Please do not destroy or throw away this publication. If you have no further use 

for it write to the Geological Survey at Washington and ask for a frank to return it

UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall, Director

Water-Supply Paper 773 B

WATEE EESOUECES OF THE EDWABDS

LIMESTONE IN THE 

SAN ANTONIO ABEA, TEXAS

BY

PENN LIVINGSTON, A. N. SAYRE, AND W. N. WHITE

Prepared in cooperation with the 

TEXAS STATE BOARD OF WATER ENGINEERS

Contributions to the hydrology of the United States, 1936 

(Pages 59-113)

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1936

For sale by the Superintendent of Documents, Washington, D. C. ------ Price 10 cents
CONTENTS

Page

Abstract........................................................... 59

Introduction....................................................... 60

Purpose of investigation....................................... 60

Previous ground-water investigations........................... 61

Importance of ground water in the area......................... 62

Climate............................................................ 63

Temperature.................................................... 63

Rainfall....................................................... 63

Topography......................................................... 65

Geology and its relation to the occurrence of ground water......... 66

Geologic structure................................................. 71

The Edwards.limestone as a ground-water reservoir.................. 72

Recharge to reservoir.......................................... 75

Discharge from reservoir....................................... 79

Discharge by springs....................................... 79

San Antonio Springs.................................... 80

San Pedro Springs...................................... 84

Salado Creek Springs................................... 85

Discharge from San Antonio and San Pedro Springs in

1934................................................. 86

Discharge from wells....................................... 86

Total discharge from springs and wells in 1934............. 89

Waste from wells........................................... 91

Fluctuation in artesian pressure............................... 92

Fluctuations at Brackenridge pumping plant................. 94

Fluctuation in well at Beverly Lodges...................... 95

Fluctuations in miscellaneous observation wells............ 98

Artesian-pressure gradients and movement of ground water....... 100

Safe yield of reservoir........................................ 102

Quality of the water........................................... 104

Conclusions........................................................ 104

Tables............................................................. 108

ILLUSTRATIONS

Page

Plate 5. Map of Bexar County and parts of Medina and Comal

Counties, Tex., showing outcrops of Glen Rose limestone and Edwards and associated limestones, important 

faulting, and lines of equal artesian pressure in the 

Edwards limestone reservoir........................... 68

Figure 6. Geologic sections across Bexar County, Tex............. 68

7. Graphs showing fluctuations of artesian-water level 

at Brackenridge Park pumping plant and rainfall at 

San Antonio, Tex..................................... 94

8. Hydrograph of the Beverly Lodges well, San Antonio, 

showing rise of water level after heavy rains in 

April and May, 1935.................................. 96

9. Diagram showing artesian-water surface in 1934 along

line C-C', plate 5................................... 99
WATER RESOURCES SAN AMTOHIO OF THE EDWARDS AREA. TEXAS LIMESTONE IH THE 

By Penn Llvlngston, A. N. Sayre, and W. N. White

Abstract

The water discharged from the large springs of San Antonio and most 

of the deep wells of the San Antonio area comes from a common reservoir 

in fissures and solution channels in the Edwards limestone.

The water enters the limestone in a zone of outcrop along the Balcones escarpment, which crosses the northern parts of Bexar and Medina 

Counties and extends a long distance both to the east and west of these 

counties. It is estimated that the combined annual losses into the limestone from the Medina, Prio, Dry Prio, Nueces, and Sabinal Rivers and 

Hondo Creek may average as much as 150,000 acre-feet a year, the 

equivalent of a continuous flow of about 134,000,000 gallons a day. 

Smaller streams also contribute to the underground reservoir, and additional recharge is provided from rainfall on the outcrop of the limestone by direct penetration and by seepage from innumerable storm-water 

channels.

Prom the outcrop the limestone dips to the south and southeast beneath younger formations to increasingly greater depths. At San Anton'io 

the top of the limestone is from 400 to 1,000 feet beneath the land surface, and in the southernmost part of Bexar County about 3,000 feet. 

The water moves from the outcrop through channels that are somewhat 

tortuous, its movements being generally toward the southeast but in 

places approximately at right angles to the dip ; along fault lines which 

in general have east-west trends. Water moves underground to the San 

Antonio area from areas of intake at least as far west as the Medina 

River and perhaps much farther. Some water may move from the vicinity 

of San Antonio toward the northeast and eventually appear in the Comal 

Springs, but the volume thus discharged is believed to be relatively 

small. This question is, however, to be given further study. Very little water moves down the dip toward the Gulf.

The San Antonio and San Pedro Springs afford large natural spillways for the Edwards limestone reservoir in Bexar County. The springs 

occur along faults that permit water in the limestone under artesian 

pressure to escape into cracks and channels in the overlying rocks and 

thence to flow to the surface. The public and industrial water supplies 

of San Antonio, nearly all the water used for irrigation, and a large 

part of the stock and farm supplies are obtained from wells in the 

Edwards limestone. In 1934 the estimated combined discharge of the San 

Antonio and San Pedro Springs amounted to about 13,000 acre-feet and the 

combined discharge of the Edwards wells to about 95,000 acre-feet a 

total of about 108,000 acre-feet, the equivalent of a continuous discharge of about 97,000,000 gallons a day. It is estimated that during 

the last 20 years (1915-34) an average of about 120 ,000 acre-feet a 

year, or about 107,000,000 gallons a day, was discharged by the springs 

and wells. A large part of this water was unused. At least one-third 

of the water discharged from the wells was wasted.

On the outcrop the water in the limestone is unconfined, and there 

is a water table. Down the dip the water is under pressure, and wells 

that penetrate the limestone in the lowlands of San Antonio and adjacent 

areas to the east, south, and southwest of the city have a flow. The 

artesian pressures vary within fairly wide limits and are an index of 

the amount of water in underground storage. The pressures rise almost 

immediately during heavy general rains. At such times large quantities 

of water sink into the reservoir at the outcrop and produce a quick 

rise in the water, the effect of which is communicated promptly by 

transmission of pressure many miles down the dip. A short time after 

the rains the pressures usually begin to decline. The records show 

that a remarkable uniformity attends the rise and fall of pressure over 

large areas in Bexar County, both in time of occurrence and in magnitude. 

The flow both from the springs and the artesian wells varies with the 

artesian pressures. The San Antonio Springs cease to flow when the 

pressures decline and the altitude of the water levels in nearby artesian 

wells falls below 668 feet. They begin to flow again when the altitude 

rises above that level. The record of artesian pressures in the area are 

reassuring, as it shows clearly that there has at no time been any longcontinued overdraft approaching dangerous depletion. Moreover, the

59
60 CONTRIBUTIONS TO HYDROLOGY, 1936

artesian pressures were about as high In the summer of 1935 as In 1915, 

showing that there had been no material net decrease In the storage In the 

reservoir during a period of 20 years in which the average annual rainfall 

was about equal to the 61-year mean. Therefore, it Is reasonable to expect that unless the streams that furnish the recharge are regulated or 

unless the climate changes toward greater aridity the reservoir will continue to yield about as much as it did between 1915 and 1934.

It appears probable that before the artesian wells were put down the 

San Antonio and San Pedro Springs were the only large outlets of the underground reservoir In Bexar County, and the average annual recharge to the 

reservoir was nearly balanced by the average annual discharge of the 

sprlngsj also, that since the well development began the discharge has 

been divided between the springs and artesian wells. The wells have made 

the water supply more accessible where it is needed, but It Is believed 

that they have not materially increased the average annual yield of the 

underground reservoir.

The water from the San Antonio and San Pedro Springs and from the 

wells in the greater part of San Antonio and in the area to the northeast, 

north, and west Is almost uniformly a calcium carbonate water of good 

quality, although somewhat hard. South of a fault that passes through 

the southern part of the city the water is highly mineralized, is generally impregnated with hydrogen sulphide, and gives off a disagreeable 

odor. The two types of water, however, come from the common reservoir,

It is concluded that the withdrawals from the underground reservoir 

by wells can be increased with safety, but the unutilized water of the 

springs and wells must be put to beneficial use if an additional demand 

of large magnitude Is to be met. The discharge of the springs has already been materially decreased by withdrawals from wells, and further 

reduction will follow Increased draft by the wells. It Is not impossible 

that the springs could be brought under control by impounding water above 

them by means of a low dam. Waste from the artesian wells can be stopped 

if the wells are closed by a cap or valve when they are not in use, as is 

required by the laws of Texas.

INTRODUCTION 

Purpose of investigation

The supply of ground water In the general area In which San Antonio 

is situated, with special reference to the ground-water resources of the 

Edwards limestone, Is the subject of an investigation started in the fall 

of 1932 as part of a survey of the ground-water resources of Texas by the 

United States Geological Survey in cooperation with the State Board of 

Water Engineers.

In several places in Texas the extensive development of ground 

water has been followed by a material lowering of the water table or by a 

large decline in the artesian head and pronounced shrinkage in the area 

of artesian flow. This has not occurred at San Antonio, but during several years since 1924 the artesian pressures in the San Antonio area have 

persistently remained below normal. The artesian pressure In the Edwards 

limestone determines the rate of discharge of the springs and flowing 

wells in this area. Moreover, the springs at the head of the San Antonio 

River oease to flow when the pressure falls below the amount necessary 

to raise the water levels In neighboring artesian wells to an altitude of 

about 668 feet above the sea. The springs have been quiescent a consider-- 

ably larger proportion of the time during the decade 1926-35 than they
WATER RESOURCES, SAN ANTONIO AREA, TEX. 61

were in the preceding decade. By some this is thought to indicate that 

there has been a decline in the average artesian pressure due to heavy 

draft on the artesian wells. To a degree this condition has become a 

matter of public concern and has led to the present Investigation, which 

was undertaken in response to public request. The chief purpose of the 

investigation has been to obtain as much Information as possible regarding 

the capacity of the artesian reservoir In the San Antonio area and the 

approximate amount of water that can be withdrawn from It each year without seriously depleting the supply. The investigation has included a 

study of the recharge of this reservoir, the discharge from It by springs 

and wells, and the fluctuation In water levels and artesian pressures in 

observation wells.

The investigation Is being made under the direction of 0. E. Meinzer, 

geologist in charge of the division of ground water in the Geological Survey. In the geologic studies connected with the Investigation, both In 

the field and In the preparation of this report, substantial assistance 

has been given by L. W. Stephenson, chief of the section of Coastal Plain 

geology In the Survey. Valuable aid has also been given by several engineers and geologists of San Antonio and by officials of the city water 

department.

Previous ground-water Investigations

The geology and artesian-water supplies of the San Antonio area were

1 

discussed by Hill and Vaughan In 1898. These Investigators were the first

to point out that the Edwards limestone is the principal source of the 

water discharged by the springs and artesian wells of the Balcones fault

zone.

2 

A list of about 60 wells In Bexar County was given by Taylor In 1907.

The springs of the Balcones fault zone, including the San Antonio and San

3 

Pedro Springs, were described In 1927 by Meinzer.

1 Hill, R. T., and Vaughan, T. W., Geology of the Edwards Plateau and 

Rio Grande Plain adjacent to Austin and San Antonio, Tex.: U. S. Geol. Survey 18th Ann. Rept., pt. 2, pp. 193-322, 1898.

2 Taylor, T. U., Underground waters of the Coastal Plain of Texas: 

U. 3. Geol. Survey Water-Supply Paper 190, pp. 55-56, 1907.

3 Meinzer, 0. E., Large springs in the United States: U. S. Geol. 

Survey Water-Supply Paper 557, pp. 27-39, 1927.
62 CONTRIBUTIONS TO HYDROLOGY, 1936

The results of investigations in the area, together with a summary

4 

of the work of others, are given in a paper by Muir. The results of an

investigation made at the request of the city council are described in a

5 

report by Potter, which includes a general discussion of the development

of water from wells in the Edwards limestone in and around San Antonio.

The geology and ground-water conditions in a part of the area have been

6 

briefly described by Stephenson.

The geology and ground-water resources of the San Antonio district

7 

are described by Sellards.

8 

Information on the geology of Bexar County is given by Deussen,

who also gathered a considerable amount of information on the ground waters 

of the San Antonio area which has not been published. This information has 

been used freely in the present investigation.

Importance of ground water in the area

Ground water contributes a great deal to the attractiveness of San 

Antonio and to the welfare of its people.

Relatively little surface water is available in this locality without 

storage, the run-off of the local streams being intermittent and flashy. 

But the area contains springs that are among the largest in Texas, and 

abundant supplies of water suitable for municipal and industrial uses and 

irrigation can be obtained from wells almost anywhere in the city and in 

an area of considerable size adjacent to it. In the lower parts of the 

area the wells flow.

The San Antonio River is fed by springs and by artesian wells. The 

river winds through the heart of the city, and its clear waters, together 

with the verdure in the parks along its banks, present a picture of uncommon beauty. The springs of the city are in two groups the San 

Antonio Springs, at the head of the river in the northern part of the 

city, immediately north of Brackenridge Park, and the San Pedro Springs, 

about 2 miles southwest of the San Antonio Springs, in San Pedro Park. 

The San Pedro Springs give rise to San Pedro Creek, which discharges into 

the San Antonio River below the city.

4 Muir, A. H., The geology of the artesian water supply of the San 

Antonio area, St. Louis, 1911.

5 Potter, Alexander, A report upon and an appraisement of the water 

supply system of the city of San Antonio, Tex., San Antonio, 1912.

6 Stephenson, L. W., The camps around San Antonio, printed on the 

reverse side of the topographic map of the San Antonio quadrangle, edition of 1919.

7 Sellards, E. H., The geology and mineral resources of Bexar 

County: Texas Univ. Bull. 1932, 1919.

8 Deussen, Alexander, Geology of the Coastal Plain of Texas west of 

the Brazos River: U. S. Geol. Survey Prof. Paper 126, 1924.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 63

The availability of a perennial flow of spring water in the San 

Antonio River in this vicinity led to the founding of the city. One of 

the most ancient Indian settlements or pueblos in the region was situated 

at the springs. Between 1718 and 1731 the Spaniards established a military post and five missions along the river in this vicinity and employed 

the natives in the cultivation of farms and gardens irrigated by the spring 

water. The winding courses of some of the streets in the older parts of 

the city are due to the fact that they were laid out to follow the ancient 

ditches.

The importance of the available supply of ground water in the San 

Antonio area has become more and more apparent. The city has grown rapidly. The population in 1910 was 96,614; by 1920 it had increased to 

161,379, and in 1930 it was 231,542. With the increase in population the 

demand for water for domestic and industrial use and irrigation has grown 

at a corresponding rate, and this has been met by larger and larger withdrawals of ground water.

CLIMATE 

Temperature

The winter climate in this part of Texas is mild, and in recent years 

San Antonio has become one of the most popular winter resorts in the Southwest. According to records of the United States Weather Bureau the annual 

mean temperature is 69° and the seasonal means are, for winter, 54°; 

spring, 69°; summer, 83°; fall, 70°. The highest temperature recorded is 

107° , and the lowest 4°. The average annual rainfall is not very heavy, 

but in most years there is enough to insure fair crops of corn, cotton, 

and grain. Irrigation is usually considered necessary, however, for the 

profitable production of garden truck and small fruits.

Rainfall

The United States Weather Bureau has obtained long-time records of 

rainfall at several localities in this part of Texas. The records that 

are of special significance in connection with this report are those obtained at San Antonio; at Hondo, about 45 miles west of San Antonio; and 

at Boerne, about 50 miles north of San Antonio. San Antonio and Hondo 

are south of the intake area of the Edwards limestone reservoir, which 

supplies the San Antonio district; Boerne is north of it. According to 

the Weather Bureau the average rainfall at San Antonio during 61 years was
64 CONTRIBUTIONS TO HYDROLOGY, 1936

27.33 inches; at Hondo during 39 years, 27.28 inches; at Boerne during 

42 years, 32.41 inches.

Some significant facts are disclosed by a study of the records obtained at these stations and others in southwestern Texas. The average 

annual rainfall varies with both the latitude and the altitude. It increases from west to east and is greater on the Edwards Plateau than on 

the lower lands of adjacent parts of the Coastal Plain. Heavy rains are 

usually general over a wide area. They commonly increase in magnitude from 

west to east and are heavier on the Edwards Plateau than on the Coastal 

Plain. In occasional storms the volume of rainfall has increased from east 

to west. During the storm of July 1932, for example, the precipitation was 

0.26 inch at Austin, 4.91 inches at San Antonio, 3.02 inches at Boerne, 

10.65 inches at Hondo, and 20 inches at Uvalde, about 45 miles west of 

Hondo.

The records at San Antonio, Hondo, and Boerne are usually in fairly 

close agreement, so far as trends in rainfall are concerned. If the rainfall during a particular month is above normal at one of these stations it 

is almost certain to be high at the other two, and the same is true of subnormal rainfall. A few outstanding exceptions to this rule have been recorded, but on the whole the records at San Antonio are a reasonably accurat 

index of the annual and periodic fluctuation's in rainfall with which this 

report is chiefly concerned. Some of the facts disclosed by a study of the 

San Antonio records are as follows. In most years some rain falls every 

month. April, May, and September have the highest average precipitation, 

and December, January, and February the lowest. The lowest annual precipitation was 10.11 inches in 1917, and the highest was 50.30 inches in 1919. 

The years of subnormal and supernormal precipitation during the period of 

record were about equal in number, but they tended to occur in groups. The 

average for the 17 years of record between 1871 and 1890 was 31.48 inches, 

or about 4 inches above the 61-year average. No records were obtained at 

San Antonio for three years of these two decades 1876, 1883, and 1884 ~ 

but the mean rainfall in those years was normal or above at Galveston, San 

Angelo, and Brownsville and at New Ulm, near Austin. The mean from 1891 

to 1910 was 24.45 inches, or about 3 inches below the average. The mean 

for 1911 to 1920, including the very wet year 1919, was a fraction of an 

inch above the average, but for that decade exclusive of 1919 it was about 

2 inches below the average. The means for 1921 to 1930 and for 1931 to 

1934 were respectively 1.41 inches and 0.93 inch below the average. The
WATER RESOURCES, SAN ANTONIO AREA, TEX. 65

records seem to suggest, therefore, that the mean rainfall during the last 

35 years may have "been somewhat below the long-time average. The mean during the last 20 years, however, has been about the same as the 61-year 

average.

The longest period of subnormal precipitation apparently was from October 1, 1908, to August 31, 1913, the accumulated deficiency below the 

average during the 59 months being 41.35 inches. Other outstanding dry 

periods were November 1, 1896, to November 30, 1899, with an accumulated 

deficiency of 26.65 inches, and July 1, 1924, to December 31, 1927, with an 

accumulated deficiency of 21.95 inches. In the wet years a relatively 

large part of the excess precipitation occurs during a few heavy storms; 

in the dry years such storms are infrequent. For example, in 1919, the 

year of heaviest precipitation, 22.4 inches fell in 11 days, scattered over 

a period of several months. More recently, in 1932, 15 inches fell in 4 

days, and in May and June 1935, 10 inches fell in 3 days. In the comparatively wet fall and winter of 1930-31 there were 7 days in October, January, and February in which the precipitation exceeded 1 inch. On the other 

hand, during the dry period of 43 months from July 1, 1924, to December 31, 

1927, there were only 17 days in which the precipitation exceeded 1 inch.

TOPOGRAPHY

The northern part of Bexar County, amounting to somewhat less than onethird of its area, lies on the Edwards Plateau. The remainder of the county 

is on the Coastal Plain. These areas are separated by the abrupt southwardfacing Balcones escarpment, which crosses the county in a nearly east-west 

direction, passing about a mile south of Helotes, in the western part of 

the county, and a short distance north of Bracken, which is Just across the 

east boundary in Comal County.

 The Edwards Plateau In Bexar, Medina, and Uvalde Counties covers practically the same area as the outcrop areas of the Glen Rose limestone and 

Edwards and associated limestones shown on the map. It is an area of pronounced relief, and its topography contrasts strongly with that of the 

Coastal Plain. From the Balcones escarpment northward and in some places 

southward is a belt in which the resistant Edwards limestone crops out in 

both valleys and hills, or at least forms the sides or the tops of the 

hills. This belt is characterized by broken topography with deep, steepwalled, flat-bottomed and relatively narrow valleys. From this belt northward for a considerable distance beyond the county boundary the less
66 CONTRIBUTIONS TO HYDROLOGY, 1936

resistant Glen Rose limestone underlies the surface, and although the 

relief in that area is nearly as great as in the belt to the south, the 

valleys are much wider and the slopes are more gentle.

The Coastal Plain in Bexar County consists in part of a gently rolling 

plain and in part of moderately hilly country. The rolling plain in most 

places is underlain by marls, marly clays, and clayey to clean sandstones 

that weather easily and form deep loamy black or yellow sandy soils. These 

soils are generally very fertile. The hills are in most places underlain 

by limestones or highly indurated sandstones or are capped by gravel and 

owe their existence to the resistance to erosion afforded by these rocks.

GEOLOGY AND ITS RELATION TO THE OCCURRENCE OP GROUND WATER

This report is chiefly concerned with the Edwards and associated 

limestones and their ability to take in water at the outcrop and to 

transmit the water long distances underground to the springs and artesian 

wells of the San Antonio district. Brief consideration is given below, 

however, to water in other formations that underlie-Bexar County. A 

generalized section _of these formations with a statement of their waterbearing properties is given in the table on page 67.

The outcrop areas of the Glen Rose limestone and the Edwards and associated limestones (Georgetown and Comanche Peak limestones and Walnut 

clay) are shown on the accompanying map. In traveling southward and southeastward from the Edwards outcrop along the lines A-A T and B-B' successively 

younger formations of Cretaceous and Eocene age are crossed. These formations are not differentiated on the map. The structure of the rocks and 

the order in which they occur along the lines A-A' and B-B 1 is shown in 

figure 6.
WATER RESOURCES, SAN AHTOHIO AREA, TEX. 

Generalized section of the geologic formations of the San Antonio area, Texas

System

Quaternary.

Tertiary)?) .

Tertiary.

Cretaceous.

Series

Recent.

Pleistocene.

Pliocene(?).

Eocene.

Upper 

Cretaceous 

(Gulf).

Lower 

Cretaceous 

( Coiranche) .

Pre-Cretaceous rocks .

Formation or group

Stream and terrace 

gravel .

Terrace gravel In- 

' eluding Leona 

formation.

Uvalde gravel.

Mount Selman formation.

Carrizo sand.

Wilcox group.

Midway group.

Navarro group.

Taylor marl.

Anacacho limestone.

Austin chalk.

Eagle Ford clay.

Buda limestone.

Del Rio clay.

Georgetown limestone.

Edwards limestone.

Comanche Peak 

limestone.

Walnut clay.

Glen Rose limestone.

Travis Peak 

formation. 1

Undifferentiated 

schists. 1

Thickness 

( feet)

0-90

0-20

(?)

200

650t

650t

300±

300±

200±

130±

30

60

60

40±

500±

40

20

1,000- 

1,200

450l

Water-bearing properties

Water-bearing in places in stream valleys.

Yields potable water for stock and 

domestic wells in some places.

Is not known to yield water to wells.

Yields water of good quality to wells.

Yields water to stock and domestic 

wells, usually rather highly mineralized.

Is not known to yield water to wells.

Is not known to yield water to wells.

o o o y o

Yields potable to highly mineralized

mestic, stock, and irrigation wells.

Does not yield water to wells.

Is not known to yield water to wells.

Does not yield water.

Is not commonly water-bearing but 

yields water to some wells.

Chief water-bearing formation in the 

area. Is the source of the large 

springs and yields water to many 

pumped and flowing wells .

Does not yield water.

Does not yield water.

Yields more or less highly mineralized 

water to domestic and stock wells on 

the Edwards Plateau.

Yields only small supplies where it 

has been reached by wells.

Probably would not yield water. Rocks 

lie too deep for practicable water 

well drilling.

1 Does not crop out in this area.
68 CONTRIBUTIONS TO HYDROLOGY, 1936

GEOLOGIC SECTION ACROSS BEXAR COUNTY ALONG LINE A-A1

FIGURE 6. GEOLOGIC SECTION ACROSS BEXAR COUNTY ALONG LINE B-B1

SCALE 

I 0 I 2 i 4 5 6 MILES

The Travis Peak formation imderlies the area at depths of about 500 

feet near the northern boundary of Bexar County and about 5,000 feet near 

the southern boundary. It is about 45Q feet thick and consists of a lower 

conglomeratic phase, often called the "Basement sands", which grade upward 

into fine sands and shales. At Dallas, Port Worth, and Austin this formation has yielded large quantities of water. In northwestern Uvalde County 

an oil test is reported to have encountered large quantities of "fresh" 

water in the formation, but in the vicinity of San Antonio several wells 

have penetrated the formation and according to reports have encountered 

only small supplies of-water.

The Glen Rose limestone overlies the Travis Peak formation and is 

the oldest formation exposed in the area. It is between 1,000 and 1,200 

feet thick and consists of beds of moderately resistant, massive chalky 

limestone alternating with beds of less resistant marly limestone. The 

difference in the resistance of the various beds to erosion has resulted 

in the development of a striking terraced topography. In general the 

limestone is only moderately permeable and contains water only in small 

joints and fissures. In places on the outcrop, however, it contains solu-
WATER RESOURCES, SAN ANTONIO AREA, TEX. 69

tion channels that range from minute openings to large caverns some of 

which take In large quantities of surface water. If these openings were 

widely interconnected the water levels In wells In the formation would 

be concordant; that they are not widely Interconnected Is Indicated by 

the fact that the altitudes of the water levels differ greatly, even In 

wells close together. South of the Balcones escarpment the Glen Rose is 

apparently almost impervious, for It yields very little water to wells.

The Walnut clay and the Comanche Peak limestone are essentially not 

water-bearing and therefore will not be further described.

The Edwards limestone crops out chiefly north of the Balcones escarpment, but It is exposed in a few places south of the escarpment, as Indicated on the map. It consists of about 500 feet of gray to white massive, 

hard, dense semlcrystalline limestone that is very resistant to erosion. 

It contains numerous beds of nodular chert and is in most places poor In 

fossils. In many places It Is honeycombed and cavernous and yields water 

freely to wells. However, In a few areas the formation lacks the usual 

cracks and solution channels, and wells In these areas yield little or 

no water. The Edwards limestone Is the chief water-bearing formation in 

the region and supplies the springs at San Antonio and most of the wells 

south of the Balcones escarpment. The occurrence of water in the Edwards 

Is the subject of the greater part of the report that follows.

The Georgetown limestone Is an argillaceous buff to brownish-buff 

fosslliferous limestone about 40 feet thick. In general It Is not very 

permeable, but a few wells apparently draw some water from It.

The Del Rio clay yields no water, but when the well driller strikes 

this easily Identified formation he knows that his drill is 100 feet or 

less above the Edwards limestone.

The Buda limestone and the Eagle Ford clay are not known to yield 

appreciable supplies of water to wells.

The Austin chalk has a thickness of about 130 feet and Is a rather 

massive fossillferous buff chalky limestone. In Bexar County It Is 

cavernous In many places, as Indicated by Robber Baron's Cave and other 

caverns reported near Brackenridge Park, In the northern part of San 

Antonio. Where similar caverns exist beneath the water table, wells 

striking them yield large quantities of water. In general, however, 

the Austin Is not as consistent a water-bearing formation as the Edwards, 

and In many parts of the area the water may be more or less heavily impregnated with hydrogen sulphide.
70 CONTRIBUTIONS TO HYDROLOGY, 1936

In some places In the vicinity of faults or fault zones the altitude 

of the water surface in wells drawing from the Austin chalk is about the 

same as that of the water surface in wells drawing from the Edwards, and 

the water levels rise and fall together. This is good evidence that in 

such localities water moves freely between the two formations. An illustration of this close agreement is afforded by the records of water-level 

fluctuations in the wells of D. T. Atklnson and Amos Lorenz. (See table 

7.) These wells are in the Alamo Heights district, in the northeastern 

part of San Antonio, and are about a mile apart. The Atkinson well draws 

from the Austin chalk, and the Lorenz well from the Edwards limestone. 

Similar agreement in the altitude and fluctuations of the water surfaces 

in wells ending in the two formations is shown in the vicinity of the 

Republic Cement mills, on the Missouri-Kansas-Texas Railroad about 5 miles 

northeast of San Antonio; in the southern part of the city in the vicinity 

of the Mission pumping plant; and in the irrigated area south of San 

Antonio and west of Somerset Road. Where the Austin crops out near the 

faults, water that enters it may eventually reach the Edwards through fissures along the fault planes. At Alamo Heights the sewage has been discharged into wells ending in the Austin chalk. This sewage must have an 

outlet somewhere. Apparently the most convenient outlet is in the fractured area in the vicinity of the San Antonio Springs. There is no 

assurance that the sewage may not pass downward in this area and enter 

the Edwards reservoir, at times when the artesian pressure is low, and 

later appear in bhe^Edwards wells, or it might move through the Austin 

Itself and be discharged from that formation directly into the springs. 

Of course storm water may enter the Edwards limestone through the Austin 

chalk at the springs on the San Antonio River or on San Pedro Creek whenever the artesian pressure declines to such an extent that these springs 

cease to flow.

The Cretaceous formations above the Austin and the Midway group do 

not yield water to wells in Bexar County, so far as is known.

The Wllcox group crops out in the southern and southeastern parts of 

the county and yields water that ordinarily is somewhat highly mineralized.

The Carrlzo sand crops out in the southernmost part of the county. 

This is one of the most prolific water-bearing formations in Texas, but so 

far as has been learned no wells of very large yield have been developed 

in the formation in Bexar County.
WATER RESOURCES, SAW ANTONIO AREA, TEX. '71

The Mount Selman formation underlies a very small area at the southernmost corner of the county, but no wells that draw water from It were found 

In the county.

In different parts of the county sand and gravel in the Leona formation 

and in Recent deposits yield water sufficient for domestic use and stock.

GEOLOGIC STRUCTURE

In the northern part of the county, on the Edwards Plateau, the rocks 

are relatively flat and free from faulting. In the central part of the 

county, in the Balcones fault zone, they dip Gulfward at comparatively steep 

angles and are extensively faulted. The Balcones escarpment in its present 

form is almost if not entirely an erosional escarpment situated mainly along 

a discontinuous fault that brings resistant Edwards limestone on the north 

side against less resistant younger formations on the south side. In a 

few places it follows the contours of hills capped by the Buda limestone, 

overlying the easily eroded Del Rio clay, and where the Buda is faulted 

into position opposite the Edwards there is no trace of an escarpment at 

the fault. The fault most generally followed by the escarpment passes 

just north of New Braunfels, in Comal County, where it has a throw of about 

500 feet. This fault extends with gradually decreasing throw to Bracken, 

near Cibolo Creek, where it divides into several minor faults, and the 

escarpment becomes lower. For a distance of several miles west of Cibolo 

Creek there are several minor escarpments, and it is difficult to determine which should be regarded as the Balcones escarpment. Prom Cibolo 

Creek several faults converge toward the west and join to form a large 

fault with a throw of about 600 feet 1 mile south of Helotes, but at 

this point the trace of the fault lies about a quarter of a mile north of 

the escarpment. Near the west side of Bexar County this fault is divided 

into two faults, the larger of which leaves the escarpment and extends 

toward Quihi, in Medina County, where it has a throw of nearly 1,000 feet. 

The other follows the escarpment into central Medina County, where its 

displacement becomes very small. There are numerous other faults, some 

of them with displacements of 500 feet or more, and most of them have a 

trace that extends a little south of west, but as in most places the 

formations on both sides of the fault are of nearly equal resistance to 

erosion, only a few of them are reflected by the topography. The traces 

of the major recognized faults in Bexar County are shown on the map, and 

their effect in displacing the formations is shown on the cross sectional
72 CONTRIBUTIONS TO HYDROLOGY, 1936

diagrams in figure 6. In most of the faults the downthrow is on the south 

side, but south of San Antonio (see map) there is a large fault and in 

some places several faults on which the downthrow is on the north.

In general the formations dip toward the south and are either monoclinal or only slightly folded, but in western Bexar County there is a 

broad anticline that plunges to the southwest.

THE EDWARDS LIMESTONE AS A GROUND-WATER RESERVOIR

The Edwards limestone is more soluble than most other limestones 

and has become honeycombed or cavernous by solution channeling over wide 

areas both on the Edwards Plateau and in the Balcones fault zone south of 

the plateau. These openings are interconnected for long distances and 

form extensive underground reservoir systems, which, to a large extent, 

control the available supply of water in the region both surface and 

underground. On the plateau several miles back of the margin the beds 

of the Edwards limestone are almost flat but have a slight dip to the 

east and southeast, about equal to the slope of the surface of the land. 

On this account and because of its resistance to erosion the limestone 

constitutes a very large part of the surface of the higher lands of the 

plateau. The valleys of most of the larger streams have cut through the 

formation to the underlying beds of the Glen Rose limestone and Travis 

Peak formation, and in places the limestone has been completely or almost 

completely removed by erosion from the interstream highlands, as well as 

from the valleys. It has been almost entirely eroded away in a belt of 

varying width extending from Uvalde County northeastward beyond Austin 

and crossing the extreme northern parts of Medina and Bexar Counties. 

South of this eroded belt the formation has been lowered by flexing and 

faulting and appears in outcrop in a belt along the Balcones escarpment. 

Thence it dips Gulfward under younger formations to increasingly greater 

depths. At San Antonio the top of the limestone is from 400 to 1,000 

feet below the land surface, and in the southernmost part of Bexar County 

about 3,000 feet. Essentially, therefore, there are two distinct systems 

of Edwards reservoirs in the region, one on the Edwards Plateau, the 

other in and south of the Balcones fault zone. The two systems are separated by the belt in which the continuity of the Edwards is persistently 

interrupted by erosion.

The plateau reservoir system is located in areas in which the Edwards 

formation caps a large part of the interstream uplands and absorbs a high
WATER RESOURCES, SAN ANTONIO AREA, TEX. 75

proportion of the rainfall. In these areas the water sinks through 

cracks and solution channels to the lower part of the formation, where it 

is prevented from going deeper by the relatively impermeable beds of the 

underlying formations. The water table in the body of ground water thus 

accumulated in many places is above the valleys of the larger streams, 

and the water moves laterally by gravity in the beds of the limestone, 

which are almost horizontal, and largely appears in the valleys as 

springs, usually along the base of the Edwards limestone. Similar springs issue along the contact between permeable and impermeable 

beds in the Glen Rose limestone and Travis Peak formation, but the largest 

contribution of spring water comes from the Edwards. These contact 

springs are the source of the perennial rivers of the Edwards Plateau, 

which are famous for the clearness of their waters and the relative constancy of their flow. The largest, named from east to west, are the 

Llano, Blanco, Guadalupe, Medina, Prio, Nueces, and Devils' Rivers. The 

streams furnish large quantities of water for hydroelectric power and 

for irrigation and add greatly to the beauty and attractiveness of the 

areas through which they flow.

The lower or fault-zone reservoir occurs in the body of the formation that extends Gulfward from the Balcones escarpment. (See map.) 

Extensive exploration by wells in this reservoir in Bexar County has 

shown that under large areas the limestone is traversed by an intricate 

system of openings. In some places the openings are small, apparently 

being confined to joint planes and fissures. In others they consist of 

solution channels of varying sizes, the largest good-sized caverns.

In places the limestone is honeycombed by small solution channels, 

which in the aggregate provide a large amount of open space. The largest 

and most extensive systems of openings occur in the vicinity of faults 

and tend to center around the faults and large springs at San Antonio. 

The honeycombed and cavernous phases of the limestone yield very large 

quantities of water to wells. The small openings may yield little or 

no water. The occurrence of the different types usually varies considerably from place to place. Even in the district in and around San 

Antonio, where the largest number of successful wells have been drilled, 

it not infrequently happens that closely spaced wells' have widely different yields. For example, in downtown San Antonio, of four flowing 

wells of about equal depth put down within a distance of a few hundred 

feet, three had a flow of only a few gallons a minute, but the fourth

had a flow of more than a thousand gallons a minute. 

42071 O 36 2
74 CONTRIBUTIONS TO HYDROLOGY, 1936

In the Balcones outcrop area and in most of the north-central part 

of Bexar County water of good quality is usually obtained from wells in 

the Edwards limestone. Down the dip in the southern part of the county 

the water is highly mineralized and not suitable for some uses. The line 

of demarcation between the two types of water is indicated on the map by 

the line D-D'. This line has been accurately drawn where wells in the 

Edwards limestone are fairly closely spaced, but elsewhere its location 

is only approximately correct and may be changed somewhat as a result of 

further studies in the area. North of the line the water from most of 

the wells is fairly fresh, indicating that the circulation of the water 

in the Edwards reservoir is comparatively free. South of it the water 

contains a very much larger quantity of dissolved minerals, indicating 

that there is little circulation and that the water has been trapped in 

the formation for a long time. The universal occurrence of water of high 

mineral content'in the Edwards in the southern part of the county is 

evidence that the underground reservoir in the Balcones fault zone is 

definitely limited in that direction and that there is little or no movement of water down the dip toward the Gulf.

The fault-zone reservoir is fed by rainfall and by seepage from 

streams on the outcrop of the Edwards limestone along the Balcones 

escarpment. This outcrop in Bexar County and the greater part of Medina 

County, as before stated, is shown on the map. The reservoir is not 

directly connected with the reservoir system of the plateau but is connected hydrologically with that system by the spring-fed streams of the 

plateau that lose heavily by seepage in crossing the outcrop. The 

principal natural outlets of the reservoir are springs that emerge along 

fault planes, among the largest of which are the Barton Springs, at 

Austin; the San Marcos Springs, at San Marcos; the Comal Springs, at New 

Braunfels; the San Antonio and San Pedro Springs, at San Antonio; the 

Las Moras Springs, at Brackettsville; and the San Felipe Springs, at Del 

Rio. These springs are among the largest and best known in the southwestern part of the United States and are the sources of good-sized rivers 

and creeks.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 75 

Recharge to reservoir

In the outcrop area of the Edwards limestone along the Balcones 

escarpment the beds usually dip to the south or southeast at an angle 

materially greater than the slope of the surface. Therefore, in traveling 

in these directions the beds become progressively lower, first occupying 

only the tops of the hills, then the slopes as well as the hilltops, then 

dropping down to the level of the valleys, and finally disappearing beneath the rocks of younger formations. This structural arrangement predominates but is disturbed by faulting in many places. The arrangement is 

ideal for the intake of water by the permeable beds of the limestone. The 

streams cross the outcrop area nearly at right angles to the strike, and 

most of them flow for miles on the Edwards limestone. In these stretches 

the water level in the Edwards reservoir is below the level of the streams, 

and the streams lose heavily into the reservoir. Ground-water recharge 

is also provided from rainfall on the outcrop by direct penetration and by 

seepage from innumerable small drainage channels that ordinarily carry 

water only during and for brief periods after exceptionally heavy rains. 

Some recharge may occur from permeable beds in the Glen Rose in localities 

where the Edwards is faulted down against such beds.

The United States Geological Survey and the State Board of Water 

Engineers have maintained gaging stations for many years on practically 

all the larger streams that cross the outcrop. On several of them stations 

have been operated both above and below the outcrop, and series of currentmeter measurements have been made between the stations to determine the 

extent of losses or gains in different parts of the intervening reaches. 

Such measurements have been made on the Guadalupe River, which crosses 

the outcrop area 35 to 40 miles northeast of San Antonio; on the Medina 

River, which crosses it about 30 miles northwest of the city; and on the 

Prio and Nueces Rivers, which cross it respectively about 75 and 90 miles 

west of the city. The records obtained on the Medina River are considered 

the most significant, because, as pointed out in the section on artesian 

pressure gradients and movement of ground water, the ground water contributed to the Edwards reservoir by this stream undoubtedly reaches the 

San Antonio area. The records of most of these measurements have been 

published in water-supply papers of the Geological Survey.

Since 1922 three gaging stations have been maintained on the Medina 

River in the vicinity of the Medina Reservoir, the dam of which is about 

30 miles northwest of San Antonio. The upper station, usually called the"
76 CONTRIBUTIONS TO HYDROLOGY, 1936

"Pipe Creek station", is a short distance upstream from the upper end of 

the reservoir and is above the main outcrop of the Edwards, The other two 

are about 4 miles below the reservoir dam, within a few hundred feet of 

the lower boundary of the Edwards outcrop. One of these lower stations is 

on the Medina Irrigation Canal; the other on the river on the diversion dam 

at the canal intake. During 1930 an intermediate gaging station was maintained about 2,000 feet below the reservoir, near Mico post office.

The gaging records show that in the 11 years from 1923 to 1933 about 

422,000 acre-feet, or an average of about 38,500 acre-feet a year, was lost 

from the river and reservoir between the Pipe Creek station and the canal 

intake. The loss was due in part to evaporation, chiefly from the reservoir, but the evaporation was at least partly balanced by storm-water 

inflow from the tributary drainage area between Pipe Creek and the canal 

intake, comprising about 190 square miles. Most of the loss was caused by 

seepage into the Edwards limestone.

The best information available on losses from the Medina River on a 

part of the Edwards outcrop is contained in the records for 1930. During 

that year about 16,000 acre-feet was lost from the 3-g-mile stretch of the 

river below the reservoir, between the Mico station and the diversion dam, 

all of which is on Edwards limestone. A few hundred acre-feet of the loss 

consisted of evaporation from the surface of the river and diversion reservoir and transpiration by vegetation along the river, but nearly all of 

the loss was due to seepage into the Edwards. The volume of water carried 

by the river in this stretch in 1930 was slightly below the 11-year average, and the loss by seepage was therefore probably somewhat less than 

 the average.

In the absence of accurate data on evaporation from the Medina Reservoir and the inflow between the Pipe Creek and lower gaging stations, the 

losses from the river into the Edwards limestone during the 11-year period 

mentioned of course cannot be closely computed. It is believed, however, 

that they amounted to an average of at least 30,000 acre-feet a year, the 

equivalent of a continuous discharge of about 27,000,000 gallons a day. 

This is more water than is used for public supply by the water department 

of San Antonio.

A seepage investigation on July 9, 1931, disclosed that the entire 

discharge of Hondo Creek, amounting to 13.9 second-feet, sank on the Edwards outcrop about 50 miles northwest of San Antonio.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 77

It was shown by measurements in June 1925 that the entire flow of 

the Prio River, amounting to about 40 second-feet, and the entire flow of 

Its principal tributary, the Dry Prio, amounting to about 10 second-feet, 

disappeared, on the Edwards outcrop. Gaging stations were operated simultaneously on the Prio River from October 1923 to September 1927 at Concan, 

just above the outcrop of the Edwards, and at Prio Town, about 40 miles 

below the outcrop. Prom studies of the records obtained at these points 

It is estimated that during the 4 years the average annual losses from 

the river into the Edwards limestone were from 40,000 to 50,000 acre-feet.

An extensive program of stream gaging has been carried out along the 

Nueces River on the Edwards outcrop and above and below the outcrop. The

results of these measurements are discussed at considerable length in

9 

another paper, in which the conclusion is reached that during 6 years,

from October 1927 to September 1933, the losses from the river into the 

Edwards reservoir amounted to an average of at least 36,000 acre-feet a 

year, and perhaps considerably more.

On the basis of these figures it appears probable that the combined 

annual losses into the Edwards from the Medina, Frio, Dry Prio, Nueces, 

and Sabinal Rivers and Hondo Creek may average as much as 150,000 

acre-feet, the equivalent of a continuous flow of about 134,000,000 gallons 

a day. Moreover, several smaller streams furnish supplies which in the 

aggregate probably amount to thousands of acre-feet a year.

The regimen of the streams of the Edwards Plateau has an important 

effect on the performance of the underground reservoir in the fault zone. 

The streams are fed in large part from the underground water systems of 

the plateau, and this ground-water inflow is nearly uniform for long 

periods. After heavy rains the ground-water discharge usually increases 

greatly and may be sustained at relatively high but slowly declining 

stages for a long time. In some dry years, such as 1925, the discharge 

of the streams of the plateau consists almost entirely of ground water. 

The rainfall in 1925 was exceedingly low, among the lowest on record at 

San Antonio and Uvalde. Nevertheless, the combined ground-water discharge of the Medina, Nueces, and Prio Rivers in that year amounted to 

about 70,000 acre-feet, most of which was derived from the Edwards reservoir of the plateau and entered the lower part of the Edwards reservoir In 

the Balcones fault zone.

9 Sayre, A. N., Geology and ground-water resources of Uvalde and 

Medina Counties, Tex.: U. S. Geol. Survey Water-Supply Paper 678, 1936.
78 CONTRIBUTIONS TO HYDROLOGY, 1936

During heavy rains and for a few days afterward the streams carry 

large quantities of storm water. This water, both in the larger streams 

and in innumerable small drainage channels, also contributes heavily to 

the fault-zone reservoir. The approximate amount of storm-water recharge 

from some of the larger streams is indicated by the stream-gaging records, 

but comparatively little is known regarding the recharge from the small 

streams and by direct penetration of rainfall. The records of artesian 

pressure and spring discharge at San Antonio give considerable information as to the time and relative magnitude of the total recharge during 

and after heavy rains. The artesian pressure in the vicinity of San 

Antonio rises almost immediately during exceptionally heavy general rains. 

At such times large quantities of water sink into the reservoir at the 

outcrop and produce a quick rise in the water table, the effect of which 

is communicated promptly by transmission of pressure many miles down the 

dip. The discharge of the San Antonio Springs also increases quickly 

when the rainfall is heavy, provided the pressure in the artesian reservoir at the beginning of the storm is sufficient to raise the water to or 

nearly to the level of the outlet of the springs. If the pressure is low 

before the storm it may be increased considerably and still fail to reach 

a point that will cause the springs to flow.

The records show that since 1913 there have been only a few periods 

of pronounced rise in the artesian pressure and spring discharge but that 

after these periods both the artesian pressure and the spring discharge 

were maintained at relatively high stages for months or even years. The 

periods of high recharge indicated by the rises are as follows: 1913, 

October to December; 1914, April and May; 1915, April and May; 1919, February, July to October; 1921, March and September; 1922, April; 1923, 

November and December; 1924, March to May; 1926, April and May; 1930 and 

1931, October to February; 1932, July to September; 1935, April, May, and 

June.

It is apparent from a study of the records that the amount of the 

ground-water recharge is affected by the intensity of the rains and their 

distribution in time as well as by the amount of the rainfall. Intense 

general rains in which 3 to 8 inches falls in 2 or 3 days or a succession 

of moderately heavy rains in rapid sequence are almost certain to cause 

heavy recharge. Rains that are widely distributed in time and slow rains 

continuing over many days apparently provide very little recharge. Rains 

in winter contribute more to the ground water than rains of similar magnitude in summer,, There is also a rather definite relation between the
WATER RESOURCES, SAN ANTONIO AREA, TEX. 79

amount of storm run-off In the streams that cross the outcrop and the 

amount of ground-water recharge.

Although exceptionally heavy recharge on the outcrop during heavy 

rains is accompanied or followed by a rise in the artesian pressures at 

San Antonio, the recharge from the relatively uniform ground-water flow 

of the streams supplied by the underground reservoirs of the Edwards 

Plateau may not have an apparent effect on the pressure. This recharge 

is going on constantly, though in varying amounts.

Discharge from reservoir

The water that reaches the Edwards limestone reservoir in the San 

Antonio area is for the most part discharged from the reservoir by the 

springs and deep wells of the area. A minor part passes out of the area 

by underground movement.

Discharge by springs

The San Antonio and San Pedro Springs afford large natural spillways 

for the Edwards reservoir in Bexar County, The springs occur along faults 

that permit water in the Edwards limestone under artesian pressure to 

escape into cracks and channels in the overlying rocks and thence to flow 

to the surface. The San Antonio Springs emerge on low land in the valley 

of Olmos Creek along the line of a fault several miles long that crosses 

the northern part of San Antonio. (See map.) In the vicinity of the 

springs the fault has a throw of several hundred feet, and the top of the 

Edwards on the upthrown side is about 400 feet below the surface. The 

same fault affords a passageway for the San Pedro Springs, about 2|r miles 

to the southwest. The fault is believed to continue to the northeast and 

to cross Salado Creek about 3 miles northeast of the San Antonio Springs. 

Small springs that rise in the gravel along Salado Creek in that vicinity 

may derive their water from the Edwards limestone.

The United States Geological Survey and the Texas State Board of 

Water Engineers have carried on an extensive program of spring and stream 

discharge measurements In the Balcones fault zone and the southern part 

of the Edwards Plateau. All the large springs of the Balcones fault zone 

have been measured repeatedly, and from several of them continuous discharge records covering periods of years have been obtained.
80 CONTRIBUTIONS TO HYDROLOGY, 1936

San Antonio Springs

When first measured by the United States Geological Survey, in Decem10 

ber 1895, the San Antonio Springs had a discharge of 49 second-feet. In

November 1896 they had a discharge of 29 second-feet,, They ceased flowing 

in the later part of 1897 and were dry also during parts of 1898 and 1899. 

In September 1900 they had a discharge of 103 second-feet. The table below gives the results of several measurements of the discharge of the San 

Antonio River at Hot Wells, a short distance.below the mouth of San Pedro 

Creek.

Discharge of San Antonio River at Hot Wells

Second- Secondfeet feet

December 1897....o.... 11 June 1904.............. 61

March 1898.... . ....... 9 September 1905......... 117

June 1899.....o.o..... 10 June 1906.............. 54

September 1900........ 125 September 1910......... 18

October 1901.......... 41 November 1911.......... 16

March 1904............ 65

During about 17 years of the period between 1914 and 1935 a gaging station 

was maintained on the San Antonio River a few miles below the San Antonio 

Springs by the United States Geological Survey and the Texas Board of 

Water Engineers. The station was established October 23, 1914, at the 

Commerce Street Bridge, 3-g- miles below the springs. On February 29, 1916, 

it was moved upstream two blocks, to Presa Street, and on April 9, 1920, 

it was transferred downstream about a mile to South Alamo Street. All 

three sites are above the mouth of San Pedro Creek* The station was discontinued in November 1929 e It was reestablished at Alamo Street November 

1, 1932, and maintained in connection with the ground-water investigation 

until November 30, 1934. A supplementary gaging station was maintained 

from April 1, 1933, to November 30, 1934, a few hundred feet above the 

Josephine Street Bridge, in the north-central part of the city about ! § 

miles below the San Antonio Springs.

Both the San Antonio River and San Pedro Creek carry considerable 

storm water at times, but the periods of such inflow are ordinarily 

brief. On this account and because of the uniformity of the discharge 

of the springs it is possible to estimate with fair accuracy the amount 

of ground water represented in the gaging records. Part of the flow of

10 Taylor, T«, U., The water powers of Texas: U. S. Geol. Survey 

Water-Supply Paper 105, p. 24, 1904. Taylor, T. U., and Lamb, W. A., Surface water supply of western Gulf of Mexico and Rio Grande drainages: 

U. S. Geol. Survey Water-Supply Paper 210, p. 45, 1907.
WATER RESOURCES, SAN ANTOHIO AREA, TEX. 81

about 30 flowing wells Is emptied Into the San Antonio River between the 

springs and the lower gaging station, and this well discharge Is included 

in the gaging records. In fact, the flow of the river was maintained entirely by artesian wells for months at a time in 1918, 1928, 1929, and 

1934. The gaging station near Josephine Street is above all wells that 

contribute to the flow of the river except three belonging to the city 

that are used to fill the municipal swimming pool at the north end of 

Brackenridge Park and to maintain a stream in the park when the springs 

are not flowing. These wells were unused In the spring of 1933 but were 

used more or less regularly during the remainder of the time the Josephine 

Street station was in operation.

The estimated monthly ground-water discharge of the San Antonio 

River, consisting of the discharge of the San Antonio Springs plus inflow 

from artesian wells, from February 1, 1915, to October 31, 1929, and from 

November 1, 1932, to November 30, 1934, is given in table 1, at the end 

of this paper. This record is considered of special significance in connection with the ground-water investigation, and therefore the daily, 

monthly, and yearly discharge of the streams and the apparent relation 

of the flow to the rainfall have been carefully studied. The regimen of 

the stream is discussed at considerable length in the following paragraphs.

The measurements were started In February 1915, following a period 

of 17 months In which the precipitation at San Antonio amounted to 59,29 

Inches an accumulation of about 21 Inches above the 61-year average. 

At the beginning of the measurements the ground-water flow averaged about 

100 second-feet, and the discharge In February and March 1915 amounted to 

about 6,000 acre-feet a month. After a rainfall of 11.64 inches In April 

the ground-water discharge increased more than 50 percent, and from April 

to August it averaged about 10,500 acre-feet a month. During the 10 

months from September 1915 to June 1916 the rainfall was low, the deficiency below the average amounting to 11.70 Inches, In this period the 

discharge of the river declined steadily for 7 months, reaching a monthly 

low of about 4,600 acre-feet In March 1916. It then increased to an 

average of 5,500 acre-feet a month in April, May, and June. From July 

to September 1916 the rainfall was high, amounting to 13,33 Inches, 

This failed to increase the ground-water flow of the river, which averaged 

only about 5,000 acre-feet a month from July to September.
82 CONTRIBUTIONS TO HYDROLOGY, 1936

Prom October 1916 to March 1918 the rainfall was subnormal, the 

accumulated deficiency during the 18 months being about 21 inches. In 

the first 8 months of this period the discharge of the river declined 

gradually, and then for 10 months it remained relatively constant at a 

low stage.

Prom April 1918 to January 1919 the rainfall was above normal, the 

surplus being 7,08 inches. Nevertheless, the discharge of the river remained small and most of the time was supplied entirely from wells.

The period from April to October 1919 was the wettest 7-month period 

in the history of the Weather Bureau station at San Antonio, the precipitation amounting to 39.96 inches, of which 31.16 inches fell in June, 

July, August, and September. In the next 8 months the estimated groundwater discharge of the river amounted to about 100,000 acre-feet, the 

equivalent of a continuous flow of about 134,000,000 gallons a day, or 

more than for any other period of equal length in the 17 years covered by 

the records.

In 1920 the rainfall was more than 7 inches below normal. Nevertheless, the stage of the river remained high throughout the year, and the 

total ground-water discharge for the year was the greatest in the period 

of the record.

During the 3-|- years from January 1920 to June 1924 the rainfall 

averaged somewhat above normal, the accumulated excess being 8.18 inches, 

and most of the time the ground-water discharge remained high, the average 

being 5,600 acre-feet a month. Pronounced rises in the ground-water discharge followed rains of 5.91 inches in March 1921; 8.27 inches in September 1921; 12.84 inches in April, May, and June 1922; 3.55 inches in October 

1922; 3.24 inches in April 1923; and 8.50 inches in November and December 

1923. A rainfall of 4.59 inches.in June 1921 failed to produce a rise.

Prom July 1924 to December 1925 the rainfall was materially below 

average, the accumulated deficiency being 10.66 inches. During the first 

12 months of this period the discharge slowly but persistently declined, 

and then for 6 months it remained at a low stage. In 1926, from January 

to June, the rainfall was 8.74 inches above normal, and the ground-water 

discharge of the river increased from a monthly average of about 2,000 

acre-feet in January, February, and March to about 5,800 acre-feet in 

April, May, and June.

Prom July 1926 to April 1928 the rainfall was 10.53 inches below 

normal, and the discharge was small, the monthly average being only about
WATER RESOURCES, SAN ANTONIO AREA, TEX. 83

1,800 acre-feet, or a. little more than the average amount contributed by 

the wells.

From May 1928 to October 1929 the rainfall was about 3-J inches above 

normal, but the springs failed to respond, the discharge of the river 

averaging only about 1,000 acre-feet a month, all of which was contributed 

by wells, and the San Antonio Springs did not flow. A rainfall of 7.73 

inches in May 1929 had little effect on the stream discharge.

The gaging station was not operated from November 1929 to October 

1932. One measurement in November 1930 gave a discharge of 45 second-feet.

In the first 9 months of 1932 the rainfall was above normal, owing to 

rains in July, August, and September amounting to 21 inches. Shortly 

afterward, on November 1, 1932, the South Alamo Street station was reestablished. In November and December 1932 and the first 4 months of 

1933 the monthly average discharge of the river amounted to about 4,300 

acre-feet. The last 3 months of 1932 and the whole of 1933 constituted 

a dry period, the accumulated deficiency below normal amounting to 12.79 

inches. During this period the river discharge persistently declined, 

reaching a monthly low of 2,480 acre-feet in December 1933.

In the first 4 months of 1934 the rainfall was 4.23 inches above normal. The ground-water discharge began to increase in the later part of 

January, and during March and April the average monthly discharge was 

about 4,400 acre-feet, or a little more than it was during the corresponding months in 1933. During the last 8 months of 1934 the rainfall was 

3.97 inches below normal, the river declined rapidly in May, and from 

June until the station was discontinued, on November 30, it was supplied 

entirely from wells.

In January to April 1935 the rainfall was about normal, but in May 

and June torrential storms that were the heaviest in many years occurred, 

the precipitation amounting to 22.48 inches, or nearly 17 inches above 

normal. These rains brought the discharge of the springs to a high stage, 

and when the river was measured, on July 2, 1935, it had a flow of 165 

second-feet, or at the rate of about 10,000 acre-feet a month, practically 

all of which was ground water. This was the highest discharge since the 

fall of 1924.

The record is summarized below. The average annual ground-water 

discharge of the river (discharge of San Antonio Springs plus inflow 

from artesian wells) during,,.the 17 years of record was about 48,000 acrefeet, or about 4,000 acre-feet a month. The smallest, 11,900 acre-feet, 

occurred in 1918, and the largest, 115,500 acre-feet, in 1920. The
84 CONTRIBUTIONS TO HYDROLOGY, 1936

average annual discharge from 1915 to 1924 was about 66,300 acre-feet, 

equivalent to a continuous discharge of about 90 second-feet. The average 

annual discharge in the 5-year period 1925-29 was about 24,000 acre-feet, 

and in the 2-year period 1933-34 about 32,000 acre-feet, and the average 

for the 7 years of these two periods was about 26,000 acre-feet. However, 

the average annual rainfall from 1914 to 1924 was 27.09 inches, as compared with 25.20 inches in 1924-29 and 26.95 inches in 1932-34. The 

longest period of continuous low flow, 39 months, occurred from August 

1926 to October 1929, when the average monthly discharge amounted to 

only about 1,400 acre-feet, the equivalent of a continuous discharge of 

23 second-feet. Most of this water was supplied from artesian wells, and 

the greater part of the time the springs were not flowing. The measurements were stopped at the end of October 1929, but it is reported that 

the low flow continued until the following September, or altogether for 

50 months.

The deficiency during 1926 to 1930 is perhaps the most outstanding 

feature of the record. The rainfall in both 1928 and 1929 was materially 

-above the 61-year average, and during the 4 years 1926-29 it was slightly 

above the average. On the other hand, 1925 was particularly dry, the 

precipitation amounting to only 14.99 inches, and, as pointed out in the 

section on rainfall, there were only a few heavy rains during the 43 

months from July 1, 1924, to December 1927. Under these conditions of 

rainfall the opportunities for ground-water recharge are not good, and 

these conditions doubtless helped to keep the ground-water discharge at a 

low ebb in 1928 and 1929. It is believed, however, that the deficiency 

was intensified and the period of shortage prolonged by the heavy draft 

on the underground reservoirs through wells.

At the time this is written (July 1935) the springs are discharging 

more water than at any time since the fall of 1924, a notable recovery 

having been produced by the heavy rains in May and June.

San Pedro Springs

The San Pedro Springs were measured by the United States Geological 

Survey only a few times prior to 1916. The recorded discharge is as 

follows: December 1895, 9 second-feetj November 1896, 12 second-feet; 

September 1900, 9 second-feet; March 16, 1904, 9 second-feet. On July 20, 

1916, a gaging station was established on San Pedro Creek at Commerce 

Street, about 1-jg- miles below the springs. On March 14, 1920, this station
WATER RESOURCES, SAN ANTONIO AREA, TEX. 85

was moved downstream about three-quarters of a mile to a point a few hundred feet south of Arsenal Street. The station was discontinued in November 1929, but it was reestablished at the old site near Arsenal Street on 

November 1, 1932, and maintained in connection with the ground-water 

studies until November 50, 1934.

There is some artesian-well Inflow into San Pedro Creek between the 

springs and the Arsenal Street gaging station. According to current-meter 

measurements the pick-up from this source was 4.3 second-feet on November 

9, 1932, and 2.1 second-feet on October 24, 1933.

Table 2, at the end of the report, gives the estimated monthly groundwater discharge of San Pedro Creek at the Commerce Street and Arsenal 

Street gaging stations, representing the discharge of the springs plus the 

Inflow from wells between the springs and the gaging station. The average 

annual discharge during the 17 years of record was about 5,000 acre-feet, 

the equivalent of a continuous discharge of about 7 second-feet. The 

years of high and low discharge correspond fairly closely with the years 

of high and low discharge of the San Antonio River, but the range in the 

annual discharge is considerably smaller. The smallest amount reported 

was in 1918 and the largest in 1920. Two prolonged periods of low flow 

occurred one of 22 months from April 1917 to January 1919, in which 

the average monthly discharge was 212 acre-feet, representing an average 

flow of about 3-g- second-feet, and one of 16 months from August 1928 to 

November 1929, in which the average monthly discharge was about 220 acrefeet. It is worthy of note that the second period of minimum flow began 

nearly 2 years after the start of the prolonged low period recorded for the 

San Antonio Springs.

Salado Creek Springs

Small springs in Salado Creek, in part above the crossing of the 

San Antonio-Austin road and in part between the Austin and Rittiman 

roads, may come from the Edwards limestone. The discharge of these 

springs apparently ranges from a fraction of a second-foot to about 3 

second-feet. Available records of their flow are as follows: May 8, 

1919, 3.0 second-feet; November 14, 1932, 2.0 second-feet; December 5, 

1932, 1.4 second-feet; April 14, 1933, 1.8 second-feet; May 20, 1933, 

1.0 second-foot; July 17, 1933, 1.5 second-feet; October 23, 1933, 

1.0 second-foot; May 7, 1934, 0.9 second-foot; June 25, 1934, 1.0 secondfoot; August 28, 1934, 0.7 second-foot; October 29, 1934, 1.5 second-feet. 

It is estimated that the discharge of the springs averaged about 1.4
86 CONTRIBUTIONS TO HYDROLOGY, 1936

second-feet, or about 900,000 gallons a day, in 1933, and about 0.8 secondfoot, or about 500,000 gallons a day, in 1934. The total discharge in each 

of these years amounted to only a few hundred acre-feet, and as there is 

some uncertainty as to whether or not the water is coming from the Edwards 

limestone it is not included in the computations that follow.

Discharge from San Antonio and San Pedro Springs in 1934

In 1934 the total discharge of San Antonio River at the South Alamo 

Street bridge amounted to about 25,700 acre-feet (table l), the total discharge of San Pedro Creek near Arsenal Street amounted to about 4,070 acrefeet (table 2), and the combined discharge of the river and creek was thus 

about 29,800 acre-feet. These discharge records include a large amount of 

inflow from artesian wells between the springs and gaging station, and perhaps some inflow from the gravel along the stream during heavy rains and 

for brief periods thereafter. Table 3 gives the discharge of the river at 

the gaging station near the Josephine Street Bridge, about 1-3/4 miles below the springs. The records at this station represent much more closely 

the actual discharge of the springs than those obtained at Commerce and 

South Alamo Streets. However, they include some inflow from city-owned 

wells that are used at times to supply the municipal swimming pool in 

Brackenridge Park and to maintain the flow of the river through the park 

when the springs are very low or are not flowing. The ground-water discharge at the Josephine Street gaging station from April to December 1933 

amounted to about 17,600 acre-feet, and during the full year 1934 about 

12,200 acre-feet. Most of the water passing the station in 1933 was spring 

water, but in 1934 a part of the discharge,* roughly estimated at 2,000 acrefeet, came from wells. On this basis the discharge of the San Antonio 

Springs themselves in 1934 amounted to about 10,200 acre-feet.

It is computed that wells contributed about 1,000 acre-feet to the 

discharge of San Pedro Creek above the gaging station in 1934, and that the 

discharge of the springs themselves amounted to about 3,000 acre-feet. 

Thus-, as computed, the combined discharge of the San Antonio and San Pedro 

Springs in 1934 amounted to about 13,000 acre-feet.

Discharge from wells

The public and industrial water supplies of San Antonio and nearly all 

the water used for irrigation in Bexar County are obtained from wells in 

the Edwards limestone. Until about 50 years ago the San Antonio and San 

Pedro Springs and shallow wells in the gravel were the chief sources of
WATER RESOURCES, SAN ANTONIO AREA, TEX. 87

water supply in the area. The drilling of wells to the artesian reservoirs 

in the Edwards limestone was started in the later*part of the decade between 1880 and 1890, when several wells drilled by George W. Brackenridge

for the publip supply of San Antonio were among the first to be put down.

11 

According to Hill and Vaughan there were more than 40 artesian wells at

or near San Antonio prior to 1907, of which 30 had a reported combined

flow of 30,000,000 gallons a day. Nine of these wells are listed as be12 

longing to the San Antonio Waterworks Co. Taylor reports that prior to

1907 there were more than 100 artesian wells in Bexar County and gives a 

partial description of 68 of them. He states that some of the wells were 

among the strongest in the State.

In the course of the present investigation detailed descriptions 

were obtained of nearly all the Edwards limestone wells in the county that 

have a flow or are equipped with a power pump, together( with a fairly large 

number of farm and ranch wells, most of which are pumped with windmills. 

Altogether- about 400 wells in the county were visited, of which about 160 

are in San Antonio. The approximate discharge from most of the wells has 

been computed, either from available records or from estimates or measurements made in the field. Prom these data and from available information 

regarding the length of time the wells are allowed to flow or are pumped 

during the year, an inventory has been compiled giving the estimated total 

discharge from wells in the Edwards limestone in Bexar County in 1934, A 

summary of the inventory is given in the following paragraphs.

Public supplies.- The city operates three pumping plants, all close 

to the San Antonio River one in the southern part of Brackenridge Park, 

another in the downtown section on Market Street, and the Mission plant,

near the southern boundary of the city close to the confluence of the

13 

river and San Pedro Creek. According to Potter the average quantities

of water delivered by the city amounted to about 8,750,000 gallons a day in 

1908, and to about 13,250,000 gallons a day in 1911. The average quantities 

delivered from June 1925 to September 1934 are given in table 4, which was 

compiled from data furnished by the City Water Board. The table shows that

11 Hill, R. T., and Vaughan, T. W., Geology of the Edwards Plateau 

and Rio Grande Plain adjacent to Austin and San Antonio, Tex., with reference to the occurrence of underground waters: U. S. Geol. Survey 18th Ann. 

Rept., pt. 2, pp. 290-298, 1897.

12 Taylor, T. U., Underground waters of the Coastal Plain of Texas: 

U. S. Geol. Survey Water-Supply Paper 190, pp. 55-56, 1907.

13 Potter, Alexander, A report upon and an appraisement of the watersupply system of the city of San Antonio, Tex., pp. 32 and 48, 1912.
88 CONTRIBUTIONS TO HYDROLOGY, 1936

the average daily delivery during this period of about 9 years was about 

22,500,000 gallons, representing about 69 acre-feet a day, or about 25,000 

acre-feet a year. The largest amount was delivered in 1927, and the 

smallest in 1929.

Independent public supplies are provided by the United States Government at Port Sam Houston, Kelly Field, Duncan Field, Randolph Field, and 

Camp Normoyle and by the suburban communities Alamo Heights, Woodlawn Hills, 

South San Antonio, and San Fernando addition. Many of the San Antonio 

hotels and offices are supplied from privately owned wells. It is computed that in 1934 the water used for public supply by the city, by independent public agencies, and by the city hotels and office buildings 

averaged about 28,000,000 gallons a day, representing about 31,400 acrefeet a year.

Industrial supplies. Practically all industrial requirements for 

water in Bexar County are supplied by privately owned wells. The heaviest 

industrial demands are for water for cooling machinery and air-conditioning theaters, hotels, and office buildings at San Antonio, and a large 

part of the water used for this purpose is emptied into the San Antonio 

River or San Pedro Creek. The total supply of water from wells in the 

Edwards limestone used in 1934 for cooling and by various industries in 

the county, chiefly factories, ice plants, dairies, breweries, slaughter 

houses, and cement mills, is estimated at about 16,200 acre-feet, or 

about 14,500,000 gallons a day. Of this quantity about 10,500 acre-feet, 

or about 9,400,000 gallons a day, was emptied into the San Antonio River 

and San Pedro Creek.

Swimming pool and river supply in Brackenridge Park. It is estimated 

that about 2,000 acre-feet of well water was contributed to the San Antonio 

River in Brackenridge Park in 1934. This water was used to supply the 

municipal swimming pool and maintain a flow in the park when the springs 

were very low or not flowing.

Irrigation. Artesian water from wells has been extensively developed 

for irrigation in two areas in Bexar County one east of San Antonio 

along Salado Creek, the other in the southwestern part of the city and in 

contiguous territory south and southwest of the city limits. It is 

estimated that about 4,500 acres was irrigated from wells in these two 

areas in 1934 and that the water used for irrigation amounted to about 

20,000 acre-feet, or an average of about 18,000,000 gallons a day, if it 

had been equally distributed throughout the year. This represents about 

4.5 acre-feet to the acre. Some irrigation water is obtained from artesian
WATER RESOURCES, SAN ANTONIO AREA, TEX. 89

wells in other parts of the county, but the amount is small. Several irrigation wells of large yield obtain water from the Austin chalk, but it 

is believed that the water of most such wells has its source in the Edwards 

limestone and has moved upward through fractures into the Austin. A large 

part of the irrigated land is supplied from flowing wells, many of which 

are allowed to flow when not needed and some of which flow all the time.

Salado Creek wells. Among the notably strong flowing wells of the 

San Antonio area are two Government-owned wells and a well belonging to 

the Salado Water Co. on the Port Sam Houston reservation, adjacent to 

Salado Creek. These three wells have an average combined flow of 20 to 

22 second-feet. They empty into Salado Creek to supply stock and some 

domestic needs on farms several miles downstream. Apparently only a relatively small part of the water is utilized during most of the year. 

Measurements of the discharge of these wells from May 8, 1919, to July 2, 

1935, are given in table 5. The combined discharge of the three wells 

in 1934 amounted to about 16,000 acre-feet, or about 14,000,000 gallons 

a day.

Farm and ranch supplies. An average of about 1,500,000 gallons a 

day, or about 1,680 acre-feet a year, is used for domestic purposes and 

stock in rural communities and on the farms.

Miscellaneous wells. In the flowing-well area south and southwest 

of San Antonio there are numerous ranch wells of relatively large flow, 

a part of which are allowed to flow all the time, some of them not being 

provided with caps or valves. Some of these wells are used for irrigation 

in a small way; others are used only for domestic supply, and most of 

the discharge is emptied into the nearest stream. Most of these wells 

yield sulphur water, but a few yield fresh water. One of the fresh-water 

wells that empties into the Medina River has a flow of about 4^- secondfeet, or about 2,900,000 gallons a day. In 1934 the total volume of water 

discharged by wells of this class amounted to about 7,800 acre-feet, or 

about 7,000,000 gallons a day.

Total discharge from springs and wells in 1954

The table below gives a summary of the estimated discharge from the 

San Antonio and San Pedro Springs and from wells in the Edwards limestone 

in Bexar County in 1934. It should be remembered that some of the figures

for well discharge are based on rather rough estimates. 

4L>ori o :!« :{
90 CONTRIBUTIONS TO HYDROLOGY, 1936

Discharge in 1934 from San Antonio and San Pedro Springs and wells

Springs:

San Antonio

San Pedro

Wells:

Public supplies

Brackenridge Park 

( swimming pool and 

river supply)

Industrial supplies

Irrigation

Farm and small town supplies

Salado Creek flowing wells

Miscellaneous wells 

Total

Total 

(acre-feet)

10,200

3,000

31,400

2,000

16,200

20,000

1,680

16,000

7,800

108,280

Average 

(million 

gallons 

a day)

9.10

2.85

28.00

1.78

14.50

17.88

1.50

14.28

7.00

96.89

According to the computations and estimates in the table and paragraphs preceding it, the total discharge of water from the Edwards limestone in Bexar County in 1934 amounted to about 108,300 acre-feet, of 

which about 13,200 acre-feet came from the San Antonio and San Pedro 

Springs and the remainder from wells. Of the discharge from wells about 

12,500 acre-feet was emptied into the San Antonio River and San Pedro 

Creek, about 16,000 acre-feet was emptied into Salado Creek, and about 

66,600 acre-feet was consumed, emptied into the sewers, or otherwise 

disposed of.

It is believed that the withdrawals from wells in the county in 

1934 were not much above the average annual withdrawals during the last 

20 years. The deliveries by the city reached a peak in 1927, and the 

mean of the annual averages shown in table 4 is probably only a few 

million gallons a day above the 20-year average. During the last two 

decades some irrigation wells have been abandoned, and new wells have 

been put down, but the net change has not been very great. There has 

been considerable increase in recent years in the use of water for industrial purposes, especially for cooling theaters and office buildings, 

but most of this water is later emptied into the San Antonio River and
WATER RESOURCES, SAN ANTONIO AREA, TEX. 91

San Pedro Creek and taken into account in the estimates of the ground-water 

discharge of these streams given in tables 1 and 2.

It is estimated from all the available data that during the last 20 

years an average of around 120,000 acre-feet a year, or 107,000,000 gallons 

a day, was discharged from the San Antonio and San Pedro Springs and from 

Edwards limestone wells in Bexar County, of which 45,000 to 50,000 acrefeet passed the gaging stations on San Antonio River and San Pedro Creek, 

and 70,000 to 75,000 acre-feet was discharged by Edwards limestone wells 

exclusive of those that empty into the river and creek above the gaging 

stations. In reaching these figures tables 1 and 2 were largely used as a 

basis for computation, and it was estimated that during the period the 

average annual discharge from wells, exclusive of those that empty into 

the river and creek, was about 90 percent of the discharge from such wells 

in 1934.

Waste from wells

The investigation has shown that large quantities of water from wells 

in the Edwards limestone are wasted in the San Antonio area, chiefly from 

flowing wells. Much of the well water that is used for cooling is used 

inefficiently or wasted. The water could be aerated and used over and 

over again instead of being emptied into the streams or sewers after one 

cooling operation. Moreover, many wells of this class are allowed to flow 

continuously. When the San Antonio Springs are not flowing or have a very 

small discharge water emptied into the river from the wells serves a useful purpose, because it helps to maintain a flow in the river in the 

central and southern parts of the city. However, the discharge of the 

wells and the amount emptied into the river tend to be the greatest 

when the artesian pressures are. high and the discharge from the San Antonio Springs is at high stages. Many of the irrigation wells are allowed 

to flow when they are not needed, and some of them flow all the time. 

Relatively large quantities of water are wasted from flowing ranch wells 

in the area south and southwest of San Antonio, mostly from wells that 

discharge highly mineralized water impregnated with hydrogen sulphide. 

(The normal Edwards water and the highly mineralized water come from the same 

reservoir, and the common supply is depleted to an equal extent by the 

withdrawal of water of either type.) The water discharged by the three 

wells of very large flow on Salado Creek near Port Sam Houston is largely 

wasted.
92 CONTRIBUTIONS TO HYDROLOGY, 1936

The total quantity of well water that is wasted each year probably 

amounts to at least one-third of the total annual discharge from wells.

Fluctuation in artesian pressure

Without doubt the artesian pressure in the Edwards limestone reservoir in this locality has always fluctuated within fairly wide limits. 

In the outcrop area of the formation water in great quantities is absorbed 

during heavy rains, the water table rises promptly, and the effect of this 

rise is quickly transmitted by hydraulic pressure many miles down the dip 0 

A sudden rise in the artesian wells follows, and the springs begin to flow, 

or, if already flowing, the discharge increases. After the rise the 

artesian pressure usually begins to decline,, If the interval between rains 

is long the pressure declines materially, and as it declines the flow of 

the springs decreases. The San Antonio Springs cease to flow when the 

altitude of the static water levels in neighboring wells falls below 

about 668 feet. During recent years the springs have been inactive a 

considerable part of the time. Some of the residents of San Antonio believe that in the past when there were no artesian wells or the number of

wells was comparatively small the springs never stopped flowing,, This

14 

belief is not in accord with the records. Taylor states that about

1895 the San Antonio River began to fail and that by the later part of 

1897 it had entirely ceased north of the city. He gives the following 

figures (see p 0 93) showing fluctuations in artesian pressure as disclosed 

by height of water in standpipes at the waterworks plant on Market Street 

and at the former upper power house in Brackenridge Park a short distance 

below the San Antonio Springs. These records show a range in head of 

15.5 feet at Market Street between 1893 and 1900 and a total rise in head 

of 16.9 feet at the upper power house between January 1 and May 24, 1900.

It is reported that in 1900 the flow of the river regained its former vol15 

ume. This is not surprising in view of the increase in artesian pressure

indicated by these records.

14 Taylor, T. U., The water powers of Texas: U. S. Geol. Survey 

Water-Supply Paper 105, pp. 23-25, 1904.

15 Taylor, T. U., and Lamb, W. A., Surface water supply of western 

Gulf of Mexico and Rio Grande drainages: U. S. Geol. Survey Water-Supply 

Paper 210, p. 45, 1906.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 

Artesian head in city wells, in feet above the pumps

93

Market

Date

May 1893

December 1897

April 1898

April 29, 1900

May 1, 1900

May 5, 1900

May 9, 1900

May 22, 1900

Street

Artesian 

head

42.10

33.80

31.60

43.00

44.10

45.10

46.20

47.10

Brackenridge

Date (1900)

January 1

February 1

March 1

April 1

May 1

May 24

June 1

July 1

August 1

September 8

October 1

November 1

December 1

Park

Artesian 

head

1.80

6.76

13.76

13.77

15.57

18.74

17.99

14.65

12.76

12.10

11.47

11.38

10.51

On January 15, 1911, the city water department began to keep a record 

of the artesian pressure at the Brackenridge pumping plant, by reading the 

water level below an ell at the top of a well just west of the old plant. 

Measurements were discontinued at this well on March 1, 1930. Since then 

the pressure at midnight on the intake header to the pumping plant has 

been recorded nearly every day. The draw-down at that hour is relatively 

small. Also, since 1922 the city water department has taken one or more 

pressure readings each year on a well at the Mission pumping plant.

In connection with the present investigation a continuous recording 

gage has been maintained since November 11, 1932, on an unused well belonging to the Beverly Lodges, ^uat north of Port Sam Houston. This well 

is somewhat remotely located from any pumping of consequence, and the graph 

drawn by the gage is an accurate record of changes in artesian pressures 

over a wide area. During the investigation periodic measurements have been 

made to determine fluctuations in artesian pressure in about 40 selected 

wells spaced over a large part of Bexar County and eastern Medina County. 

This is done by measuring with a steel tape the depth to the water surface 

below a fixed measuring point, or in flowing wells by taking the pressure 

at a fixed point. The altitudes of the measuring points on all the wells
94 CONTRIBUTIONS TO HYDROLOGY, 1936

T1VJNIVH IVflNNV

o o o ,-.

* to <M 2 O

o <" oo to

o> oo i»- to m ' 

to to to to to

13A3T V3S

3Aoav sannnv

"T1VJNIVH AIHINOW

have been determined by leveling 

and in this way the measurements 

are referred to sea level. The 

observation wells include two in 

eastern Medina County that were 

measured in February 1930, in connection with the investigation of 

the ground waters of Uvalde and 

Medina Counties. One of these 

wells is 3 miles east of Castroville, and the other at Lacoste. 

Measurements were started in the 

fall of 1932 on several wells 

located mostly in two lines leading out from San Antonio one 

line to the northwest and the 

other to the northeast. During 

August and September 1933 more 

observation wells were selected, 

and since then other wells have 

been added as the need for them 

became apparent. Since the fall 

of 1933 the measurements have 

been made nearly every month.

Fluctuations at Brackenridge 

pumping plant

The records of artesian 

pressure obtained at the Brackenridge pumping plant have been 

referred to a common datum, and the 

altitude to which the artesian water 

would rise is indicated graphically 

in figure 7. The diagram shows that 

during the period of record the 

artesian pressure at San Antonio 

varied a great deal. The lowest 

water level, about 651 feet above 

sea level, was recorded during 

the summer of 1913, after the
WATER RESOURCES, SAN ANTONIO AREA, TEX. 95

longest period of subnormal precipitation In the history of the Weather 

Bureau station at San Antonio. (See p. 65.) The highest, about 689 feet, 

was recorded In October 1919, after several months In which the rainfall 

was the highest on record, and again in July 1921, The artesian pressure 

in the later part of the summer of 1913, according to officials of the 

water department, was the lowest recorded since the city began to pump 

water from wells, 40 to 50 years ago. After heavy rains in September and 

October 1913, however, the water level rose about 27 feet, to 678 feet, 

by the end of the year. After some irregularity in 1915, it declined 

through 1916 and 1917 and reached a low of 661 feet during the late summer 

of 1918. The peaks of 689 feet in 1919 and 1921 were followed by a low 

point of 656 feet in 1923. A level of 680 feet was reached in the summer of 1924, however, and this was not again attained until June 1935. 

The low level of 653 feet, within 2 feet of the minimum of 1913, was 

reached in the summer of 1930.

In general the periods of high and low pressure agree closely with 

periods of high and low flow of the San Antonio Springs, and sudden rises 

in pressure synchronize with sudden increases in the discharge of the 

springs. Some disagreement is noted, particularly during short-time 

peaks or decreases in pressure. This may be due in considerable part to 

the effect on the pressure record of fluctuations in the volume of pumpage 

in the immediate vicinity of the gage.

Fluctuation in well at Beverly Lodges

The record obtained by the recording gage on the well at the Beverly 

Lodges shows that the water level is practically never still. (See figure 8,) The water has a high and low level each day, corresponding inversely with the high and low hourly rate of pumpage in the San Antonio 

area. During the periods of heavy pumping in the summer the fluctuations 

amount to about 1 foot, but during the winter, when the total daily pumpage is less than in summer, there is not so much variation in the hourly 

rate of pumpage and the diurnal fluctuations amount to about 0,3 foot. 

As a general rule the highest level is reached about 5 o'clock In the 

morning in summer and about 8 o'clock in winter, and the lowest from 

7 to 8 o'clock in the evening in summer and from noon until 4 o'clock In 

winter. Regular weekly fluctuations also occur. The water level usually 

rises somewhat with the week-end decline in the rate of pumping and falls 

gradually during the week. There is frequently a sudden rise of o to 9
668

667

666

665

674

672

671

670

669

668

APRIL 

18 19 20 21 22 23 24 25 26 27 28 29 30

A

wA/ 'V

f\s/^^^^

^\^-//-\

\^S' V_/"V' \-^sr\^'t

^_ __ s

s\^

MAY 

1 2 3

^^^

^^-

MAY 

4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19

^V/^

-/-r^

s\S^\ *>

 -A4^-

f^*~^r^r~>' \ *^.^V t^./^S

/

/

/.

^

, FIGURE 8.-HYDROGRAPH OF THE BEVERLY LODGES WELL, SAN ANTONIO, TEXAS, SHOWING RISE OF WATER LEVEL FOLLOWING

HEAVY RAINS IN APRIL AND MAY 1935.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 97

Inches after heavy local showers in San Antonio, due apparently to a sudden decrease in the rate of pumpage. The water level normally rises 

slowly during the fall and winter and declines during the spring and summer. These seasonal fluctuations are clearly due to seasonal changes in 

the draft on the wells. Finally and most significantly of all, the water 

levels are an index of recharge to the underground reservoir. Several 

pronounced rises that occurred during the period of record were plainly 

due to recharge from heavy rains that fell north of San Antonio.

Some of the more important details of the record from November 11, 

1932, to June 8, 1935, as recorded by the gage at Beverly Lodges are given 

below.

During the winter and spring of 1932-33, in addition to minor fluctuations, there was a net rise amounting to about 1 foot to an average 

level of about 676 feet. Beginning with the increased pumpage during 

the early summer the level declined persistently, reaching about 671 feet 

on July 28, 1933. On July 29 and 30 there was a rise of about 1 foot. 

There were small rises of less than 1 foot on August 15, 24, 30, September 16, 23-26, 1933, and January 17 to February 3, 1934, and after each 

small rise there was a steady decline. All these small fluctuations were 

probably due to temporary changes in the rate of pumping from wells in 

San Antonio.

The period from November 1932 to December 1933 was one of extremely 

low rainfall, the accumulated deficiency at San Antonio during the 14 

months being 11.14 inches. The first subsequent rises that can be correlated with the rainfall occurred with a precipitation at San Antonio 

of 0.12 inch on February 28, 1934, and with one of 1.55 inches on March 1, 

1934. The water level began to rise rapidly about noon on February 28 

from an altitude of 672.5 feet and reached 674.7 feet by noon March 5. The 

next rise, amounting to 2.1 feet, occurred April 4 to 9 and was apparently 

due to rains on April 4, 5, and 6 of 0.54, 1.08, and 0.92 inches, respectively, at San Antonio. In the period from July 25 to August 2 rains 

occurred amounting to 4.33 inches at San Antonio and 5.30 inches at 

Boerne. These rains were accompanied by a sharp rise in the water level 

in the well, beginning at an altitude of 666.8 feet at noon on July 25 

and reaching 670.8 feet on August 5. From August 1934 to the middle of February 1935 the water level fluctuated a little under 670 feet. During the 

later part of February, March, and the early part of April 1934 there 

was a general decline.
98 CONTRIBUTIONS TO HYDROLOGY, 1936

The period from April 19 to June 15, 1935, was one of the wettest on 

record, the total precipitation at San Antonio amounting to about 24 inches. 

Most of the rain fell in seven storms, as follows: April 19, 1.36 inches; 

April 24, 0.52 inch; May 2 to 5, 3.16 inches; May 9 and 10, 6.11 inches; 

May 18 and 19, 1.58 inches; May 28 and 29, 1.86 inches; June 9 to 15, 7.37 

inches. The hydrograph recorded by the gage from April 19 to May 19 shows 

that each of the heavy rains was accompanied or quickly followed by a 

sharp rise in the water level in the well, and that the net gain during 

the month amounted to about 8-J feet (fig. 8). The times and amounts of 

the principal rises.were as follows: April 19 to 21, about 0.75 foot; 

April 26 to May 3, about 0.9 foot; May 4 to 6, about 2 feet; May 10 to 12, 

about 1-| feet; May 16 to 19, about 3-g- feet. A gain of even greater magnitude occurred in June, but the graph is not available, having been 

destroyed by field mice. On June 25 the water level stood at an altitude 

of 685.16 feet as determined by a measurement with a steel tape. The 

total rise from April 19 to June 25 amounted to about 19 feet, and at the 

time of the last measurement the water had reached a level about 10 feet 

above the level at the start of the record, in November 1932.

Fluctuations in miscellaneous observation wells

A study of the records of miscellaneous measurements shows that the 

fluctuations in artesian pressure throughout the area are in close agreement most of the time and that the graph of the recording gage on the well 

at Beverly Lodges gives an accurate picture of the major fluctuation features. The remarkable uniformity that attends the rise and fall of pressure 

both in time of occurrence and in magnitude, is shown by the records of 

measurements in 12 of the observatioji wells from April 20 to October 11, 

1934. These wells are located along a line (CC 1 on map) about 40 miles 

long, extending northeastward from the vicinity of Castroville to San 

Antonio and thence to and beyond Wetmore. The results of the observations 

on these wells during the period are given in table 6 and are shown graphically in figure 9. The lines in the figure represent the altitude of the 

water surface in the wells at different times. The position of the wells 

as shown represents to scale their air-line distances from the Bexar County 

courthouse. The outstanding feature of this record is the remarkable uniformity in the rise and fall in pressure along the entire 40-mile line. 

During the greater part of the period the movement was continuously downward, the total decline being greatest in wells 1 to 4, 20 to 12 miles
WATER RESOURCES, SAN ANTONIO AREA, TEX.

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southwest of San Antonio, and least in 

wells 11 and 12, at the northeast extremity of the line, near Wetmore. Between the measurements of June 21 and 

July 31 a general rise occurred in all 

the wells measured except wel*. 12 the 

greatest rise was in wells 4 and 5, and 

the least in well 11. The pressure in 

well 12 declined between the two measurements. According to the recording gage 

at the Beverly Lodges the rise began about 

noon on July 25 and had reached a point 

within 0.2 or 0.3 foot of the maximum on 

July 31.

Of all the observation wells (see 

table 7), two near the Medina-Bexar 

County line have shown the greatest 

fluctuations in artesian head during the 

full period of record. One of these wells 

is 6 miles southeast of the Medina dam and 

belongs to Alfred Bourquin; the other is 

8-J miles southeast of the dam and belongs 

to Mrs. Kate Benke. In the Bourquin well 

the water level rose about 11 feet between 

January 9 and April 20, 1934, 7 feet oetween June 21 and July 31, 1934, 34 feet 

between April 9 and May 21, 1935, and 32 

feet between May 21 and June 28, 1935. 

In the Benke well the total rise amounted 

to 12^ feet between the June and July 

measurements in 1934 and to about 90 feet 

between the April and June measurements 

in 1935. In both wells each pronounced 

rise was followed by a sharp decline. 

Such fluctuations usually occur in or 

near areas of very heavy ground-water 

recharge.

(0 ID ID tD ID ID

13A31 V3S 3AOBW 3QnilllV
100 CONTRIBUTIONS TO HYDROLOGY, 1936

The artesian pressures increased greatly in nearly all the observation 

wells between the measurements of April and June 1935, the average rise 

amounting to about 20 feet. In four observation wells between the Bourquin 

and Benke wells and San Antonio the average rise amounted to about 25 feet. 

The Beverly Lodges well, near Port Sam Houston, northeast of San Antonio, 

displayed a rise of 19 feet. Wells 1 to 6 along the line CC» (see map), 

southwest of San Antonio, had rises ranging from 26 feet in well 1, at the 

west end of the line, down to 19 feet in well 6, near San Antonio. The 

observation wells northeast of San Antonio had the smallest gain, the rise 

ranging downward from 19 feet near San Antonio to 15 feet in well 12, at 

the northeast end of the line.

The records of artesian pressure therefore afford good evidence that 

heavy recharge to the underground reservoir comes from outcrop areas northwest of San Antonio, in the direction of Medina Lake.

Artesian-pressure gradients and movement of ground water

The direction in which water is moving in an underground reservoir 

can be determined if the shape of the water table or the direction of the 

artesian-pressure gradients is known. In an underground reservoir in a 

fairly homogeneous sand, sandstone, or gravel the direction and amount of 

slope in artesian head can usually be accurately mapped from a moderate 

number of observation wells. It is much more difficult to map the pressure 

gradients in such a formation as the Edwards limestone, in which there is 

very little uniformity in the transmission capacity of the formation from 

place to place. The openings in the Edwards vary in size from caverns 

in which the movement of water is almost as free as it is in a river and 

involves little loss in hydraulic head down to minute Joints and cracks 

in which the movement is resisted by great friction and is attended by 

large loss in head. To make an accurate artesian-pressure map under these 

circumstances a very large number of observation wells is required. In 

the vicinity of San Antonio wells in the Edwards limestone are closely 

spaced, but in most of the remainder of Bexar County and in Medina and 

Comal Counties they are rather widely separated.

During the summer of 1934 levels were run to connect many wells in the 

Edwards limestone throughout Bexar County, and the altitude of reference 

points at the surface of the wells was determined. In October 1934, within 

a period of a few days, the distance of the water level above or below 

these reference points was measured. During the same period the altitude
WATER RESOURCES, SAN ANTONIO AREA, TEX. 101

of the water levels In several wells In Uvalde and Medina Counties was 

determined. Prom these data lines of equal artesian pressure have been 

drawn and are shown on the map. The lines are more nearly accurate for 

the vicinity of San Antonio than for some other parts of the area covered, 

where they may show only the major trends in artesian gradients.

The data indicate that in October 1934 the altitude of the artesianpressure surface in the vicinity of the Edwards outcrop on the Frio River 

In Uvalde County was about 1,000 feet, in the vicinity of the outcrop on 

the Hondo River about 800 feet, in the vicinity of the outcrop on the 

Medina River over 740 feet, in the vicinity of San Antonio about 665 feet, 

and in the vicinity of the Comal Springs, at New Braunfels, about 625 feet. 

The differences in artesian pressure are therefore sufficient to cause 

water to move toward San Antonio from three known points of heavy intake 

to the west and northwest (see pp. 75-77) and from San Antonio toward the 

Comal Springs.

The area of relatively high artesian pressure in the vicinity of the 

outcrop on the Medina River indicates that the recharge in that area is 

heavy and supports the conclusions reached from measurement of the fluctuation of water levels that this is among the principal recharge areas to 

the Edwards limestone. It is believed that the water follows a somewhat 

tortuous course, entering the formation along the Medina River and moving 

down the dip to the large fault that passes near Quihl. The movement of 

the water down the dip Is halted by the fault, which in this area is of 

sufficient throw to bring the Edwards limestone opposite a relatively Impermeable formation of Upper Cretaceous age. The water therefore moves 

toward the northeast along the fault to the vicinity of the Benke and 

Bourquin wells, where the throw is less than the thickness of the Edwards. 

There the water passes across the fault into the downthrown portion of the 

Edwards and joins the main body of water in that part of the formation.

The relation of the Hondo Creek, Frio River, and Sabinal River areas 

to the San Antonio district is not so clearly established as that of the 

area along the Medina River. The contours in Medina County, as shown on 

the map, have a general east-west trend and indicate that the general 

direction of movement of the artesian water is toward the south. However, 

practically no surface outlet for the water in that direction is available, 

and there Is reason to believe that there Is no large submarine outlet. 

It seems likely that the largest and best-defined solution channels follow 

the fault lines, which also in general have east-west trends, and that the
102 CONTRIBUTIONS TO HYDROLOGY, 1936

water moves through these channels in large volume to the east or west or 

In both directions with but little loss of head. If this theory Is correct the pressure contours are farther apart and actually have north-south 

trends where they cross these major solution channels, but such trends are 

not revealed by the records of the widely spaced observation wells.

The magnitude of the faulting In the vicinity of Helotes Is sufficient 

to offset the Edwards limestone completely and apparently to prevent the 

movement of ground water across the fault. In the large area north and 

northeast of San Antonio where the Edwards limestone crops out the faulting 

Is not sufficient to affect the movement of the ground water appreciably. 

This outcrop area probably contributes water to the Edwards limestone In 

the eastern part of the county and may contribute water to western Comal 

County and ultimately to Comal Springs. Some ground water may also reach 

Comal Springs from the vicinity of San Antonio by a relatively narrow and 

tortuous course through the highly faulted area along Cibolo Creek north 

of Bracken. It is believed that not much water Is lost from the San 

Antonio area In this way, but the available evidence Is not conclusive, and 

the subject Is to be given further study.

Safe yield of reservoir

The Edwards limestone underlies all of Bexar County from the outcrop 

south (see map), but in the greater part of the southern third of the 

county it lies too deep to be reached economically by water wells, and the 

water in the formation is highly mineralized. The area in which the formation contains water suitable for most purposes is a belt that extends 

across the county, averaging about 15 miles in width and covering about 

500 square miles. If In this belt the Edwards limestone contains a volume 

of gravity water equal to only 2 percent of its own volume, the supply In 

storage in the limestone beneath Bexar County amounts to about 6,000 acrefeet for each foot of thickness of the formation. If the formation has an 

average thickness of 500 feet its total storage amounts to about 3,000,000 

acre-feet, or about 23 times the estimated combined average yearly discharge 

of the springs and wells during the last 20 years (pp. 89-91). Most of this 

stored water could not be withdrawn, however, without causing excessive 

lowering of the water levels In the wells.

The highly mineralized character of the water In the Edwards limestone 

in the southern part of Bexar County indicates that there is not much movement of water down the dip. Probably, therefore, the wells and the San
WATER RESOURCES, SAN ANTONIO AREA, TEX. 103

Antonio and San Pedro Springs are the only outlets of much consequence from 

the artesian reservoir under Bexar County, and before wells were put down 

the springs were almost the only outlets. During the last 20 years the 

mean rainfall has been about equal to the 61-year average recorded at San 

Antonio. The artesian pressures in June 1935 were apparently about as high 

as they were in 1915, and therefore there has not been much change in reservoir storage. It is assumed that during this period no water moved out of 

the area and that ground-water discharge occurred entirely through the San 

Antonio and San Pedro Springs and through wells. The average combined annual discharge of the springs and wells during the 20 years is estimated at 

about 120,000 acre-feet (p. 91). This figure, therefore, is believed to 

represent a rough approximation of the minimum future yield of the underground reservoir.

If the assumption is true that there is little movement of water 

underground from the San Antonio area, it is clear that the unutilized 

water of the springs and artesian wells must be put to beneficial use if 

an additional demand for water supplies of large magnitude is to be met. 

It is practically impossible to predict the amount of salvage that can be 

accomplished. It is believed that the normal discharge of the springs 

has already been materially redu'ced by withdrawals from wells, as indicated 

by the fact that the artesian pressure remained low and the springs 

quiescent a large part of the time from 1926 to 1930, a period of about 

average rainfall. Further lowering of the artesian pressures will result 

in further reductions in the discharge of the springs. Probably not all 

the spring water can be salvaged, but a large part of it can be. If in 

the spring of 1935 the artesian water levels at San Antonio had been about 

17 feet lower than they were, the springs would not have started to flow 

in response even to the unusually heavy rains of May and June. It is not 

impossible that the springs could be brought entirely under control by 

impounding water above them by means of a low dam at the extreme north 

end of Brackenridge Park. If this is done and the flow of the springs 

is stopped, the artesian pressure in the underground reservoir would be 

increased somewhat, and this might cause the water to escape to the surface somewhere else. The plan is believed to merit serious consideration, 

however, and it ia recommended for careful study.
104 CONTRIBUTIONS TO HYDROLOGY, 1936

Quality of the water

The water from the Edwards limestone in the greater part of San 

Antonio and in the area to the northeast, north, and west is almost uniformly a calcium carbonate water of good quality, although somewhat hard. 

Most of the 43 Edwards limestone wells that were sampled in that area 

yield water having between 200 and 270 parts per million of hardness, and 

none yield water having more than 300 parts per million. As a rule the 

water contains less than 30 parts per million of sulphate and less than 

20 parts per million of chloride. A few of the wells in that part of the 

area, however, representing only a small proportion of the Edwards wells, 

yield waters moderately high in calcium sulphate.

South of the fault that passes through the southern part of San 

Antonio the water from Edwards limestone wells is highly mineralized, containing at least 4,000 parts per million of dissolved solids. In this area 

the water contains large amounts of calcium and magnesium sulphate and 

sodium chloride. It is in general strongly impregnated with hydrogen 

sulphide and gives off a disagreeable odor. The line of demarcation between the normal Edwards water north of the fault and the highly mineralized water south of the fault is so sharp as to suggest that the fault 

retards free circulation of the water from the north to the south side and 

that this lack of circulation has been the chief cause of the high mineralization of the water south of the fault. The approximate location of 

the boundary between the normal and highly mineralized Edwards waters is 

shown on the map by the line DD'.

CONCLUSIONS

The springs and artesian wells of the San Antonio area have their 

source in a common reservoir in the Edwards limestone. This reservoir is 

fed by seepage from streams and by direct penetration of rainfall on the 

outcrop of the limestone along the Balcones escarpment, which crosses the 

northern parts of Bexar and Medina Counties and extends a long distance 

farther both east and west. Opportunities for ground-water recharge on 

this outcrop are exceptionally good. In many places on the outcrop the 

limestone is honeycombed or cavernous. Water in large quantities sinks 

into these openings to a water table and then moves down the dip under 

cover into the artesian reservoir. Recharge occurs during heavy rains by 

direct penetration and by seepage from storm-water run-off. Additional, 

practically continuous recharge is furnished by the numerous spring-fed
WATER RESOURCES, SAN ANTONIO AREA, TEX. 105

streams of the Edwards Plateau that cross the outcrop. The reservoir, 

therefore, not only has its own storage facilities but also receives the 

benefits of the storage and regulation afforded by the underground reservoir system of the Edwards Plateau.

Water moves underground to the San Antonio area from areas of intake 

on the outcrop at least as far west as the Medina River and perhaps much 

farther west. It is believed that very little water escapes underground 

down the dip toward the Gulf. Some water probably moves out of the area 

toward the northeast along the strike of the formation and eventually 

appears in the Comal Springs, but the volume is believed to be relatively 

small. Accordingly, it is concluded that before the artesian wells were 

put down the San Antonio and San Pedro Springs were the only large outlets 

of the underground reservoir, and the average annual recharge to the reservoir was nearly balanced by the average annual discharge of the springs; 

also that since the well development began the discharge has been divided 

between the springs and artesian wells, and the flow of the springs has 

been lessened by an amount approximately equal to the withdrawals from 

wells. The wells are valuable in making the water supply more accessible 

where it is needed, but it is believed that they have not materially increased the average annual yield of the underground reservoir.

The relation between recharge of an artesian reservoir and discharge 

from it are indicated by the fluctuations in the artesian pressure. If 

water is coining into the reservoir faster than it is moving out the pressure rises. If the opposite is true, the pressure drops. If the draft 

on tiie reservoir is very heavy the decline in pressure is likely to be 

large, and if the safe limit of withdrawals is exceeded the decline is 

likely to continue persistently until the artesian wells stop flowing, 

and the water levels may finally drop so low that it is no longer practicable to pump.

The record of artesian pressures in the San Antonio area is reassuring, as it shows clearly that there has at no time been any longcontinued overdraft approaching dangerous depletion. The community 

owes the security of its water supply to natural conditions (1) a 

large water supply; (2) a large underground reservoir; (3) an automatic 

control over the discharge of the springs afforded by the artesian pressures. Thus the flow of both groups of springs varies with the pressures, 

and the flow of the San Antonio Springs stops when the artesian head declines to about 668 feet with reference to sea level. 

42071 O 36 4
106 CONTRIBUTIONS TO HTDROLOGY, 1956

It Is estimated that In the 20-year period from 1915 to 1955 the 

yield of the underground reservoir averaged about 120,000 acre-feet a 

year, or about 107,000,000 gallons a day. The artesian pressures were 

about as high in the summer of 1955 as in 1915, showing that there has 

been no material net decrease in the storage in the reservoir during this 

period. The average annual rainfall during the 20-year period was about 

equal to the 61-year mean. Therefore, it is reasonable to expect that 

unless the streams are regulated in a manner that will decrease recharge 

or unless the climate changes toward greater aridity, the reservoir will 

continue to yield about as much as it did between 1915 and 1955. If any 

considerable body of water is escaping from the San Antonio area to the 

Comal Springs, further well development will tend to divert this water 

from the springs and thereby to increase the future yield of the reservoir in the San Antonio area. If in the future power or irrigation 

projects are constructed that will provide for the elimination of the 

present large seepage losses into the Edwards reservoir from the streams 

that now contribute heavily to recharge, the yield of the underground 

reservoir 3,n the San Antonio area will undoubtedly be greatly reduced.

If the draft from wells in the San Antonio area is materially increased, the artesian pressures will fall lower than heretofore, some of 

the flowing wells in the upper part of the basin will stop flowing, and 

the flow of the other wells will be reduced. Meanwhile, however, the discharge of the springs will be reduced, and the San Antonio Springs will 

be quiescent during longer periods than otherwise, and this reduction in 

spring flow will tend to conserve water that would otherwise go to waste, 

especially during high stages of the springs. Thus increased beneficial 

use of the water supply obtained from wells will to a great extent be 

balanced by the conservation at the springs. Waste from the flowing wells 

can be stopped if the wells are closed by a valve or cap when they are 

not in use.

The outstanding conclusions are, first, the underground water resources of the San Antonio area are very large; second, the withdrawals 

from the underground reservoir by wells can be materially increased with 

safety; third, without increasing the draft by wells, much more water can 

be put to beneficial use than now, if the waste is stopped and the water 

used with reasonable economy. It should be possible, for example, to irrigate an area several times the size of that now irrigated in the San 

Antonio district with the water that is now wasted in a variety of ways.
WATER RESOURCES, SAN ANTONIO AREA, TEX. 107

Well water is not considered wasted that is discharged into the San Antonio 

River to maintain an adequate flow at times -when the San Antonio Springs 

do not flow or have a very small flow. It is unthinkable that the beauty 

of the river should not "be perpetuated.
CONTRIBUTIONS TO HYDROLOGY, 1936

Table 1. - Estimated monthly ground-water discharge of San Antonio River 

at San Antonio, Tex., 1915 to 1934, In acre-feet

Feb. Mar. Apr. Hay July Aug. Sept. Oct. Nov. Dec.

1915

1916

1917

1918

1919

1920

1921

1922

1923

1924

1925

1926

1927

1928

1929

1930

1931

1932

1933

1934

5,700

4,850

1,440

l)230 2)060 l)880 2)390 2)710 2,720 5,260 5,510

15,000 12,400 12,500 10,800 10,200 9,400 8,790 8,220

6,700 5,460 7,800 6,940 6,050 5,700 5,210 4,250

4,610 3,530 3,830 6,010 6,070 6,600 5,430 4,730

3,450 3,670 4,020 4,690 4,100 3,250 2,900 1,940

8,100 7,600 9,800 9,900 11,100 11,700 10,200 8,110

8,090 7,130 6,070 5,780 98,000+

4,970 5,090 4,820 4,980 61,660

1,400 1,470 1,380 1,460 27,490

830 660 540 550 11,910

6,830 13,000 13,600 12,600 69,790

7,320 7,270 6,840 6,820 115,560

7,500 6,620 5,850 4,940 73,020

4,040 3,650 4,260 4,480 57,240

2,960 3,260 4,350 8,000 46,590

7,230 7,020 5,580 5,540 101,880

1,650 1,800 1,940 1,850 32,590

2,200 2,150 2,110 2,250 39,370

1,320 1,540 1,340 1,240 20,770

960 1,000 850 760 12,710

1,450 1,800 (*) ..... »*14,000

4,340 3,610 4,530 4,380 3,780 3,050 2,290 2,500

2,800 3,170 4,580 4,220 2,560 1,190 1,270 1,730

..... ..... 4,570 4,700 ......

2,870 2,820 2,360 2,480 39,010

1,070 1,090 990 **930 25,700

* Gaging station discontinued. ** Estimated.

Table 2. - Estimated monthly ground-water discharge of San Pedro Creek at

gaging station on Commerce and Arsenal Streets, San Antonio, Tex., 

1915 to 1934, In acre-feet

Year

1917

1918

1919

1920

1921

1922

1923

1924

1925

1926

1927

1928

1929

1931

1932

1933

1934

Jan.

820

230

260

730

540

480

470

524

460

430

340

310

280

450

460

Feb.

660

250

320

790

500

490

420

480

420

420

320

300

200

420

420

Mar.

330

270

320

810

540

450

340

700

410

470

400

280

250

480

440

Apr.

270

180

380

860

490

520

450

920

420

580

390

270

240

560

360

May

290

250

450

830

500

610

430

1,260

400

880

450

320

260

560

390

June

290

230

510

660

480

600

310

1,000

360

630

480

360

220

300

300

July

190

210

570

600

480

570

410

700

360

570

380

270

300

380

310

Aug.

170

180

790

600

400

510

340

670

390

460

330

170

260

320

320

Sept.

150

180

590

510

280

460

400

590

490

480

280

170

220

310

250

Oct.

180

180

1,050

680

600

460

420

360

420

420

320

200

210

330

280

Nov.

200

220

1,000

700

460

500

440

510

400

400

290

170

230

450

400

270

Dec.

490

180

110

900

560

490

470

420

460

390

370

350

200

*230

470

380

*270

Total

3,730

2,490

7,140

8,330

5,760

6,120

4,850

8,174

4,920

6,110

4,330

3,020

2,900

4,890

4,070

* Estimated.

Table 3. - Monthly discharge of San Antonio River at Josephine Street gaging 

station, San Antonio, Tex., April 1933 to November 1934, in acrefeet

Month

1933

April

May

June

July

August

September

October

November

December

Total

3,530

2,800

2,420

1,670

1,640

1,780

1,520

1,110

1,250

Storm 

water

.....

 .

70

50

20

.....

.....

Ground 

water

3,530

2,800

2,420

1,600

1,590

1,760

1,520

1,110

1,250

Month

1934

January

February

March

April

May

June

July

August

September

October

November

Total

1,720

1,700

2,420

3,340

1,700

494

547

486

292

307

280

Storm 

water

280

.....

S30

630

.....

.....

140

 0 ...

.....

.....

20

Ground 

water

1,440

1,700

2,190

2,710

1,700

494

407

486

29S

307

260
WATER RESOURCES, SAN ANTONIO AREA, TEX.

Table 4. - Average quantities of water delivered by the city of San 

Antonio, 1925-1934, in millions of gallons a day

illion gallons a day : about 3.07 acre-feet a day r about 1.65 second-feet/

Well 

No.

1

2

3

4

5

6

7

8

9

10

11

12

Month

January

February

March

April

May

June

July

August

September

October

November

December 

Average

Table

Date

May 8, 1919

Nov. 14, 1932

Dec. B, 1932

Jan. 14, 1933

Apr. 14, 1933

May 20, 1933

July 17, 1933

* Combined

Table

Owner

Fritz Weiblen

Robert Meohler

1925 1926

...

...

...

...

...

31.

31.

29.

24.

22.

20.

20.

...

5. -

19.7

23.7

19.2

20.7

20.8

6 25.8

2 24.1

5 29.1

7 28.6

0 23.6

8 22.3

4 20.4

23.1

Discharge 

on Salado

1927 1928

20.9 20.0

22.1 19.5

19.3 18.0

25.2 22.6

26.4 21.0

25.7 24.2

27.7 28.2

34.3 30.8

28.7 23.7

22.8 21.5

24.4 19.0

19.5 18.7

24.7 22.3

1929

18.2

20.8

17.4

21.1

22.8

27.3

22.1

30.8

26.8

20.9

18.3

17.2

22.0

of flowing wells on 

Creek near Fort Sam

Government- Salado 

owned wells Water Co.'s 

(2 wells) well

11.9

.

8.7

8.8

...

9.5

3.7

6.8

discharge of 3

6. -

9.1

11.4

11.6

12.4

11.3

10.2

14.4

wells.

1930

19.9

20.6

16.2

21.8

19.9

25.9

27.4

32.0

27.9

19.3

19.0

17.2

22.3

1931

17.7

18.9

16.3

19.5

21.5

28.1

24.2

28.2

31.9

25.4

21.9

16.6

22.5

the Government 

Houston, Tex. ,

Date

Oct.

May

June

Aug.

Oct.

July

Altitude, in feefabove sea 1« 

(1934) used in drawing curves

Distance 

from 

courthouse Apr. 20 

(miles)

Fuller's earth plant

A. J. Vogt

Robert Boenig

Lake View Addition

Unknown

R. Keilman

Sunset Wood & Coal Co

Southern Ice Co.

John Elsenhauer

H. H>. Classen

20.7 SW

17.7 SW

13.4 SW

12,0 SW

8.0 SW

4.5 SW

2.6 SW

0.6 SW

. 1.0 NE

2.0 NE

12.1 NE

13.5 NE

699.07

692.67

685.93

686.13

683.62

678.21

676.71

674.69

673.07

673.96

673.47

674.11

May 23

696.09

689.38

682.28

682.46

679.82

675.49

674.25

671.51

669.48

670.79

672.01

673.45

23, 1933

7, 1934

25, 1934

28, 1934

29, 1934

1, 1935

1932 1933 1934

16.9 16.7 17.

18.9 19.8 19.

18.2 16.7 16.

24.2 21.8 20.

20.0 25.1 21.

26.4 26.9 33.

23.8 30.2 31.

25.9 23.3 24.

21.1 22.7 25.

17.9 19.6 ...

18.6 19.2

16.3 18.1

20.7 21.7 ...

reservation 

in second-feet

0

0

9

2

5

5

6

9

2

.

.

Government- Salado 

owned wells Water Co.'s 

(2 wells) well

12.4 12.3

10.7 10.1

10.6 11.3

12.8 11.1

9.6 12.6

.... «24.4

vel, of artesian-water surface 

in figure 9

June 21

693.56

686.90

679.75

680.10

677.56

672.93

671.65

688.91

667.33

668.31

670.03

671.89

July

693

687

680

681

679

...

...

669

6S8

668

669

671

31 Aug. 24 Sept.

.96 691.27 690.

.77 684.87 684.

.88 677.71 677.

.44 678.34 677.

.09 675.82 675.

... 671.48 671.

670.41 669.

.59 667.88 667.

.28 665.98 666.

.88 666.92 666.

.78 668.95 668.

.02 670.83 669.

21

24

05

02

79

40

09

96

56

25

87

07

65

Oct.

690.

684.

676.

677.

11

08

24

39

18

674.81

670.

669.

667.

666.

667.

667.

669.

49

43

02

78

18

62

25
CONTRIBUTIONS TO HYDROLOGY, 1956

Table 7. - Water levels In observation wells In the San Antonio area, Tex. 

In feet above or below measuring point

(Owner, distance and direction of well from county courthouse at 

San Antonio, and description and altitude of measuring point.)

Westmoorland College; 

3^ miles NW.; top of

casing, 715.94 feet.

1933

Aug. 25 -40.57

Sept. 18 -40.30

Oct. 12 -40.88

Nov. 20 -40.98

Dec. 18 -41.08

1934

Jan. 18 -40.89

Feb. 19 -40.23

Mar. 19 -39.59

Apr. 18 -38.98

May 21 -40.50

June 19 -43.59

July 30 -42.34

J. H. Landa; 4J miles

NW.; top of pipe clamp,

773.09 feet.

1932

Oct. 29 -94.77

1933

Apr. 9 -94.44

July 18 -98.00

Aug. 17 -98.42

Sept. 18 -98.19

Oct. 17 -98.55

Nov. 20 -98.70

Dec. 18 -99.00

1934

Jan. 18 -98.58

Feb. 19 -98.23

Mar. 19 -97.34

Apr. 18 -96.0

May 21 -98.3

June 19 -100.75

July 27 -101.1-1

Aug. 22 -102.36

Oct. 12 -103.84

Nov. 20 -103.39

Dec. 19 -103.39

1935 

Jan. 31 -103.08

Mar. 1 -102.85

Apr. 8 -103.74

May 20 -93.25

June 26 -82.05

Davis Heights Addition;

4 miles N.; top of pipe

clamp at ground level,

761.46 feet.

1933

Aug. 24 -86.75

Sept. 18 -86.20

Oct. 17 -86.77

Nov. 20 -86.88

Dec. 18 -86.95

1934

Feb. 19 -86.21

Mar. 19 -85.40

Apr. 18 -84.74

June 19 -89.37

Aug. 22 -90.90

Sept.19 -91.40

Oct. 12 -92.02

Oct. 25 -92.50

Nov. 20 -91,45

Dec. 19 -91.43

1935

Jan. 31 -91.37

Mar. 1 -90.98

Apr. 8 -91.84

May 20 -81.69

June 26 -70.60

Mrs. Mattke; 3 miles 

N.; top of pipe clamp

at ground level, 

773.89 feet.

1933

Aug. 24 -101.5

Sept. 18 -100.89 

Oct. 17 -101.49 

Nov. 20 -101.48 

Dec. 18 -101.46

Mrs. Mattke - Cont'd.

1934

Jan. 18 -101.33

Feb. 19 -100.90

Mar. 19 -100.20

Apr. 19 -99.22

June 19 -104.12

July 27 -103.86

Aug. 22 -105.54

Sept.19 -105.81

Oct. 12 -106.42

Oct. 25 -106.72

Nov. 19 -105.69

Dec. 19 -105.44

1935

Jan. 31 -105.41

Apr. 8 -105.92

May 19 -97.75

June 26 -89.38

Amos Lorenz; &£ miles

NNE.; top of pipe clamp,

821.16 feet.

1932

July 19 -151.75

Oct. 19 -146.00

1933

July 17 -149.55

Aug. 18 -149.38

Sept.19 -149.04

Oct. 18 -149.78

Nov. 21 -149.76

Dec. 20 -149.73

1934

Jan. 19 -149,38

Feb. 20 -149.05

Apr. 19 -147.38

June 20 -152.31

Aug. 23 -153.68

Sept.20 -154.01

Oct. 10 -154.4

Nov. 20 -153.9

Dec. 19 -153.92

1935 

Feb. 4 -153.67

Mar, 1 -153.26

Apr. 8 -154.15

May 19 -145.65

June 26 -135.85

D. T. Atkinson; 5 miles

MB.; top of casing 4

inches above ground,

803.54 feet.

1932

July 20 -132.07

Oct. 19 -128.60

1933

Jan. 23 -128.49

Apr. 10 -129.20

July 17 -132.13

Aug. 18 -132.00

Sept.19 -131.61

Oct. 18 -132.31

NOT. 21 -132.32

Dec. 20 -132.31

1934

Jan. 19 -132.00

Feb. 20 -131.60

Mar. 20 -130.92

Apr. 19 -130.13

May 22 -132.58

June 20 -134.89

July 27 -134.83

Aug. 23 -136.24

Sept.20 -136.55

Oct. 12 -137.20

Oct. 25 -137.51

Nov. 19 -136.56 

Dec. 20 -136.39 

1935

Jan. 31 -136.22 

Mar. 1 -135.83

Apr. 8 -136.70

May 19 -128.63

June 26 -118.78

Southern Ice Co.; 2 

miles ENE.; top of

concrete base at ground

level, 710.34 feet.

1933

Aug. 7 -38.76

Sept.19 -37.79

Oct. 18 -38.95

Nov. 21 -38.68

Dec. 20 -38.70

1934

Jan. 20 -38.64

Feb. 20 -37.95

Mar. 20 -37.74

Apr. 19 -36.38

May 22 -39.55

June 20 -42.03

July 27 -41.46

Aug. 23 -43.42

Sept.20 -43.47

Oct. 8 -43.16

Oct. 25 -44.33

Nov. 19 -43.11

Dec. 20 -42.76

1935

Jan. 31 -42.85

Mar. 1 -42.42

Apr. 8 -43.28

May 19 -34.73

June 27 -26.24

Sunset Wood & Coal Co.;

1 mile ENE.; top of valve

38 Inches above ground

level, 678.40 feet.

1933

Aug. 4 -7.99

Sept. 18 -6.77

Oct. 18 -7.87

Nov. 21 -7.84

Dec. 20 -6.67

1934

Jan. 18 -7.11

Feb. 20 -6.16 

Mar. 20 -5.54

Apr. 19 -5.33

May 22 -8.92

June 20 -11.07

July 27 -10.12

Aug. 22 -12.42

Sept.19 -12.15

Oct. 12 -12.62

Oct. 25 -12.74

Nov. 19 -11.53

Dec. 20 -11.31

1935

Jan. 31 -11.20

Mar. 1 -10.64

Apr. 8 -11.68

May 19 -3.26

June 27 Flows

Moore Building; J mile

NE.; top of horizontal

pipe 16 Inches above

floor at well, 645.66

feet.

1933

July 26 +25.4

Sept.19 +27.9

Oct. 18 +23.9

Nov. 21 +26.6

Dec. 20 +26.6

1934

Jan. 18 +27.2

Feb. 20 +26.8

Mar. 20 +27.9

Apr. 19 +28.2

May 22 +25.4 

June 20 +22.4 

July 27 +24.5

Aug. 22 +21.5 

Sept.19 +21,7

Oct. 12 +21.7

Oct. 25 +21.9

Nov. 19 +22.6

Dec. 20 +21.4

Moore Building - 

Cont'd.

1935

Jan. 31 +23.1

Mar. 1 +23.3

Apr. 9 +22.9

May 21 +31,2

June 27 +39.3

R. Keilman; 1 mile

NW.; top of 6-inch

standplpe 60 Inches

above ground, 672.11

feet.

1933

Aug. 1 +^75

Sept. 18 +1.29

Nov. 20 +.25

Dec. 18 +.36

1934

Jan. 18 +.69

Feb. 19 +.93

Mar. 19 +1.36

Apr. 19 +2.58

May 21 -.60

June 19 -3.20

July 27 -2.52

Aug. 22 -4.23

Sept.19 -4.55

Oct. 11 -5.09

Oct. 25 -5.95

Nov. 19 -4.36

Dec. 20 -3.90

1935

Jan. 31 -3,75

Mar. 1 -3.50

Apr, 8 -4.08

May 21 +4.00

June 27 +12.75

Mrs. L. M. Bubble;

2 miles WNW.; top

of 1-i-inch plug 22 

Inches above ground,

665.23 feet.

1932

July 21 +9.5

Oct. 18 +14.1

Nov. 18 +13.0

1933

Apr. 9 +11,8

July 18 +9.0

Aug. 17 +9.2

Sept. 18 +9,2

Oct. 17 +8,8

Nov. 20 +8,6

Dec, 20 +8,6

1934

Jan. 18 +9.0

Feb. 19 +9.4

Apr. 19 +10.8

May 21 +8.5

June 19 +5,9

July 27 +7,2-^

Aug. 22 +4.48

Sept.19 +4.25

Oct. 11 +3.71

Oct. 25 +3.25

NOT. 19 +4.40

Dec. 20 +4.51

1935

Jan. 31 +4.58

Feb. 28 +4.80

Apr. 8 +4.10

May 20 +12.45

June 27 +23,6

Unknown; 3 miles WNW.; 

top of 1-lnoh pipe 

about 1.5 feet above

ground, 677.60 feet.

1933

Jan. Flow

Apr. 8 -.07

July 18 -3.05 

Aug. 17 -2.88 

Sept. 18 -2.60 

Oct. 17 -3.34

NOT. 20 -3.35

Dec. 20 -3.40
WATER RESOURCES, SAH AHTOHIO AREA, TEX.

Unknown - Cont'd.

1934

Jan. 18 -5.25

Feb. 19 -2.74

Mar. 19 -2.06

Apr. 19 -0.89

May 21 -5.35

June 19 -5.95

July 27 -4.88

Aug. 22 -7.19

Sept. 19 -7.64

Oct. 11 -8.17

Oct. 25 -8.75

Nov. 19 -7.92

Dec. 20 -7.59

1935

Jan. 31 -7.36

Feb. 28 -7.28

Apr. 8 -8.16

May 20 +0.25

June 27 +10.50

Lakeview Addition; 4&

miles W.; top of pump base

1 foot above ground,

711.26 feet.

1933

Aug. 25 -34.90 "

Sept. 18 -34.61

Oct. 17 -35.35

Dec. 20 -35.55

1934

Jan. 18 -35.42

Feb. 19 -34.94

Mar. 19 -34.18

Apr. 19 -33.05

May 21 -35.77

June 19 -38.33

Aug. 22 -39.78

Sept.19 -40.17

Oct. 11 -40.77

Oct. 25 -41.28

Nov. 19 -40.21

Dec. 20 -40.10

1935

Feb. 1 -40.17

Feb. 28 -39.78

Apr. 9 -40.44

May 21 -31.04

June 28 -21.18

M. H. White; 2-| miles

SW . ; packing box on

valve 6 inches above

ground, 652.53 feet.

1933

Sept. 15 +21.0

Oct. 18 +21.5

Nov. 20 +22.5

Dec. 20 +23.1

1934

Jan. 18 +21.9

Feb. 19 +21.9

Mar. 19 +22.4

Apr. 19 +23.3

May 21 +19.2

June 19 +18.0

July 27 +19.2

Aug. 22 +16.4

Sept.19 +16.4

Oct. 9 +16.6

Oct. 25 +15.7

Nov. 19 +17.5

Dec. 20 +17.8

1935

Jan. 31 +16.9

Feb. 28 +18.7

Apr. 8 +18.0

May 21 +26.7

June 27 +35.0

School Board of San

Antonio; 3j miles S.;

top of concrete cap on 

well, 622.57 feet.

1933

Aug. 21 +38.1

Sept.19 +39.0

Oct. 18 +38.4

Hov. 20 +37.8

Dec. 20 +37.6

1934

Jan. 18 +37.6

Feb. 19 +38.0

Mar. 19 +39.0

Apr. 19 +39.0

May 21 +37.7

School Board - Cont'd.

1934

June 19 +35.6

July 27 +33.7

Aug. 22 +33.7

Sept.19 +33.7

Oct. 9 +33.5

Oct. 25 +32.8

Hov. 19 +34.0

Dec. 20 +33.0

1935

Feb. 1 +33.6

Feb. 28 +33.8

Apr. 10 +34.0

May 21 +37.0

June 27 +47.8

San Antonio & Aransas

Pass R. R. roundhouse;

lj miles S. ; top of

8-inch cross at top of

casing, 2-jj feet above

ground, 629.55 feet.

1933

Aug. 2 +45.0

Sept. 18 +45.2

Oct. 18 +45.2

Nov. 20 +44.6

Dec. 20 +44.5

1934

Jan. 18 +44.6

Feb. 19 +45.2

Mar. 19 +46.2

Apr. 19 +46.7

May 21 +44.1

June 19 +41.1

July 27 +42.3

Aug. 22 +39.8

Sept.19 +39.6

Oct. 9 +39.9

Oct. 25 +38.8

1935

Apr. 10 +40.2

May 21 +49.5

June 27 +58.5

Robert Boenig; 8 miles

W. ; top of clamp about

1 foot above ground,

745.45 feet.

1933

Sept. 20 -63.30

1934

Jan. 4 -64.65

Apr. 20 -61.83

May 23 -65.63

June 21 -67.89

July 31 -66.36

Aug. 24 -69.63

Sept. 21 -70.05

Oct. 11 -70.64

Oct. 12 -70.90

Nov. 20 -70.10

Dec. 21 -70.29

1935

Feb. 3 -70.14

Mar. 2 -69.92

Apr. 9 -70.74

May 21 -61.26

June 28 -49.13

A. J. Vogt; 12 miles W.;

top of clamp 1 foot above

ground, 765.97 feet.

1933

Sept. 15 -81.70

1934

Jan. 4 -82.60

Apr. 20 -79.84

May 23 -83.51

June 21 -85.87

July 31 -84.53

Aug. 24 -87.63 

Sept. 21 -88.18

Oct. 11 -88.79

Nov. 20 -88.26

Dec. 21 -88.58

1935

Feb. 3 -88.40

Mar. 2 -88.31

Apr. 9 -89i 08

May 21 -79i25

June 28 -66.56

Fuller's earth plant;

14 miles WSW.; top of

concrete pump base 2

feet above ground,

790.15 feet.

1933

Sept. 15 -105.20

1934

Jan. 4 ' -106.67

Apr. 20 -104.22

May 23 -107.87

June 21 -110.40

July 31 -109.27

Aug. 24 -112.44

Sept. 21 -113.13

Oct. 11 -113.76

Nov. 20 -113.28

Dec. 21 -113,70

1935

Feb. 3 -113.68

Mar. 2 -113.52

Apr. 9 -114.28

May 21 -104.50

June 28 -91.68

Robert Mechler; 18 miles

WSW.j top of clamp 1-fc

feet above ground, 810.64

feet.

1933

Sept. 15 -118.34

1934

Jan. 4 -120.11

Apr. 20 -117.97

May 23 -121.26

June 21 -123.74

July 31 -122.87

Aug. 24 -125.77

Sept. 21 -126.59

Oct. 9 -126.40

Nov. 21 -127.05

Dec. 21 -127.47

1935

Feb. 3 -127.58

Mar. 2 -127.50

Apr. 9 -128.37

May 21 -118.84

June 28 . -103.86

Fritz Weiblen; 21 miles W.j

top of clamp 6 inches above

ground, 797.33 feet.

1930

Feb. 19 -119.50

1934

Jan. 4 -99.81

Apr. 20 -98.26

May 23 -101.24

June 21 -103.77

July 31 -103.38

Aug. 24 -106.06

Sept. 21 -107.09

Oct. 9 -107.25

Nov. 21 -107.97

Dec. 21 -108.55

1935

Feb. 3 -108.63

Mar. 2 -108.73

Apr. 9 -109.35

June 28 -83.78

G. A. Kuentz; 13 miles

WNW.; top of pipe clamp

6 Inches above ground,

849.02 feet.

1933

Sept. 21 -158.23

1934

Jan. 9 -160.66

Apr. 20 -153.87

May 23 -158.97

June 21 -161.88

July 31 -160.49 

Aug. 24 -163.80

Sept.21 -165.14

Oct. 11 -165.66

Dec. 21 -168.16

1935

Feb. 4 -166.36

Mar. 2 -165.90

Apr. 9 -166.50

May 21 -150.35

June 28 -133.58

Wm. Edgar; 26

miles WSW.; top

of pipe clamp at

ground level,

851.78 feet.

1934

Jan. 5 -166.80

May 23 -168.43

June 21 -170.75

July 31 -170.31

Sept.21 -174.05

J. C. Stinson;

24 miles W. ; top

of pipe clamp 2

feet above ground,

847.42 feet.

1934

Jan. 8 -146.24

Apr. 20 -143.99

May 23 -146.92

June 21 -149.55

July 31 -149.31

Aug. 24 -151.96

Sept.21 -153.43

Oct. 8 -153.50

Nov. 21 -154.57

Dec. 21 -155.32

1935

Feb. 3 -155.38

Mar. 2 -155.55

Apr. 9 -156.44

May 21 -146.48

June 28 -128.72

Alfred Bourquin;

22 miles WNff.j

top of pipe clamp

about 2 feet above

ground, 928.78

feet.

1934

Jan. 9 -174.73

Apr. 20 -163.62

May 23 -172.40

June 21 -176.59

July 31 -169.26

Aug. 24 -180.77

Sept.21 -184.27

Oct. 10 -185.83

Nov. 20 -188.7

1935

Feb. 3 -192,72

Feb. 4 -192.78

Mar. 2 -196.30

Apr. 9 -194.02

May 21 -160.25

June 28 -128.42

Mrs. Kate Benke;

20 miles WNW.} top

of pipe clamp 6

inches above ground.

1,044.64 feet.

1933

Sept. 22 -287.40

1934

May 23 -287.21

June 21 -292.65

July 31 -280.09

Aug. 24 -296.96

Sept.21 -300.71

Oct. 10 -302.55

Dec. 21 -303.77

1935

Feb. 3 -309.52

Feb. 4 -309,56

Apr. 9 -310,26

May 21 -255.27

June 28 -219.52

R. W. Barham; 16 

miles NW.; hole in

pump base at ground

level, 1,050.33

feet.

1934

Mar. 19 -78.00

Apr. 18 -76.20

May 21 -77.74

June 19 -77.76

July 30 -75.92

Aug. 22 -78.20

Sept.19 -78.24

Oct. 12 -78,26
CONTRIBUTIONS TO HYDROLOGY, 1936

R. W. Barnam - Cont'd.

1934

Nov. 20 -77.93

Dec. 19 -78.04

1935

Fab. 2 -78.00

Feb. 28 -77.73

Apr. 10 -77.39

May 20 -65.83

June 28 -71.11

A. L. Puller; 16 miles

NW. ; top of pipe clamp

1 foot above ground,

1,043.81 feet.

1933

Sept. 27 -162.72

1934

Jan. 19 -171.40

Feb. 19 -164.77

Mar. 1 -167.65

Mar. 19 -176.6

Apr. 18 -168.40

May 21 -168.0

June 19 -193.4-

July 30 -166.32

Oct. 12 -169.86

Dec. 19 -170.19

1935

Feb. 2 -172.15

Apr. 10 -172.80

May 20 -69.74

June 28 -134.05

Theo. Blerlng; 15 miles

NW.; top of pipe clamp,

987.74 feet.

1932

Oct. 18 -262.7

Nov. 18 -263.00

1933

Jan. 15 -265. ?

Apr. 9 -264.2

July 18 -269.42

Aug. 17 -271.2

Sept. 18 -272.93

Oct. 17 -274.29

Nov. 20 -275.62

Dec. 18 -277,04

1934

Jan. 19 -277.82

Feb. 19 -277.58

Apr. 18 -274.00

May 21 -271.51

June 19 -272.56

July 30 -273.85

Sept.19 -276.96

Oct. 13 -278.32

Nov. 20 -280.24

Dec. 19 -282.13

1935

Feb. 2 -282.78

Apr. 10 -283.56

May 20 -278.83

Ben Blerlng; 14 miles NW.;

top of casing, 969.04

feet.

1932

Oct. 18 -245.9

Nov. 18 -246.65

1933

Jan. 15 -247.95

Apr. 9 -247.81

July 18 -253.37

Sept. 18 -256.79

Oct. 17 -257.98

Nov. 20 -259.32

Dec. 18 -260.66

1934

Jan. 19 -261.57

Feb. 19 -260.96

Mar. 19 -259.56

Apr. 18 -266.75

May 21 -254.15

June 19 ' -256.05

July 30 -257.88

Aug. 22 -259.02

Sept.19 -261.01

Oct. 13 -262.23

Nov. 20 -264.06

Dee. 19 -265.90

1935

Feb. 2 -266.53

Feb. 28 -S66.12

Apr. 10 -266.94

June 28 -C30.10

Adolf Benke; 12& miles

N W.; top of pipe clamp,

907.33 feet.

1932

July 21 -205.2

Oct. 18 -201.15

Nov. 18 -201.48

1933

Apr. 9 -201.56

July 18 -205.43

Aug. 17 -206.68

Sept. 18 -307.64

Oct. 17 -208.23

Nov. 20 -209.31

Dec. 18 -210.23

1934

Jan. 19 -210.82

Feb. 19 -210.08

Mar. 19 -208.98

Apr. 18 -207.52

May 21 -206.45

June 19 -208.04

July 30 -210.04

Aug. 22 -210.33

Sept.19 -212.00

Oct. 11 -213.

Nov. 20 -214.55

Dec. 19 -215.49

1935

Feb. 2 -215.86

Feb. 28 -215.69

Apr. 10 -216.40

May 20 -212.00

June 28 -188.62

George Calvert; 9J- miles

NW.; top of pipe clamp,

876.57 feet.

1932

July 21 -191.3

Oct. 18 -185.9

Nov. 18 -186.71

1933

Apr. 9 -187.0

July 18 -191.17

Aug. 17 -191.51

Sept. 18 -191.65

Oct. 17 -192.23

Nov. 20 ' -192.65

Dec. 18 -193.03

1934

Jan. 19 -192.65

Feb. 19 -192.04

Mar. 19 -190.96

Apr. 18 -189.76

May 21 -191.84

June 19 -194.61

July 30 -193.61

Aug. 22 -196.39

Sept.19 -197.54

Nov. 20 -198.14

Dec. 19 -198.51

1935

Feb. 2 -198.39

Feb. 28 -198.05

Apr. 10 -198.70

May 20 -182.90

June 28 -171.28

Alfred Relnlngerj 8

miles NW.; top of pipe

clamp, 892.13 feet.

1932

July 21 -213.10

Oct. 18 -208.27

Nov. 18 -208.84

1933

Jan. 15 -208.55

Apr. 9 -209.30

July 18 -213.04

Aug. 17 -213.08

Sept. 18 -212.98

Oct. 17 -213.60

Nov. 20 -213.85

Dec. 18 -214.04

1934

Jan. 19 -213.59

Feb. 19 -213.19

Mar. 19 -212.15

Apr. 18 -211.36

Hay 21 -213.56

June 19 -216.24

July 30 -215.15

Aug. 22 -217^88

Sept.19 -218.67

Oct. 12 -219.39

Nov. 20 -218.93

Dec. 19 -219.01

Alfred Relnlnger -

Cont'd.

1935

Feb. 2 -218.98

Apr. 10 -219.42

May 20 -207.84

June 28 -196.32

F. A. Fitch; 6£ miles

NW.; top of pipe clamp,

881.83 feet.

1932

July 21 -203.85

Oct. 18 -199.45

Nov. 18 -199.97

1933

Jan. 15 -199.70

Apr. 8 -200.50

July 18 -204.06

Aug. 17 -204.00

Sept. 18 -203.89

Oct. 17 -204.50

Nov. 20 -204.72

Dec. 18 -204.86

1934

Jan. 19 -204.45

Feb. 19 -204.05

Mar. 19 -203.15

Apr. 18 -202.42

May 21 -204.55

June 19 -207.29

July 30 -206.12

Aug. 22 -208.72

Sept.19 -209.45

Oct. 12 -210.18

Nov. 20 -209.60

Dec. 19 -209.75

1935

Feb. 2 -209.58

Feb. 28 -209.22

Apr. 10 -210.02

May 20 -199.40

June 28 -187.85

Ed Haag; 7 miles N.j

top of pipe clamp about

6 Inches above ground,

782.81 feet.

1933

Sept. 29 -109.77

1934

Feb. 20 -109.99

Mar. 20 -109.24

Apr. 19 -108.34

May 22 -110.80

June 20 -112.89

Aug. 23 -114.76

Sept. 20 -115.00

Oct. 11 -115.4

Nov. 20 -114.94

Dec. 19 -115.00

1935

Feb. 4 -114.70

Mar. 1 -114.36

Apr. 10 -115.18

May 20 -105.00

June 26 -93.87

Albert Thels; 10$ miles

NHE.j top of casing about

1 foot above ground,

821.57 feet.

1933

Oct. 2 -138.81

Oct. 18 -139.68

Nov. 21 -139.92

Dec. 20 -140.77

1934

Jan. 19 -140.49

Feb. 20 -137.57

Mar. 20 -136.43

Apr. 19 -135.51

May 22 -134.51

June 20 -137.2

July 30 -137.66

Aug. 23 -139.84

Sept.20 -140.24

Oct. 10 -140.15

Nov. 20 -139.15

Dec. 19 -142.47

1935

Feb. 4 -139.30

Mar. 1 -135.76

Apr. 10 -137.30

May 20 -124.84

June 26 -108.00

John Elsenhaueri

12 miles NHE.; top

of casing, 874.82

feet.

1932

July 20 -202.64

Oct. 19 -200.55

1933

Jan. 16 -200.18

Apr. 10 -200.56

July 17 -203.68

Aug. 18 -203.33

Oct. 18 -203.58

Nov. 21 -203.89

Dec. 20 -204.00

1934

Jan. 19 -203.83

Feb. 20 -202.98

Mar. 20 -201.81

Apr. 19 -201.35

May 22 -202.81

June 20 -204.79

July 30 -205.04

Aug. 23 -205.87

Sept.20 -206.76

Oct. 10 -207.20

Nov. 20 -207.37

Dec. 19 -207.42

1935

Feb. 4 -206.81

Apr. 10 -207.63

May 20 -200.68

E. E. Classen; 13

miles HUE.; top of

pipe clamp, 908.65

feet.

1932

July 20 -235.08

Oct. 19 -233.4

1933

Jan. 16 -233.38

July 17 -235.68

Sept.19 -236.28

Nov. 21 -236.77

Dec. 20 -237.04

1934

Jan. 19 -237.17

Feb. 20 -235.88

Mar. 20 -234.67

Apr. 19 -234.64

May 22 -235.20

June 20 -236.76

July 30 -237.63

Aug. 23 -237.82

Sept.20 -239.00

Oct. 10 -239.40

Nov. 20 -240.00

1935

Feb. 2 -239.48

Mar. 1 -238.62

Apr. 10 -239.18

June 26 -224.25

I. 0. Yates; 14

miles NNE.t top of

casing, 949.22

feet.

1932

July 20 -260.0

Oct. 19 -261.5

1933

Apr. 10 -262.96

July 17 -263.42

Aug. 18 -262.40

Oct. 18 -263.64

Nov. 21 -263.76

Dec. 20 -263.95

1934

May 22 -260.7

Prultt and others;

15 miles SW.; top

of valve about 4

feet above ground.

594.12 feet.

1933

Aug. 26 4-93.5

Oct. 20 +93.3

1934

May 22 4-91.2

Oct. 10 +87.7
WATER RESOURCES, SAN ANTONIO AREA, TEX.

Southern Pacific Railroad; 21 miles WSff. ; 

top of pipe, 725.49 

feet.

1930 

Feb. 19 -50.50

1934

Jan. 5 -33.21 

June 28 -37.45 

Aug. 31 -39.66 

Oct. 9 -39.73

Ed Bacon; 13 miles OTW. 

top of casing 1 foot 

above ground, 1,004.92 

feet.

1933 

Dec. 22 -289.08

1934

Mar. 2 -289.50 

Oct. 12 -292.68

1935 

Mar. 1 -292.28

A. A. Rothe; 4j miles ENE.; 

top of clamp 1.6 feet above 

ground, 678.07 feet.

1932 

Nov. 13 -1.88

1934

Feb. 7 -4.81 

Oct. 8 -10.31