Artificial Recharge 

Through a Well Tapping 

Basalt Aquifers 

Walla Walla Area 

Washington

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1594-A

Prepared in cooperation with the 

State of Washington Department 

of Conservation
Artificial Recharge 

Through a Well Tapping 

Basalt Aquifers 

Walla Walla Area 

Washington

By CHARLES E. PRICE

ARTIFICIAL RECHARGE OF GROUND WATER

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1S94-A

Prepared in cooperation with the 

State of ff^ashington Department 

of Conservation

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1961
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington 25, D.C. - Price 20 cents (paper cover)
CONTENTS

	Page 

Abstract___ _ ____________________________________________________ A-l

Introduction._____________________________________________________ A-l

Purpose and scope of the investigation.__________________________ A-l

Location of the area___________________________________________ A-2

Acknowledgments. _________--______---_-___------_____________ A-2

Geologic and hydrologic features.___________________________________ A-4

Occurrence of water in basalt_______________________________________ A-7

Ground-water movement-___-_--__-_---____--___________.______ A-7

Water-level fluctuations-__-_-_-_--___-_____---_----____________ A-8

Water supply of Walla Walla._____-_-__-_-__-__--_-________________ A-9

Surface-water supply___----______-____--------_______________ A-9

Ground-water supply._________________________________________ A-10

Suitability of Mill Creek water for recharge.__________________________ A-10

Chemical compatibility_______________________________________ A-l 1

Sediment_ _______-__--_-_-__--_-_-_______--__-_-____________ A-13

Air content.__________________________________________________ A-14

Dissolved air______________________________________________ A-14

Entrained air_____.-___-_-___________-__-_________________ A-16

Biological suitability.__________________________________________ A-17

Adequacy of supply-___------_-----_-_-_---_-_--------_________ A-18

Yield characteristics of city well 3___________________________________ A-18

Recharge of city well 3 with Mill Creek water_______________________ A-19

Effect of recharge on the yield characteristics of city well 3_____________ A-21

Recovery of injected water.________________________________________ A-23

Aquifer transmissibility and boundaries._____________________________ A-27

Conclusions_____________________________________________________ A-28

References cited___________________________________________________ A-30

Index._____________________________________________________ A-33

ILLUSTRATIONS

FIGUHE 1. Map showing well locations_______________________________ A-3

2. Hydrograph of Roy Frazier well_________________________ A-9

3. Hydrograph of Walla Walla well 3___________.________ A-20

4. Hydrograph of Walla Walla well 1__________________ A-22

in
IV CONTENTS

TABLES

Page 

TABLE 1. Abridged drillers'logs of wells_________________--_-_______- A-4

2. Chemical analyses of water from city wells 1, 3, and 4, and from

Mill Creek-_________________-______-___-__--__-___-__- A-12

3. Dissolved oxygen in water from Mill Creek and city well 3__-_ A-15

4. Discharge and temperature of Mill Creek near Walla Walla _ _ _ A-16

5. Partial chemical analyses of water from Mill Creek,__________ A-24

6. Partial chemical analyses of water from Walla Walla city well

3 after completion of recharge-__________________________ A-25

7. Quantities of water pumped from Walla Walla city -well 3 after

completion of recharge._________________________________ A-26

8. Chemical analyses of water from selected wells in the Walla

Walla basin.-._.__________________________._ A-27
ARTIFICIAL RECHARGE OF GROUND WATER

ARTIFICIAL RECHARGE THROUGH A WELL TAPPING 

BASALT AQUIFERS, WALLA WALLA AREA, WASHINGTON

By CHARLES E. PRICE

ABSTRACT

Declining water levels in part of the Columbia lava plateau, owing to pumping, 

have caused concern for several years. Therefore, the U.S. Geological Survey 

in cooperation with the State of Washington Department of Conservation carried 

out an experiment to determine the feasibility of artificial recharge to halt the 

decline of water levels in part of the Walla Walla basin, Washington. During 

the experiment 71.3 acre-feet (23 million gallons) of surface water was injected 

into basalt through Walla Walla city well 3 at rates ranging from 630 to 670 

gallons per minute. The chemical and bacteriological quality of the injected 

water was excellent, and the water contained only 2 parts per million of suspended 

sediment. The injected water probably was nearly saturated with air when it 

entered the top of the well and may have entrained some additional air as it 

fell into the well.

The water injection caused a rise of the water level and hence increased the 

amount of ground water in storage in the local area. However, the subsequent 

yield and specific capacity of the well were impaired. The data obtained during 

the tests suggest that hydraulic boundaries limit the lateral movement of water. 

The tests indicate also that the coefficient of transmissibility of the basalt is 

about 400,000 gallons per day per foot and that the coefficient of storage is 

about 0.0002.

INTRODUCTION

PURPOSE AND SCOPE OP THE INVESTIGATION

This report presents the results of an investigation to determine 

the feasibility of artificially recharging deep basalt aquifers by injecting surplus water from Mill Creek through one of the public-supply 

wells of the city of Walla Walla, Wash. The investigation was begun 

in 1956 as a result of conferences among the U.S. Geological Survey, 

the State of Washington Department of Conservation, and the city 

of Walla Walla; it was agreed that the Geological Survey, as a part 

of its cooperative program with the State, would make the investigation and would prepare a report on the findings.

With the continued withdrawal of ground water in greater and 

greater quantities for irrigation, industrial, and public supply, conA-l
A-2 ARTIFICIAL RECHARGE OF GROUND WATER

servation practices will become of great importance in the planned 

development of the ground-water resources. Artificial recharge, involving the injection of surplus surface water into the ground through 

wells, is one form of conservation aimed at increasing the groundwater supply and lowering pumping costs in areas where heavy groundwater development currently is taking place.

The city of Walla Walla for several years has considered the possibility of introducing surface water into one of its public-supply wells 

in order to recharge artificially the basalt aquifer tapped by that well. 

The water-supply system of the city is easily adaptable to such a 

recharge program: excess surface water is available for recharge 

during a part of each year, and because one of the wells is only a 

few feet from the pipeline carrying Mill Creek water to the city's 

reservoir, the installation of piping and metering equipment was simple 

and inexpensive.

Because of the city's interest in salvaging surplus Mill Oreek water 

and the interest of the State and Federal agencies in recharge as 

related to conservation in general, the Geological Survey undertook 

this project to investigate the feasibility of recharge through wells. 

The Survey supervised the experimental work and determined the 

effect of such recharge on the injection well and on the basalt aquifers 

tapped by the well.

The fieldwork was done jointly by the Geological Survey and the 

State of Washington Department of Conservation, under the supervision of A. A. Garrett, district engineer, Ground Water Branch, and 

R. H. Russell, assistant supervisor, State Division of Water Resources. 

The section of this report dealing with the suitability of Mill Creek 

water for recharging the basalt aquifers has been adapted from a 

chapter in a report by Hart (1957).

LOCATION OF THE AREA

Walla Walla is in the southeastern part of the State of Washington, 

about 5 miles north of the boundary between Washington and Oregon 

and in the drainage basin of Mill Creek, a westward-flowing tributary 

of the Walla Walla River. The well in which the water was injected, 

Walla Walla well 3, is about 5 miles east-northeast of the city, near 

Mill Creek (fig. 1).

ACKNOWLEDGMENTS

The writer wishes to acknowledge the assistance of Mr. Paul F. 

Meyer, water superintendent of Walla Walla, and other of the city's 

personnel. Without the use of the city's facilities and the excellent 

cooperation of the Water Department, the collection of many important data would not have been possible.
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~3

R. 36 E. R. 37 E. 118°10'

Base from U. S. Geological Survey 

Walla Walla quadrangle

CONTOUR INTERVAL 50 FEET

DATUM IS MEAN SEA LEVEL

3 MILES 

J

APPROXIMATE MEAN 

DECLINATION, 1960 Well Well name

A Robert Moore

B Roy Frazier

C Walla Walla well 1

D Walla Walla well 2

E Walla Walla well 3

F Gerald Brunton

G Olaus Filan

H Walla Walla well 4

FIGURE 1. Map of the Walla Walla areas showing locations of wells.

The writer is indebted to Mr. Harlow Barney, Walla Walla County 

watermaster, for making a series of water-level measurements on the 

injection well after the period of recharge.
A-4 ARTIFICIAL RECHARGE OF GROUND WATER

GEOLOGIC AND HYDROL.OGIC FEATURES

Walla Walla basin is an east-trending topographic and structural 

basin that lies astride the Washington-Oregon boundary. This basin, 

about 1,300 square miles in area, is bounded on the north by the 

Touchet slope, on the east by the Blue Mountain uplift, on the 

south by the Horse Heaven uplift, and on the west by a rimrock ledge 

in the lower valley of the Walla Walla River. All these features are 

beyond the extent of figure 1, which shows only a part of the eastern 

part of this basin.

The Walla Walla basin is underlain by a series of lava flows that 

are a part of the basaltic materials designated the Columbia River 

basalt by Russell (1893). The Columbia River basalt extends in 

general from the Okanogan highlands south to the eastward-trending 

mountain systems of central Oregon, and from the Cascade Mountains 

eastward to the Rocky Mountains in Idaho. The Walla Walla 

basin lies southeast of the geographic center of that vast basaltic area, 

and the sequence of lava flows in it is of unknown thickness. At 

Walla Walla well 3, used as the injection well in the recharge experiment, the basalt is at least 1,169 feet thick (table 1). In Mill Creek 

Canyon, east of well 3, a thickness of about 2,000 feet of basalt is 

exposed. The rock on which the basalt rests is not exposed, nor has it 

been reached by drilling in the Walla Walla basin. About 35 miles 

northeast of Walla Walla, in the Tucannon River canyon, a few small 

inliers of Paleozoic (?) and Mesozoic(?) sedimentary and igneous rocks 

are exposed from beneath the basalt, according to Huntting (written 

communication, 1942). In that vicinity the basalt is at least 3,000 

feet thick. About 50 miles southwest of Walla Walla, in the Umatilla 

River basin, the basalt lies upon sedimentary rock of Eocene age 

(Hogenson, 1957, p. 15, pi. 2a) and other older rocks.

TABLE 1. Abridged drillers' logs of wells

Well 1, city of Walla Walla

[Altitude, about 1,260 ft. Drilled by A. A. Durand & Son, 1942. Casing, 10-in to 363 ft]

Materials

Soil - __ _ _ 

Gravel, clay, boulders

clay seams_ ________

Basalt, gray _ _ _ ___

Basalt, black, __ ____ _

Basalt, gray _ _ _ _ __

Basalt, black. __ __ __

Thickness 

(feet)

8

51

79

143

33

133

57

51

Depth 

(feet)

8

59

138

281

314

447

504

555

Materials

Basalt, gray _ _ _ -___

Basalt, brown______ _

Basalt, black. __ _ ____

Basalt, black. _________

Basalt, gray.. _____ __

Thickness 

(feet)

5

190

5

7

15

4

21

8

Depth

(feet)

560

750

755

762

777

781

802

810
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~5

TABLE 1. Abridged drillers' logs of wells Continued

Well 2, city of Walla Walla

[Altitude, about 1,273 ft. Drilled by A. A. Durand & Son, 1942. Casing, 16-in to 140 ft]

Materials

mented_______ _____

Gravel and boulders....

clay _______________

Basalt, black.. _ _____

Basalt, brown ___ ___

Thickness 

(feet)

15

57

38

89

14

262

Depth 

(feet)

15

72

110

199

213

475

Materials

Basalt, black and gray

(alternating layers) _ _

Basalt, black and gray.

Basalt, brown______ __

Thickness 

(feet)

2

91 

9

189

5

37

Depth

(feet)

477

568 

577

766

771

808

Well 3, city of Walla Walla

[Altitude, about 1,317 ft. Drilled by A. A. Durand & Son, 1947. Casing, 20-in to 178 ft, 16-in from 1,063 to

1,102ft]

SoiL_________. _______

Gravel and boulders _ _ 

Gravel and clay _______

Basalt, black and

Basalt, black and gray. 

"Shale," blue 

Basalt, black, porous; 

some broken layers. .

2

6 

137

26

92

7

119

11

2

8 

145

171

263 

270

389

400

brown, and gray

Basalt, black and gray

Basalt, black; gray

Basalt, black, and 

light-brown clay _

139

289

287

5

49

539

828

1, 115

1, 120

1, 169

Well 4, city of Walla Walla

[Altitude, about 1,045 ft. Drilled by A. A. Durand & Son, 1953. Casing, 24-in to 400 ft]

Gravel and clay, yellow _

5

1Q

270

103

5

24

294

397

Basalt, black, hard _____

Basalt, black, hard__ _

321

45

26

718

763

789

Gerald Brunton well

[Altitude, about 1,350 fe«t. Drilled by W. E. Euther & Son, 1957. Casing, 6-inch to about 30 feet]

Soil_____._____ _ .___

Cobbles, black__._ _

17

9

17

26

Gravel, black, cemented,

13 39

Olaus Filan well

[Altitude, about 1,400 ft. Drilled by George E. Scott, 1951. Casing, 12-in to 102 ft]

Soil___. ____.______._-

Gravel. _________ ____

Basalt, black______

Basalt, gray __ ____ _

12

5

32

25

12

17

49

74

Basalt, black.. __ __ _

hard______ _____ __

101

6

589

175

181

770

565084 61-
A-6 ARTIFICIAL RECHARGE OF GROUND WATER

TABLE 1. Abridged drillers' logs of wells Continued

Roy Frazier well

[Altitude, about 1,190 ft. Drilled by George E. Scott, 1947. Casing, 16-in to 170 ft]

Materials

Clay, yellow.- _ ____

Gravel, dirty _____

Gravel. ___ _

Clay and gravel- _

Thickness 

(feet)

13

84

11

6

41

Depth

(feet)

13

97

108

114

155

Materials

Clay, yellow-.- -- -

Thickness 

(feet)

6

9

431

3

203

Depth

(feet)

161

170

601

604

807

Robert Moore well

[Altitude, about 1,225 ft. Drilled by A. A. Durand & Son, 1955. Casing, 12-in to 164 ft)

Soil_-_-_-_-_-________

Gravel, yellow, and 

brown clay _ _ _ _ _ _

Clay, yellow, and cemented gravel, _ _

Basalt, black and blue__

36

44

90

392

36

80

170

562

Basalt, broken, and

18

40

37

153

580

620

657

810

East of the injection well the Columbia River basalt is arched to 

form the Blue Mountains. The west side of the Blue Mountains 

is essentially a monocline dipping 3°-5° toward the Walla Walla 

basin. The Blue Mountains slope is dissected by steep-sided, narrow 

canyons as much as 1,500 feet deep; Mill Creek canyon is one of the 

deepest of these. The gradient of the streams in general is less than 

the slope of the basalt beds; therefore, the outcrop pattern of each 

individual lava flow, as viewed from above, is V-shaped and points 

downstream. This outcrop pattern favors natural recharge of ground 

water into the permeable layers cropping out in the stream channels.

In the area adjacent to the well, however, replenishment is less than 

withdrawal, as shown by the long-term decline in ground-water 

levels in the city wells 1, 2, and 3 (p. A'-8). That insufficient recharge reaches this area is obvious. This isolation from natural 

recharge no doubt is caused by the existence of hydraulic boundaries.

In the Walla Walla area the basalt is dark gray, brown, or black 

and contains finely felted microscopic crystallites in a glassy groundmass (Newcomb, 1951, p. 24). Individual lava flows range in thickness from about 5 to 100 feet and average about 40 feet.

The two common systems of cooling joints in the lava are the columnar and the cubical. The columnar system cuts the lava into rude 

6-sided and 4-sided joint columns, and the cubical divides it into 

irregular boulder- or cobble-size straight-sided blocks. Both types of 

jointing can occur in one flow, though one or the other usually predominates in any one part of a flow.
RECHARGE- OF BASALT AQUIFERS, WALLA WALLA, WASH. A~7

Kegional joints and faults locally cut the basalt; the faults contain 

crushed and sheared rock that forms a barrier to the lateral movement 

of ground water. The location of a few of these faults is known; 

other faults are suspected to be in certain places, and many others 

undoubtedly exist.

OCCURRENCE OF WATER IN BASALT

GROUND-WATER MOVEMENT

The water obtained by wells in the basalt almost invariably comes; 

from the zone of contact between one basalt flow and another. According to Newcomb (1951, p. 41), the openings in these contact or 

interflow zones are mainly cracks or crevices produced primarily by 

the incomplete closure of one flow over another and by fragmentation 

of the basalt at the top of some of the flows. Although these interflow 

zones may be fairly extensive, their transmissibilities differ greatly 

from place to place. ;

From areas of recharge, where the basalt is at or near the surface, 

such as the Blue Mountains, rainwater and snowmelt percolate 

downward into the porous zones between the tabular flows of basalt. 

The water in these porous zones moves by gravity down the dip of the 

basalt toward the center of the Walla Walla basin, a few miles southwest of Walla Walla, where the basalt aquifers locally contain 

water under considerable hydraulic head. Here, water flows at the 

surface or stands but a few feet below the surface in wells tapping 

these aquifers.

Planning a successful program of artificial recharge requires knowledge of whether conditions are favorable for the recovery of the water 

after it has been injected into the aquifers. Water introduced into an 

aquifer by means of an injection well raises the water level or artesian 

pressure in the aquifer adjacent to the well and creates a mound of 

water, or a piezometric high, around the well. As a result of the recharge, local hydraulic gradients are established that allow water 

to spread out through the aquifer, away from the well, at the same 

rate it is injected into the well. If injection is discontinued and the 

well is pumped, the hydraulic gradients in the vicinity of the well 

will be reversed, so that the water will then move toward the well. 

In this manner part of the water recharged can be recovered by pumping the injection well or nearby wells. Some of the water injected 

usually cannot be recovered because it has passed beyond the area 

of influence of the pumped well; the amount so lost depends upon the 

rate of movement, the physical characteristics of the aquifer, the 

natural hydraulic gradients in the vicinity of the well, and the time 

that has elapsed since injection. However, part of any water not
A-8 ARTIFICIAL RECHARGE OF GROUND WATER

removed by pumping the injection well may be recovered by pumping 

wells downgradient from the recharge well.

In the eastern part of the Walla Walla basin, ground-water movement is, in general, from east to west; that is, from high to low parts 

of the basin. Immediately adjacent to city well 3, however, the 

direction of water movement has not been determined accurately. 

Wells in which reliable water-level elevations could be obtained are 

insufficient to warrant constructing a meaningful water-level contour 

map. When virtually simultaneous determinations of static water 

levels were made in wells 1 and 3 on May 27 and 28, October 1, and 

December 11, 1957, and on January 11, 1958, the levels in the two 

wells were about equal.

Hence, so far as these measurements showed, no hydraulic gradient 

existed between well 3 and well 1 on those dates. Earlier measurements had shown that for at least a part of the period of record a 

slight westward gradient existed; however, all those water levels were 

measured by means of air gages, which have too low a sensitivity to 

indicate small differences in altitude. Because these water-level 

comparisons were made on only two wells, they represent conditions 

only along a straight line connecting city well 3 with well 1. Obviously 

the two points are insufficient control for determining whether a 

gradient exists in the local area. Possibly either a northerly or a 

southerly component of gradient exists here.

The existence of impermeable boundaries adjacent to the recharge 

area seems probable, and they may have an appreciable, but unevaluated, effect on the direction of water movement. Elsewhere in 

the Walla Walla area there are hydraulic boundaries (Newcomb, 1951, 

p. 48).

WATER-LEVEL FLUCTUATIONS

Because the introduction of water into a well will raise the water 

level in the area around the well, an analysis of information concerning 

depth to water in and near a recharge well is important. The total 

distance between land surface and water level in a well is the maximum 

hydraulic head that can be utilized when introducing recharge water 

by gravity flow at the top of the casing. If a closed system is used, 

of course, water can be injected under pressure.

Information on the long-term fluctuations of water level in this 

area is scant. Records of water-level measurements show that the 

level in well 3 declined about 38 feet during the period April 1942-May 

1957.

There is a relatively large seasonal fluctuation of water levels in city 

wells 1, 2, and 3 and in wells adjacent to them. For example, from 

May to October 1957 the level in city well 1 declined 16 feet, and that
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~9

in well 3 declined 17 feet. From August 1957 to January 1958 the 

level in the Roy Frazier well recovered 25 feet, from 74 to 49 feet below 

the measuring point. However, a small part of this recovery may have 

been caused by the recharge operations. Although this well is a little 

more than 2 miles northwest of city well 3 (fig. 1), the short-term 

hydrograph shown on figure 2 for the Frazier well strongly suggests 

that the two are hydraulically interconnected.

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JANUARY

FJOUBE 2. Hydrograph of Roy Frazier well for Jan. 8-14,1958.

The long-term decline in levels points out the need for conservation 

measures, for it indicates that there is more water being pumped from 

the basalt aquifers in the immediate area than is being replaced by 

natural recharge or movement of water from adjoining areas.

WATER SUPPLY OF WALLA WALLA

The public water-supply system of the city of Walla Walla is served 

from both surface- and ground-water sources. The city has an established water right to withdraw 14 mgd (million gallons per day) from 

Mill Creek. However, during a part of the year the city's demand is 

greater than this maximum withdrawal rate; furthermore, for short 

periods when Mill Creek receives storm runoff, the water in that 

stream is too turbid for public supply without treatment by costly 

filtration facilities. During such periods the city's demand is satisfied 

by pumping ground water to the extent that the Mill Creek supply is 

inadequate.

SURFACE-WATER SUPPLY

Mill Creek, a perennial stream, rises in the Blue Mountains and 

flows north and then west to join the Walla Walla River about 6 miles 

west of Walla Walla. The water supplying the city is withdrawn from 

Mill Creek at a diversion dam and is then led into a settling basin
A-10 ARTIFICIAL RECHARGE OF GROUND WATER

(not shown in fig. 1) about 3,000 feet north of the Oregon-Washington 

boundary and about 11 miles southeast of Walla Walla. This settling 

basin removes only a moderate amount of the sediment present in the 

water and contains screens that stop larger debris such as pine needles. 

The settling basin also enables the operator to maintain a visual check 

on the turbidity of the water. When the water is too turbid to use, it 

can be bypassed. When being used by the city, it is chlorinated as it 

leaves the settling basin. From the settling basin the water flows 

westward by gravity through a 20-inch pipeline about 7 miles to the 

reservoir and from there into the distribution mains. The rate of 

flow through the 20-inch line is controlled by gates at the settling basin. 

At the reservoir the 20-inch line terminates in a standpipe; the water 

spills over the top of this standpipe into a vertical annular duct that 

leads to the reservoir. The height of the standpipe is such that a 

positive pressure exists in the pipeline through at least part of its 

length. For example, at well 3, about 5,000 feet east of the reservoir, 

the pressure in the 20-inch line is about 18 pounds per square inch.

GROUND-WATER SUPPLY

Four wells, ranging in depth from 789 to 1,169 feet, are used by the 

city to supplement the Mill Creek supply (table 1). The maximum 

combined installed-pump capacity of the four wells is about 7,500 

gpm (11 mgd). A fifth well had been drilled but had not been put 

into operation at the time of this study. City well 3, the deepest of 

the four and the well into which water was injected, was drilled to a 

depth of 1,169 feet, more than 1,000 feet of which was in basalt.

City wells 1, 2, and 3, near the reservoir, pump directly into the 

reservoir through separate discharge pipes. Orifice plates and manometers at the ends of these discharge pipes enable the operator to determine the rate at which each well is yielding water. City well 4, 

which is at the eastern edge of the city, pumps directly into the city 

mains. The water from the wells is not chlorinated.

SUITABILITY OF MILL CREEK WATER FOR RECHARGE

Many factors determine whether a given water will be suitable for 

injection underground. Some of these factors can be evaluated, 

others are more difficult to determine. Even under the best of conditions, where the chemical and physical characteristics of both the 

ground water and the injection water are known within rather narrow 

limits, it is often impossible to predict how the hydraulics of a recharge 

system will function.

Hart, in his preliminary study (1957), and the author of this report 

thoroughly investigated the quality of Mill Creek water and evaluated 

the suitability of this water for injection underground.
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~ll

CHEMICAL COMPATABILITY

For the purpose of this report it has been arbitrarily accepted that 

two waters will be chemically compatible for mixing in artificial 

recharge operations if they are similar in proportions of constituents 

and if the concentration of constituents in the recharge water is not 

appreciably greater than that which would be acceptable for domestic 

use.

Chemical analyses of water from Mill Creek and from city wells 1, 

3, and 4 are given in table 2 (p. A-12). Of the 7 analyses there shown, 

4 were made by the Geological Survey, and 3 were made by private 

laboratories. The analyses in this table show a marked difference 

between the amount of total solids in water from Mill Creek and the 

amount in the water pumped from the three wells. The table also 

shows that, of the three wells, city well 4 yields water in which the total 

solids content is considerably greater than that from either well 1 or 

wellS.

Although, in table 2, all the available quality data are given, of 

chief interest is the comparison of the quality of water from Mill 

Creek with that of water from well 3 the one in which injection of 

water from Mill Creek is contemplated. This comparison can be 

effected by expressing the analyses of both in terms of percentage 

equivalents per million of total cations and total anions. 1 For the 

purpose of this comparison the analysis of water from well 3 and that 

of the Mill Creek water sample collected December 19, 1957, in percentage equivalents per million, are shown in the following table.

Constituent

Calcium_______________ ___________________ _______

Magnesium. ______ __________________ _____________

Sodium and potassium. ___________________________

Bicarbonate

Sulfate ________ _ ___________ ______

Chloride _ ___ _ ___ _ ______ _ ________________ _

Fluoride. _______________ ____ _ ____ _ ___________

Percentage equivalents per 

million

Mill Creek 

water

51 

28 

21 

94 

1 

4 

1

Well 3

water

46 

29 

25 

94 

3 

2 

1

It is obvious from a comparison of the constituents in the two waters, 

in equivalents per million, that both are of the same type, for the 

dissolved solids in both are predominately alkaline earth (Ca and 

Mg) bicarbonates. The silica present is equivalent to 46 and 42 

percent of the dissolved solids in the two waters.

i Equivalents per million for any constituent (or ion) can be obtained by dividing the concentration of 

the constituent in parts per million by the chemical equivalent weight of the constituent.
TABLE 2. Chemical analyses, in parts per million, of water from city wells 

[Analyst: CLP, Charlton Laboratory, Portland, Oregon; US OS, U.S. 

Source of sample 

Date of collection

Silica (SiOa) ------------------ ----------------

Iron (Fe)

Manganese (Mn) _ _

Calcium (Ca)

Magnesium (Mg) _ _ _________ ____

Sodium (Na) _______ ._

Potassium (K) ___ _

Aluminum (Al)

Bicarbonate (HCOs)

Carbonate (CO3)_

Sultate (SO4 )

Chloride (Cl) _________________________________

Fluoride (F) ______________ ________________ _ _

Nitrate (NO3) -___--____-____ _________________

Boron (B) ___________ ___ ___ __ __ _

Dissolved solids _ _ _ __ _

Hardness as CaCOs-- _ _ _ _______________ _ _

Specific conductance (micro mhos at 25°C)___ _

pH__ __ __

Temperature (°F)__________ _ ___ __ ____ ___

Analyst _ __ ____________

City well 1 

11-26-46

KA

17

8 2

} ' >

Qfi

0

9.7

1. 8

. 2

. 2

145

76

150

USGS

City well 1 

-t-23-53

43

. 10

16

7.5

7.4

. 1

98

0

3. 1

2.8

. 2

. 2

144

69

7.6

CLP

City well 3 

1-28-57

56

. 0

17

6.5

/ 9. 3

\ 2.6

106

2.5

1.0

. 2

.2

.04

132

69

169

8.0

59

USGS

i Sample collected at diversion dam. 2 Chlorinated sample from Mill Creek pipeline. ' Calculated b
RECHARGE, OF BASALT AQUIFERS, WALLA WALLA, WASH. A~13

In general, although the proportions of all determined constituents 

are much the same in both waters, the dissolved-solids content in 

water from well 3 is more than twice that in water from Mill Creek, 

(table 2). Because the chemical character of both waters is nearly 

identical, however, as described above, the only effect that could 

take place from blending the two would be a dilution of the ground 

water. The greater mineralization of the natural ground water 

probably is due to the greater period of time during which the water 

has been in contact with rock materials.

SEDIMENT

Because of economic considerations, the ground-water recharge 

program at Walla Walla was carried out with unfiltered surface 

water. Inasmuch as surface water may contain a considerable 

quantity of sediment, particularly during periods of high runoff, it was 

necessary to determine the magnitude of the sediment load carried by 

Mill Creek and to evaluate the extent to which that sediment load 

would plug the well and the aquifers.

In order to determine the sediment load carried by Mill Creek at 

different times, 60 samples of water were taken at the city's settling 

basin by the city's personnel in April, May, and June 1956, and 50 

were taken in January, February, March, and December 1957. These 

110 samples, collected on separate days, were analyzed in the laboratory of the Geological Survey in Portland, Oreg. The samples collected in 1956 contained 4 to 6 ppm of sediment. Of those collected 

in 1957, 44 contained 2 ppm of sediment, and 6 contained 12 to 16 

ppm.

During February 23-28, 1957, when the 6 samples were collected, 

the water was not considered clear enough for public supply and was 

returned to Mill Creek. The samples of December 1957, collected 

immediately before and during recharge, all contained 2 ppm of 

suspended sediment of silt and clay size, which represents the sediment concentration of the water injected into city well 3.

A visual check on the turbidity of the Mill Creek water is made 

several times each day by the operator at the settling basin. According to him, if the turbidity is great enough to obscure the bottom of 

the settling basin, the water no longer can be used and is then returned to Mill Creek. This degree of opacity is reached when the 

sediment content exceeds about 6 ppm.

It can be assumed, therefore, that the highest concentration of 

sediment in Mill Creek water that would be available for recharge 

is about 6 ppm. Hence, the greatest amount of sediment that could 

be carried into the well would be about 16 pounds for each acre-foot 

of water injected.

565084 61 3
A-14 ARTIFICIAL RECHARGE OF GROUND WATER

AIR CONTENT

When surface water is being used for artificial recharge through 

wells, air from two different sources can enter the aquifers tapped by 

the well: air carried into the well in solution in the water, and air 

entrained in the flow of recharge water during transit.

Air introduced into a well during recharge may lessen the watercarrying capacity of an aquifer by both physical and chemical processes. 

Air entrapped in the interstices of the aquifer materials, in the form 

of minute bubbles, may impede the flow of water in the aquifer. 

Also, under certain conditions air may react chemically with native 

ground water to produce insoluble precipitates that can clog an 

aquifer. For example, iron contained in ground water is usually 

present in the partly oxidized ferrous state; upon further oxidation 

by contact with injected air, the iron may precipitate as a ferric iron 

compound. In addition, carbon dioxide from the atmosphere, 

brought into contact with dissolved silica in alkaline solution, can 

precipitate a siliceous cementing material (Uren, 1939).

With regard to the possibility that aeration might result in the 

formation of precipitates in the ground water tapped by well 3, it 

should be pointed out that no precipitate was observed in a blended 

sample of water from Mill Creek and city well 3 after it was allowed 

to stand for some time in an open container. Therefore the possibility of harmful chemical reaction resulting from the addition of 

air, at least air in solution, cannot be considered of prime concern, 

although it cannot be disregarded completely on the basis of this one 

simple test. The two methods by which air can be introduced into 

the well will be discussed separately to the extent that they apply to 

Mill Creek water and to the particular type of artificial-recharge 

system tried in Walla Walla city well 3.

DISSOLVED ATR

Water in contact with air will take into solution certain quantities 

of oxygen, nitrogen, and other atmospheric gases. The amount of 

these dissolved gases depends on pressure, temperature, and length 

of time involved. Water flowing in a stream invariably takes some 

air into solution. In deciding whether a surface water is suitable 

for artificially recharging a ground-water body, consideration should 

be given to the amount of dissolved air in the water, inasmuch as it is 

a potential source of trouble.

The following discussion evaluates the possibility of the dissolved 

air coming out of solution from Mill Creek water after injection into 

the well. The evaluation must be purely qualitative because it is 

impossible to assign values to all the variables that control the solu-
RECHARGE, OF BASALT AQUIFERS, WALLA WALLA, WASH. A~15

bility of air in water under the conditions that exist within the aquifers. 

Three samples of water from Mill Creek and one sample of water 

from city well 3 were collected by the city Health Department for 

determination of dissolved oxygen. The results of these tests, made 

by the Geological Survey, are shown in the following table. Because the oxygen-nitrogen ratio in air dissolved in fresh surface 

water that contains no oxidizable material in solution or in suspension 

is a constant under a given set of physical conditions, the amount of 

air in solution in water from Mill Creek can be computed easily if the 

amount of dissolved oxygen in solution is known.

TABLE 3. Dissolved oxygen in water from Mill Creek and city well 3

Source

Mill Creek. ________

Mill Creek_ ________

Mill Creek. ___ _ .

City well 3_________

Sampling point

Settling basin __ ______ _ _______

Tap in pipeline, near well 3 __ _

Tap in discharge line___ _ ____

Date of 

collection 

in 1957

May 29

May 30

June 13

June 13

Dissolved 

oxygen 

(ppm)

8. 3

10

14

2. 3

Because the temperatures of the samples were not taken, it is not 

possible to determine whether the water samples from Mill Creek 

were saturated with air. However, if the temperature of the sample 

taken from the pipeline to the reservoir on June 13 was within the 

range of 45°-50°F, the observed dissolved-oxygen content of 14 

ppm probably represented a near-equilibrium, or near-saturated, 

condition. Although this assumed temperature range is an estimate, 

a review of table 4 suggests that in the months of May and June, Mill 

Creek water is commonly within this temperature range.

At 45°F the ah1 in solution in fresh water contains about 34.6 percent 

oxygen and 65.4 percent nitrogen (Hodgman, 1956, p. 1606-1607). 

Hence a dissolved-oxygen content of 14 ppm would be equivalent to a 

dissolved-air content of about 40 ppm.

The temperature of the water pumped from city well 3 on May 28, 

1957, measured at the point where the water discharges into the city 

reservoir, was 59 °F. This temperature resulted from a blending, during pumping, of water entering the well at different depths. Because 

of the almost universal existence of a geothermal gradient, the temperature of the water from deeper aquifers in most places is higher than that 

from shallower ones. Therefore, water from MiU Creek that enters 

permeable zones in the lower part of city well 3 will be warmed to a 

higher temperature than that which enters zones closer to the land 

surface. The amount of air that can be held in solution is an inverse 

function of the temperature of the solvent. Thus the air will have a
A-16 ARTIFICIAL RECHARGE OF GROUND WATER

TABLE 4. Discharge and temperature of Mill Creek near Walla Walla 

[Measurements by Geological Survey]

Date

1953 

Aug. 21__.___

Sept. 2 _ .___

Oct. 6 _ _

Oct. 7 _

1954

Jan. 10 ______

Jan. 30_____ _ Mar. 19 .___

June 12__..__

July 15 ___ 

Sept. 2_______

Oct. 9_.__- ___

Nov. 18______

Dec. 29 __ ___

1955

Jan. 28 _ ____

Mar. 10__-_-

May 26-___~

July 12_._.___

Aug. 25_.._-_

Discharge 

(cfs)

36

39

36

36

151

278

88

173

40

36

36

54

42

69

112

134

40

28

Temperature (°F)

70

52

49

48

42

42

40

50

79

70

49

56

41

33

37

49

54

67

Date

1955 Con. 

Sept. 29_____.

Dec. 8_ _ _

1956

Jan. 26 _ ____

Mar. 15_.____

Apr. 18 -

May 24__-___

July 4- ------

Aiirr Q

Sept. 20____-_

Oct. 25_-_____

Dec. 11 ___ -_

1957

Jan. 18 _._ _

Feb. 21 _

Feb. 26 ___ __

Feb. 27 _

Mar. 14______

Apr. 27_______

Discharge 

(cfs)

31

73

134

582

226

120

40

31

33

42

459

39

58

655

525

143

143

Temperature (°F)

56

36

35

42

45

47

59

55

51

45

40

33

34

38

38

39

39

greater tendency to be expelled from solution in that part of Mill Creek 

water entering the deeper aquifers than in that part entering the 

shallower ones, provided that the pressures were identical. After 

injection, however, the pressure to which the recharged water will be 

subjected may range from slightly more than 1 to as much as 30 

atmospheres, and the water that is warmed the most (in the deepest 

water-bearing zones) will be subjected to the greatest hydrostatic 

pressure. Because the effect of temperature increase in forcing air out 

of solution will be dominated by the effect of pressure increase in forcing the air to remain in solution, it seems very unlikely that bubbles 

from air in solution in the recharge water will form within the aquifers.

ENTRAINED AIR

The entrainment of air in the recharge water could be far more important than dissolved air in introducing air into the recharge system. 

As indicated in the foregoing section of the report, there is a definite 

upper limit on the amount of air that can be carried in solution. On 

the other hand, there is a much higher limit on the amount of air that 

can be carried along by the water column in the form of bubbles. This 

limit is a function of the mechanical characteristics of the recharge 

system.

The city officials of Walla Walla decided that Mill Creek water will 

be led into city well 3 through the pump column. This decision was
RECHARGE, OF BASALT AQUIFERS, WALLA WALLA, WASH. A~17

made chiefly to enable water-level measurements to be made hi the 

well during recharging.

In designing the recharge system it was necessary, therefore, to limit 

the rate of recharge to a value below which the pump column could act 

as a water barometer and could produce a pressure differential of 1 

atmosphere on that part of the piping system. If a strong negative 

pressure should exist, all leaks in that section of the piping would allow 

air to enter. The air entering any leaks doubtless would be entrained 

because of the high linear velocity of the water falling through the 

column by gravity. At the planned rate of recharge, which is about 

500 to 600 gpm, the pump column could run full only if the linear 

velocity of the water in the column were less than 4 to 7 fps (feet per 

second). The velocity will be much greater under the conditions of 

free fall due to gravity. Therefore, although conditions will be favorable for the entrainment of air, there should be little possibility of air 

entering the system to be captured by the falling water.

BIOLOGICAL SUITABILITY

The water injected into city well 3 was withdrawn from the city's 

pipeline downstream from the point where chlorine is added for 

sanitation purposes. The injection of chlorine is adjusted to maintain 

a residual chlorine content of 0.35 ppm. This residual is adequate 

to destroy pathogenic bacteria, but it is not sufficiently high to 

destroy the organisms that could cause difficulty when water is 

introduced underground.

These nuisance bacteria, although not disease-producing in humans, 

are generally undesirable in that they may color the water, produce 

slimes or other objectionable products, and cause unpleasant taste 

and odor. Several types of such organisms can exist in water. Of 

these, the iron bacteria and sulfur bacteria are common (Starkey, 

1945); they can develop in water containing little or no organic 

material, but in which incompletely oxidized mineral substances occur. 

None of these bacteria exist in Mill Creek water hi quantities great 

enough to be objectionable; otherwise it could not be used for 

public supply without heavy chlorination. However, if they were 

present to some extent and were introduced into the underground 

environment, where iron likely occurs in the ferrous state and where 

some sulfur may occur in an incompletely oxidized state as well, they 

could become abundant enough to plug the well and aquifer interstices.

To obtain information concerning the existence of these bacteria in 

Mill Creek water, a sample of the water was shipped to the Sanitary 

Engineering Section of the Washington State Institute of Technology 

at Pullman. The water sample was studied by Mitsuru Nakamura of 

that organization; neither the odor-producing bacteria nor the
A-18 ARTIFICIAL RECHARGE OT GROUND WATER

hydrogen sulfide producing and iron-depositing bacteria could be 

isolated, but, cultivation in the laboratory did produce a stringy 

growth.

The State of Washington Department of Health was requested by 

both the city of Walla Walla and the State of Washington Department 

of Conservation to examine the recharge plans and to provide an 

opinion on whether injection of Mill Creek water underground would 

be practicable with regard to the possible harmful effects of bacteria. 

That agency set forth the opinion that although Sphaerotilus (ironproducing) organisms are sometimes present in chlorinated Mill Creek 

water, they would not continue to flourish underground after recharge 

of Mill Creek water ceased.

These two reports were considered by the city to be adequate 

justification for minimizing the possible effects of well damage or 

water deterioration by nuisance bacteria.

ADEQUACY OF SUPPLY

During part of the year, the city of Walla Walla does not withdraw 

as much water from Mill Creek as it is entitled to, because of the 

seasonal variation in demand. During periods of peak demand, 

exceeding 14 mgd, the additional requirement is supplied by wells; 

and when Mill Creek water is too turbid to use, usually for only a 

few days at a time, ground water is substituted for the entire surfacewater supply. During the rest of the year, some water from Mill 

Creek is available for injection into wells.

During the years 1954-57, the period for which water-use data 

were collected from the city, the city's water demand exceeded 14 mgd 

(Walla Walla's allotment) only during the 3- or 4-month period June 

to August or September.

Because of the sharp rise and decline of the demand curve prior 

to and after the seasonal peak, recharging could be undertaken for 

8 to 9 months a year, which would result in a total yearly increment 

to the ground-water body of as much as 1,600 acre-feet. However, 

during short periods of storm runoff the flow of Mill Creek would be 

too turbid for recharge purposes.

No estimate of the city's water demand in future years has been 

made. Probably at least 1,000 gpm would be available for recharging 

no less than 9 months of the year, for many years in the future. 

Hence, a recharge program could become a valuable part of the 

city's water-supply system.

YIELD CHARACTERISTICS OF CITY WELL 3

As a part of the data-collection program, pumping tests were run 

on city well 3 to determine its yield and other hydraulic characteristics
RECHARGE, OP BASALT AQUIFEUS, WALLA WALLA, WASH. A-19

before the start of the artificial-recharge test. In all, 3 tests were 

made, 2 on May 28 and 29, 1957, and 1 on October 1 and 2.

During the pumping tests of May 28 and 29, city well 3 yielded 

about 1,800 gpm with a drawdown of about 52.5 feet, which represents 

a specific capacity (yield divided by drawdown) of about 35 gpm per 

ft. For the test of October 1 and 2, city well 3 yielded 1,630 gpm 

with a drawdown of about 45 feet a specific capacity of 36 gpm per 

foot. The smaller yield for the October test resulted from a greater 

pumping lift, nearly 10 feet more than during the previous tests. In 

the period between the May and October tests a decline of 16 feet in 

static level had occurred.

Throughout these tests the levels in well 3 were measured by using 

a steel tape, but the levels in adjacent city wells 1 and 2, about threequarters of a mile west, and the Olaus Filan well, three-quarters of a 

mile southeast (fig. 1), were measured by means of air gages. During 

the May tests, the level in well 1 declined about 2 feet and that in the 

Filan well declined about half a foot. During the pumping tests of 

October 1 and 2, the level in well 1 declined about 3.5 feet, but the 

Filan well was not affected to the extent that a water-level change 

could be detected by the air gage. In both the May and October 

tests, air-gage readings at well 2 were erratic, and no interpretation 

of them could be made.

Because of the inherent inaccuracies of measurements made by 

means of the air gages on the Filan and city wells, there is doubt 

about the amount of water-level decline actually due to the pumping 

of well 3. Any small regionwide trends of the water level that may 

have existed are unkown.

RECHARGE OF CITY WELL 3 WITH MILL CREEK WATER

Injection of water from Mill Creek into city well 3 was started on 

December 11, 1957, and terminated on January 8, 1958, after 71.3 

acre-feet had been injected. Mill Creek water entered the well 

through a 6-inch branch line from the 20-inch city conduit. The 

rate of injection was measured by means of a displacement-type meter. 

Some adjustment of the valve in the 6-inch line was required to regulate the rate of flow into the well. Within 30 minutes after the start 

of injection at 8:29 a.m. the rate was adjusted at 630 gpm. Only 

slight deviation from this rate was noted during the progress of the 

experiment.

In 24 minutes the water level rose 10.65 feet and remained within 

0.03 foot of that height for at least another 22 minutes. (See fig. 3.) 

The specific capacity for this short period was calculated from the 

figures 10.65 feet and 630 gpm to be 59 gpm per ft, more than half 

again as great as the specific capacity calculated from the pumping
A-20 ARTIFICIAL RECHARGE OF GROUND WATER

120

140

180

200

5220

i

-

E

' 1, 

began 5:15 Measurements p

1

i

1

JsJ

g

?!

00

155

1

1

:ific ca

i

I

_Jnje

acity=

i

1

ttngK

59 gpn

__i

l~l

3 gpn i "'

per ft

i

1

i

1

i

I

i

H 

II

5JJ.

1_

1

,Stopp 

i

V^j;

1

1

edrecl 

3:30 an

: ificca 

6 gpm

 " *. 

i

1

arging

n

lacity 

 rft

l

1 

lf=

|S

al^- 

 ofSpe

e

g

DO

fe

i

1 r i i

Injecting 660 gpm _ . 

cific ca »acity=37 gpm per ft

i i i

-

-

-

i

9 10 11 12 13 14 15 16 17 18 19 20 1\ 22 23 24 25 26 27

140 

160 

180 

200 

220 

240

DECEMBER

LU 

CO

g 140 

160 

180 

200 

220 

240

l

_~~ 

-

-

-

i

l

. 

l

l

.

i

l

l

28 29 30 31

i 1 

Inji

i

Kiting 6

1

l 

10-670

i_

l 

8Pi"

L

1

aaM^

1

1

 i

1

1 

-»S*

L^

Spe 

=2

SP«

i 

jpped r

Too

Jficcap 

1 gpm

ificcai

schargi 

pm

lacity 

wrft

acfty =

1

1

<a

r

-

-

-

-

Yield 1540 stopped 

 - i fl*" i pumping - 

23"gpmperft| 8:00 am

1 2 3 4 5 6 7 8 9 10 11 12 13 14

140 

160 

180 

200 

220 

240

DECEMBER JANUARY

FIGURE 3. Hydrograph of Walla Walla well 3 for the period Dec. 9,1957-Jan. 14,1958.

test, which was made at a greater rate and drawdown. The difference in specific capacity is probably due to the length of time involved 

and to the difference in the rates of pumping and recharging, or due 

to the effect this difference has on the entrance loss of the well.

After about a day of recharging, the water level in well 3 rose at a 

fairly constant rate. Because the rate should have diminished appreciably with time, possibly some progressive decrease in the waterreceiving capacity was occurring. However, according to E. W. Reed 

(written communication, 1958) the linear relation of water-level rise 

to time may be only coincidental, or it may result from the existence 

of a complex set of hydraulic boundaries within the basalt aquifers.

On December 20, at 3:30 a.m., recharging was discontinued, 

because Mill Creek became turbid as a result of storm runoff. About 

half an hour before recharging was stopped, well 1 was turned on 

to supply the city's demand. Half an hour after recharging was 

stopped the water level in well 3 declined about 17.3 feet. During
RECHARGE. OF BASALT AQUIFERS, WALLA WALLA, WASH. A~21

the next 3-day period the water level declined an additional 6 feet, 

partly because of the pumping of well 1.

The specific capacity of well 3 was computed by using 17.3 feet as 

the water-level change and 630 gpm as the flow rate, and a value of

36 gpm per ft was obtained, which is 23 gpm per ft less than that 

obtained on December 11 shortly after artificial recharging commenced. 

By December 23 the flow in Mill Creek had cleared, and recharging 

at a rate of 660 gpm, was resumed at 10:00 a.m., 2 hours after well 1 

was shut down. After 135 minutes (at 12:15 p.m.) the water level 

had risen 17.7 feet. The indicated specific capacity at that time was

37 gpm per ft. After 16 days of recharging, the water level had risen 

to a level of 33.2 feet above that held before the second period of 

recharging commenced.

On January 8 recharging was stopped, which caused a drop in water 

level of about 24 feet. By using 670 gpm as the flow rate near the end 

of the test, the specific capacity was found to be 28 gpm per ft at 

the time the recharging was ended. The water level in the well held 

nearly constant for the next 3 days while the pump was idle.

As part of the recharging test, periodic water-level measurements 

were made in well 1. These measurements are shown graphically on 

figure 4. As the graph shows, the level in the well was rising prior to 

the start of recharging. Possibly this represents a residual recovery 

of the water level from the drawdown caused by the pumping of all 

three wells on December 6 to 8. At the end of the first recharging 

period, on December 20, the level in well 1 had risen almost 7 feet; 

doubtless a substantial part of this rise can be attributed to the 

recharge at well 3.

Very few measurements of the water level in well 1 were made 

during the second recharging period. At the end of the second recharging period, on January 8, the level in well 1 had risen an additional 4 feet to about 105.5 feet below the measuring point, but it 

showed a reversal and a decline within 20 minutes after recharging 

was stopped (fig. 4). Because of outside effects, that part of the 

water-level rise due solely to recharging cannot be identified.

A few scattered measurements made in the Roy Frazier well 

indicate that the water level in that well may be affected by both 

pumping and artificial recharge of well 3 (fig. 2).

EFFECT OF RECHARGE ON THE YIELD CHARACTERISTICS

OF CITY WELL 3

To permit evaluation of the effect of the recharging on city well 3, 

the well was pumped for a 48-hour period beginning at 8:00 a.m. on 

January 11, 1958.

Although the static level just prior to the start of pumping was
A-22 ARTIFICIAL RECHARGE OF GROUND WATER

FEET BELOW MEASURING POINT

l-i !- !- !- 

S

O N *

*. O O!

2635 24

DECEMBER

1 S

-

-

-

topped pumping 8:00 am 

\Started recharging 

>^vell 3, 10:00 am

\ 

\

V

Stopped recharging] 

well 3, 1:00 pm

Started pumping 

well 3. 8:00 arri

Stopped pumping^ 

- well 3, 8:00 am

A

.Started recharging 

t well 3, 8:29 am

tStarted pumping 3:00 am 

Stopped recharging well 3,3:30am

FIGURE 4. Hydrograph of Walla Walla well 1 for the period Dec. 10,1957-Jan. 14,1968.

about 164 feet below the measuring point, or about 9 feet higher 

than before the recharge tests were run, the yield of the well was 

less, only 1,540 gpm, and the pumping level was 231 feet below the 

measuring point. The observed yield together with the drawdown of 

67 feet represents a specific capacity of 23 gpm per ft, which is only 

about 65 percent of the pretest average specific capacity of 35. The 

yield was 95 percent of that (1,630 gpm) observed during the October test.
RECHARGE, OF BASALT AQUIFERS, WALLA WALLA, WASH. A~23

The lower specific capacity after recharging indicates that some 

deterioration in yield characteristics of the well occurred as a result 

of the artificial recharge experiment. At the beginning of the experiment the specific capacity was 59. As the experiment continued, the 

successive specific-capacity values were 36, 37, and 28. The drop 

from 59 to 36 represented a 40-percent decline during the first recharge period, when 24.3 acre-feet of water was introduced into the 

well. During the second period, in which 47.0 acre-feet was injected, 

a further decline of only 19 percent occurred. There is evidence, 

then, by using specific capacity as the criterion, that deterioration 

of the well was not linear and that if the recharge had been continued 

over a longer period less and less reduction would have accrued per 

unit quantity of water injected.

A water sample collected from the discharge pipe of well 3 on 

January 11, 1958, 30 minutes after pumping started, contained 76 

ppm of suspended sediment. The water pumped before this time 

doubtless contained much more sediment. However, because of the 

arrangement of piping, it was not possible to sample the first water 

pumped. Within three-quarters of an hour after the start of pumping, the sediment content had dropped to 3 ppm. It is estimated 

that about 390 pounds of sediment was carried into the well by the 

71.3 acre-feet of water recharged, and that somewhat less than half 

this amount, or about 150 pounds, was removed during the postrecharge pumping and surging period.

Well 3 was started again at 1:32 p.m. on January 14 and was then 

alternately stopped and started in a surging operation. This surging 

was done in an effort to restore the well's prerecharge specific capacity; 

however, no significant increase was detected.

RECOVERY OF INJECTED WATER

The difference between the specific conductance of Mill Creek 

water and that of native ground water from city well 3 was used to 

determine the approximate amount of injected water that was recovered during pumping of the well after completion of the recharge 

experiment. The specific conductance of water from well 3 was about 

169 micromhos per centimeter at 25 °C (table 2). That of Mill 

Creek water ranged from 53 to 64 micromhos in the samples collected 

December 11 to 28 from a faucet on the 20-inch line a few feet from 

the pumphouse at city well 3. (See table 5.)

The observed difference in specific conductance between the two 

waters results from their difference in concentration of dissolved 

solids. The relation between concentration of aqueous solutions and 

specific conductance is not exactly linear. However, within the limits
A-24 ARTIFICIAL RECHARGE OF GROTHSTD WATER

TABLE 5. Partial chemical analyses of water from Mill Creek

[Where two or more samples are grouped, the analyses are averaged. Analyses by C. E. Price and

A. A. Qarrettl

Date

1957 

Dec. 11__ ___

Dec. 12_ __ _

Dec. 13. _ __

Dec. 14______

Dec. 16_____.

Dec. 17_..___

Dec. 18. __._

Dec. 19__- ___

Dec. 19. _ __ 

Dec. 23_ _ __

Dec. 26___ _

Dec. 28- ____

Time

12:40 p. m..____

2:45 p.m. ______

10:42 a.m____-__

1:45 p.m.__ ___

3:18 p.m. ______

4:22 p.m.____ _

8:30 a.m.. __ _

10:15 a.m.___ .

11:40 a.m ___ _

4:05 p.m__. _ _

10:45 a.m______

12:06 p.m__ __

9:10 a.m. ___ .

2:16 p.m. ______

9:35 a.m.... _

12:35 p.m__-___

9:02 a.m__._.__

12:45 p.m__.__.

12:50 p.m. ._._. 

12:20 p.m______

8:00 a.m_ _ _ .

8:00a.m___ _ _

Bicarbonate 

(HC03) 

(ppm)

} 38

1 37

1

1 ,-

1

1 37

/ 37

} 39

 ^

> 42

39

38

33 

34

36

33

Hardness as 

CaCOs (ppm)

21

21

22

23

24

22

23 

22

20

20

Specific 

conductance 

(micromhos at 

25° C)

oo

59

63

64

63

60

57

62 

54

54

53

Temperature C°F)

40.5

41.5

44

42

41. 5

39

39

of accuracy of the specific conductance determinations, a linear relation is assumed. The deviation resulting from this assumption is of 

little consequence, because specific conductance for most of the 

samples is reported here to only two significant figures.

The range in the specific conductance of the samples of recharge 

water from 53 to 64 micromhos doubtless resulted in part from 

day-to-day changes in the concentration of dissolved solids in the 

water. Some of the variation may have been caused by differences in 

the length of time between the collection and the analysis of each 

sample. For example, the samples dated December 23, 26, and 28 

were collected by the city's personnel and were not analyzed until 

January 11. The specific conductances of these samples are less than 

those of the samples that were collected and analyzed during the 

period December 11 to 19.

The ratio of the specific conductance of Mill Creek water to that 

of native ground water from well 3 was 60:169, or 0.36, at the time of 

the test, based on an approximate average specific conductance of 60 

micromhos for Mill Creek water and on 169 micromhos for native 

ground water from well 3.

During the time that the well was pumped continuously from 

January 11 to 13, 1958, and also during three subsequent pumping
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~25

periods, samples of water were collected from the pump discharge. 

The chemical analysis of these are listed in table 6.

TABLE 6. Partial chemical analyses of water from Walla Walla city well 8 after

completion of recharge

[Analyses by O. E. Price and A. A. Qarrett; analytical results in parts per million]

Date

mz 

Jan. ll...____

Jan. 12 _ ___.

Jan. 13.._ _ _

Jan. 14 _ ____ 

Feb. 21_______ 

Feb. 26... _ _

Time

8:35 a.m_. ___

8:45 a. m __ _ _

9:00 a.m__ _ 

9:25 a.m.._. _ .

10:00 a.m. _ _ ..

1:30 p.m __ _ .

5:38 p.m.... _ _

10:20 p.m __ __.

10:20 a.m __ ._

3:50 p.m... . ..

ll:00p.m..__ __

3:35 p.m.... __._ 

12:30 p.m._.____ 

6:50 a.m.... _ _

Temperature (°F)

39.5

39.5

39.5

40.5

42.8

43.5

440

44.0

45.0

44.5 

54.5 

55.0

Bicarbonate 

(HOOs)

40

38

39

38

38

39

40

42

45

46

46

49

73 

93 

110

Hardness as 

CaCOs

24

24

23

23

25

23

23

23

23

27

26

26

48 

58 

64

Specific 

conductance 

(micromlios 

at 25°O)

64

63(?)

64

64

65

65

68

69

74

75

76

79

116 

148 

157

Table 6 shows a progressive increase in specific conductance, 

from 64 to 157 micromhos, in the 15 samples collected from the 

discharge of city well 3 from January 11 to February 26. The 

specific conductance of the first sample was only slightly more than 

the assumed average specific conductance of Mill Creek water as 

determined from the data presented in table 5. The specificconductance sample collected on February 26 was more nearly that 

of native ground water. The foregoing data show that, at the 

beginning of the pumping period, the water pumped from well 3 was 

a blend of Mill Creek water and native ground water, with a very 

high proportion of Mill Creek water. As pumping continued, the 

proportion of native ground water in the well effluent became greater 

and greater, until on February 26 the effluent consisted largely of 

native ground water.

The specific conductances of the samples collected during the 

period of continuous pumping, which ended with the collection of 

the sample at 7:05 a.m. on January 13, show a roughly linear decrease 

with time in the amount of Mill Creek water recovered from the well. 

During this period of 2,825 minutes, about 13.5 acre-feet of water 

had been pumped from the well. Table 7 shows that by the end of 

this period about 12 acre-feet of Mill Creek water had been recovered, 

or about 17 percent of the amount injected during the experiment.
A-26 ARTIFICIAL RECHARGE OF GROUND WATER

TABLE 7. Quantities of water pumped from Walla Walla city well 3 after completion

of recharge

Time pumping interval 

ended

9:25 a.m., Jan. !!___ 

10:00 a.m.. _ ._ __

1:30 p.m.. _ ______

5:38 p.m. __ .__

10:20 p.m. ___ _

10:20 a.m_. _ _

3:50 p.m., Jan. 12_._ 

11:00 p.m__ _ _ _

7:05 a.m., Jan. 13___ 

3:35 p.m., Jan. 14___ 

12:30 p.m., Feb. 21. _ 

6:50 a.m., Feb. 26_._

Duration of 

interval 

(minutes)

85 

35 

210 

248 

282 

720 

330 

430 

485 

2 178 

3 17, 515 

4 1, 970

Estimated 

average 

specific 

conductance 

during 

interval 

(micromhos 

at 25° C)

62 

64. 5 

65 

66.5

ea 5

71.5 

74.5 

75.5 

77.5 

97.5 

137 

156

Cumulative yield '

Mill Creek 

water 

(acre-ft)

0.400 

. 561 

1.52 

2.64 

a 88 

6.97 

8.34 

10. 1 

12.0 

12. 6 

37.2 

38. 4

Native ground 

water 

(acre-ft)

0 007 

014 

06 

13 

24 

60 

81 

1 1 

1 5 

1 8 

61 1 

70

Total 

(acre-ft)

0. 407 

.575 

1.58 

2.77 

4. 12 

7.57 

9. 15 

11.2 

13. 5 

14. 4 

98. 3 

108

1 Computed by assuming an average pumping rate of 1,560 gpm.

2 Pump idle from 8:00 a.m. Jan. 13 to 1:32 p.m. Jan. 14.

3 Pump idle from 11:00 a.m. Jan. 15 to 9:00 a.m. Jan. 17 and from 8:00 a.m. Jan. 20 to 3:00 a.m. Feb. 13. 

* Pump idle from 1:00 a.m. Feb. 21 to 10:00 p.m. Feb. 24.

The three random samples collected from city well 3 on January 14, 

February 21, and February 26, each during a separate pumping 

period, show a still further increase in specific conductance.

However, because these three pumping periods were interrupted by 

rather long intervals of inactivity, the average specific conductance 

of the effluent during the times that the well was being pumped 

(table 7) could be estimated only very roughly. Some change in 

the ratio of Mill Creek water to native ground water in the aquifers 

tapped by city well 3 doubtless occurred while the pump was idle. 

The magnitude of such change, is, of course, largely proportional to 

the rate of lateral ground-water movement within the aquifers. At 

least some of the increase in specific conductance of the sample collected 

at 3:35 p.m. on January 14 over that of the sample collected at 7:05 

a.m. on January 13 no doubt occurred during the 1,772-minute 

shutdown between these two sampling times.

During the whole period of discontinuous pumping, which began 

at 8:00 a.m. on January 11 and ended at 6:50 a.m. on February 26, 

city well 3 yielded 108 acre-feet of water (table 7). About 38 acre-feet 

of Mill Creek water was recovered in that time. This amount is 

about 53 percent of the 71.3 acre-feet injected into city well 3 during 

the artificial-recharging experiment.

Incidental to the recharging test, water samples were collected 

from several wells near the injection well for partial analysis. Table 

8 is a compilation of the partial analyses of these samples.
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~27

TABLE 8. Chemical analyses of water from selected wells in the Walla Walla basin

[Analyses by C. E. Price]

Well

Gerald Brunton well_ ______

Robert Moore well _ ___ Walla Walla well 1 __ _

Do___ _____________

Walla Walla well 2_________

Do___________________

Walla Walla well 4 _________

Date sampled, in 

1958

Jan. 14___ __

Jan. 13 _______

Feb. 26__.___

Apr. 14_____.

Feb. 26______

Apr. 14__.___

Jan. 14 __ ___

Bicarbonate 

as HO 08 

(ppm)

154

134

141

137

112

121

154

Hardness as CaCQs 

(ppm)

85

79

84

82

74

77

64

Specific 

conductance 

(miromhos 

at 26°C)

256

230

208

197

180

181

237

The quality of water pumped from city well 1, the nearest well to 

well 3 for which data are available for the period prior to the time of 

the recharge experiment, is known only from two analyses made in 

1946 and 1953 (table 2). The water pumped from well 1 after the 

end of the experiment (table 8) was considerably higher in bicarbonate 

and was slightly harder than were the earlier samples. The increase 

in the concentration of dissolved solids between 1953 and 1958 

demonstrates a significant change in quality of water, but it is probably 

not due to any effects of the artificial recharge.

The water sample from the Gerald Brunton well, which taps the 

gravel aquifer overlying the basalt, contained a high concentration of 

dissolved solids as compared with that of the samples taken from those 

tapping basalt aquifers (table 8). This fact suggests that the increase 

in dissolved solids observed in the samples taken from well 1 between 

1953 and 1958 may be due to mixing of the water from the gravel with 

that from the underlying basalt aquifers. The increase also may be 

due, in part, to the drawing in of water from different parts of the 

basalt as the level of water in the well declined.

AQUIFER TRANSMISSIBILITY AND BOUNDARIES

Data obtained during the first pumping test, May 28, 1957, and 

during the recovery after the postrecharge pumping, January 11 to 13, 

1958, were used to compute aquifer transmissibility (field permeability, 

in gallons per day per square foot, multiplied by aquifer thickness, in 

feet). The other pumping and recharging data seemed to be unsuitable for this purpose, because they were complicated by factors that 

cannot be evaluated quantitatively. The transmissibility as calculated from the first pumping test was 400,000 gpd per ft, and the 

transmissibility as computed from the postrecharge pumping test was 

370,000 gpd per ft. Water-level measurements obtained from well 1
A-28 ARTIFICIAL RECHARGE OF GROUND WATER

during the postrecharge pumping test suggest that the coefficient of 

storage was about 0.0002.

The indicated postrecharge transmissibility is only 8 percent less 

than the prerecharge transmissibility. However, the accuracy in 

transmissibility evaluations does not warrant conclusive interpretation 

from this one determination.

The water-level measurements obtained during the first recharge 

period, December 11 to 20, 1957, and during the recovery after the 

postrecharge pumping, January 11 to 13, 1958, suggest the existence 

of at least two nearly impermeable ground-water boundaries (possibly 

structural barriers) that restrict the movement of ground water in the 

vicinity of the city wells. The nearest boundary may trend about 

N. 80° W. and may pass through a point about 1.5 miles N. 10° E. 

of city well 3. The other boundary probably trends in a northerly 

direction and may pass through a point about 4 or 4.5 miles west of 

city well 3.

The long-term decline in water levels in the vicinity of city wells 

1, 2, and 3 may be due in part to the presence of these two as well as 

other possible boundaries, which may restrict lateral percolation of 

water toward the wells.

CONCLUSIONS

The basalt aquifers tapped by city well 3 accepted 71.3 acre-feet of 

water from Mill Creek during a 26-day period of artificial recharge. 

Data obtained during the recharging experiment show that the 

performance of city well 3 deteriorated somewhat during this period, 

for a decline in both yield and specific capacity was noted. Three 

potential causes of yield deterioration have been recognized in this 

report: (a) sediment in the injected water, (b) dissolved air in the 

injected water, and (c) entrained or entrapped air that originated 

from leaks or undetected openings in the piping system. The relative 

importance of the three in causing the observed deterioration cannot 

be evaluated on the basis of the data now available. Possibly the 

decrease in yield and in specific capacity resulted from a combination 

of two or more of the potential causes cited above.

The continuous blast of air emanating from the measuring port during the artificial-recharge period suggests that large amounts of 

entrained air were being carried into the well with the recharge water. 

This premise is based on the fact that an internal source of air in such 

quantity is extremely difficult to postulate.

Although the source of the air could not be determined the air 

doubtless was carried into the casing by entrainment in the water 

falling in the pump column. If upon impact near the bottom of the 

well column many of these bubbles were broken into others so small 

that further entrainment downward could occur within the well, many
RECHARGE, OF BASALT AQUIFERS, WALLA WALLA, WASH. A~29

of these would enter the aquifer interstices and cause substantial 

plugging.

Repeated surging of the well did not improve its performance 

characteristics, even after almost half the estimated 390 pounds of 

sediment carried into the aquifer with the injection water was 

recovered. Thus the sediment content of the injected Mill Creek 

water probably was not a prime cause of plugging. Also, there seems 

to be no obvious way for the dissolved air to impair the well or aquifer, 

inasmuch as it is not likely to be released from solution. It is true, 

of course, that oxidation of ferrous salts in solution to the insoluble 

ferric hydroxide would be a possible cause of aquifer plugging if 

enough ferrous iron were present to yield large quantities of precipitate. 

However, analytical data presented earlier show that the amount of 

iron in solution in native ground water from city well 3 is extremely 

small.

On the other hand, the sediment remaining in the well or in the 

aquifer immediately adjacent to the well may have a deleterious effect 

far greater than might be supposed from the small amount of sediment 

involved. Further, the oxidation of ferrous iron in the ground water 

by the air entering the aquifer, if it occurs at all, may have a much 

greater effect than is now suspected.

The air entrapped in the Mill Creek water could be removed by 

passing the water through deaeration equipment prior to its injection 

into the well. Use of a regulator foot valve at the bottom of the 

pump column would prevent the free fall of water and would virtually 

eliminate the problem of air coming out of solution above the water 

level in the pump column. Filter beds could be used to remove the 

sediment prior to injection of the water into the well.

The decision to continue experiments at city well 3 must be based 

on a realistic appraisal of all pertinent factors. The inherent risk of 

ultimate permanent damage to the well conceivably could be a strong 

deterrent to the continuation of the experiments. Three of the important factors that should be considered in arriving at a decision are:

1. Periodic redevelopment of the well by the use of chemical agents 

and other techniques might become an integral part of any longterm program of recharge. A chemical washing agent proved 

satisfactory in the redevelopment of an injection well in the 

Grand Prairie region of Arkansas (Sniegocki, 1957). Although 

the aquifers involved are different lithologically, a similar redevelopment procedure might be employed at city well 3 in the 

event that considerable loss in yield occurred.

2. A definite need for recharge exists in the general area of city wells 1, 

2, and 3. Water-level gradients here seem to be consistently low, 

of which one cause could be the existence of the hydraulic bound-
A-30 ARTIFICIAL RECHARGE OF GROUND WATER

aries detected during the recharging experiment. These boundaries may limit the natural recharge of this area. Therefore the 

small long-term water-level decline indicated by the series of 

water-level measurements that were begun in the early forties 

likely indicates local overdraft. If an overdraft is occurring, 

water will have to be pumped from increasingly greater depths 

with consequent increased pumping costs. Artificial recharge 

could be used to augment the supply.

If the air entrapment and sediment problem can be resolved, as 

described, alternate recharging and pumping of city well 3 could 

be tried, for this procedure might help sustain the highest possible 

specific capacities. Recharge water could be injected into the 

well for a selected period of time, and then the well could be 

pumped for a short while. Experimentation of this type probably 

would determine the most effective periods of alternate recharge 

and pumping. For example, it is suggested that recharge water 

be injected for about 2 days and that the well be pumped for 

about 2 hours to determine any change in yield and drawdown. 

If no appreciable deterioration occurs, a longer period of recharging could be tried.

3. The water system of the city of WaDa Walla is ideally arranged to 

supply large quantities of water from Mill Creek for artificial 

recharge with a minimum of attention. During the test 71.3 

acre-feet (23.2 million gallons) was injected in city well 3 at 

virtually no cost except that for the installation of the crossover 

piping. Because of the readily available supply of Mill Creek 

water for recharging and the definite gain that would be derived 

by the city from a recharge program, provided that a technique 

having no serious adverse effect on well or aquifers could be 

developed, continuation of the experiments seems worthwhile.

REFERENCES CITED

Hart, D. H., 1957, Feasibility of recharging basalt aquifers in the Walla Walla 

area, Washington: U.S. Geol. Survey open-file report, 35 p., 4 pis.

Hodgman, C. D., 1956, Handbook of chemistry and physics: Cleveland, Chemical 

Rubber Publishing Co., 3,206 p.

Hogenson, G. M., 1957, Geology and ground-water resources of the Umatilla 

River basin area, Oregon: U.S. Geol. Survey open-file report, 310 p., 40 pis.

Newcomb, R. C., 1951, Preliminary report on the ground-water resources of the 

Walla Walla basin, Washington-Oregon: U.S. Geol. Survey open-file report, 

203 p., 9 pis.

Russell, I. C., 1893, A geological reconnaissance in central Washington: U.S.Geol. 

Survey Bull. 108, 108 p., 12 pis.

Sniegocki, R. T., 1957, Progress report on studies of artificial recharge of ground 

water in the Grand Prairie region, Arkansas, 1956: U.S. Geol. Survey openfile report, 207 p., 11 pis., 45 figs.
RECHARGE OF BASALT AQUIFERS, WALLA WALLA, WASH. A~31

Starkey, R. L., 1945, Transformations of iron by bacteria in water: Am. Water

Works Assoc. Jour., v. 37, no. 10, p. 963-984. 

Uren, L. C., 1939, Petroleum production engineering, Oil field exploitation: Xew

York, McGraw-Hill, v. 2, 756 p.

INDEX

Page

Acknowledgments_______________ A-2-3

Adequacy of supply...____-________ 18

Air content_________..._____.-- 14

dissolved-.-.__.__--_______ 14-17

entrained - - --------------- 14,16-17

Air in solution in fresh water- ____ - __ 14,15-16 

Aquifer transmissibility and boundaries__ - 27-28

Bacteria, hydrogen sulflde producing.. __ _ 18 

iron. -.______________ 17-18 

nuisance______________ 17

odor producing. ___.________ ___ 17

sulfur____-___--___________ 17

Basalt, columnar jointing in_________... 6

cubical jointing in___......______ 6

Biological suitability.-.-------------------- 17-18

Blue Mountains_--------________ 6-7,9

Blue Mountain uplift- _____________ 4

Cascade Mountains.-..___-_-____- 4 

Chemical compatability.- _______... 11-13 

Columbia River basalt.____________ 4,6 

Conclusions--.---.. --------_...--------... 28-30

Dissolved air. __________________ 14-17 

Dissolved gases.-_-______________ 14-17 

Dissolved oxygen__.._________. 15

Entrained air_________-...__.__- 16-17 

Eoceneage, rock of._______________ 4

Faults and joints in basalt_. __ _ ___ _ 6-7

Gases, dissolved___.___ _______ 14-17

Geologic and hydrologic features_.-..._.-- 4-7 

Gerald Brunton well.-----...-------____.. 3,5,27

Grand Prairie region of Arkansas, injection

well in.-.-_____________ 29 

Ground-water movement_-__.._____ 7-8 

Ground-water supply_...--________ 10

Horse Heaven uplift___. __ 

Hydrologic and geologic features.

4 

4-7

Injected water, recovery of. _________ 23-27 

Joints and faults in basalt-._________. 6,7 

Location of the area.------_____..___ 2

Page

Mill Creek..... A-l,2,9,10,11,12,13,14,15,16,17,

18,19,20,21,23,24,25,26,28,29,30 

Mill Creek Canyon....... -_-__-___ 4,6

Mill Creek water, suitability for recharge__ 10-18

Okanogan highlands___ ____ .- 4 

OlausFilanwell.. ........................ 3,5,19

Precipitates, insoluble, in water.__.____ 14 

Purpose and scope of investigation___.-. 1-2

Recharge, effect on the yield characteristics of

city well 3 . - 21-23 

Recharge of city well 3 with Mill Creek water. 19-21 

Robert Moore well.-.-_--.-.----_------_-. 3,6,27

Rocky Mountains..________--------- 4

Roy Frazier well......... -- - 3,6,9,21

Sediment.. - 13,23

Settling basin for water..._........ ..._ 10,13

Specific capacity of well 3 .___.---. 19,21,22,23 

Surface-water supply _.. .. 9-10

Temperature of water from city well 3.._ 12,15,25 

Temperature of water from Mill Creek. _ 12,16,24 

Touchet slope...__ -._. 4 

Tucannon River canyon_. ___ 4

Umatilla River basin.

Walla Walla basin..... . 4,6,7,8,27

Walla Walla River. ...... 2,4,9 

Walla Walla well 1. 3,4,6,8,10,11,12,19,20,21,27,29 

Walla WaUa well 2- 3,5,6,8,10,19,27,28,29 

Walla Walla well 3 2,3,

4,5,6,8,9,10,11,12,13,14,15,16,17, 

18, J 9,20,21,23,24,25,26,27,28,29,30 

Walla Walla well 4..-- - 3,5,10,11,12,27 

Water, chemical analyses of 11,12,15,24,25,26,27 

Water in basalt, occurrence of... 7-9 

Water-level fluctuations. 8-9,19,20,21,22 

Water-level measurements .------ 8-9,19,21,22,28

Water, quality of, in city well 1_. ___ 12,27

quality of, in city well 2. -- __.. 27

in city well 3-. ... 11,12,23,25,26

in city weU 4 12,27

Water supply of Walla Walla ----------- 9-10

Yield characteristics of city well 3-..... 18-19,21-23 

Yield deterioration, causes..__ ------- 28

A-33