CONTRIBUTIONS TO THE HYDROLOGY OF THE 

UNITED ST .ATES, 1926 

N. C. GRoVER, Chief Hydraulic Engineer 

GEOWGY OF NO. 3 RESERVOIR SITE OF THE CARLSBAD 

IRRIGATION PROJECT, NEW MEXICO, WITH RESPECT 

TO WATER-TIGHTNESS 

. By OscAR E. MEINZER, B. CoLEMAN RENICK, and KmK BRYAN 

SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS 

Investigation of the character and structure of the rocks in the vicinity 

of the :No.3 reservoir site and of the ground-water conditions in these rocks has 

led inevitably to the conclusion that there is danger of serious leakage from 

the proposed reservoir. The rocks underlying the reservoir site and adjacent 

to it consist largely of cavernous limestone and gypsum. At the dam site 

and in much of the area immediately east and southeast of the reservoir 

site the ground-water level in these rocks is below the river level, showing 

that water which enters the openings in the rocks· in parts of this area is 

drained away from the river to some other locality where it finds a lower 

outlet. 

At least a large part of the water that leaks out of the McMillan Reservoir, 

amounting at times to as much as 300 second-feet, finds its way through a 

syste:tp of underground channels to a locality 3 or 4 miles downstream, ,-.-here 

it reappears in springs at an elevation about 35 feet below the high flow 

line (elevation 3,260 feeO of the proposed reservoir. If these springs are 

submerged the water in the system Qf underground channels will be impounded and may escape into cavernous rock having a low water table immediately to the south. 

As gypsum crops out at low levels in the reservoir site below the spring 

area there is danger that leaks will develop in the lower part of the reservoir 

somewhat similar to those that exist in the lower part of the McMillan Reservoir. The outcrops of gypsum are less extensive thah those in the McMillan 

Reservoir but the water would be under greater head. Such leaks would 

tend to become more serious in time, as the gypsum is dissolved and eroded 

away and the underground channels are enlarged. In all probability there 

would be no practicable means of stopping these leaks. 

Much of the water that would escape either by reversal ·of the springs or 

through sink holes in the lower part of the reservoir would probably not 

· return to the surface until it reached some point below the Avalon Reservoir. 

1 
2 ~ONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

It is, of course, possible that the rocks underlying the proposed reservoir 

and bordering the communicating system of underground channels are tight 

enough at all points to prevent serious leakage from the reservoir into the 

adjacent cavernous rocks with low water table. However, the known conditions are much less favorable here than in the Avalon Reservoir, which is 

apparently perched above the ground-water table, because of the outcrops of 

gypsum and cavernous limestQne that exist in the No. S site and because of 

the high head of water in the proposed reservoir. 

The conclusion has therefore been reached that the risk due to probable 

leakage is too great to warrant .the construction of a dam at the No. S site 

designed to impound water to the elevation of 8,260 feet or to any height approaching that elevation. 

INTRODUCTION 

LOCATION AND SIZE OF PROPOSED RESERVOIR 

Reservoir site No. 3 of the Carlsbad irrigation project lies several 

miles north of Carlsbad, N.Mex., in T. 20 S., R. 26 E., and T. 21 S., 

Rs. 25 and 26 E. (See fig. 1.) It extends along Pecos River for a 

distance of about 9 miles. The dam site is in sec. 6, T. 21 S., R. 26 E., 

at a point where the river at low stages is about 3,190 feet above sea 

level. If the dam is built to the height originally proposed, the 

flow line, or surface of the water when the reservoir is full, will be 

about 3,260 feet above sea level, and an area of 8 square miles will 

be submerged, as shown on the maps. (Fig. 1 and pl. 1.) At this 

elevation the capacity of the reservoir will be about 90,000 acre-feet. 

The area and capacity of the reservoir with the flow line at several 

levels are about as follows: 

AretJ ana capacity of the proposed, Reservoir No. 3 at several lewl-s 

Elevation 

Feet above Area Capacity 

river level Feet above 

atdamslte sealevel 

.Acre~ .Acre-f~tl 

30 3,220 450 4,000 

40 3,230 900 11,000 

110 3,240 1,900 26,000 

60 3,250 3,200 50,000 

65· 3,255 4,000 67,000 

70 3,260 5,000 90,000 

Reservoir site No. 3 · lies immediately downstream froin the McMillan Reservoir, which leaks badly, and almost immediately upstream from the Avalon Reservoir, which holds water without appreciable loss. The spillways of the McMillan Re~rvoir are at an 

elevation of about 3,286 feet or about 26 feet above the high flow 

line of No. 3. The spillway of the Avalon Reservoir is at an elevation of about 3,177 feet, which is 10 to 15 feet below the river level 

at the No. 3 dam site. 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 

EXPLANATION 

• Spring 

X Gypsum outcrop 

o Test hole 

3 

Numbers refer to the test 

holes drilled in 1925. 

3 

FIGURE 1.- Map of a part of the Carlsbad irrigation project New Mexico, showing location of No. 3 r eservoir site 

HISTORY OF THE PROJECT 

The Carlsbad project was started by private interests in 1888 and 

was developed in virtually its present general form prior to 1904. 

At that time impairment of the McMillan Reservoir by silting and 

increased leakage, destruction of the Avalon Dam, and financial difficulties led to the agitation for rehabilitation by the United States. 

The project was taken over by the United States Reclamation Service 
4 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

in 1906, and substantial improvements were made in the succeeding 

years, including the reconstruction of the A val on Dam and the 

enlargement of the McMillan Reservoir. Progressive silting of the 

McMillan Reservoir has been offset by two enlargements since 1904, 

the last in 1915. In recent years silting has been appreciably arrested by the growth of tamarisk (salt cedar, Tamariw gallioa) at 

the upper end of the reservoir. Leakage from this reservoir has 

gradually increased, though it was temporarily reduced by the construction in 1909 of an embankment that prevented the water from 

reaching some of the worst sink holes. 1 

:PREVIOUS INVESTIGATIONS OF THE RESERVOIR SITE 

Reservoir site' No. 3 has been under consideration for many years. 

The 5-foot contour map used in this report was made in 1905. The 

reservoir site has been examined with respect to the geologic features 

of its dam site and the water-tightness of its containing rocks by 

three geologists of the United States Geological Survey-by ·w. T. 

Lee in 1905, by G. B. Richardson in 1911, by N. H. Darton in 1922, 

and again by Mr. Lee in 1923. It was also reported on by Prof. E. M. 

Skeats in 1910. Core drilling was done at the dam site in 1905 and 

1922 and in a locality known as Hurd's pasture in 1905. 

Mr. Lee reported unfavorably with respect to the question of 

water-tightness. The reports by Messrs. Richardson, Darton, and 

Skeats were more favorable, but after Mr. Lee's second investigation 

Messrs. Richardson and Darton made the following joint statement, 

substantially supporting Mr. Lee's conclusions: 

We agree with Mr. Lee as to these major conclusions set forth in his report: 

1. That the pervious beds are sufficiently well blanketed at the dam site of 

No.3 Reservoir to assure the safety of the proposed dam. 

2. That 1t is unlikely that No. 3 Reservoir, if constructed as originally 

planned to hold water under a maximum head of 70 feet, would be watertight. 

3. That the beds of salt, gypsum, and cavernous limestone under the proposed reservoir and about it, being pervious to water, are sources of danger. 

4. That a small reservoir might be constructed at No. 3 site which, in spite of 

,Possible leakage, would be useful in the regulation of flood water. 

:PRESENT INVESTIGATION AND REPORT 

The 'present report and recommendations are based on a field 

examination made by the authors in July anq August, 1925. In 

accordance with a recommendation of the board of surveys and 

'The information glven · in the above paragraph is taken· from the report of Ferd. 

Bonstoot and E. B. Dehler, submitted in 1923. See also Dav!.s, A. P., Irrigation works 

constructed by the United States Government, pp. 225-230, New York, 1917; Why 

some irrigation canals and reservoirs leak: Eng. News-Record, vol. ,8, pp, 663-665, 1918. 
U. S. GEOLOGICAL SURVEY 

]3 

0 

Topography by J. D. Forster 

U. S. Reclamation Service 1905 

WATER-SUPPLY PAPER 580 PLATE 1 

. 1 

Scale 31, 68o 

1 

Contour interval 5 feet 

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EXPLANATION 

~ Alluvium 

(Sand, silt, and gravel) 

UNCONFORMITY 

Limestone 

~ conglomerate 

(Conglomerate forming t.ermces, most~ cobbles 

and boulde>·s of limeston<' cemente by cal- cium ca1·bonate but also .:ontains qua1"tzose 

pebbles) 

UNCONFORMITY 

Quartzose 

~ conglomerate 

( Con~lome1·ate consisting largely % qnart~?se 

pe bles in matrix o~ sand but a so contatns some limestone 1>eb les) 

UNCONFORMITY 

Castile formation 

(Red sandstone and shale with inte>·bedded 

limestone, gypsum, salt, and anhydrite) 

CONTACT CONCEALED 

Carlsbad 

-

limestone member 

(Limestone 'With thin beds o{ sandstrme, possibly some roc salt) 

UNCONFORMITY(?) 

Seven Rivers 

~ gypsiferous member 

(81ifj' and g1·een limy shale, thin limestone beds, and b·.-eccia in .places; th1ck beds of gypsum and ·red shale below the lirny beds) 

G 

Test hole 

B 

Flow li ne of proposed reservoir 

GEOLOGIC MAP AND SECTIONS OF THE AREA INCLUDING THE NO. 3 RESERVOIR SITE 

OF THE CARLSBAD IRRIGATION PROJECT, N.MEX. 

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Geology by B. Coleman Ren ick 
CARLSBAD IR.RIGATION PROJECT, NEW MEXICO 5 

adjustments that proper and complete geologic surveys be made 

of this reservoir site, the Bureau of Reclamation in financial cooperation with the Carlsbad Water Users' Association undertook 

the work. As provided in a letter from Dr. Elwood Mead, Commissioner of Reclamation, to the Director of the United States 

Geological Survey, dated May 4, 1925, this new examination was to 

be made by geologists who had not previously reported on this 

reservoir, and all salary and expenses were to be paid out of the 

cooperative funds provided under the terms of a contract between the 

Bureau of Reclamation and the Carlsbad Water Users' Associatiop.. 

Mr. Meinzer, geologist in charge of the ground-water division of 

the Geological Survey, was placed in control of the work and was 

assisted by Mr. Renick. Mr. Renick spent about three weeks and 

Mr. Meinzer about two weeks in the field. Mr. Bryan spent two 

days in the field with Mr. Meinzer. . 

At the conclusion of the field investigation 'it was recommended 

that four test holes be drilled in proximity to the reservoir site 

for the purpose of determining the depth to ground water. This 

drilling arid the testing of the ground-water conditions were carried out under the efficient supervision of Mr. J. R. Yates, of 

. the United States Bureau of Reclamation. Mr. Renick returned 

to Carlsbad for a few days in October, 1925, to examine the drilling operations and to witness some of the ground-water tests. 

The report was prepared chiefly by Messrs. Meinzer and Renick, 

most of the section relating to geology being written by Mr. Renick 

and most of the rest of the report by Mr. Meinzer. All three authors 

concur in the conclusions and recommendations. 

As the previous reports indicate that the rocks at the dam site 

are sufficiently strong to support a dam with a relatively broad base 

of the rock-fill type, such as is proposed, the question of the strength 

of the rocks at the dam site was not reopened in the present examination, the investigations being confined to the question of the 

water-tightness of the proposed reservoir. 

The authors are greatly indebted to Mr. L. E. Foster, superintendent of the Carlsbad project, and to Mr. J. R. Yates, hydraulic 

engineer, for their interest and help. The engineering and hydrometric data used in this report were largely furnished by these two 

engineers of the Bureau of Reclamation. 

TOPOGRAPHY 

From Roswell to the vicinity of Seven Rivers Pecos River flows 

near the east side of a wide alluvial plain that slopes very gently 

from the western uplands and is bordered on the east by low 

bluffs. The river occupies a shallow trench in this plain until it 

\ 
6 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

reaches the McMillan Reservoir, which lies in the southeast corner 

of the.plain. On the east and south of the reservoir high cliffs rise 

almost from the river bank. 

South of Seven Rivers the Pecos leaves the broad plain and flows 

between uplands of moderate relief. This constriction of the valley 

is due to the outcrop of resistant limestone which the river crosses 

south of Seven Rivers, within the No. 3 reservoir site. In most of 

its course through the reservoir site the river occupies a narrow 

trench with precipitous banks, 15 to 30 feet high, cut in a low terrace 

that occupies a large part of the floor of the reservoir site. Narrow 

and precipitous but shallow trenches or gullies have also been cut in 

this terrace by Seven. Rivers, Rocky Arroyo, and some of the smaller 

streamways. This low terrace is bordered by remnants of two older 

and higher terraces, which stand about 75 feet and 150 feet or more 

above the river. The top of the 75-foot terrace is for the most part 

abQve the flow line of the proposed ·reservoir. These three terraces 

represent three different levels at which the river flowed in the past. 

GEOLOGY 

STRATIGRAPHY 

FORMATIONS INCLUDED 

The rocks in the No. 3 reservoir site are of two kinds-(1) old 

rocks .that have been deposited over extensive areas of the region in 

basins of water, and (2) younger conglomerate, gravel, sand, and 

silt that have been deposited by streams. The rocks of the first 

group are of Permian age and were formed at a period of time 

very remote from that in which the rocks of the second group were 

formed. The younger rocks were probably all formed in the Quaternary period, although there is a possibility that some of them may· 

have been deposited during the Tertiary period: The distribution and 

structure of the rocks in or near the reservoir site are shown in the 

geologic map and sections in Plate 1. 

The Permian rocks include the Chupadera ·formation-divided 

into the Seven Rivers gypsiferous member below and the Carlsbad 

limestone member above--and younger deposits which according to 

Darton 2 belong to the Castile formation. The Seven Rivers member 

consists of gypsum beds and associated red sand and shale of undetermined thickness, overlain ~y at least 60 feet of interbedded 

greenish limy shale and limestone, which in places changes laterally 

into limestone breccia. West of the Atchison, Topeka & Santa Fe 

Railway the breccia becomes a persistent bed. This breccia bed possibly records an old land surface with many .sink holes. Resting 

• Darton, N. H., The Guadalupe group : Geol. soc. America Bull., vol. 37, pp. - (ln 

press). · 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 7 

on the Seven Rivers gypsiferous member. is the Carlsbad limestone 

member, which in the vicinity of the McMillan Reservoir is only 

about 40 feet thick. It thickens toward the south, however, and in 

the southern part of the No. 3 reservoir site attains a thickness of 

several hundred feet. The formation considered to be the Castile 

formation consists of sandstone and shale, ln.ostly red, and interbedded layers of gypsum, limestone, anhydrite, and salt. 

The Quaternary deposits include, from oldest to youngest, quartzose conglomerate, limestone conglomerate, and alluvium along the 

Pecos and its tributaries. The quartzose conglomerate consists 

largely of siliceous pebbles and sand, and the overlying limestone 

conglomerate consists largely of limestone cobbles and boulders. 

Both of these conglomerates are cemented by calcium carbonate. 

The deposits that cap the High Plains to the east are regarded as 

Pliocene. After they were laid down the valley of Pecos :ij.iver was 

excavated, and later the river deposited in its valley the materials 

that now form the quartzose and limestone conglomerates. These 

conglomerates are therefore regarded as Pleistocene, although their 

exact age has not been determined, and it is possible that the older · 

or quartzose conglomerate may be of late Pliocene age. The alluvium is made up of silt, sand, and gravel of Recent age and includes 

the ancient flood-plain deposits underlying the low terrace and the 

material deposited in the present river channel, chiefly by the 

tributary arroyos. · 

QUATERNARY SYSTEM 

RECENT SERIES 

ALLUVIUM 

The youngest deposits in the No.3 reservoir site have been mapped 

as alluvium, but this alluvium is not all of exttctly the same age, 

although all of it belongs to the Recent epoch of geologic time. A 

part of it lies in the immediate channel of Pecos River and its tributaries and is continually shifted and reworked by floods. The larger _ 

part of the material, however, consists of silt and gravel that underlie an ancient flood plain of the river no longer overflowed even in 

great floods. This abandoned flood plain stands as a terrace 15 to 

30 feet above the present river channel. In addition to the deposits 

largely laid down by the river the alluvium also includes some 

sand, silt, and gravel that have been washed from the adjacent 

slopes. 

The materials composing the terrace or ancient flood plain are 

different in different places. In the northern part of the reservoir 

site most of the terrace is underlain by silt and fine sand, except 
S CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

where the outcrop of the Carlsbad limestone crosses the river. In 

this stretch and for a short distance downstream there are a few 

angular fragments of limestone. In the southern part of the reservoir site, south of the mouth of Rocky Arroyo, the alluvium contains 

in addition to sand and silt a large amount of gravel, in which wellrounded limestone cobbles and boulders predominate. These cobbles 

and boulders are similar to those now carried by Rocky Arroyo and 

were evidently contributed by that stream. Such cobbles and boulders are conspicuously scarce in the alluvium in the northern part 

of the No. 3 reservoir site. 

Near the river channel the arroyos tributary to the Pecos have cut 

gullies in the terrace corresponding in depth to the incised channel 

of the river. The floods of these tributaries confined in narrow 

channels transport a considerable quantity of cobbles and boulders 

and deposit them in the form of deltas in the river. The coarse 

gravel is deposited at the mouth of each tributary as a gravel bar, 

and successively finer material is laid down in the bed of the river 

below. Consequently, at the mouths of the larger tributaries, especially of Seven Rivers and Rocky Arroyo, the river has been 

crowded against the east bank, as shown in Plate 1, and runs in 

small rapids over the gravel bars. 

PLEISTOOElii'E SERIES 

LIMESTONE CONGLOMERATE 

In the southern part of the reservoir site (pl. 1) there are ~wo 

well-defined terraces above the abandoned flood plain mapped as 

alluvium. Since these terraces were formed they have in many 

places been eroded and are now represented by hills . and ragged 

spurs. The crenulate<i topography with remnants of the original 

flat surfaces of the two terraces is well shown on Plate 1, particularly in the hill just north of Rocky Arroyo. The lower and 

younger terrace of the two is at an elevation of about 3,275 feet, 

or 75 to 85 feet above the river, and the older one, which extends 

to the west beyond the limits of the area mapped, is from 75 to 

100 feet higher, or 150 to 185 feet above the river. 

These terraces are underlain by very similar limestone conglomerates deposited by Pecos River in the two periods .when it flowed 

at these higher levels. On the geologic :Qlap (pl. 1) these two 

conglomerates have been mapped together as limestone c~mglomerate, although the conglomerate in the higher terrace is obviously 

older than that in the lower. 

The limestone conglomerate of both terraces consists mostly· of 

well-rounded cobbles and boulders of limestone ranging from about 
CARLSBAD IRBIGATION PROJECT, NEW MEXICO 9 

an inch to almost 2 feet in diameter. In addition to the limestone 

pebbles there are some siliceous pebbles, generally not over lY2 

inches in diameter, which seem to have been contributed largely 

from the underlying qu111rtzose conglomerate. Both the limestone 

and siliceous pebbles have in most places been cemented by calcium 

carbonate into a compact conglomerate. The cement is so firm 

that the conglomerate when struck with the hammer frequently 

breaks across the pebbles. 'i'he conglomerate is so largely composed of limestone pebbles and limy cement that it weathers much 

like limestone, and the surface of the terraces resemble in many / 

respects near-by limestone surfaces. The slopes of the terraces, 

however, are largely covered with rounded cobbles that have weathered out of the conglomerate. The limestone cobbles and boulders 

in the conglomerate have come from a source that lies in a general 

westerly direction, either from an ancient Rocky Arroyo or from 

similar streams farther north, and are thus local in origin. 

QUARTZOSE CONGLOMERATE 

In the bluffs along Pecos River in the lower part of the reservoir 

site a quartzose conglomerate is exposed below the limestone conglomerate that has just been described. This conglomerate consists 

largely of pebbles of chert, jasper, quartz, agate, and quartzite in 

a matrix of well~cemented sand. As the pebbles are well rounded 

and rarely exceed 172 inches in diameter, they have evidently been 

transported a long distance. There are also some pebbles and cobbles of limestone, many of which are several inches in diameter and 

apparently have not been transported as far as the siliceous pebbles. 

The matrix of this conglomerate is a fairly coarse sand which is 

held together by a calcareous cement. In this formation there are 

also lenses of sandstone interbedded with and grading into the 

typical conglomerate. 

It is believed that the quartzose conglomerate represents an ancient 

channel deposit of Pecos River. On the east side of the Pecos, in 

the central part of the reservoir site, there is a distinct trench in 

the underlying Castile formation that has been filled with this 

conglomerate, and on the near-by Castile outcrop there is a veneer 

of residual siliceous pebbles. 

The quartzose conglomerate is, in most places, so well indurated 

that it is capable of standing as a vertical face in a bluff. On 

weathering it produces a sandy soil containing siliceous pebbles, as 

for example on the east side of Pecos River about half a mile north 

of the mouth of Rocky Arroyo. 

At all places where the lower contact of this conglomerate is 

exposed it rests on the Castile formation, but on the west side of 
10 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

the Pecos it doubtless rests on the Carlsbad limestone member of the 

Chupadera formation. Although the boundary between the quartzose and limestone conglomerates is indefinite in many outcrops, 

there are indications of a distinct unconformity between them. At a 

number of places in the east bluff of the Pecos, south of the mouth 

of .Rocky Arroyo, the quartzose conglomerate is tilted and otherwise 

deformed, whereas nowhere within the area examined was the limestone conglomerate found to be deformed. The existing remnants 

of the two terraces underlain by the limestone conglomerate are 

smooth and have the gentle slopes characteristic of terraces. These 

slopes are accordant with each other, sloping from north to south, 

parallel to the. course of the river, and from each side toward the 

river, parallel to the tributary streams. The limestone conglomerate 

thus appears to be wholly undeformed, whereas the underlying 

quartzose conglomerate has been broken and tilted. The deformation of the quartzose conglomerate appears to be due to fracture and 

slumping caused by the removal of soluble material from the underlying Castile formation (p. 11). 

On the south side of the river at the dam site both con,glomerates 

are exposed ; · on the north side the quartzose conglomerate is 

probably present but is concealed by a cover of limestone cobbles 

that have weathered out of the limestone conglomerate. In the terraces just north of Rocky Arroyo, on the south side.of the river, there 

is doubtless a considerable deposit of the quartzose conglomerate, 

but in general it is covered with cobbles from the overlying limestone 

conglo~erate. · 

CARBONIFEROUS SYSTEM 

PEBJUAN SElUES 

The Permian rocks in this area have not been traced into the 

Guadalupe group of Texas, which is divided into the Delaware 

Mountain formation below and the Capitan limestone above, formations which were originally defined by Richardson 8 and lq.ter studied 

by Girty.4 Darton/ however, has recently traced the Permian rocks 

of the Guadalupe Mountains northward along the west side of the 

Pecos Valley, and according to him the Carlsbad limestone of this 

report forms the upper part of the Capitan limestone that lies at 

the top of El Capitan, at the south end of the Guadalupe Mountains. 

8 Richardson, G. B., Report of a reconnaissance in trans-Pecos Texas north of the 

Texas & Pacific R. R. ; Texas Univ. Bull. 29, 1909 ; The stratigraphy of the Uppet' Carboniferous in west Texas and southeastern New Mexico: Am. Jour. Scl., 4th ser., vol. 29, 

pp, 325-837, 1910. 

• Girty, G. H., The Guadalupian fauna: ·u. S. Geol. Survey Prof. Paper 58, 1908. • Darton, N. H., The Guadalupe group: Geol. Soc. America Bull., vol. 37, pp. -

(in press). 
CARLSBAD InR.IGATION PROJECT, NEW MEXICO 11 

· All the Permian rocks below the Castile formation described in this 

report are at present included by Darton in the upper part of the 

Chupadera formation.6 • 

CASTILE FOBHATION 

According to the recent work of Darton,7 the rocks mapped as Castile formation in Plate 1 apparently represent the lower part of the 

northern extension of the Castile gypsum 8 of Texas. The lower 

part of this formation is exposed on the east side of Pecos River in 

the No. 3 reservoir site, and thence the formation extends eastward 

and northeastward for a considerable distance. As seen in numerous 

outcrops it consists largely of soft sandstone and shale, mostly red 

but including some beds that have a greenish tint. There are also 

presistent beds of limestone and gypsum. A test hole drilled in 

1905 on the Allen Hurd land (fig. 1) encountered gypsum at a depth 

of 6 feet and continued in that material interbedded with small 

amounts of shale to a depth of 65 feet. Locally the gypsum beds 

in the Castile formation are sufficiently thick to be workable, and 

along the railroad in the NE. :14 ·sec. 18, T. 20 S., R. 2'1 E., there 

is a cement mill which uses gypsum taken from an open pit about 

half a mile east of the mill. It is reported that wells in the Artesia 

oil field encounter beds of salt and anhydrite in the Castile formation. At the outcrops the soluble materials, such as salt, gypsum, and anhydrite, have largely been dissolved out of the formation. Within the No. 3 reservoir site three outcrops of gypsum · 

have been found (fig. 1 and pp. 25-26). Solution of soluble rocks 

with resulting slumping and tilting' of the overlying strata is 

prevalent in this part of New Mexico and has recently been described by Lee. 9 As a result of this process much of the Castile 

formation that crops out within the reservoir site has been thus deformed. The spectacular results of this process are particularly 

noticeable in the limestone beds, which have been broken and contorted. Individual blocks of limestone ranging in size from a few 

feet to several hundred feet have been tilted in all directions and 

limestone breccia is common. 

In the southern part of No. 3 reservoir site the river flows very 

close to the boundary between the Castile formation and the underlying Carlsbad limestone, but the contact is largely concealed by the 

• Darton, N. H., Geologic structure of parts of New Mexico: U. S. Geol. Su~ey Dull. 

726, pp. 181-182, 1922. 7 Darton, N. H., Geol. Soc. America Bull., vol. 37, p. - (in press). 

"Richardson, G. B., U. S. GeoL Survey Oeol Atlas, Van Horn folio (No. 194), p. 

6, 1914. . 

0 Lee, W. T., Erosion by solution and flU: U. S. Geol. Survey Bull. 760, pp. 107-

121, 1925. 
}2 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

two overlying conglomerates and the alluvium. As shown on the 

geologic rna p (pl. 1) , the Castile formation crops out in only one 

place west of the river. 

CHUPADERA FORMATION 

The rocks here assigned to the Chupadera formation are divided 

into two members, for the upper of which the name Carlsbad limestone member is adopted and for the lower the name Seven Rivers 

gypsiferous member. The Chupadera is overlain by the Castile formation and is the oldest formation that crops out in this area. 

Carlsbad lilmestone member.-The limestone here designated the 

Carlsbad limestone member of the Chupadera formation has for 

some time been locally called the Carlsbad limestone, because of its 

outcrops west and northwest of Carlsbad. It is doubtless in part 

at least the equivalent of the Big lime of Lee.10 It crops out south 

and west of the reservoir site, crosses Pecos River at the constriction of the valley below the mouth of Seven Rivers, and forms the 

upper part of the bluff on the southeast side of Pecos River above 

the constriction. Where the limestone crosses Pecos River it forms 

ledges in the bed of the stream. 

Northwest of Carlsbad, in sec. 34, T. 21 S., R. 26 E., where a well 

is now being drilled for oil, the Carlsbad limestone is at least 800 feet 

thick, and southwestward toward the New Mexico-Texas line it 

apparently attains a still greater thickness. Inspection of the outcrops in the southern part of the reservoir site indicated that the 

limestone is thinner there than at the localities mentioned, but on 

the west side of the river it is still several hundred feet thick. As 

the beds are traced northward th~y are found to thin rapidly. As 

measured in the bluff south of Pecos River between the mouth of 

Seven Rivers and the railroad the limestone did not exceed 100 feet 

in thickness. The limestone that caps the bluff at the south end o£ 

the McMillan Reservoir was found to be the same bed by tracing it 

from the outcrops previously described, but here it is only about 40 

feet thick. The Carlsbad limestone, though essentially a limestone 

unit, contains lenses of sandstone, and in some places west o£ the 

areas mapped lenses of red beds (sand or shale) were noted along the 

outcrop. 

In the vicinity of the reservoir site the Carlsbad limestone is a 

relatively thin-bedded rock in which individual beds usually do not 

exceed 2 feet in thickness. The rock itself is dense, and the joints are 

clean fractures but little opened by weathering. It resists erosion 

and generally forms hills and ridges. The valley of Pecos River 

where it crosses the outcrop is narrow and marked by steep bluffs, 

•• Lee, W. T., op. cit., p. 108. 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 13 

a measure of the resistance of the rock to the lateral erosion of the 

river. 

However, the limestone yields to the solvent action of water at the 

surface and underground. In the general region lal!ge springs and 

extensive deposits of travertine testify to its cavernous condition, 

and large springs issue from crevices in it along the river in the No.3 

reservior site. To what extent the work of solution has proceeded in 

the vicinity of the reservoir site is not wholly manifest from an inspection of the outcrops of the Carlsbad limestone but must be inferred on hydrologic grounds, as set forth on pages 18-28. 

The exposures of the limestone show small folds (anticlines and 

synclines), most of which do not exceed a few hundred feet in 

length. The dips in some of these folds are as much as 45°, but 

these dips do not conform to the regional structure of the Carlsbad 

limestone. It seems likely, therefore, that these minor crumplings 

have resulted from the solution of underlying material, such as salt, 

anhydrite, gypsum, or limestone, and the consequent yielding of 

the Carlsbad limestone to slumping on the removal of its support. 

Seven Rivers gypsiferous member.-In the northern part of the 

No. 3 reservoir site and in the vicinity of the McMillan Reservoir 

beds that lie stratigraphically below the Carlsbad limestone member are well exposed. Near the McMillan Dam, just below an outcrop of the Carlsbad limestone, there is an excellent exposure of 

about 50 feet of interbedded greenish limy shale and compact limestone. These beds have been considerably deformed in small folds 

and minute faults that are doubtless due to the removal of underlying soluble material. In the south spillway, just east of the railroad and about half a mile west of the McMillan Dam, the same 

beds are exposed, but there they have been deformed to a much 

greater degree than at the McMillan Dam. In the bluff along the 

southeast edge of . the McMillan Reservoir 100 feet or more of 

gypsiferous beds are exposed. Numerous small sinks in the reservoir suggest that these gypsum beds extend northward under the 

reservoir. These beds of gypsum and associated red sand and shale 

are believed to be stratigraphically below a persistent breccia bed 

which is the stratigraphic equivalent of the interbedded greenish 

limy shale and limestone that crop out in the vicinity of the Me~ 

Millan Dam. The gypsum and the overlying deformed and brecci~ 

ated limy strata constitute the Seven Rivers gypsiferous member 

of the Chupadera formation, as defined~ in this report. The bed~ 

are given this name because they are well exposed in the bluffs,south 

of Seven Rivers, notably in the bluff that lies in sees. 17 and 18, 

T. 20 S., R. 26 E. Beds of gypsum also crop out north o£ this 

bluff, where the surface is more flat, and here sink holes are plenti-
14 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

ful. West of the railroad, in sees. 3 and 10, T. 20 S., R. 26 E., along 

the south side of the north spillway of the McMillan Reservoir, 

beds of the Seven Rivers member are at the surface, and there are 

at least four large sink holes. The one shown on the map (pl. 1) 

has been filled by alluvium. A.ll these sink holes have resulted 

from the solution of gypsum or other soluble material by the ground 

water. The dissolving of the material produced large caverns, the 

roofs of which have in some places caved in. 

Some beds in the upper part of this member consist of :fragments 

of limestone cemented in a matrix· of limy material. The limestone 

:fragments vary in shape :from angular :fragments to rounded masses. 

Most o:f the material is a true breccia, but some is more nearly a 

conglomerate. The proportion of breccia to normal material of the 

Seven .Rivers beds increases :from the McMillan Dam toward the 

southwest, and in the bluff south o:f the Pecos and west of the railroad there is a continuous and persistent bed of breccia immediately 

below the Carlsbad limestone. This bed extends :from the outcrop of 

the Carlsbad limestone to the alluvium bordering the river and has 

a maximum observed thickness of 60 :feet. 

Generally the breccia beds vary in thickness along the outcrop and 

in places end abruptly against normal limestone. A.t the A. valon 

Dam a bed of breccia lies below the normal limestone on which the 

spillway gates are built. Partly dislodged fragments of the limestone lie in the breccia adjacent to the cavities :from which they have 

been dislodged. It is evident that here the breccia was :formed after 

the overlying limestone had been laid down and consolidated. The 

breccia appears to have been deposited in a cave that once existed at 

this place and had the limestone :for its roof. The :fragments of the 

breccia consist largely o:f masses of this roof detached by caving and 

more or less transported and cemented into a hard rock by the waters 

circulating in the cave. This particular bed and doubtless many 

others furnish examples of the process of solution and fill described 

by Lee.U 

The persistent breccia at the top of the Seven Rivers gypsiferous 

member south of Pecos River and at the south spillway of the McMillan Reservoir may, however, represent an ancient sink-hole country of 

Permian time. Here solution and fill may have taken place as they 

do now, and the breccia may have been formed and cemented before. 

the Carlsbad limestone was laid down. Locally the Carlsbad lime-· 

stone does not seem to have been so much deformed as the persistent 

underlying breccia bed, and this fact adds weight to the hypothesis 

that part o:f the solution and fill which produced the breccia took 

place in Permian time and therefore records an unconformity within 

11 Lee, W. T., Erosion by solution and fill: U. S. Geol. Survey Bull. 760, pp. 107-121~ 

1925. 

... 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 15 

the Permian. According to Darton/2 unconformities in the Per-. 

mian are found at ·other places in southern New Mexico and in 

Texas. 

STRUCTURE 

No.3 reservoir site occupies the nose of a southeastward-plungmg 

syncline. This structure is not entirely defined within the area 

covered by the geologic map (pl. 1), but an examination of the rocks 

in the adjoining area shows that the Carlsbad limestone member reflects a structure of this type. In the northern part of the area 

shown on the geologic map the Carlsbad limestone dips southeast. 

West of the Pecos, just beyond the area, this limestone dips east. 

South of the reservoir site the same beds generally dip to the north, 

although in places there are notable changes in dip. East of the 

Pecos, in the latitude of the dam site, the rocks dip toward the 

southwest. This distribution of dip and strike defines a structu~al 

basin which resembles in form a basin of deformation, but may have 

been produced by solution of underlying soluble material and consequent settling of the overlying beds. In this basin is the Castile 

formation, most of which, within the reservoir site, has been covered 

by the quartzose conglomerate, the limestone conglomerate, and the 

alluvium. That settlement has played a large part in the formation 

of this basin seems the more likely because of the wide departures 

from the prevailing dip shown in all parts of the structural basin 

by outcrops of the Carlsbad limestone . 

. The Castile formation, in proximity to the river, has been greatly 

deformed, presumably because the soluble material has been dissolved out and the beds above have caved. At a distance of a mile 

east of the river and thence eastward this deformation of the Castile 

strata is not so evident, and it seems likely, therefore, that the greater 

disturbance of the beds immediately adjacent to the Pecos is directly related to a more active ground-water circulation near the 

river. On the other hand, the drainage tributary to Pecos River 

originating from rainfall on the adjacent upland east and northeast of the river is feeble. Whether it reaches Pecos River as surface or as underground streams it is incapable of large or rapid 

erosion. As this condition doubtless existed in the past underground 

solution has not been so active a process in the Castile beds at any 

great distance from: the major drainage line. Pecos River, however, 

is a_competent agent to dissolve and carry off large quantities of material. It has probably for a long time :flowed in or near its present 

channel, partly at the surface and partly as an underground stream. 

Certainly during the long period required for the formation of 

the terraces underlain by the limestone conglomerate the river has 

in this area been confined to a relatively narrow zone on each side of 

,.. Darton, N. H., oral communication, 

94680°-27--2 
16 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

its present channel. The greatest amount of solution should be 

expected near the river, and at a distance the Castile formation 

should contain more nearly its original quantity of salt, gypsum, 

and anhydrite. 

The length of time over which the process of solution has continued is uncertain, but it is important to determine to what extent 

the process is complete in the vicinity of the reservoir site. It is 

evident that some soluble material has been removed from the Castile formation ,.since the quartzose conglomerate was deposited, as 

the conglomerate.has been appreciably deformed, though not nearly 

as much as the underlying Castile strata. The limestone conglomerate, on the other hand, was at no place observed to have been 

affected by this process. These facts suggest that most of the soluble 

material in the Castile formation may have been dissolved out before 

the limestone conglomerate was deposited. A structural unconformity therefore clearly exists between the deformed quartzose conglomerate and the overlying undeformed limestone conglomerate. 

However, three outcrops of gypsum are known along the river bank, 

and gypsum was also found in the test drilling in the Hurd pasture 

and in hole No. 3 drilled in 1925 (p. 35). As a result of the early 

solution of material from the Castile formation caverns and sinks 

were developed, but presumably these have largely been filled by 

caving of the sand, shale, and limestone of the Castile formation 

and by the accumulation of the later conglomerates. The Carlsbad 

limestone is, of course, also soluble. 

INDICATIONS OF LEAKAGE OR WATER-TIGHTNESS 

GENERAL PRINCIPLES 

In order to set forth clearly the aims and purposes of the present 

investigation and to show the grounds for the conclusions that have 

been reached, the general principles pertaining .to the leakage of 

reservoirs are set forth below, followed by a detailed description of 

localities and a critical analysis of the problem of water-tightness. 

Observations of two kinds bear on the question whether a proposed 

reservoir will leak or hold water-(lj observations as to the composition, texture, and structure of the rocks that form the surface of 

the reservoir site or lie close to the surface; (2) observations as to 

the occurrence and behavior of the ground water below the reservoir site and in its vicinity. . 

Rocks that contain only small pores or joints usually form satisfactory walls and bottoms for reservoirs. The moderate amounts of 

water which they allow to percolate out of the reservoir do not 

seriously deplete the available supply. Moreover, such small openings largely become clogged or silted up in the course of time. The 
CARLSBAD ffiRIGATION PROJECT, NEW :MEXICO 17 · 

rocks that are most likely to allow serious leakage are those which 

may have large openings, such as limestone~ gypsum, extrusive basalt, 

and coarse unconsolidated gravel.· · 

Wherever a dam is built across a stream the water level in the 

resulting reservoir is raised above the ground-water level or water 

table. Unless the rocks that contain the reservoir are entirely impermeable, a hydraulic gradient is established between the water in 

·the reservoir and the ground water, and some loss from the reservoir occurs. Under what may be regarded as normal conditions 

before a dam is built, the water table slopes gently toward the 

stream from both sides. Under these conditions the water surface in the reservoir will stand highest. above the water table at the 

lower end. of the reservoir, at both sides of the dam, and will approach the water table at the head of the reservoir. Hence the mo~ 

critical part of. a reservoir with respect to leakage is 'usually at the 

lower end. If a reservoir is located along a drainage line or other 

· depression that lies above the water table the danger of leakage in 

all parts of the reservoir is obviously greater. 

The safest "reservoirs with respect to leakage are those which are 

in relatively tight rocks with only small pores and joints .and which 

lie along main drainage lines toward which the water table slopes. 

These also constitute the most common type of reservoirs. Grt1-vel or 

other permeable alluvium may occur at the dam site, resting on a 

floor of hard, dense rock and confined between walls of the same 

rock. At such a dam site leakage can be prevented by well-known 

engineering methods. Conditions of this type are the most familiar 

to hydraulic engineers; they are the most easily determined and 

evaluated and the most easily controlled. Where there is danger of 

leakage through cavernous rocks in the abutments or in other .parts 

of the reservoir, however, the problem is much more complex, and 

remedial measures are difficult or wholly impracticable. 

Tight rock in the abutments of the dam is of great importance, 

because in this part of the reservoir the. impounded water will 

necessarily stand high above the natural water table. Thus it is 

essential to determine to what extent the anti~ipated hydraulic 

head in the abutments will cause flow through the kind of rock of 

which they are composed. The amount of this flow must be esti., 

mated, and its effect on the stability of the abutments and the 

foundation of the dam must be considered. 

In the rest of the reservoir site the height of the water table and 

the character of the rock are very important. If in any given direction the water table rises to the proposed level of the water 

surface in the reservoir, there is no danger of loss by leakage in that 

direction; on the contrary, the effective capacity of the reservoir may 

be increased by underground storage. Thus the water level may be 
}8 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

raised to the height of the lowest. ground-water divide on all sides 

of the reservoir. This favorable relation to the water table exists 

in most sucC.essful reservoirs, except, of course, at the lower end. 

Observations must therefore be directed to determine the position 

of the water table--whether it slopes toward the reservoir from 

both sides and downstream or whether it lies so low or is so flat 

that it will not form a barrier to the water that may percolate outward through the sides of the reservoir. 

In general, rocks that have small openings, such as granite, clay, 

shale, and also most beds of sand and sandstone, have a low permeability, so that the water table in them has considerable slope 

and conforms in general to the slope of the land surface. Under 

such conditions reservoirs will generally be water-tight or have 

only moderate leakage to some point in the same drainage basin 

below the dam; 

On the other hand, rocks that have large openings, either original 

or secondary, such as cavernous limestone, gypsum, rock salt, extrusive basalt, and coarse unconsolidated gravel, are likely to have a 

flat water table which may not rise much above the ·stream level 

and may even lie below the stream level or slope away from the 

streams. If a reservoir is built where such conditions exist, the 

water may readily escape through the large openings in the rocks, 

may flow long distances underground, and may even make its appearance in a different drainage basin. 

Some of the worst failures due to leakage have occurred where 

the water table stood far below the reservoir site--for example, the 

Jerome Reservoir, in the basaltic rocks of Idaho, and the Hondo 

Reservoir, in the gypsiferous rocks. of New Mexico.13 In the vicinity 

of the Hondo Reservoir the channel of Hondo River is, according 

to available well data, fully 200 feet above the water table. 

DETAILED DESCRIPTION OF THE NO. 3 RESERVOIR SITE 

General relation8.-Pecos River forms the main drainage line of 

eastern New Mexico and its valley lies far below all the adjacent 

country. Numerous wells on the highland east of the Pecos obtain 

water from rocks at elevations considerably higher than the valley. 

Hence, although the rocks of the region dip gently to the east and 

southeast, they apparently do not carry water from the valley of 

Pecos River eastward into another drainage basin. It is practically 

certain that a reservoir l'ocated in the position of the No. 3 site 

would not cause leakage to any other drainage basin. 

However, the rocks of the region include much limestone, gypsum, anhydrite, and salt, in which large openings due to the solvent 

18 Davis, A. P., Irrigation works constructed by the United States Government, pp. 

231-233, 1917. 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 19 

action of circulating ground water may occur. The openings will 

permit rapid flow on low gradients, and therefore a flat water table 

may be expected, with the danger of leakage to some point farther 

downstream. These unfavorable general conditions characteristic 

of the region are, however, not conclusive with respect to the No. 

3 site, for although the McMillan Reservoir suffers excessive losse!i! 

the Avalon Reservoir has no notable leakage. The ground-water 

conditions, governed by the detailed structure and distribution of 

the rocks within and adjacent to the No. 3 site, are the critical factors in regard to the proposed reservoir. 

As shown on the geologic map (pl. 1), a large part of the No. 3 

site is occupied by the quartzose conglomerate and the limestone conglomerate. The indurated parts of these formations, especially of 

the quartzose conglomerate, may contain some large joints, and the 

slightly consolidated parts may grade into permeable gravel; but, on 

the whole, the rate of movement of water through these rocks would 

probably be slow even under considerable head. In the abutments of 

the dam there would probably be some leakage through these conglomerates, but the relatively small quantities of water that would 

be lost here would be recovered in the Avalon Reservoir .. Therefore, 

in so far as these formations occur in considerable thickness in the 

reservoir site, they are favorable to essential water-tightness. 

The alluvium, which underlies the lowest terrace, is a silty deposit with interbedded lenses of gravel. It will retard leakage but 

will not prevent the formation of sink holes if it is underlain by 

either limestone or gypsum that contains large crevices. 

The danger of serious leakage therefore lies essentially in the 

Carlsbad limestone, which crosses the river in the spring-fed stretch, 

and in the gypsum, red beds, and breccia that lie both above and 

below this limestone-the Castile formation above and the Seven. 

Rivers gypsiferous member of the Chupadera formation below. ~he 

characteristics of these rocks and their relation to the movement 

of water are considered in detail in the following paragraphs, in 

which also the essential facts that bear on the position and form of 

the water table are set forth. 

Seven Rivers m'ea.-A number of deep pool springs occur in the 

channel·of Seven Rivers a short distance upstream from the reservo~r site, at an elevation of about 3,275 feet. In July, 1925, the water 

from these springs flowed down Seven Rivers to the highway crossing, where it sank into the channel g.ravel. No ground water appeared at the surface between the highway crossing and the mouth 

of Seven Rivers. South of Seven Rivers and west of the reservoir 

site (apparently in the NW. 1,4 sec. 17) is Nelson's Spring, which 

in past years has irrigated considerable land but which in July, 

1925, was dry, with the water level at least 8 feet below the sur-
20 CON TRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

:face. North and west o:f this dry spring there are flowing artesian 

wells; south and southwest o:f it gypsum or gypseous soil are at 

the surface, and there are numerous sink holes. No information 

could be obtained in regard to ground water in the area lying south 

of this dry spring and west o:f the large spring (the largest o:f the 

group known as the Major J ohnson Springs) on P ecos River in the 

3,300 

3 ,280 

3 ,260 

- -

3 ,220 ---"' !----OJ ..1 

1&1 

> Ill • J 3,200 

( 

Ill 

(f) 

kJ 3 ,180 

> 0 

Ill 

< 1- 3 ,160 

Ill 

Ill 

... 

-

-

_ , 

~ 

(j 

~ (j 

"' ~ .., ... 0 .., 

~----~ 

1- ·- ·-

~ r ---- 0 

- " 

3 ,100 -

3,080 )-

,_ 

3 ,().40 

--

:-------

't 

r--- es 

~ 

... 

.., 

Q 

~ 

1- -

- -

1---

Flow line oFp roposed I?D.SerYoir No. 3 (S,2601eet) 

--- Statiche<YdoFwa terinho/e No. E!(S,Z"'SFeet} 

-

---Static helldof'watllrini>CJ I,. No (:J,2 Z~t 

- El. ~:;'feteN,'~ t:~7JYJ/F'f:e"/J t of' -

-

... 

- El. oF water in Pecos t~r at Clam ~ite No.3 

(about .3,1.90 reet) 

---

~ StBtic head oF upper water in hole No.I (.3)7/J leetJ El. or highest water sv rfDce in Av,/on Res.(.J,177 '1ee<) 

1---L e vsl to whiCh W8 ter dra/ntJa' out or hoi, No.3 

{.3,168 feet) r---. - El. of' lowesfj],':{,Jtj,'iJ{fg~JcBervoir 

r---

1- - S tatic head or lower water in hole No.I {3,130 leet} 

~ r---

~ 1-- -St e tic head orwatBr io Angel well in D•88er0tvw 

{.3, Ill 7/:et) 

~ I=-=· Bottom oF hole No.3 {3,099 f'Bet) 

r--

1----

fiD"pth II uncerlllt'n 

'• . 

F I GOnE 2.-Wat er levels in test holes drilled in 1925, in relation to other water levels in 

or near the No. 3 reser voir site of the Carlsbad irrigation project, New Mexico 

NW. * sec. 21. Unless very abnormal ground-water conditions 

exist west o:f P ecos River the water that seeps into the ground in 

this locality should go into ground storage and should not be lost to 

the reservoir. Test hole No. 4 was drilled in 1925 at about the 3,260-

foot flow line, in the NE. * sec. 20, about half a mile west o:f the 

large spring on the Major Johnson place. (See pp. 37- 39, pl. 1, and 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 21 

figs. 1 and 2.) This hole was drilled to determine whether the 

ground water under this area drains toward Pecos River, as it 

should, or drops abnormally toward the south. The hole was 

drilled to a depth o£ 132 feet and encountered much water below a 

depth of 28 feet. The static head of the water in the hole is 28 feet 

below the surface, or at an elevation of 3,232 feet, which is slightly 

above the water level of the Major Johnson Spring and indicates 

a normal ground-water leyel. 

L1f c.ll!ill(J;n spillway area.-The north spillway of the McMillan· 

Reservoir enters the reservoir site from the north and discharges 

into Seven Rivers about at the north line of sec. 16. (Fig. 1.) No 

springs were found in this spillway .. It passes over the Seven 

Rivers gypsiferous member. On the east side of the spillway are 

several large sink holes in gypseous red beds, which probably mark 

the course of an ancient underground channel of Pecos River. The 

general surface ;tt this locality is a little above the 3,260-foot flow 

line, but the sink holes extend down below that level. This area is 

obviously not water-tight, but as it lies at the upper end of the 

reservoir there is apparently no direction in which the water could 

escape without returning to the reservoir farther downstream. 

llfclJ.fillan Reservoir area.-The history of the McMillan Reservoir 

has been briefly sketched on page 4. The area of the reservoir is 

underlain by the red beds and gypsum of the Seven Rivers gypsi:ferous member, covered over most of the floor by alluvium and recently 

accumulated silt. The spillways of the McMillan Reservoir are at 

an elevation of about 3,286 feet. The bottom of the reservoir has 

been raised by silting, so that at the dam it lies about 20 feet below 

the spillways and in most parts of the reservoir only 10 feet below 

this level. 

Yet the waves from this shallow body of water, which exists for 

only part of the year, have eroded up to the flow line the soil that 

once covered the thick beds of gypsum that form the southeast 

wall of the reservoir. In the massive beds of gypsum exposed by 

this wave work there are large rsolution channels that, when the 

reservoir is full, take in water in large quantities. The silt floor of 

the reservoir at some distance from the shore contains numerous and 

conspicuous sink holes, which obviously drain downward into crevices in the underlying rock. The leakage through the channels on 

the shore and the sink holes is large and in 1904 was estimated at 

about 10,500 acre-feet a month, or a continuous flow o; about 175 

second-feet. Since that date many measurements and estimates of 

leakage have been made, and the highest estimated rate when the 

reservoir is full is more than 300 second-feet. 

So large a leakage· appears to indicate that prior to the construction of the reservoir large solution channels had been developed 
22 CONTRIBUTIONS TO. HYDROLOGY OF UNITED STATES, 1926 

that at one time or another carried all or part of Pecos River underground from the southeast side of the present reservoir to the vicinity 

of the Major Johnson Springs. 

In 1909 an embankment was constructed to isolate some of the 

largest sink holes, but it has not been very effective. Owing to the 

caving of the underlying material the embankment itself in some 

places has sunk, and large leakage below it is now taking place. 

The originally inconspicuous channels p.orth of the embankment 

appear to be carrying progressively larger quantities of water. 

The serious leakage from the McMillan Reservoir takes place 

through solution passages in the Seven Rivers gypsiferous member, 

and the water returns to Pecos River within No. 3 site, as described 

more at length in the next section. These rocks crop out only in 

the norther.n and shallow part of No. 3 Reservoir and pass southward under the Carlsbad limestone at considerable depth, and it is 

entirely possible that at that depth they are tigP.t and free from 

cavities. Thus, the fact that leakage occurs from the McMillan 

Reservoir does not necessarily indicate that leakage would occur from 

No. 3 Reservoir, but it seems likely that the opening of solution 

passages in the Seven Rivers gypsiferous member furnishes an 

analogy from which a similar process in the gypsum of the Castile 

:formation at the south end of the No. 3 reservoir site may be predicted. 

Stretch between McMillan Reservoir and mouth of Seven Rivers.-

From the McMillan Dam to the mouth of Seven Rivers, a distance 

of about 3 miles, the limestone breccia of the Seven Rivers member 

crops out at many places in the channel and banks of Pecos River, 

chiefly on the southeast side. The breccia doubtless rests on red 

beds and gypsum of the Seven Rivers member, but no red beds or 

gypsum are exposed along the river. The breccia is overlain by 

the Carlsbad limestone. In the vicinity o:f the railroad the contact between breccia and overlying limestone is well above the flow 

line o:f the proposed reservoir, but downstream it gradually descends, 

until below the mouth of Seven J;l.ivers the limestone appears in the 

river channel. The outcrops of breccia between the railroad and 

the mouth of Seven Rivers appear firm and tight and show no openings that would be likely to cause leakage. There are no springs or 

seeps in this stretch of the river, but salt grass occurs on the banks 

and luxuriant mesquite trees on the low alluvial terrace, and the 

presence of these plants suggests that a water table :from which 

they obtain their water supply exists at no great depth. Careful 

inspection revealed no indication that river water has escaped or 

is escaping into the rock or into the alluvium that underlies the terrace and mantles the rock in most places. Along the south spillway of the McMillan Reservoir there is a large. :fresh artificial ex-
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 23 

posure of the breccia. Here it contains many crevices and some 

rather large solution channels that could doubtless carry much 

water. · 

Spring area.-Numerous springs issue along the banks and in the· 

bed of Pecos River for a distance of about llh miles in a stretch 

beginning in sec. 16, a short distance downstream from the mouth 

of Seven Rivers, and extending about to sec. 2'7. The largest springs 

arise in the bed of the river, near the west bank, on the Major Johnson place, in the NW. ~ sec. 21. Smaller springs occur along the 

west bank for some distance, and many springs, some of them large, 

occur on the east bank. A minimlim discharge of about 40 secondfeet for the entire group has been estimated from numerous measurements of the flow of the river taken simultaneously above and below 

the springs. Most of the water doubtless issues from the large 

springs in the bed of the river, but even in a period of nearly minimum discharge in July, 1925, some of the other springs yielded 

close to 1 second-foot each. 

The extensive and careful investigation of these springs by 

Messrs. Foster and Yates shows conclusively that they are supplied chiefly by the water that leaks out of the McMillan Reservoir. When the water accumulates in the reservoir the discharge 

of the springs increases greatly, the increase becoming noticeable 

about five days after the reservoir begins to fill. Measurements 

made in 1921 when the reservoir was full showed a discharge from 

the springs of 272 second-feet. As soon as the reservoir is empty 

the discharge begins to decrease, and, according to rough •estimates 

by Bonstedt and Dehler, it declines in the course of about a month 

to the minimum of approximately 40 second-feet and thereafter continues at a fairly uniform rate until leakage from the McMillan 

Reservoir again augments the flow. This lag indicates that the 

water flows through a considerable area of cavernous rock in which 

it is temporarily stored. 

The following table showing the quantities of water that have 

been lost by leakage and that have been recovered through the 

springs has been taken from the report by Bonstedt and Dehler: 

Leakage from McMiUan Reservoir compareit with discharges ·of the entire 

group of the Major Johnson Springs, in acre-feet 

Average, 

1912-1915 1918 Average, 1921-22 

------------------------------. 

Loss from McMillan Reservoir------------------------------------------_ 140,000 72,690 134, 500 Discharge of springs ______________ -----___________________________________ 100, 000 74, 000 164, 400 

Bonstedt and Dehler assumed that 40 second-feet, or 29,000 acrefeet a year, of the spring discharge is derived from other sources than 
24 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

the leakage out of ~he McMillan Reservoir, and estimated that 70 

per cent of the leakage reappears in the springs and 30 per cent does 

not reappear anywhere above the Avalon Dam. However, Foster 

and Yates, on the basis of recent careful work, are of the opinion 

that substantially all the leakage from the McMillan Reservoir reappears in the springs. Obviously the discharge of this leakage into 

the No.3 reservoir site is a favorable condition. 

The spring area coincides almost exactly with the belt in which 

the Carlsbad limestone crops out in the channel and banks of Pecos 

River. The water from the reservoir, however, is discharged into 

the gypsum beds, and it probably flows through openings in these 

beds or in the breccia nearly to the springs. Though creviced and 

permeable where the springs rise through it, the Carlsbad limestone 

or thin shale beds in the base of the Castile formation apparently 

serve as a barrier, directing the water back to the river in the spring 

area instead of leading it to the area of low water table to the south. 

The springs issue at elevations of about 3,220 to 3;230 feet, or 30 

to 40 feet below the 3,260-foot flow line. When the proposed reservoir is full the back pressure on these springs will fill the underground channels that lead to them and will back up the water in 

these channels nearly to the McMillan Reservoir. Unless the system 

of underground channels that conveys the water from the McMillan 

Reservoir to the springs is essentially tight under the head produced 

by a water level of 3,260 feet and constitute&, a closed system of pipes, 

the water will escape underground in some unknown direction, the 

flow of ~e springs will be reversed, and the ·openings will form 

effective conduits for serious leakage. These underground channels 

presumably lie on a northeast line between the springs and the southeast border of the McMillan Reservoir. As the area to the south of 

this line is underlain chiefly by soluble rocks consisting largely of 

gypsum and salt, there is evidently danger that similar channels 

exist through which the water might escape unless the water table 

in this area were up to about the level of the proposed flow line. If 

water were lost into this area there is no assurance that it would 

return to the river above the diversion at the Avalon Dam, for it 

might continue southward through gypsiferous beds or limestone to 

the vicinity of Carlsbad. The possibility of escape from the system 

o£ underground channels leading from the McMillan Reservoir to 

the Major Johnson Springs constitutes one of the most serious 

dangers of leakage from the proposed reservoir. If the water did 

not return above the Avalon Dam, this leakage might even render 

the proposed reservoir worthless. 

The somewhat indefinite information in regard to the wells sunk 

at the Oriental Cement Works, in sec. 18, T. 20 S., R. 27 E., i~ not 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 25 

encouraging. This information was furnished from memory by 

Mr. F. E. Hubert, manager of the works, and is as follows: The first 

well, situated west of the railroad, was 3 inches in diameter and 

360 feet deep, had a water level about 320 feet below the surface, 

and when pumped with a windmill yielded an unfailing supply of 

water of bad quality. The second well, drilled in 1912 at the boiler 

house, was 8 inches in diameter and 600 feet deep. It struck gas 

but no water. The third well, drilled in 1913 and now in use, is 

a short distance east of the mill, and the elevation of the top of the 

wooden block at this well was determined: by instrumental leveling 

to be 3,308 feet. The well is 3 inches in diameter and 185 feet 

deep, contains-40 to 100 feet of water, and has never been dry. 

Test hole No. 3, drilled in 1925 in the NE. 1;4 sec. 26, T. 20 S., 

R. 26 E., at an elevation of 3,305 feet, was carried to a depth of 206 

feet without finding water. Water that was poured into the hole 

drained out to a depth of at least 137 feet, or to an elevation of 

3,168 feet, which is about 90 feet below the high-flow line of the 

proposed reservoir, 55 feet below the river level due west of the 

test hole, and 20 feet below the river level at the dam site. (See pp. 

35---37, pl. 1, and figs. 1 and 2.) 

Reservoir site below spring area.-The lower half of the reservoir 

site, below the springs, is largely underlain by rather thick deposits of the quartzose and limestone conglomerates and the Recent 

alluvium. On the west side these formations rest mainly on the 

Carlsbad limestone ; on the east side they rest on the Castile formation, which in turn rests on the limestone. Beds of the Castile formation crop out along the river, below the conglomerate beds, as 

shown on the geologic map. The quartzose conglomerate and underlying breccia of the Castile formation are exposed in several 

localities on the east side of the river in bold and rugged outcrops 

that attract attention from a distance. They form a confused mass 

of rock with cavities due to differential weathering. Careful examination, however, revealed no openings that are taking in river 

water or that appear to be sufficiently continuous to act as conduits 

:for water. 

The normal sequence of the Castile formation includes thick beds 

of gypsum, which are obviously unfavorable to water-tightness, but 

not much gypsum is visible within the reservoir site. In this respect 

the No. 3 site compares favorably with the McMillan Reservoir, 

where extensive outcrops of gypsum occur below the flow line. The 

scarcity of gypsum at the surface at the No. 3 site is believed to be 

due partly to its removal by solution in past ages and partly to its 

being covered by alluvium and debris, in contrast with the hard 

conglomerate, limestone, and breccia, which crop out in bluffs. A 

small outcrop of gypsum was observed in a gully near the middle of 
26 CONTRIBUTIONS ·TO HYDROLOGY OF UNITED ST:A.TES, 1926 

sec. 35, T. 20 S., R. 26 E., and small outcrops are report~d by Richardson near the line between sees. 35 and 26, in the same township, and 

in a low bluff in theW.% NW. % sec. 6, T. 21 S., R. 26 E. 

In order to obtain information on the occurrence of gypsum beneath this part of the reservoir site 11 holes were drilled with a 

core drill in 1905 in what is known as Hurd's pasture, in or near the 

NE. % sec. 27, T. 20 S., R. 26 E. These holes ranged in depth from 

19 to 96 feet. They encountered a great variety of materials, including much sand, gravel, and clay, and the sections of the different 

holes were very dissimilar. The largest amount of gypsum was 

found in hole No. 7, drilled on the 3,240-foot contour about onethird of a mile from the river, in the ~E. % NE. % sec. 27. This 

hole was carried to a depth of 96 feet and showed 59 feet of gypsum 

interbedded with shale. In test hole No. 3, drilled in 1925 about 1 

mile farther east, much gypsum was also encountered (p. 35). 

Condensed log of test hole No. 7 dr~llea in Hurd's pasture in 1905 

Thick- I Depth ness 

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

Silt _______ ----- _______________________________________________________________ • ______ _ 

Brown clay---------------- __ ------------------ ____ -------- ______ --------------------- Soft gypsum rock. _____ ---------------------- __________ ----- _______ ------ ____________ _ 

Gypsum·----------------------------------•------------------------------------------ , Red clay shale containing small veins of gypsum _____________________________________ _ 

Red sandy shale •. ------------------------------ _________________ ------- _____________ _ 

Gypsum------------------------------------------------------------------------------ Gypsum mixed with shale----------------------- _____________________________________ _ 

Sandy shale; "very little water returns"---------------------------------------------- Shaly sandstone ________ ------------------------- _________________________ ------- _____ _ Limestone ___________________________________________________________________________ _ Brown sandstone with partings __ --------- ___________________________________________ _ Limestone with dark shale.-------- __________________________ ------ _____________ -----_ 

Feet 4 

2 

1 

19 

5 

2 

7 

25 

22 

5 

1 

1 

2 

Feet 

4 

6-

7 

26-

31 

33 

4& 

60 

87 

92: 

93 

94 

96-

For some distance downstream from the spring area luxuriant 

mesquite and salt grass suggest the presence of the water table near 

the surface, but in the lower part of the reservoir site there is a notable scarcity of vegetation that indicates shallow water, which is possibly due to the stony character of the soil as well as to the absence 

of ground water. Rocky Arroyo, which drains a large region, is dry 

and without indications of ground water in the lower part of its 

course, even to its mouth. To determine the ground-water conditions 

west of the river in this part of the reservoir site, test hole No. 2 

was drilled in 1925 in sec. 2, T. 21 S., ~· 25 E., about 11,4 miles west 

of Pecos River and about 1,000 feet north of Rocky Arroyo, at an 

elevation of 3,260 feet. ~his hole is 100 feet deep and struck large· 

supplies of water at depths of 25 and 65 feet. The water from 

both horizons rose to a level' of 15 feet below the surface, or to an 

elevation of 3,245 feet, which is about 20 feet above the level of the 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 27 

Major Johnson Spring and about 40 feet above the river level at the 

mouth of Rocky Arroyo. (See pp. 33-35, pl. 1, and figs. 1 and 2.) 

At least eight test holes had been sunk at the No. 3 dam site prior 

to the present investigation-six in 1905, ranging between 20 and 

61 feet in depth, and two in 1922, both of which were 125 feet deep. 

The sections of these holes, with reference to the surface, river level, 

and elevation above sea level, are given in Plate 2, taken from the 

Bonstedt and Dehler report. The available logs contain several entries concerning porous or honeycombed limestone in which the 

water that was used in drilling was lost. In hole No. 5 of 1905, 

which was 61 feet deep and was started at an elevation of 3,198 feet, 

or barely 10 feet above river level, the water was lost at a depth of 

32 feet, and porous limestone was reported between depths of 28 and 

36 feet and again at 47 feet. In both of the holes put down ,in 1922 

honeycombed limestone wasreported at various depths (pl. 2). The 

log book shows that in No. 1, which was started at an elevation 

of 3,197 feet, water was lost in drilling at depths of 24, 29, 42, and 78 

feet, and perhaps at lower levels. The following statement in regard 

to these holes was made by Bonstedt and Dehler, who were associated 

with this work: "Drilling developed the existence of extensive bodies 

of cavernous limestone in which loss of water was found to be excessive." 

In order to obtain more definite information as to the groundwater conditions at the dam site a test hole (No. 1, pp. 30-33, pl. 1, 

figs. 1 and 2) was drilled in 1925 at an elevation of 3,202 feet. It 

extends to a depth of 152 feet. The .first ground water was struck 

between depths of 24 and 26 feet and stood 24.5 feet below the surface, or at an elevation of about 3,176 feet, which is 10 to 15 feet 

below the river level at the dam site. Water struck at some greater 

depth in this hole, probably between 7 4 and 76 feet, was found ~ 

have a static head 72 feet below the surface, or at an elevation of 

3,130 feet, which is about 60 feet below the river level at the dam 

site. 

Dagger Drl1JW.-Dagger Draw drains into Pecos River from the 

east, as shown in Figure 1. It reaches the river about 2 miles 

downstream from the No. 3 dam site and near the head of the 

Avalon Reservoir. There are three drilled wells in this draw. 

The Angel well, near the line between sees. 28 and 29, T. 20 S.~ 

R. 27 E., is said to be 180 feet deep. The reference point (the top 

of a heavy block of wood 18 inches above the surface) is at an 

elevation of 3,173 feet. On July 27, 1925, the water level in the 

well stood 62.2 feet below the reference point, or at an elevation 

of about 3,111 feet. This is about 80 feet below river level at the 
28 CONTRIBUTIONS TO HYDROLOGY OF UNITED STaTES, 1926 

No. 3 dam site and also far below the bottom of the Avalon ReservOir. 

Avalon Reservoir.-The location of the A val on Reservoir is shown 

in Figure 1. The bottom of the reservoir is at an elevation of 

about 3,158 feet and the spillway at 3,177 feet. Its capacity is 

about 7,000 acre-feet. At the dam there is massive limestone underlain by breccia. Small quantities of water are seeping through 

the joints in the limestone and from more irregular cavities in the 

underlying breccia. Farther up the reservoir is underlain by alluvium, conglomerate, and red beds similar to those found in the 

No. 3 site. As this reservoir is effectively tight, it indicates similar 

favorable conditions for the proposed Reservoir No. 3.· However, 

on account of its low head of water and small size the two are 

not wh9lly comparable. The leakage at the dam under a 10-foot 

head indicates that the leakage through the same rock under a 

70-foot head would be considerable and perhaps dangerous. Certainly extensive grouting at the dam would be necessary. 

Area between Avalon Reservoir and Oarlsbad.-When no water 

is released at the Avalon Dam only a small amount of water appears in the channel of Pecos River for a considerable distance below 

the dam, but before reaching Carlsbad the stream increases tQ 

about 80 second-feet, most of this water being supplied by springs 

between the flume, in the SE. 1,4 sec. 26, T. 2i S., R. 26 E., and the 

Tansil power dam. (See fig.· 1.) The river level is about 3,120 

feet above sea level at the flume and about 3,100 feet at Carlsbad. 

It appears evident that this water is ground water from distant 

sources and not seepage out of the canals or return water from 

irrigation. Several second-feet are contributed to this flow by Carlsbad Spring, which is on the west bank of the river just below the 

flume. It is not possible with the information at hand to say just 

where the water from Carlsbad Spring or the other springs in this 

vicinity originates. In aU probability at least part of it is contributed 

by the great catchment area to the west. On this supposition this 

water, and particularly that from Carlsbad Spring, must pass 

through the upfold of the Carlsbad limestone that lies to the west. 

However, it is fairly certain that in past ages the water of Pecos 

River has drained in part through several underground channels, 

and it is entirely reasonable to suppose that the springs in the river 

bed above Carlsbad are supplied in part from the north through 

such underground channels. Either postulate involyes the assumption of large underground channels in the Carlsbad limestone, which 

superficially presents the appearance of being a tight rock. 
U. S. GEOLOGICAL SURVEY 

32 7 

32 s 

'"' ...132 

w 

> w 

..J 

<( 

w 

1/) 

11.1 

~ Ill 

<t 

1-31 

w 

w 

LL. 

.31 

so 

00 

I~ 

0 

"" '-....... !'--... ........... 

C\1 

0 

-

bl 

0 

:I: 

500 

WATER-SUPPLY PAPER 580 PLATE 2 

I 

I 

/ 

!"-.... I lli~e I 

SCJndand ~el I 

=:::::::::::::: =· 4>1 "' <Ditl1V r----._ o' ol o, '

1 6 o1 

Sandstone and conglome!"'lte :Zl z: z, :2:2: :ZI I 

Limestone conglomerate lA J 

Clay 

noneycorr lbeO It m e::.tone Clay 

Clav 

Honevcorr bed limestone 

Honeycombed 

limestone 

Red clay Honeycon bed limestone 6 

Cla.Y 2 

~oneycon bed lime~tone w 

Red sand ~stone 0 ll..lay 

l Gr.:w s- I.J~+A-d :X: I C. 

HoneycOJ bed li me~tone ·Limestone 

210_0 __ 1800 1900 - 2000 

HOLES DRILLED 1905 

2200 FEET 

~~% I limestone f.lioneycombed 

limestone 

Sandstone 

Hard limestor~ 

1000 1500 2000 2500 FEET 

HOLES ORI LLED 1922 

\ I ' b 

t I 

I 

I .~ I 

I 

I ~ \ 

I 

I 

I .. . •I · 

I 

I 

I II) ' I ~ ' ~ I I c.> I \ I 

~ I I 

I I I 

TOPOGRAPHY ALONG LINE OF PROPOSED DAM AT NO. :l DAM SITE OF THE CARLSBAD IRRIGATION PROJECT, NEW MEXICO, AND LOGS OF TEST HOLES DRILLED IN 1905 

AND 1922 

94680°- 27. (Face p. 28. ) 
CARLSBAD IRlUGATION PROJECT, NEW MEXICO 

RESULTS OF TEST DRILLING 

HISTORY AND PURPOSE OF TEST WELLS 

29 

On August 3, 1925, after the field work for the present report had 

been completed, the drilling of four test holes was recommended, as 

indicated in a letter to Mr~ L. E. Foster, superintendent of the 

Carlsbad project. This recommendation was .made in order to 

determine more definitely the position of the water table and the 

ground-water conditions in the reservoir site and to ascertain whether 

there is unsaturated cavernous rock in the reservoir site below the 

level of the river. The letter written to Mr. Foster is as follows: 

As I suggested to you in our conversation, it will be necessary to obtain some 

information as to the position of the ground-water table in and near the 

proposed Reservoir No. 3 before a recommendation can properly be made in 

regard to this project. For this purpose four test holes should be sunk at 

the following locations : · 

No. 1. At the dam site, as near as possible to hole No. 5 drilled in 1905 and 

No. 1 drilled in 1922. 

No.2. In sec. 2, T. 21 S., R 25 E., north of Rocky Arroyo, about 11~ miles up 

the arroyo from its mouth and about one-fifth mile north of the arroyo ; about 

at elevation 3,260 feet. 

No.3. Near the northwest corner of sec. 36, T. 20 S., R. 26 E. 

[This hole was drilled about a mile north of this location, in the NE. lA, sec. 

26, T. 20 S., R. 26 E.} 

No. 4. On or near the NW. :JA, NE. :JA, sec. 20, T. 20 S., R. 26 E., one-half to 

three-fourths mile west of the large spring on the Major Johnson place, at the 

3,260-foot elevation or slightly higher. 

These holes can be drilled with an ordinary fairly heavy portable solid-tool 

percussion rig, such as is used in drilling water wells a few hundred feet deep. 

The boles should preferably be 6 inches in diameter and should not be less 

than 4 inches in diameter at the bottom. They need not be cased unless it 

should be found necessary to use casing in order to sink the hole to the 

required depth. The holes should be not less than 150 feet deep and should 

be carried to a depth of as much as 250 feet if this appears necessary to 

determine conclusively the ground-water conditions. 

The driller should keep a log and should save samples of drillings every 20 

feet, or whenever the formation changes. The purpose of this drilling is, 

however, not primarily to determine the nature of the rock but to ascertain 

the position of the water table and the ground-water conditions in relation 

to the river and the proposed reservoir. 

At intervals of 20 feet, or whenever the formation changes, the following 

tests should be made under the personal supervision of an engineer of the 

Bureau of Reclamation: 

After the tools have been withdrawn and the hole has been cleaned out, 

determine whether the hole is still dry or whether ground water has been 

struck. 

If the hole is still dry, run water _into it to determine whether the rock is 

tight or will take in water. The water for this purpose can probably be sup-
30 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

plied most conveniently from a tank wagon. If the hole takes water, make and 

record observations as to the quantity of water put into the hole and the time 

required for it to escape. 

Obviously if the rock is tight and not water'bearing, it will be desirable to 

continue drilling until permeable rock is struck which will either take water 

or yield water. 

After the ground water has been struck, the depth to the water level in the 

well should be measured, and then water should be withdrawn for some time 

with a good bailer and observations should be made as to length of time the 

bailing was continued, rate at which water was withdrawn, and temporary 

draw down in the water level produced by the bailing. Drilling should, if 

possible, be continued to a considerable depth after water has been struck, and 

tests should be made at intervals of 20 feet, or whenever there is a notable 

change in the conditions. 

The elevation of the top of the hole should be determined by instrumental 

leveling. Depths of the hole and depths to the water level in the hole should 

be measured from the same reference point. The elevations should, of course, 

be referred to the same datum as was used on the contour map of the reservoir 

site. 

The elevations should be determined of the Angel well, situated west of the 

railroad in the Dagger Draw, and the well at the cement mill at Globe station. 

The reference point of the Angel well is the top of the wooden block that rests 

on the casing and supports the pump pipe. As soon as possible the depth to the 

water level in the mill well should be measured from a reference point whose 

elevation is determined .. 

Drilling operations were begun September 27, 1925, and were completed November 22, 1925. The data obtained from the test holes 

are given on the following pages, condensed from a manuscript 

report prepared by Mr. Yates. A log of the materials encountered 

in the holes was kept by the driller, and samples saved by him have 

been examined by Mr. Bryan. All the tests were carefully supervised and observed by Mr. Yates. The measurements of depth to 

the water level were made with a float. and steel tape. 

RECORDS OF TEST HOLES 

By J. R. YATES 

[Descriptions of samples and geologic comments by Kirk Bryan} 

:HOLE NO, 1 

Location, on the middle line of the No. 3 dam site, 120 feet south of the river 

bank. 

Depth, 152 feet. 

Drilling begun October 8, 1925 ; completed October 18, 1925. 

ElevatioP. of top of hole, 3,202 feet ; of bottom, 3,050 feet. 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 31 

RecfN'd of hole No. 1 

[Ailuvlnm, 0 to 42 feet;· Carlsbad limestone, 42 to 152 feet; cavernous to depth of 

106 feet] 

Driller's log 

Materlsl 

Soil, gravel and boulders ••• 

Red clay------------------- Sand and graveL _________ _ Boulders __________________ _ 

Limestone and sand _______ _ 

Limestone, honeycombed .. Yellow clay---------------- Limestone._. ______ --.. _ ••. 

Brown ahsle ______________ _ 

Blue shsle _________________ _ 

Limestone, honeycombed •. Gray shsle .•.•..••••.•.. "--

Limestone ••• --------------

Yellow clay.: _____________ _ 

Limestone. __ -------------- Yellow clay _______________ _ 

Limestone .•.. __ ----------- Yellow clay---------------- Limestone .• ------------ __ _ Yellow clay _______________ _ Blue shsle ________________ _ 

Limestone. _______________ • 

Blue shale •...• --------------

Blue limestone, hard ••••••• 

Feet 

20 

4. 

2 

10 

6 

20 

2 

6 

2 

3 

2 

5 

3 

2 

3 

3 

3 

1 

5 . 

6 

6 

~ 

32 

. Character of sample 

Material Depth 

Feet Feet 

{

Brown aandy loam..-------------------------- o - 7 20 Compact brown aandy clay___________________ 7 - 16~ 

Compact clayey gravel with limestone pebbles. 16~- 20 

24 Red aandy claY-----------"------------------- 20 - 24 

26 }No samples taken ):>ecause cuttings were lost ------------ 36 In open ground. 42 Pinkish silt containing a few pebbles, both 36 - 40 • siliceous and limy, also decayed vegetation. 62 Red clay with limestone fragments____________ 41 - 62 64 Yellow sandy clay _____ c______________________ 62 - 64 

69 Yellow clay and comminuted weathered and 64 - 67 

porous limestone. 71 Comminuted fragments. of red shsle, lime- 67 - 71 

74 stone, and limestone J:?reccia. 

~~ }Buff sandy claY-----"·-·---------------------- 68 - 79 

84 Comminuted yellow, pink, and gray lime- 79 - 83 stone. 89 Comminuted limestone fragments in rusty 83 - 8Q 

yellow clay. 

~ !Yellow claY----------------------------------- 89 - 97 

101 Comminuted limestone in rusty yellow clay__ 97 .-105 

106 

112 Comminuted limestone, fragments gray, 105 -112 rusty, etc. 118 Comminuted limestone _______________________ 112 -118 

120 Comminuted limestone and gray clay _________ 118 -123 

152 {~~!~;~~~~~~~:~~~i~~;£~==ir~~~a=~£i=~i= m ~i~ varied color. 

It is obvious from a consideration of this log that the hole penetrated 

alluvium and possibly part of the limestone conglomerate for 42 feet. The 

lower part of this material is sufficiently impervious to prevent downward 

seepage from the river and to support the perched water table having a water 

level.of 24 feet 6 inches that is described below, under the tests. Below 42 

feet the hole entered the Carlsbad limestone, which for 64 feet is weathered and 

apparently contains caverns .full of clay. The cavernous condition of the limestone explains the discrepancies in the logs of adjacent holes drilled in 1905 

and 1922 (shown diagrammatically in pl. 2). Below 106 feet the Carlsb11d 

limestone is but little affected by solution and doubtless forms the tight flo1•r 

which supports the water table that, as shown in the tests, has a level of 72 

feet below the surface. The cavernous condition of the upper part of the 

limestone at this place would be a menace to the reservoir, for when it was 

full the movement of water through this area would . be greatly increased. 

The easily eroded clay .would be readily washed out of these caverns, leaving 

large openings for the passage of water v.nder the dam. 

First water test, October 10: Depth of hole, 20 feet; diameter of hole, 10 

inches; casing, none; water level, none, dry hole. Water was poured into the 

hole, and the depth to the water level in the hole was then measured. At the 

first measurement the water level stood 7 feet below the surface, and one hour 

later it stood 8 feet 6 inches below the surface. Eight-inch casing was theu 

set to the depth of 20 feet to prevent caving, and drilling was resumed. The 

94680°-27--3 
32 CONTRIBUT'IONS TO HYDROLOGY OF UNITED STATES, 1926 

first ground . water was struck between 24 and 26 feet, but drilling was continued to 36 feet to obtain a sufficient depth of water to submerge the bailer. 

Second water test, October 11 : Depth of hole, 36 feet ; diameter of hole, 

10 inches; casing, 8-inch to 20 feet; water level, 24 feet 6 inches below surface. 

A test was made with a bailer having a capacity of 19 gallons. In a period 

of 10 minutes the baUer was filled and removed twenty-two times, giving a withdrawal of 418 gallons, or about 42 gallons a minute. The water level was 24 

feet 6 inches below the surface before the bailing was begun and was found 

to be at essentially the same level immediately after the bailing was stopped. 

Drilling was continued to 40 feet, and 8-inch casing was inserted to this 

depth. The drilling was then carried to 65 feet, when it was found that the 

water had not been successfully cased oil. Casing 6% inches in inside diameter 

was inserted to 65 feet and was set on limestone below 2 feet of impervious 

yellow clay, but· this casing also failed to shut out the water. Drilling was 

resumed, and the casing was carried to 103 feet. About 10 feet of red impervious clay was placed inside the casing. Later the casing was driven to 

107 feet, the clay was drilled out, and the drilling was carried to 111 feet. 

Third water test, October 16: Depth of hole, 111 feet; diameter of hole, 

6% inches; casing, 8-inch to 41 feet, 6%-inch to 107 feet; water level, 24 feet 

6 inches below surface. The well was bailed for 15 minutes, and during that 

period the water level in the hole was lowered from 26 feet 4 inches to 108 feet 

below the surface. One hour later the water level still stood 108 feet below the 

surface, indicating that the outside water was completely cased oil. Drilling 

was continued to 118 feet, when the water rose in the hole to the old level of 

24 feet 6 inches below the surface. Drilling was continued to 131 feet, the 

8-inch casing was pulled, and more clay was placed above the packer at 107 .feet. 

Fourth water test, October 17 : Depth of hole, 131 feet; diameter of hole, 

6% inches; casing, 6%-inch to 107 feet; water level, 24 feet 6 inches below 

surface. Before the bailing was begun the water .level stood 26 feet 4 inches 

below the surface. The balling was continued 10 minutes, and the water 

level was thereby lowered to 75 feet below the surface. Four and a half hours 

later another measurement showed that the water level had gone down to 76 

feet 6 inches. This test was made to ascertain the leak around the packer set 

at 107 feet, as it was thought at the time that the water came from the 25-foot 

level. It was not thought advisable to ball out the water below the 75-foot 

level on account of the pressure of the outside water on the packer. Later 

tests, however, seemed to show that this water came from 72 feet and that the 

water that was lost was absorbed in the hole between the end of the packer at 

107 feet and the bottom of the well at 131 feet. Evidently the water was 

temporarily cased off during this test. Drilling was continued to 140 feet. 

The last slush bailed out showed tints of red clay, which indicated that 

water was leaking around the packer at 107 feet. 

Fifth water test, October 17: Depth of hole, 140 feet; diameter of hole, 6% 

inches; casing, 61}8-inch to 107 feet. The water was bailed down to 96 feet. 

Bailing was then sto:gped and measurements of the depth to the water level 

were made as follows: 

Measurements of depth to water 'teveZ i-n fifth. test 

Feet 

1.00 p.m. (end of bailing) _______ 96 

1.15 ---------------------------- 84 

1.20 ---------------------------- 81 

1.25 ---------------------------- 79 

1.30 ~--------------------------- 77 

Feet 1.38p.m ________________________ 75 

1.50 ----·------------------------ 73 

2.00 ---------------------------- 72 

3.00 ---------------------------- 72 
r 

., 

CARLSBAD ffiRIGATION PROJECT, NEW MEXICO 33 

Sixth water test, October 17 : At 3 p. m. more red clay was placed around the 

casing, and another test was made, as follows : 

Mea.surements of depth, to water ZeveZ in siiDth, test 

Feet 

3.15 p. m. (beginning of bailing)__ 72 

3.30 (end of bailing)------------ 136 

3.43 ---------------------------- 119 

3.48 ---------------------------- 113 

3.53 ------------~--------------- lOs 

3.58 ---------------------------- 102 

4.03 ---------------------------- 98 

4.08 ---.,------------------------- 93 

Feet 

4.13 p. m-------~---------------- 89 

4.23 ---------------------------- 83 

4.33 ---------------------------- 78 

4.43 ---------------------------- 76 

4.53 ---------------------------- . 72 5.03 ________ .:____________________ \ 72 

6.03 ---------------------------- 72 

In this test, as in the previous one, the water evidently rose to the 72-foot 

· level as a result of leakage around the packer at 107 feet. Drilling was continued to 142 feet. The water level in the hole was 93 feet below the surface 

at 9.30 p. m. and 80 feet at 7.30 a. m. the next morning, no drilling being done 

in the meanwhile. This slow rise was probably due to a slight leak around 

the packer. Drilling was then carried to 152 feet. 

Seventh water test, October 18: .Depth of hole, 152 feet; diameter of hole, 

6% inches; casing, 6%-inch to 107 feet. · 

Measurements of depth, ta water ZeveZ in. seventh, test 

Feet 

11.30 a. m. (beginning of bailing) _ 72 

11.45 (end of bailing) ___________ 146 

11.53 --------------------------- 120 

11.55 --------------------------- 110 

12.00 noon______________________ 97 

12.05 p. m---------------------- 85 

Feet 

12.10 p. m---------------------- 78 

12.15 --------------------------- 73 

12.20 --------------------------- 72 

1.20 ---------------------------- 72 

2.20 ---------------------------- 72 

As in the fifth and sixth tests, the water evidently rose to the 72-foot level 

as a result of leakage around the packer. In making the sixth and seventh 

tests water could be plainly heard pouring into the hole until the water level 

had risen to the packer at 107 feet. ~ The last four tests show that there is a second bod of ground water with a 

static head of 72 feet below the top of the hole. A· this water was tapped 

before the first water at the 25-foot level was cas d off, its exact horizon 

can not be determined. IIowev-er, the log of the hole ndicates that the waterbearing stratum probably lies between 74 and 76 fee . The water level still 

remained at the 72-foot level on October 25, a week af er the last test had been 

made. It is evident, therefore, that the first water as bridged off from the 

second at the time the 8-inch casing was pulled. he fourth test seems to 

indicate that the second body of ground water is also rched. 

ROLE NO. 8 

Location, sec. 2, T. 21 S., R. 25 El., about l:JA miles west of Pecos River and 

about 1,000 feet north of Rocky Arroyo, at an elevatio of 3,260 feet. 

Depth, 100 feet. · ~ 

Drilling begun October 23, 1925; completed Novemb r 3, 1925. 

Elevation of top of well, 3,260 feet ; of bottom, 3,16 feet. 
34 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

Reoorll of hole No. Z 

[Alluvium, 0 to 18 feet; Castile formation or Carlsbad limestone, 18 to 65 feet; Carlsbad limestone, 65 to 

100 feetl 

Driller's log 

Material 

Limestone boulders and 

washed sand. 

Limestone._-----------------

Red clay with sand _________ _ 

Yellow clay and lime _______ _ 

Blue shale and sand cavings __ 

Red sandstone and blue shale. 

Roo sandsto~e---------------

Red sandstone, fine _________ _ 

Soft sandstone and blue shale. 

Blue sandy shale ____________ _ 

Blue shale and sandstone •• __ 

Blue limestone, soft _________ _ Blue limestone, hard ________ _ Blue limestone, very hard ___ _ Blne limestone with brownish tint, very hard. 

Feet 18 

7 

7 

5 

3 

2 

3 

4 

2 

4 

10 

5 

7 

13 

10 

Charaoter of samples 

Material Depth 

Feet Feet 18 Cemented gravel of limestone pebbles with o-18 

limy cement. • 25 Red clayey sand derived from red shaly sand- 18-25 stone. 32 Red sand and red clay derived from red sand- l!O-aO stone and shale. 

Reddish silt and clay derived from red shale.___ 3o-32 

red shale fragments. !

Reddish clayey silt with limestone pebbles and ~5 

37 Yellow clay with red sandstone fragments and 36-37 limestone pebbles somewhat rounded; cave breccia (?). 40 Pinkish silt with limestone fragments; cave 37-40 breccia (?). 

42 ----.do ___ ----------------------------'----------- 4o-42 45 Reddish sandy cley derived from red shale and 42-46 

sandstone. 

49 Pinkish silt derived from red or variegated shale_ 45-49 

51 Gray clay with some sand derived from gray 49-51 

shale and sandstone. 

55 Gray clay derived from gray shale_______________ 51-55 

{

Gray clayey sand derived from gray shale and 55-00 65 sandstone. 

Gray cley derived (J.-om gray shale------------ 6IHI5 

77 

90 70 I 10 samples of oomminuted gray limestone...----- 65-100 

100 

Thl.g hole is adjacent to ·Rocky Arroyo, and the log shows that it passes 

through 18 feet of alluvium of the gi'avelly type characteristic of this vicinity. 

The next 57 feet consists of sandstone and shale, of which the upper part is 

red and the lower part gray. This material resembles parts of. the Castile 

formation, and it is possible that a concealed outlier of this formation lies 

below the alluvium and terrace deposits of Rocky Arroyo. On the other hand, 

it may be that this 57 feet of sandstone and shale is part of a lens within the 

Carlsbad limestone, as that formation crops ouf at a higher elevation on the 

adjacent hills. The limestone encountered in the hole from 65 to 100 feet is 

similar in every way to that observed in outcrops of the Carlsbad limestone. 

Hole No. 2 was spudded in October 23. After three days of slow progress 

the first hole was abandoned at 17 feet on account of caving boulders, and a 

second hole was begun October 26. In the _second hole the boulders were 

successfully cased o:tr with 13 feet of 8-inch ·casing, and drilling was continued 

to 20 feet, when the first test was made. 

First water test, October 27-28: Depth of hole, 20 feet; diameter of hole, 

8 inches; casing, 8-inch to 13 feet; water level, none, dry hole. The hole was 

filled by pouring in water. The water level went down only 6 inches in 12 

hours. The drilling w.as then carried to 36 feet. The first water, struck. be-

. tween 24 and 26 feet, rose within 15 feet of the surface. The hole was cased 

to 20 feet. 

Second water test, October 28: Depth of hole, 36 feet; diameter of hole, 8 

inches ; casing, 8-inch to 20 feet; water level, 15 feet below surface. In a test 

of 15 minutes an 18-gallon bailer was filled and withdrawn thirty-five times, 

giving a withdrawal of 630 gallons, or 42 gallons a minute. Before the test 
.. 

CARLSBAD IBRIGATION PROJECT, NEW MEXICO 35 

was begun the water level was 15 feet below the surface ; at the end it was 16 

feet; and one minute later it ~as back to about the 15-foot level. The hole 

was drilled to 42 feet, and 6%-inch casing was inserted with a casing shoe to 

42 feet and was set on sandstone and blue shale, these being the first strata on 

which the casing could be set with reasonable assurance of shutting off the 

water. The water inside the casing was bailed out, and two hours later the 

hole was found to be dry. Drilling was carried to 60 feet in the hole, from 

. which the outside water remained completely cased off. The slush and about 3 

feet of water used in drilling were removed, and then the third test was made. 

Third water test, October 30--31 : Depth of hole, 60 feet; diameter of hole, 

6% inches; casing, 8-inch to 20 feet, 6%-inchs to 42 feet; water level, none, 

dry hole. Water was poured into the hole until it was filled to a level 20 

feet below the surface. After an interval of 10 hours the water level was still 

20 feet below the surface, showing that the rock between 42 and 60 feet was 

impervious. Drilling was continued, and the second ground water was struck 

at 65 feet. This water rose within 15 feet of the top of the hole, or to the 

same level as the water found at 25 feet. 

Fourth water test, October 31 : Depth of hole, 65 feet ; diameter of hole, 6% 

inches; casing, same as jn third test; water level, 15 feet below surface. The 

water level could not be lowered noticeably with a small bailer, such as would 

go inside the 6%-inch casing, although water was removed at the rate of 20 

gallons a minute. Drilling was continued to 100 feet. From 70 to 100 feet 

the rock was very hard blue limestone with traces of iron. 

HOLE NO. 3 

Location, 100 feet south and 100 feet west from the northeast corner of 

sec. 26, T. 20 S., R. 26 E. 

Depth, 206 feet. 

Drilling begun September 27, 1925 ; completed October 4, 1925. 

Elevation of top of hole, 3,305 feet; of bottom, 3,099 feet. 

Record of hole No. 3 

[Soil, 0 to 3 feet; Castile formation, 3 to 205 feet] 

Driller's log 

Material Thick· Depth bess 

Feet Feet 

SoiL ______ ----- __ --- ___ 3 3 

Limestone_------------ 2 5 

Gypsum~-------------- 10 15 

Red clay--------------· 29 44 

Gypsum rock __________ 16 60 

Do _________________ 20 80 Do _____ ------------ 16 96 

Red clay--------------- 14 110 Red beds and gravel(?)_ 10 120 Lime and red beds _____ 13 133 Do _______ ---------- 8 141 Red clay beds __________ 29 170 Gypsum rock and lime_ 10 180 Gypsum rock, hard ____ 5 185 

Gypsum rock, soft _____ 12 197 

Gypsum rock, hard ____ 8 205 

Character of samples 

Material Depth 

Feet 

No samples taken _____________ ---------_- ___ ---------- -------- ----_do ___ --- _____________ ----- _____ -- ________ --------- __ --- __ _ ----_do ___ --- __ -- ________ --- ______ -- ____ --------------- --------

e~~J~~~:-~~?::~~~~-~~~~~-~r::~~~~~-~~~!:~~~:~=:::: ~&= ~ Gypsum and red clay derived from. impure gypsum 44- 60 

bed. 

White and red gypsum________________________________ 6Q- 80 

Gypsum and red clay derived from gypsum beds so- 00 

with layers of clay. Red clay with fragments of gypsum___________________ 96-110 

}Re.d clayey gravel derived from red shale and cave llQ-133 

breccia. _____ do _______ -~ __________________________________ -----

Red sandy clay _________________________ --- __ --_------ Broken fragments of massive gypsum ________________ _ 

Finely comminuted gypsum ___ -----------------------

{

Pulverulent gypsum _________ --_----------------------

~~~:iufeJ't~~rstiill-ali<i-aD.Il;V<iJ.it:Ei==:=::::=:=::--=:=: Anhydrite, with minor quantity of gypsum probably derived from rock above. 

133-141 

141-170 

17Q-180 

18o-185 

185-190 

19Q-194 

194-197 

197-205 
36 CONTRIBUTIONS TO HYDROLOGY OF UNITED STATES, 1926 

Except for 3 feet of soil at the top, this hole is entirely in the Castile formation, in which it encountered 89 feet of gypsum and 8 feet of anhydrite. So 

large a proportion of gypsum in this formation would not be suspected at the 

outcrops in the bluffs along Pecos River. Near the river the soluble gypsum 

beds have doubtless been largely dissolved. Moreover, the existing beds of 

gypsum are largely concealed by talus or slope wash. As will be noted in the 

account of the tests, the greatest loss of water took place at a level between 

110 and 120 feet. This phenomenon is explained by the sample taken between . 

110 and 133 feet. for it consists of red clayey gravel that can. be interpreted 

only as a mixed mass of· fragments of shale and limestone such as would 

accumulate in a cave. Evidently this cave breccia does not completely fill 

these caves, which are capable of carrying off considerable quantities of water. 

This hole. was !hilled· 10 inches in diameter from top to bottom, and no 

casing was used. No ground water was encountered, but 12 tests were made 

by pouring water into the hole and measuring the depth to the water level 

thus produced in the hole. 

First water test, September 28 : The first test was made when the hole· had· 

reached a depth of 20 feet. Water was poured into t~e hole until it was 

filled. In six hours the water level receded 4 feet, probably owing to absorption by the top soil. 

S~ond water test, September 28 : The second test was made when the hole 

was still 20 feet deep and was virtually a duplicate of the first. The hole was 

refilled, and the water level went down 4 feet in four hours. The drilling 

was then carried to 40 feet. 

Third water test, September 28 : When the hole was 40 feet deep it was filled 

with water. The water level went down 1 foot in about one hour. Drilling 

was then carried to 60 fe(lt. 

Fourth water test, September 28: The 60-foot hole was filled with water. 

The water level went down 1 foot 6 inches in three hours. · Drilling was carried to 65 feet. 

Fifth water test, September 28-29: The 65-foot hole was filled within 5 feet 

of the top, and the water level was observed to go down 4 feet in 13¥.! hours. 

Drilling was carried to 85 feet. 

Sixth water test, October 29: The 85-foot hole· was filled within 7. feet of the 

top, and the water level was observed to go down 3 feet in one hour. Drilling 

was carried to 130 feet. 

Seventh water test, September 29: The 130-foot llole was filled to a level 80 

feet below the surface. The water level went down 10 feet in one hour. The 

leak was believed to be between 110 and 120 feet. Drilling was carried to 160 

feet. 

Eighth water test, September 29 : The 160-foot hole was filled to a l~vel 100 

feet below the surface. The water level went down 20 feet in one hour, the 

leakage presumably being between 110 and 120 feet. The water did not recede 

below the 120-foot level in a period of 17¥.! hours. Drilling was carried to 200 

feet. 

Ninth water test, October 2: The 200-foot hole was filled to a level 150 feet 

below the surface. The water level receded 1 foot in about one hour. After 

drilling to about 206 feet, the swivel came off the drill stem and left the tools 

at the bottom of the hole. After vatious unsuccessful attempts had been made 

to recover the tools, three more water tests were made with the tools in the 

hole. 

Tenth water test, October 4-5: The hole was about 206 feet deep. At 6 p. m. 

October 4 work was begun in filling it from about the 151-foot level. By 1 
CARLSBAD IRRIGATION PROJECT, NEW MEXICO 37 

p. m. 700 gallons had been placed in the well, but no measurement of the depth 

to the water level was made. At 10 a. m. October 5 the water level stood 

137 feet below the surface. The drillers reported that the water receded very 

fast down to 120 feet. 

Eleventh water test, October 5: The test was begun at 10.15 a. m., when the 

water in the hole stood about 137 feet below the surface. Between 10.15 and 

10.30 about 300 gallons of water were poured into the hole, and at 10.31 the 

water level was 102 feet below the surface. The water level then went down 

and was 112 feet below the surface at 10.36, 117 feet at 10.46, and 122 feet at 

11.06. 

Twelfth water test, October 5 : At 11.10 a. m. the water level was about 122 

feet below the surface. Between 11.10 and 11.30 about 300 gallons of water 

was added. The water level was 92 feet below the surface at 11.32, 105 feet 

at 11.37, 112 feet at 11.42, 117 feet at 12.02 p. m., 122 feet at 12.22, 124 feet at 

12.42, 127 feet at 1.22, and 137 feet at 6. It is believed that the main leak was 

between 110 and 120 feet. The hole was then abandoned. 

ROLE NO. 4 

Location, in the NE. :14 NE. % sec. 20, T. 20 S., R. 26 E., one-half mile west 

of large spring on Pecos River. 

Depth, 132 feet. 

Drilling begun November 5, 1925; completed November 22, 1925. 

Elevation of top of hole, 3,260 feet; of bottom, 3,128 feet. · 

Recora of hole No. 4 

{Alluvium, 0 to 35 feet; Seven Rivers gypsiferous member of Chupader·a formation, 35 to 132 feet} 

Driller's log Character of samples 

Material Thick- Depth Material Depth ness 

Feet Feet Feet Soil, sandy at base _____________ 6 6 Soil ___________________________________________ o- 6 

c~~:!~:~~~~~ !~~-~~=- ~~~~~~~- } 19 25 JBufl'-colored clayey gravel, angular limestone &- 10 l crrn~~i~d-gravei; -,wgtii;,r -iiiiiestone-pebbies ~ = 1Q- 25 Sandrock and conglomerate, 10 35 Yellow sandy cemented graveL _______________ 25-- 35 moderately hard. Formation open ________________ 26 61 No samples could be collected _________________ --;ji::.-66 Sandrock, reddish and medium 5 66 Pink silty sand derived from red clayey sandhard. stone. Open formation ________________ 26 92 No samples could be collected _________________ Open -------- cavern ___________________ 3 95 _-- __ do _______________ --- _____ --_--------------- -------- Sandrock, waterbearing ________ 6 101 Pink sand derived from red sandstone _________ 10Q-101 Open formation ________________ 9 110 No samples could be collected _________________ 

Sandrock, soft----------~------- 7 117 Fine silt derived from shale ___________________ -iiO::.ii7 Sandrock, hard _________________ 8 125 Red clayey·sand derived from shaJy red sand· 117-125 stone. Conglomerate, loosely cemented_ 7 132 Pink silty clay with limestone pebbles, prob- ably a cave breccia. 125-130 

After penetrating 6 feet of soil this' hole entered gravel that is more or less 

cemented. The lowest 10 feet of this gravel is very compact and lies upon open 

cavernous material that extends 25 feet to a red clayey sandstone 5 feet thick. 

Below this sandstone is 29 feet of similar cavernous material. The lower 3 

feet of this interval was a hole that offered no obstruction to the drill. Below 

a second bed of red sandstone there is a similar open formation for 9 feet, 

and below it shale, shaly sandstone, and breccia extend to the bottom of the 
38 CONTRIBUT'IONS TO HYDROLOGY OF UNITED STATES, 1926 

well at 130. feet. As reported by the driller the open formation contained 

water, the sides of the drill hole readily sloughed off, and the drill cuttings 

were pushed to the side into the cavities, so that no samples could be recovered. 

Evidently the original gypsum beds of this locality,. which were part of the 

Seven Rivers gypsiferous member, have been dissolved by the ground water. 

Thin ·beds of the interbedded sandstone and shale remain separated by rubbish 

collected in the caves. 

A 10-inch hole was drilled to a depth of 20 feet. No water was struck, and 

no casing was inserted, but a test was made by filling the hole with water. 

The water level receded 2 feet in about one hour, probably owing to absorption 

by the top soil. 

Drilling was continued to 40 feet. The first ground water was found between 28 and 30 feet and stood at a level 28 feet below the surface, but it was 

necessary to drill at least 10 feet below the water level before making a 

bailing test in order to submerge the bailer. Eight-inch casing was inserted 

to the depth of 21 feet, but between 21 and 40 feet there was a 10-inch uncased 

hole. About 350 gallons of water was run into the hole in 20 minutes without 

producing any noticeable rise or fall in the water level, which stood 28 feet 

below the surface. A bailing test was then made, with a bailer of 18 gallons 

capacity. This bailer was filled and removed twenty-eight times in 10 minutes, 

giving a withdrawal of about 500 gallons, without noticeably lowering the 

water level. 

Drilling was then carried to 60 feet in open water-bearing material of which 

no cutting could be obtained, and a 6%-inch casing with casing shoe was inserted to 62 feet. Drilling was carried to 85 feet, and the casing followed 

to 70 feet. The hole caved badly, and no cuttings could be collected. Drilling 

was carried to 107 feet, and 6%-inch casing followed the drill to 97 feet with 

light driving. The bailer brought out only clear water with no cuttings between 85 and 107 feet, and an open cavern was found between 92 and 95 

feet. The casing was set at 97 feet in sandstone, and the water was bailed 

out. The well remained dry for three minutes, after which water began to 

enter from a leak around the bottom of the casing. The casing was driven 

to 107 feet 2 inches. The fact that the 6%-inch casi11g, which measured 7% 

inches outside diameter over couplings, followed a 5-inch bit from 60 to 107 

feet indicates that the formation is soft and without strength. 

The drilling tools were then inserted, but the lip of the drill bit caught under 

the casing shoe at the end of the casing. The casing was raised 3 feet with 

jacks, but this operation did not release the drill bit. Pulley blocks and " gin " 

pole were rigged up to pull the casing. It was started with jacks assisted by 

the machine but was pulled apart at the first joint, 22 feet below the surface. The final pull was made with the jacks directly on the cable to which 

the tools were attached, and the tools were recovered. 

It was discovered that a dent had been made in the casing near the bottom_ 

Hence a string of old tools was made up with 4-inch bit and jars. The tools 

uncoupled in the hole four times in one day but were each time recovered 

within a few minutes after being lost. Drilling was carried to 109 feet, and 

100 pounds of plaster of Paris was placed in the hole for the purpose. of cementing off the water at the end of the casing. The setting time of plaster 

under water was considered to be one hour, but the plaster was left undisturbed overnight. An attempt was then made to bail out the hole, and it was 

found that the water had not been cemented off by the plaster. When the bailer 

was inserted to the bottom of the hole it was found t!lat the plaster had est 
,. 

CARLSBAD IRRIGATION PROJECT, NEW MEXICO 39 

caped into the open formation. Only a very small portion of the plaster was 

recovered by the bailer. 

When the drill bit was placed in the hole it went doWJ1. to a depth of 109 

feet. Drilling was continued to 132 feet with the 5-inch bit and stem that 

were used in the first 107 feet, and the first part of this work was in caving 

material. The tools became wedged in the casing three times and were 

each time recovered by pulling with the jacks. The hole caved below the 

bottom of the casing. The cavings were bailed out, and a liberal sample of 

the formation was obtained. To drill deeper than 132 feet would have required a liner of not less than 150 feet of 5-inch casing to case off the caving material. Upon telegraphic advice from Mr. Renick the hole was considered completed at a depth of 132 feet. ·The casing was not recovered, 

because the cost of pulling it would probably have' exceeded its value.