, and cement from the top of the 

gravel to land surface. A berm was built-up around the 

well to cover the seal. Well-construction information 

is presented in table 2.

Intensive-Study Site

The three well fields of the City of Cedar Rapids 

all have a similar lithologic sequence and hydraulic 

properties. This similarity in material and properties 

throughout the study area allowed the study to focus 

on one municipal well, Seminole 10, and to assume 

that the hydrologic interpretations for this well are 

applicable to other municipal well locations. The 

intensive-study site is located northwest of Cedar 

Rapids at municipal well Seminole 10 and adjacent to 

the Cedar River (figs. 7 and 8). The aquifer in the 

vicinity of municipal well Seminole 10 has a transmissivity of 10,836 ft2/d and a hydraulic conductivity of 

158.0 ft/d, which is representative of the well fields. 

The well is 48 ft from the river, and its land-surface 

elevation is 725.4 ft (table 2).

Sixty feet of 6-in. diameter pipe were laid in a 

trench extending from the top of the riverbank down 

into the river, near municipal well Seminole 10, to 

monitor changes in water level and selected waterquality properties and constituents in the Cedar River 

(fig. 8). The trench was filled and covered with rip-rap 

for protection. The end of the pipe was perforated to 

allow for the free flow of water.

Two, 4-in. diameter observation wells, CRM-3 

and CRM-4, were installed to monitor changes in 

water levels and selected water-quality properties and 

constituents in the alluvial aquifer. Wells CRM-4 and 

CRM-3 were placed between Seminole 10 and the 

river and beyond Seminole 10, respectively (fig. 8). 

The observation wells were installed in the alluvial 

aquifer by the USGS using a hollow-stem auger. 

CRM-3 is located 58 ft east, and well CRM-4 is 

located 22 ft west of municipal well Seminole 10 

(fig. 8). Another 4-in. diameter observation well, 

CRM-6 (fig. 8), was installed into the bedrock. Depths 

for the observation wells are listed in table 2. The 

wells are constructed of schedule-80 polyvinyl 

chloride (PVC) pipe with a 2.5-ft screened interval at 

the bottom. The annular space was filled by allowing 

the sides to collapse in around the well casing after 

placement of the screen and pipe. A seal of bentonite 

clay was placed at a depth of 6 to 7 ft for wells CRM-3 

and CRM-4 and at 80 ft for well CRM-6. Seal 

thickness varied between observation wells.

10 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapida, Iowa
91 0 40'20"

Base from U.S. Geological Survey digital data, 1:24,000,1983 

Universal Transverse Mercator projection, zone 15

1 KILOMETER

EXPLANATION

A A' 0 Trace of litologic section

20. Municipal well and number

Figure 6. Location of municipal wells and traces of lithologic sections A-A' and B-B' in the Cedar Rapids East and 

West Well Fields.

Description of Study Area 11
91°42'40"

Seminole 

well field

Intensive 

study site 

(figure 8)

J

Base from U.S. Geological Survey digital data, 1:24,000,1983 0 

Universal Transverse Mercator projection, zone 15

0.5 1 KILOMETER

EXPLANATION 

C'

0 Trace of litologic section

17. Municipal well and number

Figure 7. Location of municipal wells and traces .of lithologic sections C-C' and D-D' in Cedar Rapids Seminole Well Field.

12 Effect of the Cedar River on the Quality of the Ground-Weter Supply for Cedar Rapids, Iowa
Table 2. Construction information for municipal water wells, test holes, and observation wells in the vicinity of Ceda

[ft, feet; in., inches; NR, no record]

Latitude/longitude 

Well name and number (degrees, minutes, 

(figs. 6,7, and 8) seconds)

Landsurface 

elevation 

(ft)

Well 

depth 

(ft)

Depth to 

bottom of 

sealed 

annular 

space 

(ft)

Diameter 

of hole 

(in.)

Diameter 

of casing 

(in.)

Depth t

top of 

well 

screen 

(ft)

Municipal wells

1

 a

o

3

a

Cedar Rapids East 1

Cedar Rapids East 2

Cedar Rapids East 3

Cedar Rapids East 4

Cedar Rapids East 5

Cedar Rapids East 6

Cedar Rapids East 8

Cedar Rapids East 9

Cedar Rapids East 10

Cedar Rapids East 1 1

Cedar Rapids East 12

Cedar Rapids East 13

Cedar Rapids East 14

Cedar Rapids East 15

Cedar Rapids East 1 6

Cedar Rapids East 17

Cedar Rapids East 1 8

Cedar Rapids East 19

Cedar Rapids East 20

Cedar Rapids West 1

41°59'47"

41°59'49"

41°59"50"

41°59'52"

41°59'55"

42°00'09"

41°59'41"

41°59'44"

41°59'48"

41°59'50"

41°59'52"

41°59'55"

41°59'58"

41°59'59"

42°00'02"

42°00'04"

42°00'07"

42°00'09"

42°00'H"

42°00'13"

91°40'40"

91°40'45"

91°40'48"

91°40'48"

91°40'55"

91°40'37"

91°40'42"

91°40'48"

91°40'52"

91°40'56"

91°40'58"

91°41'01"

91°41'05"

91°41'07"

91°41'09"

91°41'11"

91°41 ' 13"

91°41 ' 15"

91°41' 17"

91°41'29"

728.0

728.0

728.0

728.0

728.0

726.0

724.0

725.0

726.0

726.0

724.0

724.0

724.0

724.0

724.0

721.0

721.0

721.0

721.0

724.0

70

72

72

72

71.6

70

69.6

67

67

56.5

61

61

65

67

69

59

59

57

56

64

NR

NR

NR

NR

NR

NR

NR

NR

42

18

18

18

19

20

20

15

18

18

16

NR

42

42

42

42

42

42

42

52

42

42

42

42

42

42

42

42

42

42

52

NR

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

50

52

52

52

51.6

50

NR

54

52

36.5

41

41

44.5

47

49

39

39

37

36

54
Table 2. Construction information for municipal water wells, test holes, and observation wells in the vicinity of Ceda

Effect oftheCeda

3D

I

o

3

I

0

1

o

f

O

5

1

m

n

C/>

c o

0

I

3D

S

u>

Well name and number 

(figs. 6,7, and 8)

Latitude/longitude 

(degrees, minutes, 

seconds)

Landsurface 

elevation 

(ft)

Well 

depth 

(ft)

Depth to 

bottom of 

sealed 

annular 

space 

(ft)

Diameter 

of hole 

(in.)

Diameter 

of casing 

(in.)

Depth 

top o

wel

scree

(ft)

Municipal wells Continued

Cedar Rapids West 2

Cedar Rapids West 3

Cedar Rapids West 4

Cedar Rapids West 5

Cedar Rapids West 6

Cedar Rapids West 7

Cedar Rapids West 8

Cedar Rapids West 9

Cedar Rapids We si 10

Cedar Rapids West 11

Cedar Rapids Seminole 1

Cedar Rapids Seminole 2

Cedar Rapids Seminole 3

Cedar Rapids Seminole 4

Cedar Rapids Seminole 5

42°00'17"

42°00'26"

42°00'29"

42°00'33"

42°00'37"

42°00'36"

42°00'31"

42°00'32"

41°00'36"

42°00'37"

42°00'31"

42°00'24"

42°00'19"

42°00'15"

42°00'09"

91°41'34"

91°41'47"

91°41'53"

91°42'02"

91°42'14"

91°42'28"

91°42'36"

91°41'57"

91°42'07"

91°42'22"

91°42'47"

91°42'58"

91°43'05"

91°43'12"

91°43'18"

723.0

723.0

724.0

723.0

723.0

724.0

724.0

724.0

724.0

724.0

720.0

720.0

720.0

720.0

720.0

72.2

72.4

69

68

70.9

51.5

61.8

63

67

66

64

53.9

62.9

54.9

64

NR

NR

NR

NR

NR

NR

NR

38

42

41

5

NR

20

10

15

NR

NR

NR

NR

NR

NR

NR

42

42

42

52

NR

52

52

52

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

62.2

62.4

54

53

NR

36.5

51.8

48

52

51

53.8

43.9

52.6

34.7

53.7
Table 2. Construction information for municipal water wells, test holes, and observation wells in the vicinity of Ceda

Well name and number 

(figs. 6,7, and 8)

Latitude/longitude 

(degrees, minutes, 

seconds)

Landsurface 

elevation 

(ft)

Well 

depth 

(ft)

Depth to 

bottom of 

sealed 

annular 

space 

(ft)

Diameter 

of hole 

(in.)

Diameter 

of casing 

(in.)

Depth 

top o

well 

screen 

(ft)

Municipal wells Continued

1 

f

0

a 

w

Cedar Rapids Seminole 6

Cedar Rapids Seminole 7

Cedar Rapids Seminole 8

Cedar Rapids Seminole 9

Cedar Rapids Seminole 10

Cedar Rapids Seminole 1 1

Cedar Rapids Seminole 1 2

Cedar Rapids Seminole 1 3

Cedar Rapids Seminole 14

Cedar Rapids Seminole 15

Cedar Rapids Seminole 16

Cedar Rapids Seminole 17

Cedar Rapids Seminole 18

Cedar Rapids Seminole 19

Cedar Rapids Seminole 20

Cedar Rapids Seminole 21

Cedar Rapids Seminole 22

Cedar Rapids Seminole 23

42°00'04"

42°00'00"

41°59'56"

41°59'53"

41°59'54"

42°00'23"

42°00'15"

42°00'17"

42°00'20"

42°00'25"

42°00'30"

42°00'13"

42°00'13"

42°00'14"

42°00'19"

42°00'24"

42°00'30"

42°00'35"

91°43'24"

91°43'31"

91°43'37"

91°43'46"

91°43'53"

91°43'03"

91°44'13"

91°44'20"

91°44'25"

91°44'27"

91°44'30"

91°44'19"

91°44'27"

91°44'34"

91°44'39"

91°44'40"

91°44'41"

91°44'41"

721.0

721.0

722.0

724.0

725.4

722.0

724.0

724.0

725.0

727.0

726.0

724.0

724.0

724.0

719.0

718.0

721.0

724.0

61.1

63.1

57.3

57.5

68.6

62

58

61

59

62

65

58

52

40

43

51.7

57

57

16.6

5

1.1

12.2

5

37

NR

NR

NR

NR

NR

34

20

14

10

14

14

14

52

52

52

52

52

42

42

42

42

42

42

42

42

42

42

42

42

42

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

30

50.9

52.9

47.1

47.2

58.4

47

43

46

44

47

50

34

32

28

28

36.7

42

40
Table 2. Construction information for municipal water wells, test holes, and observation wells in the vicinity of Ceda

3

o

a

Er

o 

O

£D>

3)

1

O

3

Depth to 

bottom of

Well name and number

(figs. 6,7, and 8)

Test Hole 10- A

Test Hole 10-B

Latitude/longitude

(degrees, minutes,

seconds)

NR

NR

Landsurface

elevation

(ft)

725.0

725.0

Well

depth

(ft)

Test holes

40.0

45.0

sealed

annular

space

(ft)

NR

NR

Diameter

of hole

(in.)

NR

NR

Diameter

of casing

(in.)

NR

NR

Depth 

top o

well

scree

(ft)

NR

NR

to Observation wells

O

s

3

9.

Er

o

1993 USGS CRM-3

1993 USGS CRM-4

1993 USGS CRM-6

41°59'53"91°43'50"

41°59'53"91°43'53"

41°59'54"91°43'53"

725.9

725.8

725.7

39.5

42.5

95

6

7

80

6

6

6

4

4

4

37

40

92.5

o 

3

'Lateral distances to surface-water source were measured on March 22, 1994. Water-surface elevation at surface-water monitoring site (fi

above sea level.

(/)

 o

 o

o 

o
91=43'53 - 91"43'50'

41°59'52'

CRM-6y

CRM-4y

Seminole-10o

CRM-3y

Base from U.S. Geological Survey 1:24.000 

Cedar Rapids South, Iowa, 1967

30 40 FEET

-1 

10 METERS

EXPLANATION

A Surface-water-quality monitoring site

CRM-4^ Observation well Name and number correspond to the used in table 2 

emmo e-iOQ Municipal well Name and number correspond to that used in table 2

Figure 8. Intensive study site in vicinity of Cedar Rapids municipal well Seminole 10.

DATA COLLECTION AND RESULTS

A multiprobe instrument, Hydrolab 

DataSonde@3 , was used to continuously monitor 

water level, specific conductance, pH, temperature, 

and dissolved oxygen in the Cedar River, observation

'Any use of product names is for descriptive purposes only 

and does not constitute endorsement by the U.S. Geological 

Survey.

wells CRM-3 and CRM-4, and municipal well Seminole 10 (fig. 8). The Cedar Rapids municipal watertreatment plant (fig. 6) also was monitored for the 

selected water-quality properties and constituents. The 

data were recorded at 15-, 30-, or 60-minute intervals 

and are stored in the National Water Information 

System (NWIS) data base of the USGS. Selected 

water-quality properties and constituents, and surfacewater biogenic particulates were collected at the intenData Collection and Results 17
o o

01 

CO

cc

LJJ 

Q.

100,000

70,000

60,000

50,000

40,000

30,000

20,000

5 10,000

7,000

6,000

5,000

4,000

u

H

UJ

cc

< 3,000

U

52 2,000

1,000

I 1

Discharge

MPA sampling

N 

1992

I________I________[_

JFMAMJJASOND

1993

J 

1994

Figure 9. Daily mean discharge of the Cedar River at Cedar Rapids and collection dates of samples for microscopic 

particulate analysis (MPA), October 1992 through January 1994.

sive study site (figs. 7 and 8), while discharge 

measurements were collected about 5 mi downstream 

from the intensive study site below the low-head dam 

(fig. 1).

The multiprobes in observation wells CRM-3 

and CRM-4 were attached to a packer to isolate the 

instrument in the screened section of the well. Multiprobes were secured in the wells on a cable attached to 

the well caps. The multiprobe for the Cedar Rapids 

municipal water-treatment plant was placed just before 

the first step in the treatment process. Data from the 

multiprobes were retrieved every 2 weeks. During the 

winter months, retrieval of data from the river multiprobe was less frequent due to water freezing in the 

pipe. After data retrieval multiprobes were recalibrated and returned to the monitoring point. Specificconductance, pH, and dissolved-oxygen values were 

adjusted automatically by the multiprobe for 

temperature.

Cedar River Discharge and Stage

Discharge of the Cedar River is systematically 

measured as part of the long-term, ongoing USGS 

data-collection program (Southard and others, 1994). 

Discharge measurements used in this study were made 

at the USGS gaging station at Cedar Rapids located 

3,000 ft downstream of the low-head dam (fig. 1). The 

annual mean monthly flow for 1903 to 1993 at the 

USGS gaging station at Cedar Rapids is 3,658 ftVs. 

The highest daily mean of 71,500 ft3/s occurred on 

March 31, 1-961, and the lowest daily mean of 140 ftVs 

occurred on November 18, 1989 (Southard and others, 

1994).

For the period of this study, December 1992 to 

January 1994, the highest daily mean discharge of 

70,500 ft3/s occurred on April 4, 1993; the lowest 

daily mean of 1,600 ft3/s occurred on February 23, 

1993, and the annual mean monthly flow was 

15,130 ft3/s. A hydrograph (fig. 9) for the Cedar River

18 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, lowe
at Cedar Rapids shows the mean daily discharge. 

Conditions during most of the study period were about 

400 percent of normal for discharge and runoff. 

Annual runoff during the study was 31.55 in. compared to the mean annual runoff of 7.64 in. Due to the 

above-normal conditions the low-head dam had little 

effect on the flow of the river, which normally 

withholds and releases water to generate power during 

peak hours.

Stage of the Cedar River was measured by the 

multiprobe at the intensive-study site. Stage data are 

shown in figure 10. Records show that the ground 

surface at municipal well Seminole 10 was inundated 

four times by the Cedar River in 1993 once in April, 

twice in July, and once in August.

drawdown from pumping. Water levels measured 

February 1 through 9, 1993, show that the direction of 

ground-water flow was from the alluvial aquifer to the 

river. During this period, municipal well Seminole 10 

was not pumping.

On November 4 and December 20, 1993, comarative water levels for observation wells CRM-3, 

CRM-4, and CRM-6 indicate that ground-water flow 

from the bedrock aquifer was upward toward the alluvial aquifer. The upward gradient indicates that the 

bedrock is a source of recharge to the alluvial aquifer 

at this location.

Selected In-Situ Water-Quality Properties and 

Constituents

Ground-Water Levels

The multiprobes in observation wells CRM-3 

and CRM-4 were fitted with strain gages to measure 

water levels within a range of 0-33 ft with a precision 

of 0.15 ft. The multiprobe used in municipal well 

Seminole 10 was fitted with a strain gage to measure 

water levels within a range of 0-328 ft with a precision 

of 1.48 ft (Hydrolab Corporation, 1991). The waterlevel sensor automatically compensated for water 

density. Periodically, manual water-level measurements were made with a steel tape and were recorded 

to within 0.01 ft to verify the multiprobe 

measurements.

Mean daily water levels for observation wells 

CRM-3 and CRM-4 and municipal well Seminole 10 

are listed in tables 8 through 11 at the end of this report 

and are graphically compared to stage of the Cedar 

River in figure 10. The majority of missing water-level 

data for well CRM-4 resulted from water levels exceeding the tolerance of the sensor. Results of periodic 

manual measurements in wells CRM-3, CRM-4, and 

CRM-6 are listed in table 12 at the end of this report.

Water levels for wells CRM-3 and CRM-4 

closely follow the stage of the river. During pumping, 

municipal well Seminole 10 drawdown causes the 

water level to range from 12 to 20 ft below river stage, 

which results in a steep gradient between the Cedar 

River and well Seminole 10. The direction of groundwater flow is toward the well. When the well was not 

pumping, water levels in wells CRM-3, CRM-4, and 

Seminole 10 were similar to the level of the river.

Generally the direction of ground-water flow 

was from the river to the alluvial aquifer as a result of

Specific Conductance

The mean daily specific-conductance values for 

water in the Cedar River ranged from a maximum 

value of 640 |o,S/cm (microsiemens per centimeter at 

25 °C) on February 1, 1993, to a minimum value of 

223 |J.S/cm on March 5, 1993. Maximum and 

minimum values for mean daily specific conductance 

for observation well CRM-4 and municipal well 

Seminole 10 are similar in range and time period to 

those of the river. Observation well CRM-4 had a 

maximum value of 658 [iS/cm on February 25, 1993, 

and the minimum value of 272 |o,S/cm on March 10, 

1993. Municipal well Seminole 10 had a maximum 

values of 640 [iS/cm on January 11 and 12, 1994; 

635 [iS/cm on February 15, 1993; and 636 (0,S/cm on 

March 3, 1993. The minimum value for well Seminole 

10 was 287 [iS/cm on April 10, 1993. Values of mean 

daily specific conductance for observation well 

CRM-3 and the municipal water-treatment plant were 

less similar to values in the river. The maximum was 

655 [iS/cm on February 17, 1993, and the minimum 

was 426 (iS/cm on May 14, 1993, for observation well 

CRM-3. The maximum specific-conductance value for 

the municipal water-treatment plant was 602 (o,S/cm on 

March 2, 1993, and the minimum value was 

418 [iS/cm on August 20, 1993. Mean daily specific 

conductance values are tabulated at the end of this 

report in tables 13 through 17.

PH

The data show no significant or rapid changes in 

pH for water from wells and the municipal watertreatment plant compared to that from the Cedar River.

Data Collection and Results 19
LLJ

735

730

725

720

715

710

705

LLJ

w 700

LLJ

g 695

Note: Breaks in lines indicate no data.

Cedar 

River

Observation 

Observation well CRM-4

well CRM-3

Municipal well 

Seminole 10

February March April May June July

1993

Observation 

well CRM-3 Observation 

well CRM-4

Municipal well 

Seminole 10

August September October 

1993

November December January 

1994

Figure 10. Water levels in the Cedar River, Cedar Rapids municipal well Seminole 10, and observation wells CRM-3 and 

CRM-4, February 1, 1993, through January 31, 1994.

The pH data are tabulated in tables 18 through 22 at 

the end of this report. The daily mean pH values for 

the river water ranged from a minimum of 7.3 in 

March 1993 to a maximum of 8.5 in May and June of 

1993. Values for observation well CRM-4 were similar 

in range from 7.4 to 8.2 and for municipal well 

Seminole 10 from 7.2 to 8.0. pH. Values of pH for 

water from observation well CRM-3 and the municipal water-treatment plant were smaller, ranging from 

6.9 to 7.5 and 6.3 to 7.5, respectively.

Temperature

Maximum mean daily river temperature was 

24.6 °C on August 27, 1993, and a minimum mean 

daily temperature of -0.1 °C was recorded from 

February 1 through March 6, 1993, and from 

December 23, 1993, through January 25, 1994. 

Maximum and minimum mean daily values for 

observation well CRM-4 were 24.5 °C on 

September 3, 1993, and 0.1 °C from February 14 

through March 14,1993 and from December 31, 1993, 

through January 31, 1994. Maximum and minimum

20 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
mean daily values for municipal well Seminole 10 

were 21.4 °C on September 13, 1993, and -0.2 °C 

from February 5-16, 1993, and on January 23, 24, and 

26-29, 1994. Maximum and minimum mean daily 

values for observation well CRM-3 were 18.7 °C on 

December 2, 1993, and 0.6 °C from February 10-13, 

1993. Maximum and minimum mean daily values for 

the municipal water-treatment plant were 17.6 °C on 

September 13, 1993, and 5.9 °C on April 10, 1993. 

Mean daily temperature values are tabulated at the end 

of this report in tables 23 through 27.

The water temperatures for observation well 

CRM-4 seem to follow the trend of water temperatures 

in the Cedar River. Water temperatures for municipal 

well Seminole 10 also follow the trend of water temperatures in the river but not as closely as those for 

observation well CRM-4. Water temperatures for 

observation well CRM-3 and the municipal watertreatment plant do not follow the variations in water 

temperatures for the river as the temperature in the 

river increases and decreases throughout the year.

Dissolved Oxygen

The Cedar River had a maximum concentration 

of dissolved oxygen of 15.2 mg/L on February 3, 

1993, and a minimum concentration of 6.0 mg/L on 

August 20, 1993. Maximum and minimum concentrations for observation well CRM-4 were 12.3 mg/L on 

December 28, 1993, and 0.1 mg/L on September 2, 

1993. Maximum and minimum concentrations for 

municipal well Seminole 10 were 11.5 mg/L on 

January 2, 1994, and 0.4 mg/L from February 1-3, 

February 10, August 1-5 and 17-23, and September 

11-13 and 15-18, 1993. Maximum and minimum 

concentrations for observation well CRM-3 were 

3.1 mg/L on February 10, 1993, and 0.2 mg/L from 

February 14-16, November 10, 25, 26, and 28, 

December 3-5, 1993, and on January 31, 1994. 

Maximum and minimum concentrations for the municipal water-treatment plant were 11.2 mg/L on July 17, 

1993, and 0.4 mg/L on February 25, 1993. Mean daily 

concentration values of dissolved oxygen are tabulated 

at the end of this report in tables 28 through 32.

Concentrations of dissolved oxygen in the river 

tend to be higher than the dissolved-oxygen concentrations in water from observation well CRM-4, municipal well Seminole 10, observation well CRM-3, and 

the water-treatment plant. The trend of dissolvedoxygen concentration in well CRM-4 is similar to the 

concentrations in the river but in smaller quantities.

Concentrations in well Seminole 10 are similar to 

concentrations in well CRM-4 except during May 

through September. Dissolved-oxygen concentrations 

in well CRM-3 were fairly stable throughout the study 

period.

Microscopic Particulate Analysis

Microscopic paniculate data were collected 

using the method outlined by the U. S. Environmental 

Protection Agency (USEPA) to determine if a groundwater source is GWUDI according to the SWTR 

(Vasconcelos and Harris, 1992). Prior to sampling, 

municipal wells were pumped for a minium of 1 week 

to assure sufficient time for aquifer conditions to stabilize. Samples were collected from the Cedar River, 

municipal wells East 1 and 19, West 6, and Seminole 

2, 3, 10, 14, and 16, and the Cedar Rapids municipal 

water-treatment plant during April 1993, a period of 

above-normal flow. Additional samples for the river 

and Seminole wells 10, 14, and 16 were collected 

throughout the study period. Samples collected during 

a period of high flow, when several wells were inundated, are important because the alluvial aquifer could 

be at a higher risk of contamination by surface water 

during this period. Samples were collected by USGS 

personnel and sent to the laboratory of Analytical 

Services, Inc., in Essex Junction, Vermont, for MPA.

Analysis of 29 samples found no Giardia cysts 

or Crytosporidium oocysts in water collected from 

municipal wells and the municipal water-treatment 

plant (table 3). A total of five Giardia cysts and four 

Crytosporidium oocysts were detected in the Cedar 

River samples, some with and some without internal 

structure.

Chlorophyll-containing algae (table 3) were 

detected in all but one of the wells sampled. The algae 

counts in the selected wells generally were insignificant compared to the algae counts in the river water. 

The largest counts occurred during flooding in April 

1993. Counts of algae found in samples from the 

municipal water-treatment plant and municipal wells 

Seminole 3, 14, and 16 ranged from 1.9 x 103 to 

7.9 x 104 per 100 gal of water during this time, three 

orders of magnitude higher than normally found. In 

comparison, the river samples contained algae counts 

of 1.6 x 107 to 3.8 x 107per 100 gal of water, whereas 

samples from municipal wells East 1 and 9, West 6, 

and Seminole 2 and 10 contained counts ranging from 

1 to 16 per 100 gal.

Data Collection and Reauita 21
Table 3. Results of microscopic particulate analysis for primary indicators in water from study area, December 1992 thro

[Values are counts per 100 gallons of water, except as noted; I, inundated at the time of sampling; ND, not detected]

m

r+

a 

1

31

|

0

3

1

O

c 

»

a

1

o

5

c

3

a

i

0

I?

TJ

 o,

31

g

S

31

TJ

&

Date 

Municipal wells or sampling site (month- 

(figs. 6 and 7) day-year)

Cedar River 12-07-92

04-06-93

04-13-93

04-26-93

08-02-93

11-16-93

Cedar Rapids municipal water- 04-06-93

treatment plant 04-07-93

04-08-93

04-26-93

Giardia 

cysts

2

1

ND

ND

ND

2

ND

ND

ND

ND

Cryptosporidlum 

oocysts

ND

3

ND

ND

1

ND

ND

ND

ND

ND

Vegetative 

debris

l.OxlO3

l.lxlO3

l.OxlO3

l.OxlO3

ND

ND

2

ND

ND

4

Diatoms

1.2xl04

5.7xl05

5.1xl05

2.7xl03

ND

3.3xl03

1

1

ND

ND

Algae

7.4xl06

l.SxlO7

3.4x1 07

1.6xl07

2.3xl05

6.0xl07

7.9x1 04

1.9xl04

l.lxlO4

2.7x1 04

Prot

1.7

1.2

1.9

7.8

6.4

ND

l.S

16

ND

4.1

Cedar Rapids municipal wells

East 1 04-14-93

East 19 04-26-93 I

West 6 04-15-93

04-26-93

ND

ND

ND

ND

ND

ND

ND

ND

1

ND

ND

ND

ND

2

ND

ND

16

8

1

4

2.0

2.4

3.5

63

Seminole 2 04-15-931 ND ND ND ND 4-l

Seminole 3 04-15-931

09-22-93

11-16-93

ND

ND

ND

ND

ND

ND

ND

ND

ND

8

ND

ND

1.9xl03

22

35

2.0

ND

29
Table 3. Results of microscopic particulate analysis for primary indicators in water from study area, December 1992 thro

November 1993 Continued

Municipal wells or sampling site 

(figs. 6 and 7)

Date 

(monthday-year)

Giardia 

cysts

Cryptosporidium 

oocysts

Vegetative 

debris Diatoms Algae Prot

Cedar River municipal wells Continued

Seminoie 10

Seminole 14

Seminoie 16

12-08-92

04-13-93

09-22-93

11-16-93

04-06-93 I

08-02-93

11-16-93

04-06-93 I

04-07-93 I

08-02-93

11-16-93

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

1

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

2

ND

ND

ND

ND

ND

ND

ND

ND

ND

8

9

ND

25

4.0x1 03

34

2

3.7x1 03

1.6xl04

47

2

4

2.4

3.6

6.5

36

ND

17

2.0

7

ND

3

o

D>

s

o

D>

3 

Q.

C 

;» 

in
Diatoms (table 3) were found only in samples 

from three wells and the municipal water-treatment 

plant during the period of flooding. The counts ranged 

from 1 to 8 compared to counts ranging from 2.7 x 103 

to 5.7 x 107 per 100 gal in the river samples throughout the period of sampling. The count of rotifers found 

in the wells also was small compared to those found in 

the river samples (table 4). Some free-living rotifers 

have highly specialized food habits not associated 

with surface water if sufficient organic debris, fungi, 

and bacteria are present as a food supply (Vasconcelos 

and Harris, 1992). Vegetative debris (table 4), spores, 

pollen, crustaceans, crustacean eggs, nematodes, 

nematode eggs, amoebae, and invertebrate eggs (table 

5) all showed very small counts in the well samples 

compared to the larger counts in the river samples. No 

insects or insect parts were found in any of the 

samples collected (table 4). Results for volume of 

sample filtered, turbidity, filter color, pH of sample, 

and amorphous debris are presented in table 5. Turbidity of water from the wells sampled is generally less 

than the turbidity of the river except where wells have 

a high occurrence of iron bacteria.

EFFECT OF THE CEDAR RIVER ON 

SELECTED WATER-QUALITY 

PROPERTIES AND CONSTITUENTS OF 

THE ALLUVIAL AQUIFER

Variations in the specific conductance, pH, 

temperature, and dissolved-oxygen concentrations of 

water in the alluvial aquifer can be related to the Cedar 

River. Before addressing these relations, some aspects 

of water-quality variations in the Cedar River and 

traveltimes of water in the alluvial aquifer are 

discussed.

Specific conductance, pH, and the concentration of dissolved oxygen change inversely with 

changes in river stage or discharge (Schulmeyer, 

1991). Increases in discharge of the Cedar River 

resulting from runoff had an inverse effect on the 

values of specific conductance, pH, and concentration 

of dissolved oxygen in the river as a resu!f of dilution 

(figs. 11, 12, and 13). Precipitation, resulting in ove-- 

land flow generallv hp« a smaller specific condnrtar.ee 

and pH, ranging from 5 to 74 jaS/cm and 4.0 to 7.3 pH 

(Southhard and others, 1994), respectively, compared

to the specific conductance and pH of ground water in 

alluvial and bedrock aquifers, which ranges from 390 

to 1,800 nS/cm and 6.8 to 8.0 pH (Wahl and Bunker, 

1986). Because the Cedar River can receive a major 

part of its flow from ground-water contribution, 

especially during periods of below-normal precipitation, the specific-conductance, pH, and dissolvedoxygen values of river water can be similar to values 

measured in the ground water. When runoff occurs 

dilution takes place. With a large amount of runoff, 

substantial decreases in values of specific conductance, pH, and dissolved oxygen for water from the 

Cedar River can take place. Subsequently, these 

changes can be seen in the alluvial aquifer as water 

from the river moves toward municipal well Seminole 

10 over a period of time.

Water-quality properties and constituents of 

water pumped from the alluvial aquifer change as 

water flows from the Cedar River to municipal well 

Seminole 10 as a result of drawdown. The amount of 

time needed for water to travel through the aquifer 

could be an indication of the susceptibility of the alluvial aquifer to surface-water effects. Giardia cysts 

have a period of viability dependent on length of time 

in the environment and temperature (Wilson and 

others, 1992). Viability is largely lost in about 20 days 

in water at 20 °C, 30 days in water at 10 °C, and 

90 days in water of only a few degrees Celsius (Wilson 

and others, 1992). Traveltime represents the residence 

time the water has in contact with the aquifer material, 

which may enhance the filtering efficiency of the 

aquifer material.

The most notable example of change started on 

February 28, 1993, in the Cedar River for specific 

conductance, pH, and dissolved oxygen. The values 

for specific conductance and pH and the concentration 

of dissolved oxygen decreased with a corresponding 

increase in the discharge of the river. This decrease is 

subsequently seen in observation well CRM-4, 

municipal well Seminole 10, and to a lesser extent in 

observation well CRM-3 and the municipal watertreatment plant. A traveltime for water moving from 

the Cedar Rivet to other sampling sites can be estimated from the data. A traveltime is estimated Dy 

determining fiorn the plotted or tabulated data when a 

change starts in the river and counting the days until 

correlative changes occur at other at sampling sites.

24 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
i?

c 

&

JQ

C

Table 4. Results of microscopic paniculate analysis for secondary indicators in water from study area, December 1992 th

[Values are counts per 100 gallons of water, except as noted; 1, inundated at time of sampling; ND, not detected]

i

o

=?

o

a.

Dl

31

1

i

o

5?

Q.

Dl

5f 

6

C 

Dl

Municipal well or Date 

sampling site (month- 

(figs. 6 and 7) day-year

Cedar River 12-07-92

04-06-93

04-13-93

04-26-93

08-02-93

11-16-93

Cedar Rapids municipal 04-06-93

water-treatment plant 04-07-93

04-08-93

04-26-93

Spores

4.3x1 02

6.5x1 03

3.6x1 03

1.3xl03

1.4X104

ND

ND

ND

ND

1

Pollen

5.6xl03

1.6xll04

l.lxlO4

9.3x1 03

8.8x1 03

ND

3

ND

3

9

Crustaceans

ND

ND

5.2xl02

3.3xl02

ND

ND

ND

ND

1

ND

Crustacean 

eggs

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

Nematodes

l.lxlO3

7.3x1 03

3.6x1 03

l.OxlO3

4.4x1 03

ND

20

10

3

12

Nematode 

eggs

4.3xl02

3.8x1 02

ND

ND

ND

ND

26

17

1

ND

Rotifers

1.6xl03

3.8xl02

l.OxlO3

1.7xl03

1.6xl03

l.OxlO5

1

5

3

92

Rotife

eggs

2.1x

3.8x1 

2.1x

ND

ND

ND

ND

1

ND

ND

 < Cedar Rapids municipal wells

T> 

1

CD

5'

(A

Dl

D

Q.

O

o

D

(A

East 1 04-14-93

East 19 04-26-931

West 6 04-15-93

04-26-93

ND

3

ND

ND

10

20

1

5

1

ND

ND

ND

ND

ND

ND

ND

ND

1

ND

ND

ND

ND

ND

ND

ND

3

ND

ND

ND

ND

ND

ND

Seminole 2 

Seminole 3

04-15-931 ND ND ND ND ND ND ND ND 

04-15-931

09-22-93

11-18-93

3

2

1

7

ND

ND

ND

ND

ND

ND

ND

ND

4

ND

ND

ND

ND

ND

1

1

NF

1

ND

NF

10 

Ul
10

<n

m 

3)

IB

TJ_ 

Q.

Table 4. Results of microscopic particulate analysis for secondary indicators in water from study area, December 199

November 1993 Continued

i

o Municipal well or 

3 sampling site 

£ (figs. 6 and 7)

IB

3i Seminole 10

§

o

3

<D

O

C

2L

 31 Seminole 14

a

1

0

3

c

a- Seminole 16

1

CO

c 

 o 

 o

Date 

(monthday-year SporesCrustaPollen ceans

Crustacean 

eggs

Nematodes

Nematode 

eggs Rotifers

Rot

eg

Cedar River municipal wells Continued

12-08-92

04-13-93

09-24-93

11-16-93

04-06-93 I

08-02-93

11-16-93

04-06-93 I

04-07-93 I

08-02-93

11-16-93

1

2

ND

ND

1

ND

ND

1

ND

ND

ND

1

18

1

ND

1

2

ND

2

6

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

2

1

ND

1

ND

ND

3

3

ND

ND

ND

1

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

39

17

ND

ND

ND

2

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

O 

i
Table 5. Results of microscopic particulate analysis for selected water-quality properties and select

secondary indicators in water from study area, December 1992 through November 1993

'[Values are counts per 100 gallons of water, except as noted; amorphous debris, organic detritus, and sand sizes are greater than 5 micro

confluent, large concentration of amorphous debris; f, size is 1 -5 micrometers; vf, size is less than 1 micrometer; I, inundated at time of 

NTU, national turbidity units; begin/end, values at beginning and end of sample collection; ND, not detected; NS, not sampled]

a

5

<D

0)

^

30

I

O

3

I? 

<D

I 

I

I 

«

0)

3 

Q.

?

I

I

<D

Municipal well or 

sampling site 

(figs. 6 and 7)

Cedar River

Cedar Rapids municipal

water-treatment plant

Date 

(monthday-year

12-07-92

04-06-93

04-13-93

04-26-93

08-02-93

11-16-93

04-06-93

04-07-93

04-08-93

04-26-93

Volume 

filtered 

(gallons)

93

158

130

130

100

150

1,343

1,720

478

552

Turbidity (NTU)

begin

15

48

22

65

85

7.2

4.6

4.7

9.0

2.8

end

12

54

21

66

94

6.4

4.7

9.0

.60

3.4

Filter color

dark brown

dark brown

dark brown

brown

brown

brown

dark orange

orange

orange

orange

pH (standard 

unit)

begin

8.3

7.7

8.1

8.1

8.0

7.9

7.4

7.5

7.7

7.6

end

8.3

7.8

8.1

8.1

8.2

8.3

7.5

7.7

7.5

7.6

Am

d

conflu

conflu

2

conflu

conflu

vf con

conflu

conflu

conflu

conflu

Cedar Rapids municipal wells

East 1

East 19

West 6

Seminole 2

Seminole 3

04-14-93

04-26-93 I

04-15-93

04-26-93

04-15-931

04-15-931

09-22-93

11-16-93

1,342

1,222

1,358

1,196

1,377

1,633

3,388

1,261

113

1.1

1.2

.73

.79

.75

.18

.09

8.4

1.4

.72

1.7

.45

.82

NS

NS

orange

light tan

peach

light tan

light tan

light tan

light tan

tan

7.6

7.5

7.6

7.5

7.6

7.6

8.3

7.0

7.4

7.5

7.6

7.5

7.6

7.6

NS

7.0

conflu

conflu

16

conflu

4

2

confl

7
Table 5. Results of microscopic particulate analysis for selected water-quality properties and select

secondary indicators in water from study area, December 1992 through November 1993 Continue

a

5

3

o

3

<D 

O

m

a 

I

o 

3

1

(0

I < 

o 

o

Municipal well or 

sampling site 

(figs. 6 and 7)

Date 

(monthday-year

Volume 

filtered 

(gallons)

Turbidity (NTU)

begin end Filter color

pH (standard 

unit)

begin end

Am

d

Cedar Rapids municipal wells Continued

Seminole 10

Seminole 14

Seminole 16

12-08-92

04-13-93

09-22-93

11-16-93

04-06-93 I

08-02-93

11-16-93

04-06-93 I

04-07-93 I

08-02-93

11-16-93

1,178

1,380

1,430

1,163

1,200

1,265

1,092

1,235

1,340

1,200

1,133

0.71

1.1

.18

.14

53

8.9

15.8

98

12

17

21

0.

NS

15

2.

12

11

53

,28

,84

,09

,3

,98

.85

pale tan

light tan

light tan

tan

orange

orange

orange

orange

orange

orange

orange

7

7

.8

.8

8.4

7.2

7.5

7.6

7.1

7.3

7

7

7

.3

.5

.1

7

7

8

7,

7,

7,

6

.8

.8

.3

.1

.4

,4

.8

7.4

7,

7

6

.6

.5

.8

conflu

conflu

1

f conf

conflu

conflu

f conf

conflu

conflu

conflu

f conf

3D 

0)

TJ

E 

(a
C/3 

D 

C/3

LU 

U 

C/3

in csi

700

600

500

400

300

ILU 

O

cc

LU 

Q_

C/3

C/3 

O 

QC 

O

200

Note: Breaks in lines indicate no data.

20 25 

February

10 15 20 

March

25 30

1993

10 15 

April

20

700

600

500

400

o

I

o

Q

2 

O

o 

o

O 30°

LU 

Q_ 

C/3

200

Specific conductance

Discharge

80,000

70,000

60,000

50,000

40,000

30,000

20,000

10,000

25 29

 -, 80,000

o 

m

D 

O

25 30 5 10 15 20 25 30

June July

1993

5 10 15 20 25 30 

August

70,000

60,000 oo

50,000

40,000

30,000

20,000

10,000

Figure 11 . Specific conductance and discharge for the Cedar River at Cedar Rapids gaging station from February 20 through 

April 29 and June 25 through August 30, 1993.

Specific Conductance

Specific-conductance values for the Cedar River 

started to decrease on February 28, 1993, with a subsequent decrease in values at observation well CRM-4 

on March 4, 1993, and at municipal well Seminole 10 

on March 7, 1993 (fig. 14). Water of lower specific 

conductance took 4 days to travel to well CRM-4 and

Effect of the Cedar River on Selected Water-Quality Properties and Constituents of the Alluvial Aquifer 29
8.4

8.2

{2

8.0

7.8

Q 

DC

g

~ 7.6

Q.

7.4

7.2

Note: Breaks in lines indicate no data

Discharge

20 25 

February

5 10 15 20 

March

25 30

1993

10 15 

April

20 25 29

80,000

70,000

60,000

50,000

40,000

30,000

20,000

10,000

0

Q 

Z 

O 

o

w

oc

LU 

LU 

Uo

CD 

D 

O

z

LU

ID

oc

<

o

Figure 12. pH and discharge of the Cedar River at Cedar Rapids gaging station from February 20 through April 29,1993.

7 days to travel to well Seminole 10. Three other 

selected events are shown starting on March 5 and 

October 2, 1993, and January 2, 1994, for the Cedar 

River. Traveltimes to well CRM-4 were 5, 5, and 4 

days for observable changes to start at well CRM-4 

and 12, 7, and 9 days to start at well Seminole 10, 

respectively. Water at observation well CRM-3 had an 

estimated traveltime of 29 days from the river on 

February 28, 1993, based on a correlative change that 

occurred on March 29, 1993 (fig. 15). Water entering

the municipal water-treatment plant generally follows 

the trend of specific-conductance values for the river, 

but abrupt changes that occur in the river are not 

apparent in the water-treatment plant and no correlation of changes was possible from the data.

PH

There is no obvious correlation between the 

change in pH of the Cedar River that can be traced

30 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
o

O 

o 

a o

CO o

o ao

CD§

&3 CD

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o 3 " T3

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(D I5i-^3

^T* *~*

- 3-Hg-

 n> -y rt

I. "5 "I.

 -n o :?>

s |s

3 2: o

ff - p 

p. =" E

p CL 2.

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p fl> J=-

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CD CD" CD^

H cr 

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^ « 3 - 5' 5'

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<w "5 o

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c 

SL

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 o5 o

CD

rties andCoi

nstituents oftl

^ o=<

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CL

1 munic

 5'

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oo

CD 

3'

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CD

3" O|

5'

CDE

cf 3

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D.

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(D 

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it occurred

(Schneider,

i 

ri\

to^ "' 1

CD

CD

3 

 o

CD 

H. C

CDC

CD

5'

CD

CD 

j-t

CL

L/l

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3-

CD

amoun 0

CDE

CDC3

CD 

(JQ3e

3 

D.

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CD

3 C-^

(JQ

CD

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CD

CD 3

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CD

'J*.

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CDC3

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CD C

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CD

CL 

CD

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cr

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CD^

cr

cT

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CD a

CD 

CL

s.

CD

winter

CL3

CD

5'

CD

v>33

CP

r*

CB

3 

 a

CD

&3E

C/3 O

> -n

"i"5"

§8

CD O^

U, O l

= 

CD

CD ^ 

00 o

E? 

CDO

DISSOLVED OXYGEN, IN MILLIGRAMS PER LIT

33 -* O

CD 

Q.

-I

ci

CO 

(O

u"

(O

O O3

Tl 

CD 

CT

ro ooc

(O

CD

cr

CO 

CO 

OJ

 > 

o

o 

o o

ro 

o 

o 

o o

u 

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o 

o o

DISCHARGE, IN CUBIC FEET PER SECOND
700

Traveltimes 

4 days 

7 days

Note: Breaks in lines indicate no data

Municipal well 

Seminole 10 Observation 

well CRM-4

April 

1993

June July

| 70° 

co

o 

cc

y 600

U 500

O 

CJ

y 300 -

CJ

Q. 

CO

Traveltimes 

7 days 

5 days

Cedar

Observation 

well CRM-4

Traveltimes 

4 days 

9 days

Municipal well 

Seminole 10

200 August September October 

1993

November December January 

1994

Figure 14. Specific conductance of water from the Cedar River, observation well CRM-4, and Cedar Rapids municipal well 

Seminole 10, and estimated traveltimes of water from the river to observation well CRM-4 and municipal well Seminole 10, 

February 1, 1993, through January 31,1994.

figure 17. Figure 18 ,shows temperature for the Cedar 

River, observation well CRM-3, and water-treatment 

plant.

On March 24, 1993, the water temperature 

increased in the river, and a corresponding increase 

was observed in observation well CRM-4 on March 

31, 1993 (fig. 17). Thus, the traveltime of water from 

the Cedar River to observation well CRM-4 is estimated to be 8 days. Similar estimates of traveltime 

from the Cedar River to observation well CRM-4 were 

made for August 27 to September 3, 1993, and from 

October S to October 15, 1993; both events had traveltimes of 7 days. Traveltimes for March 24 to April 11, 

1993, August 27 to September 13, 1993, and October 

8 to October 18, 1993, ranged from 10 to 17 days. The 

traveltimes are not long enough to have a substantial

32 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Municipal water 

treatment plant

Note: Breaks in lines indicate no data.

Figure 15. Specific conductance of water from the Cedar River, observation well CMR-3, and the municipal water-treatment 

plant, February 1, 1993, through January 31, 1994.

effect on the viability of Giardia cysts in water 

pumped by municipal well Seminole 10.

Water temperatures for observation well CRM-3 

(fig. 18) do not corollate to the temperatures in the 

Cedar River. The maximum temperature for water in 

well CRM-3 was reached on December 2, 1993, at 

18.7 °C while the river water was at 0.8 °C.

Water temperature measured at the 

water-treatment plant (fig. 18) changed slowly from a 

minimum on April 10, 1993, to a maximum on 

September 13, 1993. A traveltime is estimated from 

March 24, 1993, when the water temperature in the 

river started to warm, to the minimum temperature 

observed at the water-treatment plant on April 10, 

1993 (17 days). Traveltime from the maximum water 

temperature in the river on August 27, 1993, to the 

maximum water temperature on September 13, 1993, 

at the water-treatment plant is also 17 days. This is the 

same traveltime as the traveltime to municipal well 

Seminole 10 in April and in August. There were no . 

rapid changes in water temperature observed at the 

municipal water-treatment plant.

Dissolved Oxygen

In a stream, dissolved oxygen is a function of

the equilibrium concentration of dissolved oxygen and 

is controlled mainly by pressure and temperature at the 

contact between the atmosphere and the water surface 

(Hem, 1989). Some aquatic organisms require oxygen 

and may deplete concentrations of dissolved oxygen, 

whereas other organisms may increase the dissolvedoxygen concentration through photosynthesis. 

Concentrations of dissolved oxygen in ground water 

usually are the result of recharge to the aquifer, and 

concentrations can be similar to those of surface water 

(Hem, 1989). Dissolved-oxygen concentrations in 

water from the Cedar River, observation well CRM-4, 

and municipal well Seminole 10 are shown in 

figure 19, and in water from the Cedar River, observation well CRM-3, and municipal water-treatment plant 

are shown in figure 20.

Dissolved-oxygen concentrations in water from 

the Cedar River shows seasonal trends (fig. 19). 

During the colder winter months, the concentration of 

dissolved oxygen is about 14 to 15 mg/L. During the 

summer months, dissolved-oxygen concentrations 

average 7 to 9 mg/L (table 28). Colder water can hold 

more dissolved oxygen than warmer water. Diurnal 

fluctuations were present throughout the study and 

probably result from biological activity. Dissolvedoxvgen concentrations in water from observation well

Effect of the Cedar River on Selected Water-Quality Properties and Constituents of the Alluvial Aquifer 33
I

D

Q 

DC 

<

o

I

z 

a

Note: Breaks in lines indicete no data

Februery March April May 

1993

June

8.6 

8.4 

8.2 

8.0 

7.8 

7.6 

7.4 

7.2 

7.0 

6.8

Cedar 

River

Municipal well / 

Seminole 10 '

/ Observation 

well CRM-4 '

August September October November December

1993

January 

1994

Figure 16. pH of water from the Cedar River, observation wells CRM-3 and CRM-4, and Cedar Rapids municipal well 

Seminole 10, February 1,1993, through January 31,1994.

CRM-4 and CRM-3 and municipal well Seminole 10 

are dependent on the biological activity in the alluvial 

aquifer material and the movement of surface water 

through the material. The concentration of dissolved 

oxygen has been found to decrease abruptly in the first 

50-65 ft of sediments as a result of mineralization of 

dissolved organic compounds by microorganisms

(Bourg and Berlin, 1993). This could account for the 

observed decrease of about 2 to 4 mg/L in the 

dissolved-oxygen concentration between the river and 

observation well CRM-4 (fig. 19) throughout the study 

period.

On March 9, 1993, the decreasing concentration 

of dissolved oxygen in water from the river ceased and

34 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
26

24

22

C/3

2 20

03

LU 18 

u

C/3 1C LU lu 

LU

cc. 14 CD l4

LU

Q 12

cc

LU 

QNote: Breaks in lines indicate no data. Traveltimes 

7 days 

17 days

Cedar 

River

Traveltimes 

7 days 

10 days

Municipal well 

Seminole 10

Observation 

well CRM-4

Traveltimes 

8 days 

17 days

M M J 

1993

O J 

1994

Figure 17. Temperature of water from the Cedar River, observation well CRM-4, and Cedar Rapids municipal well 

Seminole 10, and estimated traveltimes of water from the river to observation well CRM-4 and municipal well Seminole 10, 

February 1, 1993, through January 31,1994.

started to increase. This change was observed on 

March 15, 1993, for observation well CRM-4 and on 

March 17 for municipal well Seminole 10 (fig. 19). 

Traveltimes based on these changes were 6 and 8 days, 

respectively. On November 1, 1993, the river concentration of dissolved oxygen stopped increasing. This 

change was observed on November 6, 1993, at well 

CRM-4 and on November 8, 1993, at well Seminole 

10, indicating ground-water traveltimes of 5 and 7 

days, respectively.

The concentrations of dissolved oxygen in water 

from observation well CRM-3 (fig. 20) showed very 

little change compared with well CRM-4. This could 

be due to ground water of low concentrations of dissolved oxygen seeping up from a deeper aquifer. No

traveltimes based on dissolved oxygen could be determined between the river and well CRM-3.

Dissolved-oxygen concentrations in water from 

the water-treatment plant show only small changes 

(fig. 20). There are three peaks shown on the graph 

(fig. 20) for the water-treatment plant on May 10, June 

23, and November 14, 1993, which could be a result of 

changes in the river on April 17, May 26, and 

November 1, 1993, respectively. These changes 

indicate traveltimes from the river to the watertreatment plant of 23, 28, and 13 days, respectively. 

The larger concentrations between July 17 and August 

5, 1993, could be the result of algal growths in the pipe 

of the aeration tower in which the multiprobe was 

placed.

Effect of the Cedar River on Selected Water-Quality Properties and Constituents of the Alluvial Aquifer 35
Note: Breaks in lines indicate no data Traveltime 

17 days

Municipal water 

treatment plant

Observation 

well CRM-3 Traveltime 

17 days

S O N D

I- -5

M

Figure 18. Temperature of water from the Cedar River, observation well CRM-3, and the municipal water-treatment plant, and 

estimated traveltimes of water from the river to observation well CRM-3, February 1, 1993, through January 31, 1994.

ASSESSMENT OF RELATIVE RISK OF 

ALLUVIAL AQUIFER TO CONTAMINATION 

BY PATHOGENS

The above-normal streamflow and precipitation 

during the study increased the effect of the Cedar 

River on the alluvial ground-water system and the 

potential for contamination by a pathogen. The 

increase in runoff could increase the amount of animal 

wastes reaching streams that could contribute to 

increased numbers of biogenic pathogens in the surface water. Several municipal wells were inundated for 

considerable periods of time during this study. With 

wells inundated, there could be a shorter path from 

the ground surface down to the well screen for 

biogenic pathogens to travel. However, several of the 

wells are completed through a silty clay and clay layer 

in the East Well Field (fig. 3) and a fine sandy silt layer 

in Seminole Well Field (fig. 5). These layers of relatively low hydraulic conductivity could help in restricting the movement of biogenic pathogens through the 

aquifer to the well.

The dissolved-oxygen data indicate that anaerobic conditions were not present in the alluvial aquifer 

in the vicinity of observation well CRM-4 and municipal well Seminole 10. This lack of anaerobic conditions could allow a very active microbiological community to develop that could aid in the natural filtration process that occurs in the alluvial aquifer. Investigators are finding that microbial activity and diversity 

are much greater than once thought in aquifers and 

that lake bottoms, streambeds, and soil zones are similar to the biologically active surface layer, known as 

the schmutzdecke, in slow, sand-filter systems (Boria 

and others, 1992). This layer is thought to allow perdition to occur as part of the filtering process (Boria and 

others, 1992). The filtration process itself is complex 

and involves a combination of straining, interception, 

sedimentation, Brownian diffusion, hydrodynamic 

retardation, and surface-interaction forces (Boria and 

others, 1992). Ground-water supplies in porous-media 

(sand and gravel) aquifers that induce recharge from 

surface water through pumping generally can be 

considered low-risk situations for Giardia contamination (Boria and others, 1992).

Data from MPA were used to determine the 

relative risk factor of water from the municipal wells 

tested and the raw water prior to treatment at the 

municipal water-treatment plant. This is done by 

determining the numerical range of each of the bio36 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
oc

oc

LU 

Q.

(Si

a

x

o

Q

O 

(Si 

(Si

Note: Breaks in lines indicate no data.

Traveltimes 

7 days 

5 days

Traveltimes 

8 days 

6 days

Municipal well 

Seminole 10

Observation 

well CRM-4

M

Figure 19. Concentrations of dissolved oxygen in water from the Cedar River, observation well CRM-4, and Cedar Rapids 

municipal well Seminole 10, and estimated traveltimes for water from the river to observation well CRM-4 and municipal well 

Seminole 10, February 1, 1993, through January 31, 1994.

16

14 

oc

LU

zb 12

LU-I

Occ 

>uj 10

O(Si

Note: Breaks in lines indicate no data.

Cedar 

River

Municipal water 

treatment plant

Observation 

well CRM-3

D | J 

1994

Figure 20. Concentrations of dissolved oxygen in water from the Cedar River, observation well CRM-3, and the Cedar FJapids 

municipal water-treatment plant, February 1, 1993, through January 31, 1994.

Assessment of Relative Risk of Alluvial Aquifer to Contamination by Pathogens 37
Table 6. Risk of surface-water contamination as determined by microscopic 

participate analysis of water in the study area, December 1992 through 

November 1993

[Information provided by Tom Noth of the Cedar Rapids Municipal Water Department]

Municipal wells or 

sampling site (figs. 6 and

Cedar River

Cedar Rapids municipal 

water-treatment plant

Date 

(month-day7) year)

12-07-92 

04-06-93 

04-13-93 

04-26-93 

08-02-93

11-16-93

04-06-93 

04-07-93 

04-08-93

04-26-93

Risk 

factor

77 

57 

37 

37 

18

74

21 

21 

15

17

Risk of surfacewater 

contamination

High risk 

High risk 

High risk 

High risk 

Moderate risk

High risk

High risk 

High risk 

Moderate risk

Moderate risk

Cedar Rapids municipal wells

East 1

East 19

West 6

Seminole 2

Seminole 3

Seminole 10

Seminole 14

Seminole 16

04-14-93

04-26-93

04-15-93

04-26-93

04-15-93

04-15-93 

09-22-93

11-16-93

12-08-92

04-13-93

09-22-93

11-16-93

04-06-93

08-02-93

11-16-93

04-06-93

04-07-93

08-02-93

11-16-93

4

5

4

4

4

21 

10

9

0

10

2

10

14

9 

4

14

14

9

4

Low risk

Low risk

Low risk

Low risk

Low risk

High risk 

Moderate risk

Low risk

Low risk

Moderate risk

Low risk

Moderate risk

Moderate risk

Low risk

Low risk

Moderate risk

Moderate risk

Low risk

Low risk

38 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
indicators tabulated in table 33 for a particular sample 

from tables 3 and 4. A rating of extremely heavy (EH), 

heavy (H), moderate (M), rare (R), or not significant 

(NS) is assigned to each bio-indicator of the sample. A 

numerical value then is assigned from table 34 for 

each bio-indicator according to its rating, and a sum is 

determined for the numerical values. A relative risk 

factor is determined from the scale at the bottom of 

table 34. A detailed explanation of the procedure is 

described in U.S. Environmental Protection Agency 

(1989).

Following this procedure, the river was evaluated to be at high risk (table 6) for the period of study 

due to the presence of Giardia cysts and Cryptosporidium oocysts and large counts of algae, diatoms, and 

rotifers (table 3 and 4). Of the eight municipal wells 

tested during the April 1993 flooding, municipal well 

Seminole 3 had a high-risk factor, three other wells 

had a moderate-risk factor, and four wells had a lowrisk factor (table 6). Five of the eight wells were inundated during this time (table 4), one at high risk, two at 

moderate risk, and two at low risk. For the remainder 

of the study period two wells had a moderate-risk 

factor at different times, and the rest of the wells 

sampled had a low-risk factor.

To measure the efficiency of the filtering process 

of the alluvial aquifer a log-reduction rate is used 

(Clancy, 1992). Using the particulate concentrations in 

table 4 for the wells and the river at concurrent times, a 

log-reduction rate can be calculated (table 7). The logreduction rate is calculated for an indicator by taking 

the log of the number of counts for the surface-water 

source (surface water) minus the log of the number of 

counts for the well. The log-reduction rate was calculated for vegetative debris, diatoms, and algae. Indicators that were not detected in both ground water and 

surface water were not used. If a ground-water sample 

had no detection for one of the indicators tested, a 

value of 1 was assumed to calculate the log-reduction 

rate.

The data for selected municipal wells tested 

show at least a three-log (99.9-percent) reduction between the river and the wells (table 7). A three-log 

(99.9-percent) reduction of algae is likely to achieve a 

three-log (99.9-percent) reduction in Giardia cysts 

(Boria and others, 1992). The log reduction for algae 

for municipal well Seminole 3 was 4.3 when it received ite high-risk rating on April 15, 1993. To date 

(1994), there has been no record of an outbreak of 

waterborne disease in the City of Cedar Rapids (John

North, City of Cedar Rapids Water Department, oral 

commun., 1994). A three-log (99.9-percent) reduction 

is required by the USEPA and the Iowa Department of 

Natural Resources for filtration and disinfection 

(U.S. Environmental Protection Agency, 1989; Iowa 

Administrative Code, 1992). The log-reduction data 

obtained in this study show that the natural filtration of 

the alluvial aquifer is very effective.

The presence of algae in some of the wells could 

indicate an inadequate surface seal around the casing. 

Another possibility could be macropores caused by 

tree roots, which could enhance vertical seepage to the 

aquifer from flooded areas. Municipal wells Seminole 

14 and 16 are near heavily wooded areas. The count of 

algae detected at the water-treatment plant in April 

1993 was higher than at all of the eight wells sampled 

during April 1993 (table 3). Some of the wells tested 

had counts of less than 20 per 100 gal. Because the 

water sampled at the water-treatment plant is a mixture 

of water from many wells, the count of algae might be 

expected to be lower than the results from most 

individual wells, but this is not the case. Algae 

growing inside the pipe of the aeration tower, where 

the sample was collected, could be one explanation. 

The log reduction for the municipal water-treatment 

plant compared to the river water was less than three 

for 3 of 4 samples of algae and 2 of 4 samples of 

vegetative debris.

Counts of protozoa in samples are similar to 

those for algae. Large counts are found in the river 

with smaller counts for the wells and water-treatment 

plant. Larger counts were measured during the flooding in March of 1993 than at other times of the year.

SUMMARY

Alluvial aquifers adjacent to large streams are 

important sources of water for many municipalities. 

Alluvial aquifers can have large transmissivities and 

hydraulic conductivities, which make them very desirable for water supply because large amounts of water 

can be withdrawn. The Surface Water Treatment Rule 

under the 1986 Amendment to the Clean Water Act 

requires that public-water supplies be evaluated for 

susceptibility to surface-water effects (U.S. 

Environmental Protection Agency, 1989). The groundwater source is evaluated for biogenic material and 

monitored for selected water-quality properties and 

constituents to determine the effect of surface water on 

the water supply.

Assessment of Relative Risk of Alluvial Aquifer to Contamination by Pathogens 39
s

I

a

2

<

o

3

O

O

Table 7. Filtration efficiency calculated as a log-reduction rate between the Cedar River and selected muni

the Cedar Rapids municipal water-treatment plant, December 1992 through November 1993

I Values are counts per 100 gallons of water; log-reduction rate is the log of the value for ground water minus the log of the value for surface water; 

ground water; ND, not detected]

3 

Q.

ID 

(O

 o

 o

o

0> 

Q. 

ID

ID a

O

Municipal well or 

water-treatment plant 

(figs. 6 and 7)

Seminole 2

Seminole 3

Seminole 10

Seminolel4

Seminole 16 '

Water-treatment plant

Date 

(monthday-year)

04-15-93

04-15-93

11-16-93

12-07-92

04-13-93

11-16-93

04-06-93

08-02-93

11-16-93

04-06-93

04-07-93

08-02-93

11-16-93

04-06-93

04-07-93

04-08-93

04-26-93

Vegetative debris

SW

l.OxlO3

l.OxlO3

ND

l.OxlO3

l.OxlO3

ND

l.lxlO3

ND

ND

l.lxlO3

l.lxlO3

ND

ND

l.lxlO3

l.lxlO3

l.lxlO3

l.OxlO3

GW

ND

ND

ND

1

ND

ND

ND

ND

ND

ND

ND

ND

ND

2

ND

ND

4

^ °9: Diatoms 

reduction

rate

3.0

3.0

3.0

3.0

3.0

3.0

3.0

2.7

3.0

3.0

2.4

SW

5.1xl05

5.1xl05

3.3xl03

1.2xl04

5.1xl05

3.3xl03

5.7xl05

ND

3.3xl03

5.7x1 05

5.7x1 05

ND

ND

5.7x1 05

5.7x1 05

5.7x1 05

2.7x1 03

GW

ND

8

ND

ND

2

ND

ND

ND

ND

ND

ND

ND

ND

1

1

ND

ND

Log- A, 

reduction 

rate

5.7

4.8

3.5

4.0

5.4

3.5

5.8

3.5

5.8

5.8

3.5

5.8

5.8

5.8

3.4

SW

3.4xl07

3.4xl07

6.0x1 07

7.4xl06

3.4xl07

6.0x1 07

l.SxlO7

2.3xl05

6.0x1 07

l.SxlO7

l.SxlO7

2.3x1 05

6.0x1 07

l.SxlO7

l.SxlO7

l.SxlO7

1.6xl07
The City of Cedar Rapids uses the alluvial aquifer adjacent to the Cedar River for its drinking-water 

supply. The alluvial aquifer is hydraulically connected 

to the Cedar River, bedrock, and upland areas in the 

study area. The city has three well fields in use along 

the Cedar River (figs. 6 and 7) with a total of 

53 municipal wells (table 2). The three well fields all 

have a similar lithologic sequence and hydraulic 

properties. A multiprobe instrument was used to 

continuously monitor water levels and selected waterquality properties and constituents in the Cedar River, 

observation wells CRM-3 and CRM-4, municipal well 

Seminole 10 (fig. 9), and selected water-quality properties and constituents at the municipal watertreatment plant (fig. 6).

Selected water-quality properties and constituents of the river changed inversely with changes in 

river stage or discharge (Schulmeyer, 1991). Selected 

water-quality properties and constituents of the alluvial aquifer changed as water flowed from the Cedar 

River to municipal well Seminole 10 as a result of 

drawdown. The values of specific conductance, pH, 

temperature, and dissolved oxygen for observation 

well CRM-4 and municipal well Seminole 10 generally follow the trends of values for the Cedar River. 

Values of specific conductance, pH, temperature, and 

dissolved oxygen at observation well CRM-3 and the 

municipal water-treatment plant show very little 

correlation with values for the Cedar River. The 

traveltime of water through the aquifer could be an 

indication of the susceptibility of the aquifer to 

surface-water effects. Estimated traveltimes from 

Cedar River to municipal well Seminole 10 ranged 

from 7 to 17 days. The data indicate that ground water 

has a short residence time in the aquifer before it is 

pumped out for consumption. Traveltimes were not 

long enough to have a substantial effect on the 

viability of Giardia cysts.

The above-normal conditions of streamflow and 

precipitation present during the study could have increased the effect that the Cedar River had on the alluvial aquifer and the possibility of contamination by a 

pathogen. The dissolved-ox.ygen data indicate that anaerobic conditions are not present in the alluvial aquifer in the vicinity of observation well CRM-4 and municipal well Seminole 10. This lack of anaerobic conditions could allow a very active microbiological community to develop, which could aid in the natural 

filtration process that occurs in the alluvial aquifer. 

Microscopic particulate data were collected using the

method outlined by the USEPA to determine if a 

ground-water source is GWUDI according to the 

SWTR (Vasconcelos and Harris, 1992). Analysis of 

29 samples found no Giardia cysts or Crytosporidium 

oocysts in water collected from municipal wells and 

the municipal water-treatment plant.

Data from the MPA were used to determine the 

relative risk factor of the ground-water source and the 

log-reduction rate, a measure of the efficiency of the 

filtering process of the alluvial aquifer. Using MPA 

data it was determined that, of the eight municipal 

wells tested during the April 1993 flooding, one municipal well, Seminole 3, had a high-risk factor, three 

other wells had a moderate-risk factor, and four wells 

had a low-risk factor. Data indicate that the aquifer is 

filtering out large numbers of algae, diatoms, rotifers, 

and nematodes as well as filtering out Cryptosporidium, Giardia and other protozoa. The filtering efficiency of the aquifer is equivalent to a 3 log-reduction 

rate or 99.99-percent reduction in particulates.

REFERENCES CITED

Boria, W.T., Wilson, M.P., and Gollnitz, W.D., 1992,

Natural filtration in porous media aquifers: American 

Water Works Association, Proceedings, Water Quality 

Technology Conference, November 15-19, Toronto, 

Ontario, p. 1871-1888.

Bourg, A.C.M. and Berlin, C., 1993, Biogeochemical

processes during the infiltration of river water into an 

alluvial aquifer: Environmental Science and 

Technology, v. 27, no. 4, p. 661-666.

Clancy, J.L., 1992, Interpretation of microscopic particulate 

analysis A water quality approach: American Water 

Works Association Water, Proceedings, Quality 

Technical Conference, November 15-19, Toronto, 

Ontario, p. 1831-1847.

Freeze, R.A., and Cherry, J.A., 1979, Groundwater: 

Englewood Cliffs, N.J., Prentice Hall, 604 p.

Hansen, R. E., 1970, Geology and ground-water resources 

of Linn County, Iowa: Des Moines, Iowa Geological 

Survey Water-Supply Bulletin 10, 66 p.

Heath, R. C., 1987, Basic ground-water hydrology: U.S. 

Geological Survey Water-Supply Paper 2220, 

p. 60-61.

Hem, J.D., 1989, Study and interpretation of the chemical 

characteristics of natural waters (3d ed.): U.S. 

Geological Survey Water-Supply Paper 2254, 263 p.

Hydrolab Corporation, 1991, DataSonde@3, Multiparameter water quality datalogger Operating manual: 

Austin, Texas, Hydrolab Corporation, 83 p.

References Cited 41
Iowa Administrative Code, 1992, Water supplies Design 

and operation: Des Moines, Iowa, Environmental 

Protection[567], chap. 43, v. XI, IAC 10/14/92, 30 p.

Iowa Department of Environmental Quality, 1976, Water 

quality management plan, Iowa Cedar River basin: 

Des Moines, Planning and Analysis Section, Water 

Quality Management Division, 376 p.

Last, M.D., 1994, Giardia and Cryptosporidium flood 

connection?: Lab Hotline, Hygienic Laboratory, The 

University of Iowa, v. 32, no. 10, p. 1-2.

Prior, J.C., 1991, Landforms of Iowa: Iowa City, University 

of Iowa Press, 153 p.

Reading, H. G., 1978, Sedimentary environments and 

facies: Oxford, England, Blackwell Scientific 

Publications, 34 p.

Schneider, Robert, 1962, An application of thermometry to 

the study of ground water: U.S. Geological Survey 

Water-Supply Paper 1544-B, 16 p.

Schulmeyer, P.M., 1991, Relation of selected water-quality 

constituents to river stage in the Cedar River, Iowa: 

U.S. Geological Survey Toxic Substances Hydrology 

Program, Proceedings of the Technical Meeting, 

Monterey, California, March 11-15, 1991, p. 227-231.

Southard, R. E., Sneck-Fahrer, D., Anderson, C.J., 

Goodrich, R.D., and German, J.G., 1994, Water 

resources data, Iowa, water year 1993: U.S. Geological 

Survey Water-Data Report, IA-93-1, 388 p.

Squillace, P. J., Liszewski, M. J., andThurman, E. M., 1993, 

Agricultural chemical interchange between ground 

water and surface water, Cedar River Basin, Iowa and 

Minnesota A study description: U.S. Geological 

Survey Open-File Report 92-85, p. 26.

U.S. Department of Agriculture, 1976, Iowa-Cedar Rivers 

basin study: Des Moines, Iowa, 250 p.

U.S. Environmental Protection Agency, 1989, Guidance 

manual for compliance with the filtration and 

disinfection requirements for public water systems 

using surface water sources: Washington, D.C., 400 p.

Vasconcelos, Jay, and Harris, Stephanie, 1992, Consensus 

method for determining groundwaters under the direct 

influence of surface water using microscopic particulate analysis: Washington, D.C., U.S. Environmental 

Protection Agency, 52 p.

Wahl, Ken, and Bunker, B. J., 1986, Hydrology of carbonate aquifers in southwestern Linn County and 

adjacent parts of Benton, Iowa and Johnson Counties, 

Iowa: Des Moines, Iowa Geological Survey Water 

Supply Bulletin 15, 56 p.

Wilson, M.P, Gollnitz, W.D., and Boria, W.T., 1992, 

Temporal concepts in ground water transmission of 

Giardia cysts and other microscopic particulates: 

American Water Works Association, Proceedings, 

Water Quality Technology Conference, November 

15-19, Toronto, Ontario, p. 1859-1869.

42 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 8. Mean daily water levels in the Cedar River at the surface-water monitoring site, 

February 1, 1993, through January 31, 1994

[Water levels given in feet above sea level; . no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

717.07

717.20

717.18

717.32

717.22

717.04

716.78

716.95

716.88

717.23

717.78

717.19

717.06

717.16

_

_

716.65

716.55

717.08

717.78

716.55

Mar.

716.35

716.09

717.97

720.74

721.44

721.52

722.06

723.01

722.24

721.02

720.87

719.41

717.72

717.64

717.02

716.76

718.26

718.70

718.17

717.87

717.68

717.85

718.65

717.63

718.85

719.79

720.22

720.68

721.41

722.41

723.70

719.47

723.70

716.09

Apr.

725.25

727.56

730.14

730.49

729.35

727.28

724.74

722.90

721.75

721.52

721.90

721.83

721.40

720.76

720.81

721.22

721.17

721.16

722.61

722.88

722.34

722.21

723.21

724.85

724.61

722.94

721.79

720.84

720.25

723.44

730.49

720.25

May

719.90

719.65

720.19

719.93

720.52

720.88

721.78

722.21

722.12

721.74

721.36

720.73

720.67

720.58

720.91

720.89

720.30

718.23

717.84

717.97

718.15

717.96

717.71

718.00

718.36

717.94

718.03

719.80

722.21

717.71

June

717.93

718.08

718.70

719.25

719.74

719.92

719.94

720.14

720.89

721.66

722.65

723.49

723.33

722.81

722.16

721.28

720.86

720.98

721.36

722.73

722.44

723.22

724.13

724.66

724.35

722.98

721.42

720.40

719.74

720.38

721.39

724.66

717.93

July

720.60

720.46

720.49

721.08

723.01

722.40

721.02

720.69

723.05

724.90

726.42

727.14

725.55

724.88

725.33

725.33

725.08

727.09

725.88

724.44

724.35

724.5 1

723.76

722.59

721.26

720.39

719.73

720.13

720.72-

720.68

720.69

723.02

727.14

719.73

Aug.

721.79

720.86

720.36

720.69

720.82

720.97

720.41

719.43

719.02

722.40

720.72

719.45

719.59

720.33

721.53

721.90

722.64

722.10

723.75

726.00

727.02

725.74

724.63

724.05

723.51

723.17

723.41

722.50

722.13

721.47

721.65

722.07

727.02

719.02

Sept.

721.57

721.33

721.40

720.99

720.60

720.04

719.48

718.88

718.32

718.47

718.15

717.58

717.59

718.06

718.76

718.79

718.77

719.05

719.05

718.66

718.74

718.58

718.60

718.22

717.97

718.49

718.57

718.44

718.33

717.69

718.97

721.57

717.58

Oct.

717.26

717.48

717.16

717.00

717.24

717.00

716.78

716.56

717.12

717.85

717.84

717.59

717.57

717.38

717.17

717.03

717.02

717.19

717.21

717.00

717.16

717.34

717.10

716.82

716.74

716.83

716.69

716.26

717.04

717.23

717.23

717.13

717.85

716.26

Nov.

717.28

717.19

716.86

716.53

716.83

717.15

717.05

717.20

717.34

717.24

716.94

716.79

716.59

716.88

717.24

717.26

717.23

717.02

716.81

716.97

716.88

717.10

716.92

717.10

717.14

717.03

716.79

716.79

717.07

717.88

 

717.04

717.88

716.53

Dec.

718.56

717.32

716.97

716.64

716.50

716.80

716.82

716.80

716.42

716.58

717.05

716.54

716.42

716.52

716.68

716.90

716.78

716.71

716.67

716.52

716.65

717.89

718.74

718.10

717.90

718.32

718.53

718.44

718.54

718.35

717.26

718.74

716.42

Jan.

718.34

718.84

718.80

718.80

718.56

718.38

718.51

718.45

718.43

718.15

718.33

718.05

717.94

718.05

718.15

717.67

717.65

717.84

717.74

717.95

717.67

717.44

717.26

717.28

717.29

717.35

716.92

716.95

717. 20

717. 67

717.55

717.91

718.84

716.92

Mean Daily Water Levels in Cedar River 43
Table 9. Mean daily water levels in observation well CRM-4, February 1,1993, through January 31,1994

[Water levels given in feet above sea level; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

MaxFab. Mar. Apr. May

717.33 ... ... 718.26

717.45 ... ... 717.98

717.44 ... ... 718.42

717.55 ... ... 718.16

717.43 ... ... 718.70

717.26 719.03

717.00 

717.17 

...

...

_ . _ _

...

719.22

719.10 719.53

719.13 719.51

718.89

718.16

717.71

717.30

717.01

716.70

716.29

716.42

716.62

717.14 ... 716.44

717.53 716.22

718.03 716.49

718.80 716.82

718.73 716.39

716.48

717.33 717.87 718.99 717.61

717.55 718.80 719.13 719.53

June

716.40

716.47

717.13

717. 67

718.19

718.44

...

719.16

...

...

...

...

...

...

_

...

...

...

_

...

...

...

...

...

...

719.22

...

...

717.83

719.22

July Aug. Sept.

...

...

719.42 

719.69 

...

719.32

718.84

718.42

717.80

717.84

717.44

716.82

716.77

717.39

717.86

717.94

717.90

718.12

718.13

717.73

717.52

717.13

717.14

716.97

716.80

717.24

719.15 717.30

719.37 717.19

717.14

716.56

...

719.26 719.55 717.57

719.37 719.69 719.32

Oct.

716.38

716.57

716.22

716.05

716.24

715.97

715.76

715.55

716.06

...

_

...

...

716.48

716.27

716.09

716.07

716.21

716.23

716.03

716.16

716.19

715.87

715.60

715.51

715.66

715.76

715.66

716.36

716.49

716.47

716.07

716.57

Nov.

716.49

716.39

716.08

715.56

715.60

715.88

715.74

715.90

715.68

715.23

714.94

714.77

714.38

714.70

715.04

715.09

715.32

715.14

714.87

714.97

714.73

714.95

714.76

714.94

714.94

714.81

714.54

714.53

714.78

715.40

715.20

716.49

Dec.

715.99

715.05

714.71

714.34

714.10

714.37

714.38

714.60

714.31

715.97

716.41

715.90

715.80

715.90

716.06

716.27

716.17

716.11

716.11

716.05

714.63

713.90

714.75

715.73

715.41

715.17

715.66

715.82

715.70

715.76

715.55

715.38

716.41

Jan.

715.51

715.99

716.04

...

715.97

715.77

715.99

715.78

715.73

715.43

715.63

715.35

715.24

715.38

715.54

715.00

715.01

...

...

_

714.41

714.19

714.30

714.38

714.36

713.92

713.92

714.17

714.60

714.59

715.08

716.04

imum

Mini- 717.00 717.14 718.73 716.22 716.40 719.15 719.42 716.56 715.51 714.38 713.90 713.92

mum

44 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Raplde, Iowa
Table 10. Mean daily water levels in municipal well Seminole 10, February 1, 1993, through 

January 31, 1994

[Water levels given in feet above sea level; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14 

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

__

...

_._

715.73

709.21

699.76

699.41

699.46

699.39

699.18

709.77

714.80

714.23

714.11

696.82

697.00

697.61

697.64

697.31

697.52

703.47

715.73

696.82

Mar.

__

...

698.43

700.82

701.79

701.89

702.13

702.70

702.85

703.05

702.90

701.67

700.27

699.81

699.06

698.68

699.49

699.93

699.36

699.03

698.82

699.04

699.78

699.04

699.74

698.72

700.37

703.05

698.43

Apr.

...

...

...

703.55

703.33

703.82

703.98

703.66

703.19

703.26

703.74

703.66

703.82

703.85

703.74

703.76

703.29

704.27

705.72

705.77

704.38

703.77

703.08

702.67

703.82

705.77

702.67

May

702.35

702.12

702.49

702.31

702.83

703.13

718.19

722.10

722.05

721.74

721.29

718.18

714.06

705.59

705.76

705.87

705.68

705.32

705.09

704.73

704.49

703.95

703.49

703.93

704.16

704.02

703.88

704.04

704.24

703.84

704.08

707.58

722.10

702.12

June

704.16

704.08

704.90

705.43

706.23

706.69

711.52

716.53

704.85

705.62

706.4 1

717.59

723.01

722.29

721.51

712.83

706.72

708.41

708.54

709.52

709.38

710.14

710.89

711.42

711.16

709.97

708.81

707.97

707.32

710.13

723.01

704.08

July

710.06

719.49

720.03

722.03

721.41

720.02

719.71

721.96

723.89

725.38

726.11

724.49

723.87

724.31

724.27

724.02

726.02

724.81

717.80

713.79

712.27

711.73

710.47

709.43

708.83

708.46

709.04

709.70

709.47

709.28

717.74

726.11

708.46

Aug.

710.31

709.57

709.17

709.37

709.47

709.53

715.74

720.12

713.71

716.20

711.45

712.82

716.85

7 1 1 .73

721.69

715.55

711.19

711.13

712.67

715.14

715.65

714.68

713.75

713.38

713.06

712.71

712.97

712.17

711.83

711.13

711.32

713.10

721.69

709.17

Sept.

711.40

711.13

711.15

710.61

710.29

708.66

708.55

708.86

708.30

708.24

707.84

707.19

706.87

708.99

708.43

709.19

708.97

709.16

709.15

708.82

707.70

706.43

706.45

705.72

705.23

705.76

705.78

705.48

705.45

705.44

708.04

7 1 1 .40

705.23

Oct.

705.74

705.90

705.5 1

705.35

705.62

705.19

704.88

704.74

705.25

705.77

705.89

705.78

705.87

705.63

705.34

705.06

705.05

705.13

705.20

704.94

705.10

705.09

704.80

704.63

704.55

704.61

704.54

703.90

704.26

704.33

704.32

705.10

705.90

703.90

Nov.

704.37

704.36

704.03

703.57

703.70

703.80

703.55

703.73

703.82

703.65

703.46

703.23

702.57

702.54

702.89

703.24

703.72

703.57

703.09

703.20

703.04

703.56

703.35

703.56

703.33

703.20

703.02

702.97

703.15

703.61

703.43

704.37

702.54

Dec.

704.05

703.22

702.95

702.42

702.21

702.53

702.67

704.36

704.69

715.52

716.01

715.45

715.34

715.42

715.66

715.87

715.78

715.75

715.82

715.79

706.36

700.57

701.39

702.40

700.87

700.71

702.16

702.28

702.09

701.95

701.33

707.21

716.01

700.57

Jan.

701.27

701.80

702.17

702. 1 1

701.86

702.63

701.27

701.14

700.87

701.35

701.14

701.09

701.48

702.02

701.18

 _

698.94

698.63

699.29

699.96

699.37

698.96

698.87

699.17

699.57

700.02

700.65

702.63

698.63

Mean Daily Water Levels in Municipal Well Seminole 10 45
Table 11. Mean daily water levels in observation well CRM-3, February 1, 1993, through 

January 31, 1994

[Water levels given in feet above sea level; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

...

...

...

...

...

_

...

...

...

716.51

716.33

715.07

714.93

714.99

714.89

714.75

715.72

716.18

716.15

716.02

714.18

714.50

714.80

714.79

714.42

714.70

...

...

...

715.23

716.51

714.18

Mar.

...

...

715.38

718.27

...

_

...

721.00

720.49

719.39

719.49

718.30

716.72

716.19

715.47

715.20

716.28

...

715.91

715.68

715.69

716.61

715.86

...

_

718.15

718.65

719.43

720.56

722.21

717.77

722.21

715.20

Apr.

724.21

726.68

729.22

729.55

728.48

726.49

723.94

722.02

...

720.88

720.59

721.00

720.96

720.51

719.94

719.98

720.31

720.24

720.27

721.56

721.91

721.47

721.33

722.34

724.03

723.88

722.29

721.16

720.26

719.57

722.59

729.55

719.57

May

719.11

718.80

719.21

718.95

719.52

719.86

721.72

722.62

722.61

722.26

721.85

721.15

720.73

719.92

720.22

720.21

719.61

719.01

718.74

718.35

718.07

717.68

717.27

717.38

717.56

717.39

717.17

717.40

717.70

717.32

717.38

719.25

722.62

717.17

June

717.33

717.37

717.90

718.37

718.85

719.10

719.51

720.17

719.94

720.82

721.88

723.71

724.03

723.53

722.94

721.44

720.49

720.63

720.97

722.21

722.08

722.96

723.91

724.50

724.18

722.84

721.45

720.37

719.71

720.19

...

721.11

724.50

717.33

July

720.35

720.17

720.33

720.90

722.88

722.36

721.03

720.66

722.79

724.70

726.24

727.00

725.39

724.68

725.18

__

724.81

726.86

725.66

724.27

724.21

724.28

723.53

722.38

721.18

720.39

719.63

719.84

720.28

720.24

720.18

722.75

727.00

719.63

Aug.

721.16

720.37

719.93

720.16

720.24

720.30

720.40

720.12

719.15

721.94

720.35

719.49

719.84

719.82

721.59

721.55

721.97

721.48

723.08

725.40

726.47

725.13

724.02

723.55

723.13

722.71

723.02

722.13

721.71

721.07

721.11

721.69

726.47

719.15

Sept.

721.06

720.80

720.87

720.47

720.17

719.59

719.07

718.61

717.95

717.84

717.33

716.74

716.73

717.27

717.73

717.78

717.72

717.91

717.93

717.58

717.48

717.17

717.19

717.11

717.01

717.42

717.50

717.48

717.50

716.99

 .

718.13

721.06

716.73

Oct.

716.55

716.76

716.34

716.15

716.31

716.06

715.86

715.64

716.10

716.80

716.91

716.81

716.68

716.27

716.08

715.90

715.88

715.99

716.02

715.83

715.96

716.00

715.73

715.47

715.39

715.50

715.59

715.05

715.44

715.57

715.55

716.01

716.91

715.05

Nov.

715.58

715.50

715.22

714.59

715.12

715.41

715.30

715.43

715.45

715.19

714.83

714.68

714.38

714.66

715.03

715.08

715.14

714.80

714.49

714.57

714.37

714.57

714.49

714.76

714.77

714.63

714.37

714.36

714.60

715.17

...

714.88

715.58

714.36

Dec.

715.74

715.00

714.62

714.26

714.02

714.24

714.18

714.35

714.00

715.19

715.64

715.15

715.03

715.15

715.31

715.50

715.43

...

715.46

715.33

714.76

714.27

715.07

716.11

715.86

715.58

715.98

716.11

715.98

716.04

715.86

715.17

716.11

714.00

Jan.

715.82

716.26

716.32

...

716.28

716.09

716.26

716.12

716.05

715.78

715.91

715.66

715.56

715.67

715.82

715.33

715.33

715.45

715.29

715.43

__

714.65

714.46

714.54

714.62

714.61

714.18

714.23

714.45

714.89

714.84

715.38

716.32

714.18

46 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 12. Water-level measurements for observation wells CRM-3, CRM-4, and CRM-6, February 1993 through 

January 1994

[Water-level measurements, in feet above sea level, made using a steel tape and measured to 0.01 ft; . no data]

Date 

(month-dayyear)

02-04-93

02-09-93 '

02-11-93

02-1 8-93 '

03-02-93

03-18-93

03-25-93

04-09-93

04-23-93

06-03-93

06-16-93

07-01-93

08-24-93

09-10-93

10-12-93

10-13-93

10-28-93

11-04-93

11-09-93

11-23-93

1 2-06-93

1 2-20-93 '

01-04-94

01-21-94

02-19-94

Observation

Time 

(24-hour)

1350

1425

1510

1255

1145

1530

1415

1350

1220

1310

1135

1120

1215

1145

1230

1235

1130

1305

1200

1145

1400

0830

well CRM-3

Water 

level

717.49

716.36

714.73

716.43

717.35

722.14

722.30

718.53

721.33

720.98

724.47

718.80

717.40

716.47

716.21

716.00

715.59

715.17

716.62

717.06

715.26

715.60

Observation

Time 

(24-hour)

1510

1100

1455

1310

1310

1135

0855

1522

1235

1140

1115

1115

0915

0905

0850

1015

0955

1200

1025

0950

1025

1100

1045

1330

0830

well CRM-4

Water 

level

717.46

716.80

716.11

716.93

714.54

716.31

717.24

721.46

721.67

718.09

721.00

720.70

724.22

718.57

717.19

716.95

716.04

715.86

715.58

715.35

714.88

717.12

716.69

714.86

715.47

Observation well CRM-6

Time Water 

(24-hour level

_

___

___ _

...

0856 720.78

_ _

0930 721.06

___

0830 719.92

Municipal well Seminole 10 was not operating on this day.

Water-Level Measurements for Observation Wells 47
Table 13. Mean daily specific conductance of water from the Cedar River, surface-water monitoring site, 

February 1, 1993, through January 31, 1994

[Specific conductance given in microsiemens per centimeter at 25 degrees Celsius; , no data]

Day

l

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

640

631

635

625

594

595

596

595

592

571

500

553

576

583

_

...

...

__

636

638

597

640

500

Mar.

636

627

408

237

223

238

260

274

281

283

280

290

369

406

437

486

454

403

366

433

443

343

401

323

285

283

261

238

227

240

348

636

223

Apr.

251

237

229

237

262

310

368

414

434

446

455

458

464

472

471

468

471

462

437

446

447

436

400

380

408

451

479

496

487

406

496

229

May

467

468

432

452

452

450

408

411

433

446

456

465

462

450

448

459

471

549

553

557

559

563

560

553

537

545

550

487

563

408

June

555

555

533

506

508

516

521

491

454

416

389

405

430

460

478

483

482

481

442

388

402

385

376

387

415

461

497

518

530

460

464

555

376

July

434

438

411

409

380

411

464

477

358

273

249

262

314

331

342

367

392

355

372

388

380

396

424

466

500

519

526

496

458

462

476

404

526

249

Aug.

397

436

454

445

434

437

480

518

527

348

408

488

481

411

379

391

370

404

337

286

314

365

384

397

421

401

408

452

450

454

435

417

527

286

Sept.

433

440

473

487

502

521

535

541

544

540

535

539

540

523

502

503

517

500

473

486

499

512

526

544

549

528

529

539

556

563

516

563

433

Oct.

565

565

562

554

536

525

517

507

499

479

482

505

514

519

525

533

538

542

543

550

549

545

540

536

527

523

527

526

532

536

539

530

565

479

Nov.

541

543

547

554

559

562

563

567

565

562

561

561

560

559

553

554

556

561

562

563

563

563

569

575

574

573

572

569

569

575

562

575

541

Dec.

576

578

583

586

589

588

582

582

580

576

571

572

573

570

567

573

572

567

561

554

556

568

589

600

609

612

619

619

625

626

584

626

554

Jan.

628

632

627

620

610

600

600

604

609

616

615

607

603

604

604

603

606

611

614

614

616

609

603

597

593

591

590

591

591

585

586

606

632

585

48 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 14. Mean daily specific conductance of water from observation well CRM-4, February 1, 1993, through 

January 31, 1994

[Specific conductance given in microsiemens per centimeter at 25 degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14.

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minmum

Feb.

581

581

585

594

604

612

618

623

...

625

628

628

618

582

539

560

574

584

593

590

596

611

627

655

658

654

651

...

...

...

607

658

539

Mar.

...

644

645

624

464

330

291

275

272

279

286

292

303

314

330

363

415

446

479

497

469

408

391

418

452

415

415

381

351

342

400

645

272

Apr.

332

312

300

287

283

283

285

293

...

294

321

388

450

478

488

488

...

...

...

_

...

467

466

453

426

404

417

438

380

488

283

May

453

469

480

485

477

460

472

474

476

479

477

476

476

479

475

478

471

482

505

516

526

534

539

542

544

543

543

543

546

545

542

500

546

453

June

530

532

538

546

548

536

516

507

510

516

493

470

467

462

458

450

421

406

445

478

478

471

439

413

411

403

395

404

439

486

472

548

395

July

511

523

...

...

...

...

...

...

...

...

518

510

504

503

503

493

442

438

429

390

392

409

453

493

502

478

447

470

523

390

Aug.

443

466

414

405

439

439

435

436

437

429

430

480

490

379

373

387

431

432

388

361

387

387

345

315

323

355

380

394

415

412

410

407

490

315

Sept.

444

447

449

445

437

436

457

477

496

513

525

530

532

532

532

533

536

525

508

504

508

502

480

495

513

531

541

538

526

524

501

541

436

Oct.

524

524

537

549

554

556

556

550

538

_

...

485

481

493

512

523

531

539

545

549

551

556

553

546

540

546

550

549

550

537

556

481

Nov.

546

543

541

543

544

544

549

556

558

558

558

560

562

563

565

566

566

565

560

561

562

565

566

568

567

567

565

565

566

565

559

568

541

Dec.

560

557

558

563

566

554

548

552

555

556

555

557

557

557

557

557

557

565

571

571

570

571

576

575

568

570

576

590

604

611

619

568

619

548

Jan.

626

631

632

...

630

634

634

628

616

608

607

609

613

619

623

618

614

...

624

627

628

628

623

617

612

609

608

606

620

634

606

Meen Daily Specific Conductance of Water From Observation Well CRM-4 49
Table 15. Mean daily specific conductance of water from municipal well Seminole 10, February 1, 1993, 

through January 31, 1994

[Specific conductance given in microsiemens per centimeter at 25 degrees Celsius; , no data]

Day

l

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

538

539

539

541

542

542

541

...

...

575

587

608

627

634

635

630

615

609

610

609

627

600

590

595

606

619

...

...

...

590

635

538

Mar.

...

...

636

635

634

634

635

626

596

571

520

445

383

348

325

310

305

306

313

326

349

381

417

453

469

463

...

...

...

462

636

305

Apr.

...

...

...

...

...

...

...

'...

...

287

288

290

299

321

355

390

423

450

470

487

495

500

506

510

508

499

492

486

477

429

...

427

510

287

May

386

381

388

402

416

430

414

404

395

393

405

405

422

448

453

453

451

478

505

505

505

507

510

514

522

531

538

545

547

550

550

463

550

381

June

550

550

547

546

544

541

533

522

541

538

531

515

517

517

522

521

516

509

500

488

473

454

449

449

454

459

460

453

443

...

505

550

443

July

418

461

460

464

443

447

467

473

470

466

468

468

465

458

468

478

476

480

458

438

435

441

449

455

456

453

446

439

439

443

456

480

418

Aug.

447

453

461

470

475

459

440

431

438

442

447

436

437

434

427

429

431

431

428

427

425

426

426

444

459

456

451

449

444

441

438

442

475

425

Sept.

432

428

427

429

428

415

417

422

425

416

413

419

425

433

436

446

459

468

477

485

495

496

491

510

517

515

518

525

534

538

461

538

413

Oct.

537

535

534

536

541

548

553

556

557

555

549

535

526

520

512

501

493

492

498

506

515

522

530

535

539

542

544

546

546

544

540

532

557

492

Nov.

537

536

535

534

533

532

531

530

527

525

528

533

534

537

542

546

548

550

551

551

551

551

562

570

570

572

574

575

574

574

547

575

525

Dec.

574

573

573

572

571

562

556

557

558

553

552

550

550

548

547

547

547

546

546

546

551

558

566

570

571

571

572

572

571

570

571

560

574

546

Jan.

575

583

593

...

617

623

628

632

636

638

640

640

637

633

628

625

...

 .

...

...

586

585

585

585

587

589

591

592

592

591

608

640

575

50 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Repids, Iowa
Table 16. Mean daily specific conductance for water from observation well CRM-3, February 1, 1993, 

through January 31, 1994

[Specific conductance given in microsiemens per centimeter at 25 degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

...

...

...

...

...

...

604

598

588

608

624

637

648

655

647

622

628

633

627

628

629

609

603

...

...

...

623

655

588

Mar.

...

...

610

613

...

...

605

605

608

604

597

598

600

598

600

604

...

...

609

614

601

602

606

...

__

624

611

592

572

559

601

624

559

Apr.

513

513

528

566

616

623

626

630

...

614

622

634

643

649

650

640

625

629

640

641

638

638

621

589

575

546

524

507

486

471

...

593

650

471

May

462

460

461

458

455

452

451

447

444

451

453

443

435

426

455

470

469

475

468

480

512

516

515

516

510

503

498

490

484

480

478

472

516

426

June

474

472

474

476

473

466

462

465

465

459

458

461

462

459

463

464

456

444

443

445

448

451

444

439

446

452

456

458

458

446

...

458

476

439

July

441

445

457

473

484

483

471

465

477

494

506

515

508

507

508

...

523

526

530

504

492

524

535

539

535

505

501

502

513

542

563

502

563

441

Aug.

579

575

565

557

548

533

515

515

499

492

492

498

509

470

472

490

511

520

517

517

530

528

515

509

501

505

546

597

594

600

629

530

629

470

Sept.

647

674

687

675

665

640

617

633

533

...

476

485

497

509

505

507

511

508

496

492

505

514

516

524

519

514

520

536

565

588

...

554

687

476

Oct.

585

587

588

587

579

565

558

561

573

583

591

592

593

593

595

594

585

598

620

630

642

651

634

618

596

577

564

554

541

535

529

587

651

529

Nov.

523

519

515

515

518

514

512

510

511

512

512

513

514

515

515

515

514

516

515

515

516

519

521

523

524

524

526

527

530

537

518

537

510

Dec.

548

545

540

550

553

554

556

552

553

552

579

587

582

587

586

575

561

...

568

575

577

561

564

579

584

596

631

602

590

600

596

573

631

540

Jan.

592

581

580

...

544

549

553

556

557

559

559

560

560

559

559

558

558

557

556

556

 

564

565

567

567

568

569

572

575

577

581

564

592

544

Mean Daily Specific Conductance for Water From Observation Well CRM-3 51
Table 17. Mean daily specific conductance of water from the Cedar Rapids municipal water-treatment plant, 

February 1, 1993, through January 31, 1994

[Specific conductance given in microsiemens per centimeter at 25 degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

__

...

...

...

_

...

_

...

__

588

588

581

585

586

581

567

580

566

__

563

581

...

579

588

563

Mar.

590

602

594

585

584

585

582

586

586

...

564

576

575

565

571

564

544

578

584

573

576

563

569

557

563

549

530

518

513

511

567

602

511

Apr.

522

512

516

530

499

503

...

476

489

498

486

489

491

492

496

498

508

507

507

509

492

494

490

483

466

465

466

474

...

495

530

465

May

471

477

473

492

486

471

464

468

467

467

460

475

491

487

479

470

473

474

477

480

481

483

491

499

497

496

502

508

513

510

506

483

513

460

June

505

502

494

496

500

505

506

503

500

502

500

500

499

495

493

490

492

507

500

494

490

491

502

497

487

483

475

468

474

473

...

494

507

468

July

473

464

466

462

464

462

459

...

...

_

...

...

_

...

...

...

...

...

...

_

...

464

473

459

Aug.

...

...

...

_

422

425

419

424

430

424

424

430

420

421

424

425

420

418

423

431

431

440

453

453

441

443

438

436

441

430

453

418

Sept.

443

445

451

439

443

442

447

448

448

449

465

475

471

478

492

479

486

489

486

485

486

483

481

490

492

486

483

484

488

485

...

471

492

439

Oct.

487

488

499

488

488

489

483

482

481

480

486

478

478

478

473

484

476

479

477

474

472

479

477

471

474

475

476

493

513

509

507

484

513

471

Nov.

509

504

501

503

501

506

496

506

513

525

520

522

518

517

517

518

500

498

513

513

513

511

517

525

524

520

522

522

519

512

513

525

496

Dec.

517

516

516

517

520

__

543

544

544

540

531

528

525

522

521

520

518

...

540

538

536

536

534

535

536

...

...

529

544

516

Jan.

...

...

...

551

548

543

531

528

525

527

520

527

521

523

528

529

525

521

526

514

509

514

511

523

516

519

519

504

519

524

551

504

52 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 18. Mean daily pH of water from the Cedar River, surface-water monitoring site, February 1,1993, 

through January 31, 1994

[pH given in standard units; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

7.9

7.9

8.0

7.9

7.8

7.8

7.9

7.9

7.9

7.9

7.8

7.8

7.9

7.9

_

_

_

7.8

7.8

7.9

8.0

7.8

Mar.

7.8

7.8

7.8

7.6

7.5

7.5

7.4

7.5

7.5

7.6

7.6

7.6

7.7

7.7

7.8

7.8

7.9

7.7

7.6

7.6

7.7

7.7

7.7

7.7

7.6

7.5

7.4

7.4

7.3

7.3

7.4

7.6

7.9

7.3

Apr.

7.4

7.4

7.5

7.5

7.5

7.6

7.7

7.7

7.9

7.9

7.9

7.9

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

8.1

8.2

8.2

8.2

7.9

8.2

7.4

May

8.1

8.1

8.0

8.0

8.0

8.0

7.9

7.9

8.0

8.0

8.1

8.1

8.1

8.1

8.1

8.2

8.2

_

8.3

8.3

8.3

8.3

8.4

8.5

8.4

8.3

8.4

8.4

8.2

8.5

7.9

June

8.5

8.5

8.3

8.2

8.2

8.2

8.2

8.1

8.0

7.9

7.9

7.9

8.0

8.0

8.1

8.0

7.9

7.8

7.8

7.7

7.8

7.7

7.7

7.8

7.8

7.9

7.9

7.9

8.0

7.9

8.0

8.5

7.7

July

7.9

8.0

8.0

8.0

8.0

8.0

8.0

8.1

8.0

7.9

7.8

7.8

7.9

8.0

8.0

7.9

7.8

7.8

7.8

7.9

7.9

7.9

8.0

8.0

8.0

8.1

8.1

8.1

8.1

8.1

8.1

8.0

8.1

7.8

Aug.

8.0

8.1

8.1

8.2

8.2

8.0

7.8

7.9

8.0

7.8

7.8

7.9

7.9

7.9

7.8

7.8

7.8

7.9

7.8

7.8

7.8

7.9

7.9

8.0

8.1

8.1

8.1

8.1

8.1

8.1

8.2

8.0

8.2

7.8

Sept.

8.2

8.2

8.3

8.3

8.3

8.3

8.4

8.4

8.4

8.3

8.3

8.3

8.3

8.2

8.2

8.2

8.3

8.3

8.2

8.2

8.2

8.2

8.3

8.2

8.0

8.0

8.0

8.1

8.2

8,2

8.2

8.4

8.0

Oct.

8.2

8.3

8.4

8.4

8.3

8.2

8.2

8.1

8.2

8.2

8.2

8.3

8.3

8.2

8.1

8.2

8.2

8.2

8.2

8.2

8.3

8.4

8.3

8.2

8.2

8.2

8.2

8.3

8.3

8.4

8.4

8.3

8.4

8.1

Nov.

8.4

8.4

8.4

8.4

8.4

8.4

8.4

8.4

8.3

8.1

8.2

8.1

8.1

8.1

8.1

8.1

8.1

8.2

8.2

8.2

8.2

8.2

8.3

8.3

8.3

8.3

8.3

8.3

8.3

8.3

8.3

8.4

8.1

Dec.

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.1

8.2

8.1

8.1

8.1

8.1

8.1

8.1

8.1

7.9

7.8

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

8.0

8.2

7.7

Jan.

7.8

7.8

7.8

7.8

7.8

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.7

Mean Daily pH of Water From Cedar River 53
Table 19. Mean daily pH of water from observation well CRM-4, February 1, 1993, through 

January 31, 1994

[pH given in standard units; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

7.8

7.8

7.8

7.9

7.9

7.9

7.9

7.9

7.9

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.7

7.8

7.7

7.7

7.7

7.7

7.7

7.7

7.7

...

7.8

7.9

7.7

Mar.

_

7.8

7.8

7.8

7.9

8.0

8.0

8.1

8.1

8.1

8.0

8.0

8.0

8.0

8.0

8.0

7.9

7.8

7.8

7.8

7.8

7.8

7.9

7.8

7.7

7.7

7.8

7.8

7.8

7.8

7.9

8.1

7.5

Apr.

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.7

7.7

7.7

7.7

7.6

_

...

7.5

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.8

7.6

May

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.7

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.7

7.8

7.5

June

7.8

7.8

7.6

7.5

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.5

7.5

7.5

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.8

7.4

July

7.5

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7.6

7.7

7.7

7.6

7.6

7.6

7.6

7.6

7.6

7.5

7.7

7.5

Aug.

7.6

7.6

7.7

7.7

7.7

7.6

7.5

7.5

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.4

Sept.

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.7

7.7

7.5

7.4

7.4

7.4

7.4

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.6

7.8

7.6

Oct.

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.9

_

...

7.6

7.6

7.6

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.8

...

...

...

...

...

7.8

7.9

7.6

Nov.

_

_

...

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.9

7.9

7.9

8.0

8.0

8.0

8.0

7.8

8.0

7.8

Dec.

8.0

8.0

8.0

8.1

8.1

8.0

7.8

7.9

7.9

7.9

7.9

8.0

8.0

8.0

8.0

8.0

8.0

8.1

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.2

8.1

8.2

7.7

Jan.

8.2

8.2

8.2

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

8.1

...

_

7.8

7.8

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

8.0

8.2

7.7

54 Effect of the Cedar River on the Quality of the Ground-Water Supply for Ceder Rapids, lowe
Table 20. Mean daily pH of water from municipal well Seminole 10, February 1, 1993, through 

January 31, 1994

[pH, given in standard units; . no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14.

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.2

7.3

7.5

7.5

7.5

7.5

7.6

7.5

7.4

7.5

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.5

7.7

7.2

Mar.

...

7.4

7.4

7.4

7.4

7.5

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.6

7.6

7.6

7.6

7.6

7.6

7.6

...

...

7.6

7.7

7.4

Apr.

...

_

7.7

7.8

7.8

7.8

7.8

7.8

7.7

7.7

7.7

7.7

7.8

7.9

7.7

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.9

7.6

May

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.7

7.7

7.7

7.7

7.6

7.6

7.6

7.6

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.7

7.8

7.6

June

7.8

7.8

7.6

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7.5

7.5

7.5

7.5

7.6

7.6

7.5

7.5

7.5

7.6

7.6

7.6

7.5

7.6

7.6

7.5

7.6

7.6

...

7.6

7.8

7.5

July

...

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.6

7.5

7.5

7.6

7.5

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7-7.

7.7

7.7

7,6

7.8

7.5

Aug.

7.7

7.7

7.7

7.7

7.7

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.9

7.9

7.9

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.7

7.9

7.6

Sept.

7.8

7.8

7.8

7.8

7.9

7.9

7.9

7.9

7.9

7.8

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.9

7.6

Oct.

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.6

7.7

7.7

7.8

7.8

7.9

7.9

7.9

7.9

8.0

8.0

8.0

8.0

8.0

8.0

8.0

7.8

8.0

7.6

Nov.

...

...

...

7.4

7.4

7.5

7.5

7.5

7.5

7.5

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

...

7.6

7.7

7.4

Dec.

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.5

7.5

7.5

7.6

7.6

7.6

7.6

7.7

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.8

7.8

7.8

7.8

7.8

7.8

7.8

7.7

7.8

7.5

Jan.

7.8

7.8

7.8

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.7

...

...

7.6

7.6

7.6

7.6

7.7

7.7

7.7

7.7

7.7

7.7

7.7

7.8

7.6

Mean Daily pH of Water From Municipal Well Seminole 10 55
Table 21 . Mean daily pH of water from observation well CRM-3, February 1, 1993, through 

January 31,1994

[pH, given in standard units; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

...

...

...

...

_

...

7.3

7.3

7.3

7.3

7.3

7.2

7.2

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

...

...

...

...

7.2

7.3

7.2

Mar.

...

...

7.2

7.2

...

_

7.2

7.2

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

...

7.2

7.2

7.2

7.2

7.2

_

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

Apr.

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

...

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.1

7.2

7.2

7.2

7.2

7.3

7.4

7.1

May

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.4

7.3

June

7.4

7.4

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

7.2

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

...

7.3

7.4

7.2

July

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.1

7.1

7.1

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

7.3

7.1

Aug.

7.3

7.3

7.3

7.3

7.3

7.2

7.1

7.1

7.1

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.2

7.3

7.1

Sept.

7.1

7.0

7.0

7.0

7.0

7.0

7.0

7.0

7.1

7.0

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.2

7.1

7.0

7.1

7.1

7.1

7.1

7.1

7.1

7.2

7.0

Oct.

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.0

7.0

7.0

7.0

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

6.9

_

...

...

...

7.1

7.1

6.9

Nov.

...

...

...

_

7.0

7.0

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

...

7.1

7.3

7.0

Dec.

7.3

7.3

7.3

7.3

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

...

7.2

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.4

7.4

7.3

7.4

7.2

Jan.

7.4

7.4

7.4

...

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.5

7.1

7.1

7.1

7.1

7.1

7.1

7.2

7.2

7.2

7.2

7.3

7.5

7.1

56 Effect of the Cedar River on the Quality of the Ground-Weter Supply for Cedar Rapids, iowa
Table 22. Mean daily pH of water from the Cedar Rapids municipal water-treatment plant, 

February 1, 1993, through January 31, 1994

[pH given in standard units; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15 .

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

...

_

...

...

...

...

...

...

. 

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

7.3

...

7.2

7.3

7.2

Mar.

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

...

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

...

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

Apr.

7.3

7.3

7.3

7.3

7.3

7.4

...

7.3

7.4

7.3

7.3

7.3

7.3

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.4

7.3

7.2

7.2

7.2

7.3

7.4

7.2

May

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.5

7.3

7.5

7.2

June July

7.5 7.4

7.5 7.4

7.4 7.4

7.3 7.4

7.3 7.4

7.3 7.4

7.3 7.4

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

.7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.4

7.3

7.4

7.3 7.4

7.5 7.4

7.3 7.4

Aug.

...

...

_

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.2

7.0

6.7

6.7

...

...

...

7.1

7.2

6.7

Sept.

...

...

_

...

...

7.2

7.2

7.2

7.2

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

7.1

7.1

7.1

7.0

6.9

6.9

6.9

...

7.2

7.3

6.9

Oct.

6.9

6.9

6.9

7.0

7.0

7.0

7.0

7.0

7.0

7.0

7.0

7.0

7.1

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

7.3

6.9

Nov.

7.3

7.3

7.3

. 7.3

7.3

7.3

7.3

7.4

7.3

7.2

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

7.2

7.2

7.2

7.2

7.2

7.3

7.3

...

7.3

7.4

7.2

Dec.

7.3

7.3

7.3

7.3

7.3

__

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.3

7.2

7.3

7.3

7.3

7.3

7.4

7.3

...

...

...

...

7.3

7.4

7.2

Jan.

...

...

6.3

6.3

6.3

6.3

6.3

6.3

6.3

6.3

6.3

6.3

6.3

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.4

6.3

Mean Daily pH of Water From Water-Treatment Plant 57
Table 23. Mean daily temperature of water from the Cedar River, surface-water monitoring site, 

February 1, 1993, through January 31, 1994

[Temperatures given in degrees Celsius;. , no date]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb. Mar.

-0.1 -0.1

-.1 -.1

-.1 -.1

-.1 -.1

-.1 -.1

-.1 -.1

-.1 0

-.1 .1

-.1 .1

-.1 0

-.1 0

-.1 0

-.1 .1

-.1 .2

.4

.5

.2

j

j

.2

j

.1

3

1.6

2.5

3.4

-.1 3.3

-.1 3.5

3.6

3.7

4.2

-.1 .9

-.1 4.2

-.1 -.1

Apr.

3.7

3.4

3.6

3.7

4.2

5.2

6.4

7.3

8.1

8.4

7.9

7.7

7.1

6.0

4.8

5.9

7.4

8.5

8.1

8.8

9.3

9.6

10.3

10.8

11.8

12.2

12.3

13.5

14.1

7.9

14.1

3.4

May

14.2

13.9

13.7

13.0

13.1

13.5

14.4

16.4

17.9

18.4

18.7

19.1

18.3

18.0

18.0

17.4

16.6

_

13.9

14.0

14.1

14.1

15.3

16.9

17.4

16.3

16.0

15.7

15.9

19.1

13.0

June

15.3

14.1

13.5

13.7

13.8

15.1

15.7

16.7

17.9

18.8

19.8

20.4

20.6

21.1

20.7

19.7

19.4

20.3

20.5

20.1

20.0

20.7

21.3

21.5

21.5

21.6

22.0

22.0

21.7

20.5

19.0

22.0

13.5

July

19.8

20.6

21.9

22.5

21.5

21.1

21.1

21.0

20.9

21.2

21.5

21.9

21.7

21.4

21.3

21.3

21.4

21.6

21.9

22.3

22.1

21.6

20.9

21.0

21.8

22.7

23.2

23.2

22.6

22.7

22.5

21.7

23.2

19.8

Aug.

21.6

21.6

21.5

21.1

20.3

19.7

19.9

20.4

20.9

21.4

22.4

23.0

23.5

23.6

22.7

22.6

23.0

23.3

22.9

22.9

22.8

22.4

22.6

23.1

23.6

24.2

24.6

23.8

22.1

21.4

20.7

22.2

24.6

19.7

Sept.

20.2

19.9

19.6

19.5

19.0

18.1

18.1

18.2

18.0

17.3

16.7

17.5

18.9

17.7

15.6

14.7

14.6

14.9

14.6

14.7

15.3

16.0

16.1

15.6

14.9

13.7

12.9

12.9

12.5

12.1

16.3

20.2

12.1

Oct.

12.6

12.5

12.4

13.2

13.0

13.8

15.6

16.8

15.0

12.6

11.4

11.2

10.9

11.3

12.1

12.7

12.8

12.2

12.4

12.4

11.1

10.2

10.5

11.1

11.6

11.3

9.8

9.0

7.3

5.7

4.6

11.6

16.8

4.6

Nov.

4.1

4.3

5.0

6.6

6.6

4.4

3.0

3.4

3.9

4.4

5.2

5.0

6.1

6.0

5.5

4.7

5.0

4.5

4.6

3.8

3.9

4.3

4.8

4.9

4.3

2.3

1.0

.6

.1

-.1

4.1

6.6

-.1

Dec.

0.1

.8

1.3

2.0

2.4

2.4

1.6

1.6

2.2

2.2

.6

.2

1.2

1.7

2.3

2.8

3.2

3.3

2.7

1.5

.4

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

1.2

3.3

-.1

Jan.

-0.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

-.1

0

0

0

0

0

0

-.1

0

-.1

58 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 24. Mean daily temperature of water from observation well CRM-4, February 1,1993, through 

January 31,1994

[Temperatures given in degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14 

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

0.9

.9

.9

.9

.9

.9

.9

.9

.9

.8

.7

.4

.2

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

...

...

.4

.9

.1

Mar.

...

...

0.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.2

.2

2

.3

.2

.2

.3

.4

.5

.5

.4

.3

.3

.3

.4

.6

1.1

.3

1.1

.1

Apr.

1.8

2.6

3.1

3.3

3.5

3.6

3.7

3.9

4.0

3.9

4.1

4.7

5.9

7.2

8.0

...

...

_

8.2

8.4

8.7

9.2

9.6

10.1

10.6

...

5.8

10.6

1.8

May

11.5

12.1

12.5

13.6

14.2

14.3

14.1

14.1

14.1

14.1

14.1

14.0

14.0

13.7

13.3

13.3

14.1

16.5

18.0

18.1

17.8

17.1

16.3

15.5

14.7

14.1

14.1

14.1

14.2

14.3

15.0

14.5

18.1

11.5

June

16.3

17.1

16.8

16.4

16.0

15.6

14.9

14.4

14.0

13.9

14.3

15.2

15.4

15.6

15.7

15.9

16.8

17.8

18.6

19.4

19.7

19.6

20.0

20.4

20.5

20.4

20.3

20.5

21.0

21.5

...

17.5

21.5

13.9

July

...

...

...

...

...

_

...

22.0

21.9

21.9

21.9

21.6

21.0

20.7

20.6

21.1

21.9

22.1

21.5

21.4

22.6

23.5

21.7

23.5

20.6

Aug.

23.3

22.9

22.8

22.9

22.0

21.8

21.8

21.7

21.7

21.6

21.3

20.8

20.6

20.2

20.0

20.2

20.8

21.6

22.6

23.3

23.5

23.2

23.1

23.4

23.2

23.1

23.0

22.9

22.7

22.9

23.4

22.2

23.5

20.0

Sept.

23.9

24.4

24.5

23.8

22.6

21.7

21.0

20.5

20.1

19.8

19.6

19.1

18.6

18.3

18.3

18.2

17.8

17.3

17.5

18.4

18.3

16.7

15.3

15.0

14.9

15.1

15.7

16.1

16.1

15.8

...

18.8

24.5

14.9

Oct.

15.3

14.6

13.8

13.3

13.0

12.8

12.6

12.6

12.6

...

_

15.6

15.9

15.0

13.4

12.2

11.6

11.4

11.6

12.1

12.6

12.7

12.6

12.4

11.9

11.2

10.8

10.9

11.3

12.8

15.9

10.8

Nov.

11.4

11.1

.10.3

9.4

8.2

6.8

5.6

4.8

4.8

5.3

5.9

6.1

5.5

4.3

3.8

4.1

4.6

5.1

5.6

6.0

6.0

5.7

5.3

5.0

4.8

4.5

4.2

4.3

4.6

4.9

...

5.9

11.4

3.8

Dec. Jan.

4.7 0.1

3.8 .1

2.5 .1

1.5

.8 .1

.4 .1

.2 .1

.3 .1

.8 .1

1.5 .1

1.7 .1

1.8 .1

1.8 .1

1.9 .1

1.9 .1

1.9 .1

1.8 .1

1.9

1.8

1.8

2. 1

2.3 .1

2.0 .1

1.9 .1

1.9 .1

2.2 .1

2.4 .1

1.5 .1

.6 .1

.2 .1

.1 .1

1.7 .1

4.7 .1

.1 .1

Mean Daily Temperature of Water From Observation Well CRM-4 59
Table 25. Mean daily temperature of water from municipal well Seminole 10, February 1,1993, through 

January 31, 1994

[Temperatures given in degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

6.5

6.5

6.5

6.5

6.5

6.4

6.4

...

...

6.1

5.1

1.7

1.0

.8

.6

.4

2.9

4.4

4.4

4.5

.7

.2

0

0

-.1

-.1

3.2

6.5

-.1

Mar.

__

...

-0.1

-.1

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.2

-.1

-.1

-.1

-.1

__

-.

-.

-.

-.

-.1

-.2

-.1

-.2

Apr.

__

...

...

...

_._

...

2.2

2.5

2.8

3.0

3.1

3.3

3.4

3.7

4.1

4.6

5.4

6.1

6.2

6.3

6.7

6.9

6.7

6.5

6.6

6.8

7.0

4.9

7.0

2.2

May

7.2

7.5

8.0

8.5

9.0

9.5

7.3

6.8

6.7

6.8

7.3

7.3

8.3

10.2

10.8

11.3

11.8

12.0

12.1

12.3

12.5

12.9

13.2

13.5

13.8

14.1

14.5

14.8

15.1

15.2

15.1

10.8

15.2

6.7

June

15.0

14.8

14.7

14.7

14.7

14.7

13.7

12.4

15.1

15.3

15.4

13.1

12.5

12.8

12.7

13.8

15.1

15.0

15.0

14.9

14.9

15.2

15.5

15.7

15.7

15.9

16.2

16.5

16.9

...

14.8

16.9

12.4

July

...

17.1

14.5

14.5

14.4

15.7

15.5

14.6

13.6

13.6

13.6

14.4

14.6

14.2

13.7

13.7

13.7

13.4

14.1

15.2

17.0

18.2

18.6

18.9

19.0

19.1

19.6

20.0

20.3

20.5

20.7

16.2

20.7

13.4

Aug.

20.8

20.9

21.0

21.0

21.1

21.0

19.2

18.5

19.2

19.2

19.6

19.6

18.8

19.9

18.5

19.5

20.3

20.1

20.4

20.2

20.3

19.9

19.7

19.2

18.5

18.6

18.7

18.5

18.5

18.4

18.2

19.6

21.1

18.2

Sept.

18.4

18.5

18.5

18.3

18.5

20.3

20.3

19.9

20.2

20.8

21.1

21.2

21.4

20.6

21.2

21.1

21.2

21.0

20.8

20.6

19.8

19.1

18.7

18.1

17.4

17.0

16.6

16.3

16.0

15.9

19.3

21.4

15.9

Oct.

15.8

15.7

15.5

15.3

15.0

14.6

14.3

13.9

13.6

13.4

13.2

13.0

13.0

13.0

13.2

13.5

13.8

13.9

13.8

13.6

13.3

12.9

12.6

12.4

12.4

12.4

12.4

12.3

12.2

12.1

11.9

13.5

15.8

11.9

Nov.

11.8

11.7

11.6

11.5

11.4

11.2

10.9

10.5

10.1

9.5

8.9

8.2

7.8

7.2

6.7

6.3

5.9

5.7

5.4

5.2

5.0

5.0

5.0

5.0

5.0

5.0

5.0

5.0

5.0

5.0

7.6

11.8

5.0

Dec.

5.0

4.9

4.9

4.8

4.7

4.5

4.3

4.5

4.4

6.8

6.4

6.4

6.5

6.5

6.5

6.6

6.6

6.6

6.6

6.6

6.1

3.8

2.7

2.0

1.7

1.6

.6

.6

.6

.7

.8

4.5

6.8

1.6

Jan.

1.8

1.8

1.7

1.3

1.1

.9

.7

.5

.4

.3

.2

.1

.1

0

0

...

...

...

-.1

-.2

-.2

-.1

-.2

-.2

-.2

-.2

-.1

-.1

.4

1.8

-.2

60 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 26. Mean daily temperature of water from observation well CRM-3, February 1, 1993, through 

January 31,1994

[Temperatures given in degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

...

...

...

...

0.6

.6

.6

.6

.7

.7

.8

.9

...

1.0

1.1

1.3

1.5

1.6

1.8

2.0

2.3

...

...

1.1

2.3

.6

Mar.

...

3.4

3.6

...

3.1

3.0

3.0

3.0

3.0

3.0

3.0

3.0

3.0

3.0

3.0

3.1

3.3

3.3

3.3

3.3

3.2

3.2

3.1

3.0

3.1

3.6

3.0

Apr.

3.0

3.0

2.9

2.9

2.9

2.9

3.0

3.2

3.6

3.7

3.8

3.9

4.0

4.1

4.2

4.2

4.3

4.3

4.3

4.4

4.4

4.4

4.4

4.5

4.5

4.6

4.7

4.8

4.9

3.9

4.9

2.9

May

5.0

5.0

5.1

5.1

5.0

5.0

5.0

5.0

5.0

5.0

5.0

5.0

4.9

4.9

4.9

4.9

4.9

4.9

4.9

4.9

4.9

4.9

5.0

5.0

5.1

5.2

5.2

5.2

5.3

5.3

5.3

5.0

5.3

4.9

June

5.4

5.4

5.3

5.2

5.2

5.1

5.1

5.0

5.0

4.9

5.0

5.0

5.0

5.1

5.1

5.0

5.0

5.0

5.0

5.1

5.1

5.1

5.2

5.2

5.3

5.3

5.5

5.6

5.7

5.2

5.7

4.9

July

5.9

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.1

6.1

6.1

6.1

__

6.1

6.1

6.1

6.2

6.4

6.5

6.6

6.7

6.9

7.1

7.3

7.5

7.8

8.1

8.3

6.5

8.3

5.9

Aug.

8.5

8.6

8.8

8.9

9.1

9.3

9.3

9.5

9.9

10.3

10.4

10.2

10.3

10.6

10.7

11.3

11.7

11.5

11.4

11.4

11.5

11.6

11.7

11.8

11.8

11.7

11.6

11.7

11.6

11.6

11.7

10.6

11.8

8.5

Sept.

11.8

12.0

12.2

12.3

12.5

12.7

12.9

13.2

13.4

13.9

14.0

14.2

14.3

14.6

14.7

14.9

15.0

15.2

15.4

15.4

15.4

15.3

15.4

15.3

15.3

15.3

15.2

15.1

15.1

...

14.2

15.4

11.8

Oct.

15.1

15.2

15.3

15.4

15.5

15.7

15.8

15.9

16.0

16.2

16.3

16.2

16.1

16.1

16.1

16.1

16.2

16.2

16.2

16.3

16.3

16.3

16.3

16.3

16.3

16.3

16.3

16.3

16.4

16.4

16.4

16.0

16.4

15.1

Nov.

16.5

16.5

.16.6

16.6

16.6

16.7

16.8

16.8

17.0

17.1

17.1

17.2

17.3

17.3

17.4

17.5

17.5

17.7

17.8

18.0

18.1

18.1

18.2

18.2

18.3

18.3

18.4

18.4

18.4

18.5

17.5

18.5

16.5

Dec.

18.6

18.7

18.6

18.5

18.4

__

18.3

18.2

18.0

17.7

17.2

16.8

16.6

16.5

16.5

16.3

15.8

...

13.9

12.6

11.6

12.6

14.2

15.1

15.7

15.9

16.0

16.0

15.9

15.8

15.7

16.3

18.7

11.6

Jan.

15.7

15.6

15.4

15.1

15.0

14.8

14.7

14.6

14.4

14.3

14.2

14.1

14.0

13.9

13.8

13.7

13.6

13.5

13.5

 

13.2

13.1

13.1

13.0

12.9

12.8

12.7

12.6

12.5

12.4

13.9

15.7

12.4

Mean Daily Temperature of Water From Observation Well CRM-3 61
Table 27. Mean daily temperature of water from the Cedar Rapids municipal water-treatment plant, 

February 1, 1993, through January 31, 1994

[Temperatures given in degrees Celsius; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minmum

Feb.

__

...

...

...

...

...

_

...

...

...

_

11.0

11.4

11.1

10.9

10.5

10.4

10.8

10.6

10.6

10.5

10.5

10.6

...

...

10.7

11.4

10.4

Mar.

10.7

10.8

10.7

10.5

10.5

10.5

10.5

10.5

10.3

...

9.3

9.4

9.7

9.5

9.4

8.8

8.8

9.4

9.0

9.0

9.0

9.6

9.5

9.3

...

9.5

9.4

8.9

8.5

8.0

8.1

9.6

10.8

8.0

Apr.

8.0

6.8

6.6

6.8

6.4

6.7

7.2

...

5.9

6.0

6.3

6.6

6.7

6.8

6.8

7.1

7.1

7.0

7.2

7.3

7.5

7.4

7.5

7.6

7.5

7.7

7.9

8.1

7.7

...

7.1

8.1

5.9

May

7.8

7.9

7.9

8.0

8.1

8.3

8.7

8.2

8.5

8.8

9.6

9.7

9.7

9.9

9.8

10.3

10.7

11.2

11.3

11.5

11.0

10.8

10.9

10.7

10.8

11.1

11.2

11.0

10.8

11.0

11.1

9.9

11.5

7.8

June

11.4

11.2

11.8

12.0

11.3

10.8

11.5

12.2

12.1

11.5

11.5

11.7

11.8

12.2

12.1

12.7

12.2

11.1

11.2

11.7

11.8

12.0

11.3

11.9

12.2

12.2

12.6

12.9

12.7

12.7

...

11.9

12.9

10.8

July

12.9

13.5

13.0

13.3

13.3

14.0

14.0

...

_

...

...

...

_

15.0

14.7

15.1

15.6

15.3

14.7

15.1

15.7

16.3

15.6

16.3

16.6

16.5

15.8

16.2

14.9

16.6

12.9

Aug.

16.8

16.9

17.0

16.9

17.1

17.3

16.7

16.6

17.3

16.7

16.4

16.9

17.0

16.3

17.3

17.3

16.7

16.7

17.2

17.0

16.4

16.4

16.6

16.6

16.3

16.6

17.5

16.7

16.8

17.0

16.9

16.8

17.5

16.3

Sept.

16.7

16.8

16.5

17.5

17.3

16.8

17.3

16.8

16.8

17.1

17.2

17.2

17.6

16.3

16.2

17.0

16.2

16.0

16.0

16.6

16.8

16.9

16.8

16.9

17.1

17.0

16.9

16.8

16.5

16.6

...

16.8

17.6

16.0

Oct.

16.4

16.3

15.9

15.9

15.8

15.6

16.2

15.9

15.8

15.8

15.3

15.7

15.6

15.6

15.7

15.5

15.5

15.3

14.8

14.6

14.6

14.5

14.5

14.8

14.8

14.7

14.6

14.5

14.4

14.3

14.2

15.3

16.4

14.2

Nov.

14.2

14.2

14.1

14.1

14.1

14.0

13.8

13.8

13.7

13.5

13.4

13.1

13.2

13.2

13.0

12.6

13.0

13.1

12.8

12.7

12.5

12.5

12.4

12.4

12.4

12.6

12.9

12.8

12.1

11.8

13.1

14.2

11.8

Dec.

11.5

11.3

11.3

11.2

11.0

 

11.0

10.9

10.8

10.6

10.7

10.7

10.4

10.7

10.7

10.6

10.3

10.2

10.1

10.1

10.1

10.1

10.3

10.2

...

...

...

...

...

10.6

11.5

10.1

Jan.

__

...

...

...

9.7

9.5

9.4

9.3

8.9

8.4

8.5

8.9

8.6

8.5

8.7

8.4

8.2

8.4

8.7

8.4

 

8.4

8.5

8.8

8.4

7.9

7.8

8.1

8.0

8.7

8.4

8.6

9.7

7.8

62 Effect of the Cedar River on the Quality of the Ground-Weter Supply for Cedar Rapids, Iowa
Table 28. Mean daily concentration of dissolved oxygen in water from the Cedar River, surface-water monitoring 

. site, February 1, 1993, through January 31,1994

[Dissolved-oxygen concentration given in milligrams per liter; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14 

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

12.0

12.2

12.1

12.2

12.3

12.1

12.2

12.2

12.3

12.3

11.9

11.2

11.2

11.8

...

_

..-

__

14.5

14.5

12.3

14.5

11.2

Mar.

14.6

14.7

15.2

15.1

14.4

13.7

12.9

12.3

11.9

12.1

12.2

12.8

13.4

13.7

13.9

14.2

14.6

14.7

14.7

14.6

14.7

15.0

15.1

14.6

14.0

12.9

12.6

11.7

10.9

9.9

9.2

13.4

15.2

9.2

Apr.

10.4

11.3

11.9

12.4

12.2

11.8

11.3

10.8

10.7

10.5

10.7

10.9

11.0

11.5

12.2

12.2

11.6

11.0

10.9

11.0

10.8

10.3

9.8

9.5

9.4

9.6

9.8

9.8

9.9

10.9

12.4

9.4

May

9.7

9.5

9.2

9.5

9.8

9.7

9.1

8.6

8.5

8.4

8.5

8.4

8.3

8.2

8.2

8.4

8.4

_

9.3

9.0

9.0

9.5

9.8

9.6

8.6

8.1

8.6

9.0

8.9

9.8

8.1

June

9.3

8.8

8.7

8.4

8.4

8.3

8.0

7.4

6.9

6.7

6.5

6.4

6.4

6.3

6.4

7.1

7.6

7.4

7.2

6.9

7.2

7.1

6.8

6.5

6.7

6.9

6.9

6.9

7.1

7.0

7.3

9.3

6.3

July

7.0

6.9

6.7

6.6

6.7

6.7

6.8

6.9

6.7

6.3

6.2

6.2

6.4

6.5

6.5

6.9

7.1

6.8

6.8

6.9

6.9

6.9

7.1

7.2

7.1

7.0

6.8

6.6

6.4

6.5

6.4

6.7

7.2

6.2

Aug.

6.2

6.6

6.7

6.8

7.1

7.6

7.8

7.7

7.7

6.9

6.8

7.0

6.9

6.7

6.4

6.4

6.3

6.4

6.1

6.0

6.2

6.4

6.4

6.9

7.3

7.1

7.0

7.0

7.2

7.2

7.4

6.8

7.8

6.0

Sept.

7.7

7.8

8.0

8.0

8.0

8.2

8.6

8.8

8.9

9.1

9.1

9.1

8.5

8.1

8.5

9.1

9.5

9.1

8.9

8.9

8.9

8.8

8.8

9.6

9.9

9.9

10.2

10.5

II. 1

11.1

9.0

11.1

7.7

Oct.

11.1

11.3

11.5

11.5

11.5

11.6

11.3

10.8

11.1

10.5

11.0

11.5

12.3

12.3

11.5

10.9

10.6

10.8

10.9

10.5

11.3

12.1

12.2

12.2

12.1

11.4

11.8

12.9

13.4

13.9

14.6

11.7

14.6

10.5

Nov.

14.8

14.4

14.1

13.5

12.6

13.4

14.3

14.1

13.5

12.7

12.4

11.7

11.1

11.1

11.4

11.7

11.9

12.0

11.9

12.1

12.2

12.0

12.5

12.4

12.3

13.1

13.6

13.9

14.1

14.0

12.8

14.8

11.1

Dec.

14.0

13.7

13.5

13.0

12.7

13.5

14.5

14.5

14.1

13.8

14.6

14.9

14.3

13.8

13.7

13.4

13.1

12.9

13.1

13.8

14.4

14.7

14.9

14.6

14.2

13.8

13.8

14.0

14.4

14.2

13.9

14.9

12.7

Jan.

13.9

13.7

13.3

13.1

13.1

13.0

12.9

12.9

12.7

12.5

12.3

12.1

11.9

11.8

11.8

11.7

11.6

11.5

11.3

11.2

11.0

10.7

10.7

10.7

10.7

10.9

11.0

11.0

11.1

11.2

11.3

11.9

13.9

10.7

Mean Daily Dlssolved-Oxygen Concentration in Water From Cedar River 63
Table 29. Mean daily concentrations of dissolved oxygen in water from observation well CRM-4, 

February 1, 1993, through January 31,1994

[Dissolved-oxygen concentration given in milligrams per liter; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

5.2

5.4

5.8

6.4

6.0

5.7

5.7

6.0

6.1

5.8

7.4

6.8

6.4

6.0

7.5

8.8

9.0

8.4

9.5

9.0

6.8

7.6

9.6

9.4

9.3

...

...

...

7.2

9.6

5.2

Mar.

...

9.7

7.9

8.9

8.2

6.6

4.0

1.1

.8

.7

.6

.6

.6

.5

.5

.6

2.2

2.6

4.2

4.5

3.8

3.4

3.7

3.8

3.1

2.0

1.0

.9

.9

3.1

9.7

.5

Apr.

0.8

.8

.8

.8

.8

.8

.7

.7

.8

.8

1.3

3.6

3.8

4.8

5.5

...

7.1

6.6

6.1

5.2

4.5

4.2

5.2

3.0

7.1

.7

May

5.2

5.0

4.8

4.3

3.9

3.8

3.5

3.3

3.3

3.1

2.7

2.6

3.0

2.3

1.2

2.2

2.8

2.7

3.1

3.0

3.1

3.4

4.0

4.3

4.5

4.5

4.5

5.1

4.7

3.7

2.7

3.6

5.2

1.2

June

2.4

2.7

2.5

1.9

1.5

2.1

2.4

2.6

2.4

1.7

1.6

1.5

.8

.7

.7

1.2

.6

.4

1.7

2.0

1.5

.5

.4

.4

.3

.3

.3

.4

.4

.7

...

1.3

2.7

.3

July

0.9

.8

_

_

.3

.3

.3

.3

.3

.3

.3

.3

.6

1.2

1.2

1.4

2.6

2.4

2.3

.9

2.6

.3

Aug.

1.9

2.1

2.0

1.4

2.0

2.2

2.2

1.3

1.1

1.3

.9

2.0

1.9

.5

.2

.2

.3

.2

.5

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.9

2.2

.2

Sept.

0.2

.1

.2

.3

.4

1.0

1.3

1.6

1.7

1.5

1.8

2.0

2.5

3.2

3.2

2.7

2.3

3.1

3.8

4.1

3.8

3.7

4.1

4.4

4.6

4.4

4.2

4.1

...

2.5

4.6

.1

Oct.

4.3

4.4

4.7

5.1

5.1

5.2

5.2

4.8

4.9

...

1.7

1.6

1.9

2.3

2.0

1.2

.6

.7

.9

1.1

1.4

3.5

4.8

4.5

4.9

4.4

3.4

4.6

3.3

5.2

.6

Nov.

5.4

6.0

6.8

7.7

8.5

8.7

8.4

7.0

6.6

7.3

7.7

7.6

7.5

7.1

6.7

6.0

5.7

6.0

6.5

6.5

6.3

6.3

6.9

7.6

7.7

7.6

7.7

7.8

8.2

9.2

7.2

9.2

5.4

Dec.

9.9

10.1

10.6

11.0

11.0

11.4

11.3

10.9

10.6

11.0

11.0

10.9

10.8

10.7

10.6

10.6

10.6

11.0

11.1

11.7

8.5

4.8

7.7

11.4

11.9

12.2

12.3

12.0

11.7

11.2

10.7

12.3

4.8

Jan.

11.0

11.2

11.7

11.5

10.9

10.2

9.8

10.0

10.2

9.9

9.7

9.4

9.1

8.6

8.3

8.4

...

6.7

6.5

6.4

6.0

5.7

5.5

5.3

5.0

4.7

4.4

8.3

11.7

4.4

64 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 30. Mean daily concentration of dissolved oxygen in water from municipal well Seminole 10, 

February 1, 1993, through January 31, 1994

[Dissolved-oxygen concentration given in milligrams per liter; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

0.4

.4

.4

.6

.5

.5

.4

2.5

5.2

6.4

7.2

7.5

7.6

4.6

4.2

2.6

1.9

7.1

6.3

6.0

6.9

7.8

7.8

4.1

7.8

.4

Mar.

...

...

9.6

9.2

9.2

9.1

8.8

8.4

8.2

8.0

7.2

5.8

4.0

2.5

1.8

1.4

1.2

1.4

1.3

1.2

1.5

2.1

3.0

3.9

4.5

5.0

...

4.9

9.6

1.2

Apr.

...

...

...

...

_

1.0

1.0

.9

.9

.9

.9

.9

.9

.8

.8

.8

.9

1.2

1.4

1.7

1.9

2.0

2.1

2.3

2.2

2.0

...

1.3

2.3

.8

May

1.6

1.3

1.3

1.2

1.2

.9

1.1

1.0

.9

.9

.9

.9

.9

.7

.7

.7

.6

.7

.7

.7

.7

.7

.7

.7

.7

.7

.7

.7

.7

.7

.8

.9

1.6

.6

June

0.8

.7

.7

.7

.6

.6

.8

.7

.7

.7

.7

.9

.7

.7

.7

.7

.7

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

...

.7

.9

.6

July

.5

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.6

.9

.7

.7

.6

.6

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.6

.9

.5

Aug.

0.4

.4

.4

.4

.4

__

1.0

1.5

.7

.5

.5

.6

.7

.5

.6

.5

.4

.4

.4

.4

.4

.4

.4

.5

.5

.5

.5

.5

.5

.5

.5

1.5

.4

Sept.

0.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.4

.4

.4

.5

.4

.4

.4

.4

.5

.5

.6

1.0

1.3

1.5

1.7

1.8

1.9

2.0

2.3

2.4

...

.9

2.4

.4

Oct.

2.4

2.5

2.7

2.9

3.1

3.3

3.4

3.6

3.8

3.8

3.9

3.9

3.8

3.4

3.1

2.9

2.7

2.8

3.2

3.3

3.0

2.6

2.4

2.5

2.7

3.1

3.8

4.5

4.7

4.9

4.9

3.3

4.9

2.4

Nov.

4.6

4.2

4.1

4.3

4.9

5.7

6.6

7.5

7.4

7.2

7.0

6.8

6.7

7.1

7.7

8.0

7.9

7.8

7.6

7.4

7.2

6.9

7.2

7.4

7.6

7.8

8.0

8.3

8.5

8.6

...

6.9

8.6

4.1

Dec.

8.6

8.5

8.6

8.9

9.4

10.3

10.9

10.6

10.5

5.1

4.0

3.1

2.5

2.0

1.6

1.4

1.2

1.2

1.1

1.0

5.6

9.8

9.7

9.5

8.6

7.5

6.7

7.0

7.8

9.3

10.6

6.5

10.9

1.0

Jan.

11.3

11.5

11.3

11.0

10.9

11.0

11.1

11.1

10.9

10.6

10.4

10.1

10.0

9.8

9.8

...

...

...

7.6

7.4

7.1

6.9

6.8

6.7

6.6

6.4

6.2

6.0

9.1

11.5

6.0

Mean Daily Dissolved-Oxygen Concentration in Water From Municipal Weil Seminoie 10 65
Table 31. Mean daily concentrations of dissolved oxygen in water from observation well CRM-3, 

February 1, 1993, through January 31, 1994

[Dissolved-oxygen concentration given in milligrams per liter; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb.

__

. 

...

3.1

2.4

1.1

.3

.2

.2

.2

.4

...

.6

.6

.5

.5

.5

.5

.5

...

.8

3.1

.2

Mar.

__

...

0.8

.4

...

_

.4

.4

.3

.3

.3

.4

.4

.4

...

.4

.4

.4

.4

.4

__

1.9

1.4

.8

.5

.5

.6

1.9

.3

Apr.

0.5

.5

.5

.5

.4

.4

.4

.4

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

...

.8

.7

.6

.6

.6

.6

.6

...

.5

.8

.4

May

0.6

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.5

.4

.4

.4

.4

.4

...

.5

.5

.5

.5

.5

.5

.4

.4

.4

.4

.4

.4

.5

.6

.4

June

0.4

.4

...

.5

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

_

.4

.4

.4

.4

.4

.4

...

.4

.4

.4

.4

.4

.4

.4

.5

.4

July

...

0.9

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

__

.5

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.4

.3

.4

.9

.3

Aug.

0.3

.3

.3

.3

.3

 

.3

.4

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

...

.4

.4

.4

.4

.4

.4

.4

.3

.4

.3

Sept.

0.4

.4

.4

.4

.4

.4

.4

.4

.4

...

.4

.3

.4

.4

.4

.3

.3

.3

.3

.3

.3

.3

.3

...

.4

.3

.3

.3

.3

.3

.3

.4

.3

Oct.

0.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.4

.4

.4

.4

.4

.4

.3

.3

.4

.4

.3

.3

.3

.3

.3

.3

.4

.3

Nov.

0.3

.3

.3

.3

.3

.3

.3

.3

.2

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

...

...

.2

.2

.3

.2

.3

.3

...

.3

.3

.2

Dec.

0.3

.3

.2

.2

.2

__

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

...

.4

...

.4

.4

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.4

.2

Jan.

0.3

.3

.3

1.0

.6

.5

.4

.4

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

__

.2

.3

.3

.3

.3

.3

.3

.3

.3

.2

.3

1.0

.2

66 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapids, Iowa
Table 32. Mean daily concentrations of dissolved oxygen in the water from the Cedar Rapids municipal watertreatment plant, February 1, 1993, through January 31, 1994

[Dissolved-oxygen concentration given in milligrams per liter; , no data]

Day

1

2

3

4

5

6

7

8

9

10

11

12

13

14 

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Mean

Maximum

Minimum

Feb. Mar.

0.7

.7

.5

.6

.7

.7

.7

.7

.8

1.1

1 .0

1.0

1.0

.9

.9

0.7 1.0

1.3 .9

1.1 .9

.9 .9

.8 .8

.7 .8

.8 .7

.7 .7

.4

.8

.6 .9

.9 1.3

1.3

1.1

.8

.8 .9

1.3 1.3

.4 .5

Apr.

0.6

.6

.7

1.4

.9

.6

1.5

1.4

1.4

1.2

1.0

.8

.8

.7

1.0

1.4

1.4

1.4

1.4

1.5

1.6

1.6

1.6

1.6

1.4

1.4

1.2

1.6

.6

May

1.5

1.2

1.2

1.3

1.3

1.2

1.4

1.5

2.9

3.0

2.9

2.8

2.9

2.6

2.0

2.0

2.3

2.5

2.4

2.6

 

1.6

1.6

1.5

1.5

1.5

1.6

1.7

1.7

1.5

1.5

1.9

3.0

1.2

June

1.4

1.4

1.4

1.4

1.4

1.4

1.4

1.5

1.5

1.7

1.6

1.5

1.4

1.4

1.4

1.3

1.4

2.9

3.1

3.9

3.1

3.9

4.5

3.8

2.1

1.3

1.2

1.2

1.2

1.2

1.9

4.5

1.2

July

1.1

1.1

1.1

1.0

.9

1.0

1.0

_

_

11.2

10.3

10.6

10.7

10.7

10.1

9.7

9.0

9.3

9.8

9.5

9.4

9.8

9.3

8.6

7.1

11.2

.9

Aug.

8.8

8.8

8.4

8.2

8.1

__

1.1

1.0

1.1

1.0

1.0

1.0

1.0

.9

.9

.9

.9

.8

.8

.8

.8

.8

.8

.9

1.1

1.1

1.1

1.0

1.0

1.0

1.0

2.2

8.8

.8

Sept.

1.0

1.0

1.0

.9

.9

.9

.9

.9

.9

.9

.9

1.0

1.0

.8

.8

.8

.8

.8

.8

.8

.8

.8

1.0

1.2

1.3

1.3

1.4

1.1

1.1

1.1

1.0

1.4

.8

Oct.

1.1

1.0

.9

1.0

1.1

1.0

1.0

1.0

.8

.8

.8

.8

1.1

1.4

1.4

1.3

1.5

1.5

1.4

1.4

1.3

1.3

1.2

1.1

1.1

1.1

1.0

1.2

1.5

1.4

1.3

1.2

1.5

.8

Nov.

1.3

1.3

1.3

1.3

1.2

1.2

1.2

1.2

1.3

1.8

3.2

3.6

3.7

3.9

3.5

3.7

3.2

2.5

2.6

2.7

2.8

2.7

2.5

2.2

2.4

2.4

2.3

2.4

2.4

2.3

3.9

1.2

Dec.

2.7

2.7

2.7

2.7

2.7

__

1.7

1.8

1.7

1.7

1.7

1.6

1.7

1.5

1.6

1.6

1.6

2.3

2.4

2.6

2.6

2.5

2.5

2.4

_

 .

2.1

2.7

1.5

Jan.

__

 .

2.8

2.7

2.5

2.6

2.8

2.8

2.5

2.4

2.4

2.9

2.4

2.3

2.5

2.9

2.6

2.5

2.3

2.8

2.7

2.5

2.8

2.9

2.9

2.8

1.9

2.2

2.6

2.9

1.9

Mean Daily Dissolved-Oxygen Concentration in Water From Municipal Water-Treatment Plant 67
Table 33. Numerical range of each primary bio-indicator (particulates) counted per 100 gallons of water

[EH, extremely heavy; H, heavy; M, moderate; R, rare; NS, not significant, >, greater than; <, less than; fromVasconcelos and Harris (1992)]

Indicators for 

surface water1

Giardia

Coccidia

Diatoms

Other algae3

Insects/larvae

Rotifers

Plant debris3

EH

>30

>30

>150

>300

>100

>150

>200

H

16- 30

16- 30

41 -149

96 -299

31 - 99

361 -149

71 -200

6

6

11

21

16

21

26

M

- 15

- 15

- 40

- 95

- 30

- 60

- 70

R NS

1-5 <1

1-5 <1

1-10 <1

1-20 <1

1-15 <1

1-20 <1

1-25 <1

1 According to U.S.Environmental Protection Agency, 1991, Guidance manual for compliance with the filtration and disinfection 

requirements for public water systems using surface-water sources, Washington D.C.

2 If Giardia cysts or coccidia are found in any sample, irrespective of volume collected, score as though the sample was counted per 100 

gallons.

3 Chlorophyll containing.

Table 34. Relative surface-water risk factors associated with scoring of primary bio-indicators 

(particulates) present during microscopic particulate analysis of water from the study area

[EH, extremely heavy; H, heavy; M, moderate; R, rare; NS, not significant; from Vasconcelos and Harris (1992)]

Indicators for

surface water1

Giardia

Coccidia

Diatoms

Other algae

Insects/larvae

Rotifers

Plant debris

EH

40

35

16

14

9

4

3

H

30

30

13

12

7

3

2

Relative risk factor2

M

25

25

11

9

5

2

1

R

20

20

6

4

3

1

0

NS

0

0

0

0

0

0

0

' According to U.S. Environmental Protection Agency, 1991, Guidance manual for compliance with the filtration and disinfection 

requirements for public water systems using surface-water sources, Washington D.C.

2 Risk of surface-water contamination: 

greater than or equal to 20, high risk; 

10-19, moderate risk; 

0-9 low risk.

68 Effect of the Cedar River on the Quality of the Ground-Water Supply for Cedar Rapida, Iowa