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1952

Reconnaissance of the Geology and Ground-Water Resources of the Pumpkin Creek Area, Morrill and Banner Counties, Nebraska With a Section on the Chemical Quality of the Water

H. M. Babcock

F. N. Visher

W. J. Durum

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Babcock, H. M.; Visher, F. N.; and Durum, W. J., "Reconnaissance of the Geology and Ground-Water Resources of the Pumpkin Creek Area, Morrill and Banner Counties, Nebraska With a Section on the Chemical Quality of the Water" (1952). Publications of the US Geological Survey. 94. https://digitalcommons.unl.edu/usgspubs/94

This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Publications of the US Geological Survey by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. GEOLOGICAL SURVEY CIRCULAR 156

RECONNAISSANCE OF THE GEOLOGY AND GROUND-WATER RESOURCES OF THE PUMPKIN CREEK AREA, MORRILL AND BANNER CQUNTIES, NEBRASKA

By H. M. Babcock and F. N. Visher

WITH A SECTION ON THE CHEMICAL QUALITY OF THE WATER

By W. H. Durum

Prepared as part of a program of the Department of the Interior for Development of the Missouri River Basin

UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 156

RECONNAISSANCE OF THE GEOLOGY AND GROUND-WATER RESOURCES OF THE PUMPKIN CREEK AREA MORRILL AND BANNER COUNTIES, NEBRASKA

By H. M. Babcock and F. N. Visher

WITH A SECTION ON THE CHEMICAL QUALITY OF THE WATER

By W. H. Durum

Prepared as part of a program of the Department of the Interior for Development of the Missouri River Basin

Washington, D. C., 1962. Free on application to the Geological Survey, Washington 25, D. C.

U. S. Geological Survey Surface Water Branch 541 Federal Office BJdg. San Francisco I, CaHf.

CONTENTS Page . Page Abstract...... 1 Geology and ground water--Continued Introduction...... 2 Depth to ground water...... 12 Purpose and scope of the investigation. 2 Ground-water recharge...... 12 Location and extent of the area...;.... 2 : Precipitation...... *...... 12 Methods of investigation...... 3 Irrigation...... 12 Well-numbering system...... 3 Ground-water discharge...... 12 Previous investigations*.....-...... 3 Transpiration and evaporation...... 12 Acknowledgments...... 3 Streams...... 13 Geography...... 3 Underflow...... 13 Topography and drainage...... 3 Springs...... 13 Climate...... 5 Wells...... 13 Agriculture...... 5 Fluctuations of the water table...... 13 Geology and ground water...... 5 Ground water for irrigation...... 15 Sunoary of stratigraphy...... 5 Present development...... 15 Summary of geologic and physiographic Potential development...... 15 history...... 6 Unconfined ground water...... 15 Cretaceous period...... 6 Artesian water...... 15 Tertiary period...... 6 Cost of pumping water...... 16 Quaternary period...... 7 Chemical quality of the ground water..... 16 Geologic formations and their relation Introduction...... 16 to ground water...... 7 Chemical character in relation to Cretaceous system...... 7 source...... 17 Lance formation...... 7 Alluvium...... 19 Tertiary system...... 8 Brule formation...... 20 White River group...... 8 Chadron formation...... 20 Chadron formation...... 8 Lance formation...... 20 Brule formation...... 8 Springs...... 21 Arlkaree sandstone...... 8 Quality of water in relation to drain- Ogallala formation.*...... 9 age...... 21 Quaternary system...... 9 Quality of water in relation to use.... 21 Alluvium...... 9 Conclusions...... 22 Principles of occurrence of ground References cited...... 2k water...... 9 Logs of wells...... 25 Hydrologic properties of the principal Records of wells and springs...... 27 water-bearing formations...... 10 Lance formation...... 10 Brule formation...... 10 Alluvium...... 10 Pumping test...... 10 Interference between wells...... 11 Specific capacity...... 12

ILLUSTRATIONS Page Plate 1. Map of Pumpkin Creek valley, Nebr., showing areal geology and location of wells and springs...... Inside back cover Figure 1. Map of the Missouri River basin showing areas in wMch ground-water studies have been made under the Missouri Basin development program...... 2 2. Sketch showing well-numbering system...... * * 3. Block diagram, looking west in Pumpkin Creek valley, Nebr...... » k. Graph showing annual precipitation at Bridgeport and Scottsbluff, Nebr...... 6 5. Graph showing theoretical drawdown, according to the Theis formula, due to pumping a well at a constant rate...... 11 6. Map showing sampling points in the Pumpkin Creek area, Nebr...... 16 7. Mineral constituents and reacting values of basic radicals in waters, Pump­ kin Creek area, Nebr...... *«.. 1? 8. Classification of waters in the Pumpkin Creek area for irrigation use...... 23

iii TABLES Page Table 1. Total runoff, in acre-feet, of Pumpkin Creek near the mouth...... 13 2. Water levels, in feet below land-surface datum, in observation veils...... Ik 3. Chemical analyse**, in parts per million, and related physical measurements of waters in the Pumpkin Creek area, Ifebr...... 18 k. Chemical analyses, in equivalents per million, of samples of water in the Pumpkin Creek area, Nebr...... *... 19 5. Range in mineral constituents, in parts per million, of samples of water from several geologic sources...... 20 6. Logs of wells in the Pumpkin Creek area, Nebr...... 2$ 7* Records of wells and springs in the Pumpkin Creek area, Nebr...... 28 RECONNAISSANCE OF THE GEOLOGY AND GROUND-WATER RESOURCES OF THE PUMPKIN CREEK AREA, MORMLL AND BANNER COUNTIES, NEBRASKA

WITH A SECTION ON THE CHEMICAL QUALITY OF THE WATER

ABSTRACT tion could be obtained from this material; however, it may be possible in some places to The area described in this report includes obtain water for irrigation on a small scale. the eastern, or lower, end of the valley of Pumpkin Creek and is in Morrill and Banner Alluvium, which underlies the floodplains Counties, in western Nebraska. A reconnais­ of Pumpkin Creek and some of its major tribu­ sance of the geology and ground-water taries, is the principal aquifer in the area. resources of the area was made to determine The alluvium of Quaternary age consists of the possibilities of developing ground-water coarse sand and gravel and yields sufficient supplies for irrigation. water for irrigation. In most places yields of 1,000 to 2,000 gpm probably could be ob­ Rocks that crop out in the Pumpkin Creek tained from properly constructed wells in area are shown on a geologic map that is in­ this material. cluded in the report. They range in age from Oligocene to Recent and consist of the Brule, It is estimated that about 21,000 acre-ft Arikaree, and Ogallala formations and of the of ground water annually leaves the area as .alluvium. The Chadron formation, of Oligo­ stream flow. This represents approximately cene age, underlies the area but is not ex­ the amount of additional ground water avail­ posed at the surface. The Lance formation, of able for development; however, if sufficient Late Cretaceous age, underlies the Chadron ground water is pumped to lower the water formation. Sandstones, which are thought to table appreciably, the additional water sal­ be in the Lance formation, contain ground vaged from loss by evaporation and transpira­ water under artesian pressure and might yield tion also would be available for irrigation sufficient water for irrigation on a small use. The development of any additional scale. Several thousand feet of Pierre shale, ground water from the unconfined ground-water which is not known to yield appreciable quan­ reservoir will cause a reduction in the flow tities of water to wells, underlies the Lance of Pumpkin Creek. formation. In some places sufficient water for irrigation can be obtained by wells from Water from the alluvium and the Brule forma­ fractures in the Brule formation. Large sup­ tion is moderately mineralized. Although * plies of water can be expected in places where most water is hard, some soft water is ob­ the fractures are extensive or where they are tained from the Brule. The dissolved solids overlain by saturated alluvial material. A in water from the Brule formation and the few springs that are fed by recharge from the alluvium ranged from 236 to 356 ppm. Hard­ upland area issue at the contact of the Brule ness in these two water-bearing formations and Arikaree formations. The Ogallala forma­ ranged from 6.0 to 20k ppm. tion yields water to domestic and stock wells in the upland areas south of Pumpkin Creek Water obtained from deep wells in the Lance valley. Inasmuch as this formation is high formation is more mineralized and softer than topographically and is well drained, the depth water obtained from the overlying formations. to water is considerable generally 100 ft or The dissolved solids, which consist largely more and the thickness of the saturated mate­ of sodium bicarbonate and sodium chloride, rial probably is not great. It is doubtful, range from 812 to 1,170 ppm. Although the therefore, that sufficient water for irriga­ water from the Lance formation is satisfactory for domestic needs, the high percentage of logical Survey, and G. H. Taylor, regional sodium restricts its use for irrigation. engineer in charge of ground-water investiga­ tions in the Missouri River basin, and under the immediate supervision of S. W. Lohman, INTRODUCTION district geologist for Colorado and Wyoming. Purpose and scope of the investigation The water-quality studies were under the «eneral direction of S. K. Love, chief of the This investigation is one of several being >* ility of Water Branch, and under the immed­ made by the United States Geological Survey iate supervision of P.'C. Benedict, regional as a part of the program undertaken by the engineer in charge of Missouri River basin Department of the Interior for the control, later-quality investigations. The chemical conservation, development, and use of the analyses of the ground-water samples collected water resources of the Missouri River basin. in the area were made by W. M. Barr, L. R.

Area described in other reports

Figure 1. Map of the Missouri River basin showinK areas in which ground-water studies have been made under the Mssouri Basin development program. The purpose or this study is to determine the Kister, R. H. Langford, and A. S. Moehl, character, thickness, and extent of the water­ chemists of the Quality of Water Branch, bearing formations, the source, occurrence, Lincoln, Nebr. movement, quantity, and quality of ground water, and the possibility of developing ground-water supplies for irrigation in the Location and extent of the area Pumpkin Creek area. The Pumpkin Creek area is in Morrill and This report covers the progress of the work Banner Counties, in western Nebraska (see from the beginning of the investigation in fig. l); it lies in the northwestern part of May 19^9 through December 19^9. The work was the High Plains section of the Great Plains under the general supervision of A. N. Sayre, physiographic province. The area studied chief of the Ground Water Branch of the Geo- comprises the eastern part of the valley of Pumpkin Creek. It extends westward from the position within the section. The first num­ Junction of the creek with the North Platte eral of a well number indicates the to^abLip, River to State Highway 29, a distance of about the second the range, and the third the sec­ 3^ miles. The area lies within Tps. 18 and tion in which the well is located. The lower­ 19 N., and Rs. 50 through 55 W., and covers case letters following the section number lo­ about UOO sq mi. cate the well within the section. The first letter denotes the quarter section (160-acre tract), the second the quarter-quarter section Methods of investigation (IfO-acre tract), and the third the quarter- quarter-quarter section (10-acre tract). Records of 83 wells and springs in the area These subdivisions are designated a, b, c, and were obtained. Most of the information re­ d; the letters are assigned in a counterclock­ garding the character of the water-bearing wise direction, beginning in the northeast material and the yield and drawdown of the quarter of the section. When more than one wells was obtained from well drillers or well well is situated in a 10-acre tract, consecu­ owners. Thirty-five of the wells recorded tive numbers beginning with 1 are added to were measured using a steel tape to determine the well number. the depth of well and depth to water below some fixed measuring point, generally the top This method of well numbering is illustrated of the casing or the bottom of the pump base. in figure 2. Reported data were recorded for those wells that could not be measured. Records of "shot holes" made during seismic surveys by oil Previous investigations companies were studied but are not listed in this report. Twenty-five samples of water The geology of the Pumpkin Creek area has for chemical analysis were collected from been described by Darton in the Camp Clark , representative wells and springs and from (1903a) and the Scotts Bluff (I903b) folios. creeks in the area, and five samples were An investigation of the geology and ground- collected from wells outside the area. water resources of Scotts Bluff County, north of the Pumpkin Creek area, was made by Wenzel, In May 19^9> five representative wells were Cady, and Waite (19^6). The information in selected for monthly observations of water these reports proved very helpful in this in­ level in order to obtain information concern­ vestigation. ing the seasonal fluctuations of the water table. Water-level measurements of one other well (l9-55-29acb) have been made intermit­ Acknowledgments tently since 1934 in cooperation with the Conservation and Survey Division of the Uni­ Residents of the area were very cooperative versity of Nebraska. in supplying information and permitting the measurement of their wells. Seismograph com­ The geologic and hydrologic field data were panies and well drillers were very helpful in recorded on large-scale aerial photographs giving subsurface information. and later transferred to a base map that was prepared by the Nebraska Department of Roads and Irrigation. The geologic mapping and GEOGRAPHY hydrologic studies were restricted to the valley of Pumpkin Creek, where irrigation from Topography and drainage wells is deemed most practicable. Logs of wells and shot holes were useful in the deter­ The Pumpkin Creek valley, which is about 8 mination of the character, extent, and thick­ miles wide, is bounded on the south by bluffs ness of the alluvium. that mark the edge of the High Plains. The valley is bounded on the north by the narrow Wells and springs shown on the map were lo­ Wildcat Ridge, which rises about 500 ft above cated within the section by use of an odometer Pumpkin Creek valley (fig. 3) and separates and by inspection of the aerial photographs; it from the valley of the North Platte River. the locations are believed to be accurate to The upper ^00 ft of the north valley wall 0.1 mile. consists of nearly vertical bluffs; the lower 100 ft consists of rock-cut pediment slopes that are steep at the foot of the bluffs and Well-numbering system gradually decrease in gradient toward Pumpkin Creek. On the south side of the valley, In this report, the wells and springs are gravel-mantled pediments gradually rise about numbered according to their location within 350 ft from Pumpkin Creek to the foot of the the General Land Office system of land sub­ nearly vertical bluffs, which rise an division. The well number shows the location additional 300 ft. of the well by township, range, section, and" 1 See list of references at end of report. RANGES WEST 60 59 58 57 56 55 5k 53 52 51 50 k9 kQ 2 1 21 20

19 o PRINCIPALSIXTHMERIDIAN I/ e 18 / 17 ' ' / 16 /

2 r / 1 / BASE LINE

-Well number 19-53-26acb Well number 18-50-Ibcd

R. 53 W. Sec. 26 6 5 k 3 2 l 7 8 9 10 11 12 / T. 18 17 16 15 Ik i 19 19 20 21 22 fek N. -5 +**" 30 29 28 27 26 25 31 32 33 3* 35 36

Figure 2. Sketch showing well-numbering system.

: : ?- -. Alluvium , ;:' '.; : .; . '.<.'*' ' ;. v-*\*.'

Figure 3. Block diagram, looking west in Pumpkin Creek valley, Nebr. Pumpkin Creek rises near the Wyoming- summer and decreases to a minimum in the fall Nebraska line at an altitude of ^,600 ft, and and winter, when it usually takes the form of flows eastward about 50 miles to its conflu­ light dry snow. The summer rains occur ence with the North Platte River, at an alti­ largely as thunderstorms that are usually tude of 3,600 ft. It has an average gradient, sporadic and unevenly distributed. The therefore, of about 20 ft to the mile. In amount of rainfall in a single storm varies the mapped area, however, the stream has an greatly from one part of the area to another. average gradient of only 16 ft to the mile. These storms occasionally are accompanied by high winds and hail that cause considerable The main tributaries that enter Pumpkin damage to crops. Cre«k from the south rise as springs in the 'canyons that are cut into the adjacent table­ The mean annual temperatures are 48.3 P land. The water from most of these springs U8.5 F at Bridgeport and Scottsbluff, respec­ flows on the surface only a few hundred feet tively. The length of the growing season is and disappears into a thin alluvial mantle usually about 5 months. that covers the canyon floors. Greenwood Creek and Lawrence Fork are the only tribu­ taries that are perennial throughout most of Agriculture their courses. The flow of these streams normally does not empty directly into Pumpkin Detailed descriptions of the soils in the Creek but sinks into the alluvium that under­ area are contained in the reports on the soil lies the flood plain of Pumpkin Creek. Most surveys of Banner (Hayes and Bedell, 1921) of the other tributaries from the south are and Morrill (Hayes, Hawker, and others, 1921) ephemeral and many do not have recognizable Counties, and no attempt is made to describe channels at their confluence with Pumpkin them in this report. Creek. The small tributaries that enter Pumpkin Creek from the north carry water only Most of the area is utilized for dry farm­ during periods of very heavy rainfall. ing of grain crops, but the rougher parts are used for pasture. Some land along Pumpkin Creek and its tributaries is Irrigated from Climate creeks and wells. Wheat, oats, hay, and corn are the main crops raised on the irrigated The climate of the Pumpkin Creek area is lands. much like that of other parts of the High Plains section. It is characterized by low precipitation, rapid evaporation, and a wide GEOLOGY AND GROUND WATER range of temperature. The weather is vari­ able from year to. year, but usually the sum­ of stratigraphy mers are dry and hot and the winters are very cold. The summer days generally are hot but, The rocks that crop out in the Pumpkin Creek owing to the movement of wind and to the low area are sedimentary and range in age from humidity, the nights generally are cool. Oligocene to Recent. (See pi. 1.) The Ter­ tiary formations that crop out in the area There are no climatological stations in the include the Brule, Arikaree, and Qgallala Pumpkin Creek area; however, the U. S. Weather formations. Quaternary sediments which in­ Bureau maintains a station at Bridgeport, 2 clude alluvium, dune sand, and terrace depos­ miles north of the eastern part of the area, its overlie the Brule formation in parts of and at Scottsbluff, 10 miles north of the the valley of Pumpkin Creek, but only the western part. The annual precipitation during alluvium is shown on plate 1. the period of record for these stations is shown graphically in figure U. The normal The Chadron formation of Oligocene age, amual precipitation is 16.21 in. at Bridge­ which is the oldest Tertiary formation in the port and 15.62 in. at Scottsbluff. The area, underlies the Brule formation but does greatest annual precipitation recorded was not crop out. The Lance formation of Late 23.67 in. at Bridgeport and 2?. 1*8 in. at Cretaceous age underlies the Chadron forma­ Scottsbluff. The least annual precipitation tion. In adjacent areas both the Chadron and recorded at the two stations was 7.93 in. and Lance formations contain water-bearing sand­ 9.k7 in., respectively. Extremely dry periods stones. Beneath the Lance formation lies like those that prevailed from 1931 through several thousand feet of Pierre shale, which 1937 caused repeated crop failures where the is not known to yield appreciable quantities land was not irrigated. Monthly precipitation of water to wells in western Nebraska. reaches a maximum during the spring and early Bridgeport Normol 16.21 7 20-

30-

Scottsbluff Normal 15.62 20-

10-

Figure it. Graph shoving annual precipitation at Bridgeport and Scottsbluff, Nebr. (From records of the U. S. Weather Bureau)

Summary of geologic and physiographic history "Later in Tertiary time, after the outlines of the great mountain ranges to the north and Cretaceous period west had been carved, there was a long period in which streams of moderate declivity flowed Toward or at the close of the Cretaceous across the central Great Plains region; these, period, the sediments that had been accumu­ with frequently varying channels and exten­ lating almost without interruption since sive local lakes, due to damming and the early Carboniferous time were uplifted and sluggish flow of the waters, laid down the folded into the vast anticlines and synclines widespread mantle of Oligocene or White River of the Rocky Mountains, and the mountains deposits. These began with the sands of the were eroded as they were uplifted. The Chadron formation, which show clearly the streams flowing eastward from the mountains course of old currents by channels filled began to aggrade and develop broad flood with coarse sandstone and areas of slack plains on which were deposited the sands and water and overflow in which . . . clays were clays of the Lance formation. At times dur­ laid down . . . The White River epoch was ing this period, part of the area east of continued by the deposition of the Brule the mountains was occupied by an inland sea. (silts) under conditions in which the cur­ rents were less strong and local lakes and slack-water overflows were more extensive. Tertiary period "At the beginning of Miocene time the gen­ At the beginning of the Tertiary period, eral conditions had not changed materially, further uplift ended the deposition and there but doubtless for a while an extensive land followed a long period of erosion during surface existed in the central Plains area. which the Lance formation was deeply dis­ In ... the stream channels extending across sected and, in many places, was removed en­ this surface the Gering member of the tirely. The following discussion is taken Arikaree was laid down, one channel extend­ from the Camp Clark folio (Darton, 1903a, ing across this area. Next came the deposi­ P- M: tion of a widespread sheet of sands derived from the mountains to the west . . . The about 200 ft below its present level, and the streams of this time shifted their courses channel cutting extended up Pumpkin Creek and across the plains, spreading the debris from its major tributaries. Subsequently, the the mountains in a sheet whioh in some por­ streams aggraded and their channels were tions of the area attained a thickness of filled with sand and gravel to about the 1,000 feet. This is the Arikaree formation." level of the present flood plain, which cor­ responds to the third terrace of the North Following another period of erosion the Platte River valley. streams in Pliocene time again began to aggrade and spread out over the vast expanse A protective mantle of gravel, which was of material that had previously been depos­ derived from the Ogallala formation, has pre­ ited east of the mountains. This later de­ served the older pediments on the south side posit is the Ogallala formation. of the valley. Lacking a protective mantle, the entire pediment slope on the north side of the valley was lowered with each success­ Quaternary period ive rejuvenation of erosion, hence, while the down cutting was taking place, the tribu­ At the close of Ogallala time, the streams taries of Pumpkin Creek were eroding headward of the area flowed eastward across a broad into the Ogallala-covered upland to the south nearly featureless alluvial plain, a large and were intercepting the existing drainage remnant of which exists today between Pumpkin courses. Most of the drainage areas thus Creek and Lodgepole Creek. The ancestral intercepted were small; however, the piracy Pumpkin Creek extended to the Laramie Range that resulted in the present drainage of and was one of the major tributaries to the Lawrence Fork embraced a large area. Law­ ancestral North Platte River. Following the rence Fork eroded headward and captured the uplift of the area, the main streams began to trunk stream that drained most of the upland deepen and enlarge their valleys. This val­ between Pumpkin Creek and Lodgepole Creek. ley cutting caused a lowering of the water Since the time of capture, Lawrence Fork has table in the divide areas between the main cut a deep canyon into the upland. streams and dried up minor streams and tribu­ taries that had previously been fed by ground During the third terrace stage of the North water. As surface water was the primary Platte River valley, the retreating Goshen agent of erosion, this disappearance of the Hole escarpment intercepted the middle course minor streams virtually stopped erosion in of ancestral Pumpkin Creek near La Grange, the divide areas. Wyo., and the headwaters were diverted. The upper part of ancestral Pumpkin Creek and its The valley that Pumpkin Creek cut into the present extension through Goshen Hole is now Ogallala and Arikaree formations probably called Horse Creek. Deprived of its main was relatively narrow until the stream cut source of water, Pumpkin Creek became a mean­ down into the Brule formation. Erosion was dering, aggrading stream, and did not partic­ then greatly accelerated, and the sides of ipate in the down cutting associated with the the valley began to retreat. The southern development of the first and second terraces escarpment retreated until the gravel from of the North Platte River valley. the uplands covered the springs that issued from the top of the Brule and that previously had been undermining the overlying formations. Geologic formations and their relation to During the same time, the upland between ground water Pumpkin Creek and the North Platte River was eroded to a narrow ridge. Cretaceous system This escarpment retreat resulted in a pedi­ Lance formation ment, which corresponds to the second pedi­ ment above the third terrace of the North . The Lance formation of Late Cretaceous age Platte River valley. The terraces and pedi­ underlies the area but does not crop out. ments of the North Platte River valley are The shale encountered from 530 to 835 ft in described by Visher in a report on the Dutch well 19-55-33aaa is referred to as Lance by Flats area (Babcock and Visher, 1950, pp. 10- Cady (Wenzel, Cady, and Waite, 19^6, p. 58). 12). Subsequent erosion and down cutting Cady's interpretation of the driller's log of deepened the valley an additional 100 ft and this well has been essentially substantiated produced a pediment that corresponds to the by more recent drilling. first pediment above the third terrace of the North Platte River valley. A coarse clean sand about UO ft thick, which may be a part of the Lance formation, Following the development of this pediment, underlies the northeastern part of the area. the North Platte River deepened its channel This sand, overlain by Tertiary sediments and and thus, lowered the mouth of Pumpkin Creek underlain by Cretaceous sediments, has many of the characteristics of the Chadron forma­ 1946, p. 6?) indicates the material Is 69 tion observed In Goshen County, Wyo. Al­ percent silt and only ^percent clay. though this sand is not similar to materials encountered in the Lance formation in the The Brule formation is traversed by numer­ western part, the chemical quality of the ous vertical to nearly vertical fractures water is similar to that of water from the that range in width from a few inches to sev­ Lance formation, and on this basis, the sand eral feet. The fracturing is thought to have tentatively is classified as Lance. resulted from the weight of overlying sedi­ ments and from regional warping. The Brule The Lance formation possibly underlies all is a weak, brittle formation and tends to the area. It is about 300 ft thick in well succumb to induced tension rather than to 19-55-33aaa. The formation thickens to the induced shear. The weight of the overlying west and thins to the east. The eastern formations was sufficient to cause failure extent of the formation is not known. when regional warping caused relief of the lateral support; consequently, the fracturing Well l8-56-2cca, which is 3 miles west of tends to parallel the strike of the warping. the southwest corner of the mapped area, ob­ tains water from the Lance formation. This Because fractures or groups of fractures well penetrates the entire formation but does constitute zones of weakness in the bedrock, not produce more than a few gallons a minute. many of the water courses occupy valleys and draws that are controlled in part by under­ Well 19-50-Head, in the eastern part of lying fractures In the Brule. the area, flows at a rate of about 200 gpm from the sand that underlies the northeastern The entire area is underlain by the Brule part. The chemical quality of the water from formation, which extends beneath the surface this sand is similar to water from other of western Nebraska and adjoining regions. wells in the Lance formation in adjacent Only the upper 300 ft of this formation is areas. exposed in the Pumpkin Creek area; in Scotts Bluff County it is reported (Wenzel, Cady, and Walte, 19^6, p. 66) to be 560 ft thick. Tertiary system The Brule is the source of water supply for White River group many wells. Fractures in the formation gener­ ally contain water and in most places yield Chadron formation.--The Chadron formation sufficient water to wells for domestic and of Oligocene age underlies the Pumpkin Creek stock use. In some areas where the fractures area but is not exposed. Where outcrops of are overlain by saturated alluvium, suffi­ the formation were studied nearby, the mate­ cient water for irrigation can be developed rial was found to consist chiefly of red, from the Brule formation. green, and brown clay that contains channel sandstones. The Chadron formation was depos­ Arikaree sandstone ited on an erosional surface of strong relief and, consequently, varies considerably in The Arikaree sandstone of Miocene age forms thickness. Well 19-55~33aaa penetrated Wildcat Ridge on the north and is exposed Chadron-like material between the depths of along most of the escarpment south of Pumpkin kOQ and 530 ft. (See log in table 6.) Creek valley. The sandstone has a thickness of more than 1*00 ft on Wildcat Ridge but Where channel sandstones are present in the lenses out to the southeast where the Ogal- Chadron formation, they may yield sufficient lala formation directly overlies the Brule. water for domestic and stock use. These The Arikaree sandstone consists mainly of channel sandstones generally are narrow and silt, sand, and soft sandstone. widely separated and, therefore, are diffi­ cult to locate. Water in the sandstones is , As the sandy soils formed from the Arikaree confined under artesian pressure; hence, it sandstone absorb most of the precipitation, would rise above the points at which it is there is little surface runoff and, hence, encountered, and in some parts of the area, not much erosion. On the other hand the con­ it might flow at the surface. siderable runoff on the relatively imperme­ able Brule surfaces causes the Brule to erode Brule formation. In its typical develop­ rapidly. The contact between the rapidly ment the Brule formation of Oligocene age is eroding Brule formation and the slowly erod­ a pale-buff or flesh-colored sandy siItstone ing Arikaree sandstone, therefore, generally of compact texture and massive structure and is marked by an escarpment several hundred locally is called "hardpan." The formation feet high. Springs that issue* from the con­ was called the Brule clay by Barton; however, tact between the Brule and the Arikaree for­ a mechanical analysis that is given in the mations are fed by recharge from the upland Scotts Bluff report (Wenzel, Cady, and Waite, areas and erode the Brule and undermine the Arlkaree. The Arikaree is high topographi­ The alluvium is highly permeable and yields cally and only the lover part of the forma­ large quantities of water to irrigation wells. tion is saturated; hence, the depth to water probably is considerable. Principles of occurrence of ground water Ogallala formation The fundamental principles of the occur­ The Ogallala formation of Pliocene age lies rence of ground water are set forth in an unconformably on the Arikaree or Brule for­ authoritative and detailed report by Meinzer mations and caps the high tableland south of (1923). Only a brief discussion of the sub­ Pumpkin Creek valley. The formation is 200 ject will be given here, and the reader is ft thick at Langs Point and thickens toward referred to Meinzer*s report for a more de­ the south. tailed discussion. The Ogallala formation consists-of beds of Ground water is derived mainly from water sand, gravel, and poorly to moderately that falls as rain or snow. A part of this cemented sandstone. The Ogallala, like the precipitation runs off directly into streams, Arikaree, is topographically prominent be­ a part evaporates, a part is returned to the cause its highly permeable soils have little atmosphere through transpiration by plants, surface runoff and, consequently, erode and a part percolates through the soil and slowly. Under recent climatic conditions, underlying rocks to the zone of saturation. the contact springs at the top of the Brule Much of the water in the zone of saturation seemingly lacked sufficient flow to remove eventually returns to the surface through the gravels that have slumped over them from seeps, springs, or wells, or Is discharged the overlying Ogallala. Most of the springs by plants. The porous rocks in the zone of have been buried by these gravels and the saturation will yield water to wells only if water passes directly into the gravel-choked the rocks are sufficiently permeable. canyons without coming to the surface. The Pumpkin Creek valley contains three The Ogallala formation yields water to do­ geologic units from which ground water is mestic and stock wells in the upland areas obtainable in sufficient quantities for irri­ south of Pumpkin Creek valley. Inasmuch as gation use: (l) the coarse alluvium that this formation is high topographically and is underlies the flood plain of Pumpkin Creek well drained, the depth to water Is consider­ and its tributaries; (2) the fractures in the able --generally 100 ft or more and probably Brule formation; and (3) the sandstones in only a small part of the total thickness is the Lance formation. saturated. It is doubtful, therefore, that sufficient water for large-scale Irrigation The upper surface of the zone of saturation could be obtained from this material; however, in permeable soil or rocks is the water table* in some places it may be possible to obtain The water table is not a level surface, but water for irrigation on a small scale. generally conforms somewhat to the land sur­ face and hence has many irregularities. It does not remain stationary but fluctuates. Quaternary system The major irregularities are caused chiefly by local differences in the gain or loss of Alluvium water, and the fluctuations are caused principally by differences in the ratio of The flood plains of Pumpkin Creek and many ground-water recharge to discharge. Where of its tributaries are underlain by deep the ground water occurs in a confined forma­ channels filled with sand and gravel. The tion under artesian pressure, the water will alluvium averages about 1 mile in width along rise above the level at which it is encoun­ Pumpkin Creek and extends up most of the major tered in tightly-cased wells to a level re­ tributaries. Although little information is ferred to as the piezometric surface. Both available regarding the maximum thickness of water-table and artesian conditions exist in this material, It is known to be 199 ft thick the Pumpkin Creek area. near the mouth of Pumpkin Creek and at least 60 ft thick at a point 26 miles above the The amount of water released from storage mouth. in an aquifer is proportional to the coeffi­ cient of storage, which is defined as the The alluvium consists of uncemented well- amount of water, in cubic feet, discharged sorted stream-laid deposits of sand and from each vertical column of the aquifer with gravel. Some of the material may have come a base 1 ft sq, as the water level or arte­ directly from the mountains to the west, but sian head declines 1 ft. The coefficient most of it probably was derived locally from of storage of an unconfined aquifer commonly the Ogallala formation. is called the specific yield. The rate of movement of ground water is determined by the mile. It is evident that where the Brule quantity, size, shape, and degree of inter­ formation as a whole is no more permeable connection of the interstices in the aquifer, than its constituent materials, the discharge and by the slope or hydraulic gradient of the through it is slight, even where the forma­ water table or piezometric surface. The tion is thick. The cracks and fissures, how­ capacity of a rock to transmit water under ever, that occur in the Brule at most places hydraulic head is its permeability* The in Scotts Bluff County greatly increase the field coefficient of permeability may be ex­ permeability of the formation, the degree of pressed as the rate of flow of water, in this increase depending on the number, size, gallons a day, through a cross-section 1 ft and interconnection of the openings. Because high, 1 mile wide, under a hydraulic gradient their character differs so greatly from place of one foot per mile at the prevailing tem­ to.place, it is difficult to determine the perature. The coefficient of transmlssl- effect of these openings on the permeability bllity may be defined as the number of gallons of the formation as a whole . . . The porosi­ of water a day transmitted through each ver­ ties of the samples were 51 and $k, an aver­ tical strip 1 ft wide and extending the age, of 52.5* Thus the average specific thickness of the aquifer, under a unit- yield of the samples is 29.6. This Indicates gradient and at the prevailing temperature* that a cubic foot of Brule, if allowed to The coefficient of transmissibility is the drain for a long period,will yield about product of the coefficient of permeability 0.296 cubic foot of water and will retain and the thickness of the aquifer, in feet. about 0.229 cubic foot. "Investigations have shown that a sample of Hydrologic properties of the principal water­ material after being saturated will not yield bearing formations its water at once but the water will drain rather slowly, the rate of draining being Lance formation somewhat proportional to the permeability of the material. The Brule, because of its No tests were made to determine the water­ tight character, yields water sluggishly, bearing properties of the Lance formation. and several months to a year or more are The formation underlies at least part of the doubtless required before the specific yield Pumpkin Creek area and contains sandstones in calculated in the laboratory is reached. As which ground water is confined by relatively a result the quantity of water that is removed impermeable beds of clay. Inspection of the from storage by a decline of the water table cuttings from well 19-50-Head Indicates that in the Brule cannot be calculated from the the water-bearing material is a coarse­ specific yield determined in the laboratory grained loosely cemented sandstone, which has unless the water table remains below the been tentatively classified as Lance. Addi­ material for a long period. The comparatively tional information is needed to determine the large seasonal fluctuation of water levels in water-bearing properties of the formation. wells that tap the Brule results in part from the incomplete draining of the material during the time allowed. This means that the water Brule formation table may decline for a considerable period before much water comes out of storage, ex­ No attempt was made by the authors to de­ cept what drains from the cracks and fissures* termine the water-bearing properties of the This decline, however, will gradually slow up Brule formation as a detailed study of this as the water table reaches lower stages, and material in the Scotts Bluff area was made by a greater thickness of the formation thereby Wenzel and others (Wenzel, Cady, and Waite, becomes available for draining." 19^6, pp. 83-86). The following discussion of the Brule formation is taken from their report: Alluvium "The coefficient of permeability of a sam­ Pumping test ple of typical Brule, taken from a fresh road cut on the face of Scotts Bluff monument half­ A pumping test was made on well 19-52-26ddc2 way between tunnels Nos. 1 and 2, and IkO in order to determine the coefficients of feet below the contact with the Gerlng forma­ transmissibility and storage (specific yield) tion, was determined in the hydrologic lab­ of the alluvium. The well is 18 in. in oratory of the Geological Survey to be U. diameter and 83 ft deep. The total thickness Another sample, taken at the lower portal of of the aquifer is not known, but it is tunnel Ho. 2 had a coefficient of permeability assumed that the well penetrates most, if not of 7* This means that k or 7 gallons a day of all, the saturated thickness of the water­ water at 60° P. would percolate through a bearing material, and that the error caused cross section 1 mile wide and 1 foot thick by possible partial penetration of the aqui­ under a hydraulic gradient of 1 foot to the fer probably is small. 10 The test well was pumped continuously at would be necessary to conduct pumping tests an average rate of 1,^80 gpm for 29-J- hr. A of longer duration at several place* in the longer period of pumping would have been de­ area. sirable, but this was not possible. During the pumping test, the changes in water level Interference between wells were observed in two observation wells that were 100 ft and 6*tO ft from the test well. In areas where irrigation wells are closely Measurements of the recovery of the water spaced, pumping lifts may be greatly in­ level in the pumped well were made after the creased by interference between wells. Fig­ pump was shut off.. The data from the pumping ure 5 shows the theoretical shape and extent test were used to compute the coefficients of of the cones of depression around a well transmissibility and storage by both the (19-52-26ddc2) that has been pumped at a rate Theis formula (Theis, 1935» PP» 519-2U), and of 1,000 gpm for various periods of time. the Thiem formula (Wenzel, 19^2, pp. 81-85). The theoretical drawdown curves were computed by the Theis formula using the data obtained The average value of the coefficient of from the pumping test. transmissibility obtained by these formulae was 310,000 gpd/ft, and the average value Inspection of the curves shows that the of the coefficient of storage was 0.15. theoretical drawdown decreases as the dis-

_ ll4-6 Q r JL! s " T J ,.67r2S u

0=1,000 gallons per minute T = 310,000 gallons per day per foot S= 0.15

1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Distance from pumped well (r), in feet

Figure 5. Graph showing theoretical drawdown, according to the Theis formula, due to pumping a well at a constant rate. average coefficient of transmissibility de­ tance from the pumped well increases. For termined by the test, although probably example, the theoretical drawdown after pump­ representative, is not necessarily indicative ing for 5 years at a rate of 1,000 gpm would of the value throughout the entire area as it be 2.6 ft at a distance of 1,000 ft from the varies considerably with differences in com­ pumped well and 2.06 ft at a distance of position and thickness of the aquifer. The 2,000 ft. As the drawdown is directly pro­ average coefficient of storage computed from portional to the rate of discharge, the the test represents a minimum value. Under theoretical drawdown for various rates of water-table conditions the coefficient of discharge also can be determined from the storage increases with time as additional curves. water drains from that part of the aquifer within the cone of depression that is created A hypothetical case with the following by pumping. The values obtained from the ideal conditions is set up to explain the pumping test, although subject to the errors effect of pumping water for irrigation. The mentioned above, are thought to be accurate following four assumptions are made: (1) the enough for use in determining the approximate coefficients of transmissibility and storage effects of pumping wells. To obtain more are constant throughout the area of influence; accurate values of these coefficients, it (2) no recharge occurs during the pumping n period from irrigation; rainfall, or surface Ground water recharge flow; (3) the pump supplies 2 acre -ft of water per acre for a farm of 160 acres, or a Precipitation total of 320 acre -ft of water; (k) all the water is pumped during a 3 -month period. Recharge is the term used to denote the addition of water to the ground-water reser­ The average rate of pumping would be voir. Recharge to the unconfined ground- water reservoir is derived mainly from or 3 ' 55 acre "ft precipitation, which falls as rain or snow in Prom the curve in figure 5, the theo­ the valley of Pumpkin Creek and on the adja­ retical drawdown is computed as ^°° x 1.0 cent upland areas. Of the total precipita­ 1,000 tion in the area, part is discharged as or 0.8 ft at a distance of 2,000 ft from the runoff, some is used by growing plants, a pumped well at the end of 90 days pumping. small part percolates to the water table, Owing to recharge from adjacent areas and and the remainder is lost by evaporation. from Pumpkin Creek during the remaining 9 After the water becomes part of the ground- months of the year the water level would water reservoir, it moves in the direction of recover most, if not all, of the drawdown the slope of the water table and is dis­ that occurred during the pumping period. The charged at some point down gradient. The above values represent only the drawdowns movement of the unconfined ground water is that would result from pumping from storage; from the areas of recharge toward Pumpkin the fluctuations that would occur due to the Creek and its tributaries, where it either effects of natural recharge and discharge flows on the surface or continues as under­ are not taken into consideration. flow in the alluvium. In places, the ground water temporarily appears at the surface as Specific capacity springs and is subsequently returned to the ground-water reservoir. The specific capacity of a well is defined as the number of gallons a minute that a well Recharge to the confined ground-water res­ yields for each foot of drawdown. Under ervoir in the Lance formation occurs where water-table conditions, this relation is con­ the formation crops out west of the Pumpkin stant only when the drawdown is a small frac­ Creek area, or from the overlying Tertiary tion of the saturated thickness of the aqui­ sediments. fer; it also varies with the differences in the construction and development of wells. However, a comparison of the specific capac­ Irrigation ities of wells is useful in estimating the relative efficiency of wells and the relative Part of the water used for irrigation transmissibility of formations. The specific seeps down to the water table. No attempt capacities of the irrigation wells In the was made to determine the amount of water alluvium range from 20 to l8l gpm and average recharged to the ground-water reservoir from 78 gpm per foot of drawdown. The drawdown irrigation, but it is possibly as much as 50 and discharge of wells in the area are given percent of the amount applied. Studies made in the remarks column in table 7. in the Safford valley, Arizona (Turner, and others, 19^1, p. 28) show that about half the water diverted from the Gila River and about Depth to ground water one-fourth of all water pumped from wells is returned to the ground-water reservoir. The depth to the water table In the Pumpkin Creek area, In general, increases with the distance from the creek and in some places is Ground-water discharge more than 100 ft below the land surface. In the valleys the depth to water in most places Water is discharged from the unconfined is less than 25 ft below the land surface. ground-water reservoir in the Pumpkin Creek area by transpiration and evaporation, by Ground water under artesian pressure was seepage into streams, by underflow out of the encountered in what is thought to be the Lance area, by springs, and by wells. formation in wells 19-50-Head and 19-51-21dad. Both wells flow at the surface. Considerable test drilling would be necessary to determine Transpiration and evaporation the extent and thickness of this formation and the slope of the piezometric surface. Water may be taken into the roots of plants directly from the zone of saturation or from

12 the capillary fringe and may be discharged Underflow from the plants by the process known as transpiration. The depth from which plants Sufficient data were not available to de­ will lift ground water ranges from a few termine accurately the amount of water leaving inches for some grasses and field crops to the Pumpkin Creek area as underflow. However, more than 50 ft for some desert plants. an approximate estimate can be made by apply­ ing the value of transmissibility obtained The discharge of ground water by trans­ from the pumping test on well 19-52-26ddc2 at piration and evaporation is limited mainly to Redington. The total thickness of the satu­ the flood plain of Pumpkin Creek and a few of rated alluvium where Pumpkin Creek valley its main tributaries where the water table is joins the North Platte River valley is greater shallow. The areas of greatest rate of loss than the thickness at Redington; consequently, by transpiration generally are indicated by the coefficient of transmissibility would be an abundance of cottonwood and willow trees. greater at the lower end of the valley. By Some of the water now being lost by evapo­ using the value of transmissibility computed ration and transpiration could be salvaged by from the pumping test, it is estimated that lowering the water table to such an extent about 2,500,000 gpd, or 2,800 acre-ft of that these processes would be reduced mate­ water a year, leave the area as underflow. rially, thus adding to the amount of ground water available to wells. Although this would increase the total amount of ground Springs water available for development it would de­ crease the rate at which water could be de­ Several springs on the south side of the veloped from each individual well. valley discharge water from openings in the Brule formation or from gravel overlying the fractured Brule. These springs occur near Streams the contact between the Brule and the over­ lying Arikaree or Ogallala formations. Seeps Pumpkin Creek is an effluent stream through­ and moist areas were observed in some places out its entire course in the studied area, and where the contact between the Brule and the most of the surface flow of the creek is de­ Arikaree or Ogallala formations is covered by rived from ground water. The daily precipi­ slope wash. Records of some of the springs tation records in the area and the daily in the area are given in table 7* The total discharge measurements of the flow of Pumpkin quantity of water discharged from springs in Creek indicate that runoff occurs only after the area is believed to be small. periods of exceptionally heavy rainfall. Observations made in the field during the spring and summer of 19^9 verify this. The Wells amount of ground water leaving the entire drainage basin of Pumpkin Creek as stream Water is pumped from wells for irrigation, flow is estimated to be about 90 percent of stock, and domestic uses. Twenty wells in the total runoff, or an average of about the area obtain ground water for irrigation, 21,OCX) acre-ft per year. (See table 1.) and their reported yields range from 200 to 2,1*00 gpm. Most of these wells are used only Table 1.--Total runoff, in acre-feet, of Pump­ a small part of the year and the annual com­ kin Creek near the mouth bined pumpage of the wells probably does not [From records of the Surface Water Branch of exceed 2,000 acre-ft of water. A more de­ the U. S. Geological Survey obtained in tailed discussion of the irrigation wells is cooperation with the Nebraska Department presented in the section on the development of Roads and Irrigation] of ground water for irrigation. Most of the stock and domestic wells in the Year Total Year Total area yield from less than 1 gpm to several runoff runoff gallons a minute. Their yields are generally 1931-32 21*, 300 191*0-1*1 19, MO small because little water is available or 1932-33 22,600 191*1-1*2 23,770 19Jt2-U3 because they are not constructed or equipped 1933 -3^ 21,380 22,300 to yield large quantities of water. 193^-35 26,090 1943 -10* 26,190 1935-36 22,280 1944-^5 31,610 191*5-1*6 1936-37 11* ,290 29,190 Fluctuations of the water table 1937-38 22,1 to 191*6-1*7 26,780 1947-1*8 1938-39 23,660 27,11*0 The water table does not remain stationary 1939-to 19,090 Average 23,700 but fluctuates with the changes in the rates of recharge and discharge. If the discharge

13 from a ground-water reservoir exceeds the re­ 19-50-30cdd charge, the water table will decline, and vice versa. Therefore, the average level of Date Water 1 Date Water the water table depends upon the net rate at level level which the reservoir is depleted or replen­ May 18, 19*9 23.61 Mar. 28, 1950 23.7* ished. A ground-water reservoir is in equi­ July 12 2*.l8 May 9 23.55 librium when the recharge is equal to the Aug. 19 23.91 29 23.58 dischargej then the water table is more or Sept. 15 2*. 03 June 22 23.67 less fixed in position within seasonal limits. Oct. 13 23.99 July 17 23.66 Nov. 17 23.81 Aug. 20 23.82 In order to observe the fluctuations of Dec. 16 23.88 Sept. 21 23.**' ground-water levels in the area, six wells Jan. 27, 1950 23.06 Oct. 19 23-35 were selected for regular observation. Feb. 20 23.70 Jan. 18. 1951 23.1*9 Periodic water-level measurements have been made in one of these wells (19-55-29acb) since 193*1 Water-level measurements in !9-52-26ddc2 these wells are given in table 2. From the available data, it appears that no signifi­ May 18, 19*9 18.99 May 9, 1950 19.1* cant change In ground-water storage in the July 6 18.53 29 19.20 area has occurred in recent years; however, Aug. 19 19-. 36 July 17 22.62 the measurements indicate a seasonal rise and Oct. 17 23.50 Aug. 20 19-68 decline of the water levels. The water level Jan. 27, 1950 19.38 Sept .21 19.89 in well 19-55-29acb was about 2 ft higher in Feb. 20 20.70 Oct. 19 19-63 November 19*9 than it was during the same Mar. 28 19.60 Jan. 18. 1951 19.51 month in 193*** If extensive development of ground water 19"53-25acc for irrigation is undertaken in the future, a considerable change in the position of the June 27, 19*9 23.9* Feb. 20, 1950 2*. 12 water table may take place. Discharge of July 13 2*. 32 May 9 23.86 ground water by wells in part is a new dis­ Aug. 19 2*.*7 29 23.9* charge that is superimposed on the natural Sept. 15 2*.** June 22 2*. 2* balanced system. Before equilibrium under Oct. 13 2*.39 Sept .21 3*.91 pumping conditions can be established, water Nov. 17 2k. 20 Oct. 19 2*. 82 levels must fall sufficiently throughout the Dec. 16 2*.16 Jan. 18, 1951 2*.37 aquifer to increase the natural recharge or Jan. 27. 1950 2*. 15 to decrease the natural discharge, or both, by the net amount being discharged from the wells. In the alluvium, water levels will 19-5*-15bbb decline in the vicinity of the pumping wells during the irrigation season but can be ex­ May 16, 19*9 22.72 Feb. 20, 1950 23.38 pected to recover during the nonpumping July 13 22. *0 Mar. 28 23.39 season when the ground-water reservoir is re­ Aug. 19 22.78 May 9 23-33 plenished from stream flow and from underflow Sept. 15- 2*.0* 29 23.19 from adjacent areas. Also, the withdrawal of Oct. 13 23.19 Sept .21 2*. 10 water from the alluvium will cause a decrease Nov. 17 23.27 Oct. 19 2*. 39 in the flow of Pumpkin Creek and, during Dec. 16 23.30 Jan. 18, 1951 23.83 periods of heavy withdrawal, may dry It up in Jan. 27, 1950 23. *1 places. Table 2.--Water levels, in feet below land- 19-55-29acb surface datum, in observation wells Oct. 12, 193* 32.53 Aug. 7, 1936 30.*7 18-52-llddd Nov. 19 32.88 29 30.75 Jan. 10, 1935 33.27 Dec. 3 31.9* Date Water Date Water Mar. 5 33.96 Apr. 7, 1937 33.31 level level June 15 32.37 June 2* 33.85 May 18, 19*9 23.66 Mar. 28, 1950 23.5^ July 18 29.70 Aug. 12 3*.22 July 12 2*. 11 May 9 23-76 Aug. 20 28.28 Oct. 19 3*.*5 Sept. 15 23.76 29 23.82 Sept. 19 26.99 June 27, 1938 3*-52 Oct. 12 ' 23.68 June 22 23.8* Oct. 26 27.21 Oct. 27 26.38 Nov. 17 23-56 Aug. 20 2*. 13 Nov. 29 27.32 June 13, 1939 27.90 Dec. 16 23.51 Sept .21 23.90 Jan. 2, 1936 27.60 Dec. 6 30.50 Jan. 27, 1950 23.57 Oct. 19 23.81 22 27.85 Apr. 6, 19*0 32.17 Feb. 20 23.50 Mar. 31 28.78 July 28 32.92 June 9 29-75 Nov. 8 31.11 14 Table 2.--Water levels, in feet below land- the path of least resistance, valleys cut in surface datum, in observation veils Con. the Brule tend to develop along fracture zones; therefore, the principal fracture 19 -55 -29acb Continued zones of the Brule formation often underlie the alluvium of the valleys. Where a suffi­ Date Water Date Water cient quantity of vater can not be obtained level level from the alluvium, additional vater sometimes Oct. 25, 19^1 30.41 Feb. 20, 1950 32.13 can be obtained by drilling into the Brule Nov. 27, 19^2 33-58 Mar. 28 32.70 formation. June 21, 19*19 30. 2U May 9 33.39 July 13 30.21 29 33.68 The amount of vater that can be vithdravn Aug. 19 30.36 June 22 3^.12 from the ground-vater reservoir vithout Sept. 15 30.5^ July 17 35-05 causing excessive permanent levering of the Oct. 13 30.65 Aug. 20 35.60 vater table depends upon the capacity of, and Nov. 17 31-05 Sept. 21 35.25 the recharge to, the reservoir. If vater is Dec. 16 31. U8 Oct. 19 3k. ik pumped continuously from the ground-water Jan. 27. 1950 31.75 Jan. 18. 1951 35.33 reservoir faster than it is being recharged, the vater levels in veils vill decline, and the supply vill eventually be depleted. If Ground vater for irrigation the recharge during the nonpumping period replaces the vater removed, vater can be Present development pumped from the reservoir in excess of the rate of recharge for short periods of time Information was obtained on all the irri­ vithout causing serious damage. To develop gation veils in the area, but no attempt vas the maximum amount of ground vater from the made to obtain data on all the domestic and alluvium, vater must be pumped in excess of stock veils. Of the 20 irrigation veils in the rate of recharge during the grovlng the area, 16 obtain vater from the alluvium, season. The vlthdraval of additional ground 2 obtain vater from both the Brule forma­ vater in the area vill cause a reduction in tion and the alluvium, 1 obtains vater from the flov of streams leaving the area. the Brule formation, and 1 obtains vater from vhat is thought to be the Lance formation. It is estimated that an average of about Most of these veils have a large diameter and 21,000 acre-ft of ground vater leaves the penetrate most of the available vater-bearing valley of Pumpkin Creek annually as surface material. Information on the operation of flov. (See table 1.) This represents the the irrigation veils is given in the remarks amount of rejected or excess ground vater and column in table 7. is approximately the amount of additional ground vater available for development. If sufficient ground vater is vithdravn to cause Potential development a decline of the vater table, additional vater would be salvaged from loss by evapo­ Unconfined ground vater ration and transpiration and vould be avail­ able for irrigation use. Also, some of the Additional ground vater could be developed vater pumped for irrigation vould percolate from the alluvium underlying the flood plains into the ground-vater reservoir. Part of of Pumpkin Creek and some of its major tribu­ this "return flov" could be re-used; hovever, taries. If selection of the sites is pre­ part of this vater should be alloved to leave ceded by adequate test drilling to determine the area in order to prevent accumulation of the most favorable areas, veils that yield salts in the soil and ground vater. 1,000 to 2,000 gpm probably could be devel­ oped from this material in most places. Also, If an extensive program of ground-vater pumping tests should be run to determine the development is undertaken in the area, yield and the proper spacing of veils and the records should be kept of the amount of vater potential yield of the aquifer. pumped and the changes in vater level, and samples of vater should be collected from In some places, ground vater can also be selected veils for chemical analysis. obtained in sufficient quantities for irriga­ tion from fractures in the Brule formation. Artesian vater Large supplies of vater may be obtainable in places vhere the fracturing is very extensive In parts of the area, irrigation veils of or vhere the fractures are overlain by satu­ relatively small yield probably could be rated alluvial material. Under the latter developed from sandstones, which are thought conditions vater from the overlying alluvium to be in the Lance formation. Considerable travels dovnvard into the fractures in the test drilling vould be necessary to determine Brule and moves laterally through the frac­ the lateral extent and thickness of the sand­ tures to the veils. Because erosion follows stones. Water in the sandstones is confined 15 under artesian pressure; hence, it would rise 1.6 kwhr per acre-foot per foot of lift for a appreciably above the point at which it is pumping test run in the Dutch Flats area encountered and, in some parts of the area, (Babcock and Visher, 1950, p. 37). The would flow at the surface. Where the water electric motor and pump had an over-all effi­ is not under sufficient pressure to flow at ciency of 6k percent. During a detailed the surface, water could be obtained by pump­ study of the ground-vater resources of Deer ing. Valley, Ariz. (Eluhm and Walcott, 19^9, p. 9), it was determined that 1.8 kwhr were required to lift 1 acre-ft of water a height of 1 ft. Cost of pumping water The over-all efficiency of the pumping plants used in these tests probably was somewhat The cost of pumping water from wells de­ less than the 6k percent computed during the pends upon the cost of well development, the test in the Dutch Plats area, and probably cost of the fuel or power, the cost of drill­ more nearly represents the average conditions ing the well and installing the pump, and the that would exist in a pumping project. No cost of maintenance and operation. The main attempt was made to determine the cost of consideration in determining the operating electric power required to pump water owing cost of pumping ground water the cost of the to the very complicated sliding scale used in fuel or power is the only one discussed in computing electric power costs. this report.

Legend Alluvium Brule formation Lance formation F_ COUNTY Spring Surface water

R sow

R 55 W R 54 W R 53 W R 52 W R 51 W R 50W

Figure 6. Map showing sampling points in the Pumpkin Creek area, Nebr.

Records were kept of the amount of fuel CHEMICAL QUALITY OF THE GROUND WATER used during the pumping test on well 19-52-26ddc2. During the test, 97.6 gal of Introduction butane were used to pump 7.9 acre-ft of water a height of 36 ft (total pumping lift). This In this section, the chemical quality of amounted to 12.3 gal of butane per acre-foot the ground water is discussed briefly with of water pumped, or 0.3^ gal per acre-foot per reference to its general suitability for do­ foot of lift. At the present price of butane, mestic or irrigation use. Consideration is about 12f? per gallon, the cost of fuel would also given to the quality of the water as re­ be about ^ per acre-foot per foot of lift. lated to the mineral substances in the geo­ logic source. This discussion is based on The amount of electric power required to the results of analyses of 31 samples (see pump an acre-foot of water was computed as fig. 6), which include 5 samples that were 16 collected from wells outside the area. Ground-water samples were obtained from the sources are shown diagrammatical!} in figure following: (1) relatively shallow wells, 25 7, in which the height of the bar is equal to to 83 ft deep, drawing water from the allu­ the total cation or anion equivalents for the vium; (2) wells, 1*5 to 330 ft deep, pene­ particular analysis. trating the Brule formation; and (3) very deep wells, k$k to 925 ft deep, tapping the Chadron and Lance formations. Several of the Chemical character in relation to source samples collected outside the area are help­ ful in correlation work relating to the deep Water from deep wells that encounter the water-bearing formations. Three springs Lance formation is generally more highly flowing from contact zones between the Arik- mineralized, softer, and less siliceous than aree and Brule formations and two springs water in the overlying bedrock and alluvium. issuing from the alluvium were sampled. In The range in concentration of principal min­ addition, surface samples were obtained from eral constituents in water from the several Pumpkin Creek and its main tributaries. geologic sources is more easily noted in table 5-

EXPLANATION Alluvium Brule formation Lance formation | | Sodium Spring Magnesium Surface

Calcium

-Alluvium ' -Brule- Lance Springs- - Surf ace-

Figure 7. Mineral constituents and reacting values of basic radicals in waters, Pumpkin Creek area, Nebr. Analytical results, in parts per million, Hardness of the water tends to decrease for water samples from k wells drilled in the with depth of well both in the alluvium and alluvium, 12 wells drilled in bedrock (Brule, Brule formation; however, this relationship Lance, and Chadron formations), and 5 springs, is not well defined. Hardness, in parts per and 9 surface-water samples are given in million, ranges as follows: in the alluvium, table 3- The wells are listed by number and 119 to 20^; in the Brule formation, 6.0 to under geologic source. Springs are listed by lUO; and in the Lance formation, 17 to 1*3. number only, as the exact source of spring water generally is difficult to determine; The quantity of dissolved solids in water the probable source of the water from various shows no correlation with depth of well in springs is discussed on page 21. either the alluvium or Brule formation. With the exception of water in very deep water­ The results of analyses, in equivalents per bearing horizons, most of the mineral accumu­ million, are given in table k. In addition, lation in the water in deposits of Tertiary analyses of representative water from various age has occurred in the upper strata of bedrock. 17 Table 3.--Chemical analyses, in parts per million, and related physical measurements of waters in the Pumpkin Creek area, Nebr.

4* CD a Hardness Tr as CaCOj H ^ ^ ? s S I" |a a Date of ii 8 g & g Source '!~ V collection 1 4» I « S s 1-1§ 1 1 ** ^l?f £ S cf « 5 1 C ir\ at a ca jQ Hg S 14 V s 38 01 § § s *> g g g *«« H 1 2 * 1 ! i i S 1 fe g 1 3 | 11 £ Alluvium July 13, 1949 30 41? 8.0 19 7.2 0 234 15 5.0 0.4 8.1 288 178 0 ift 19--52-23cdd...... Oct. 12 7.7 419 54 O nji a& 7-0 55 6.7 0 250 21 8.0 ,4 9.0 0.30 338 119 0 4R 19-52 -26ddc2...... July 11 Qo 7 0 466 4o .03 66 9.5 20 5.6 0 P66 12 5.0 .4 16 328 204 0 17 19 -54-7bab...... Oct. 13 25 7.6 394 5? .64 36 8.5, 45 6.2 0 224 19 9.0 .4 18 .30 320 125 0 42 arule formati on 17-51-l4ddb * ...... Oct. 13, 1949 225 7.7 313 50 0.07 42 5.3 13 5.2 0 172 9.0 6.0 0.4 7.4 0.20 236 127 0 18 Oct. 13 330 8.2 OOA 41 .06 39 8.2 16 6.3 ft 16P 9.0 8.0 .4 8.7 30 24o 131 0 PO 18-51 -23baa...... Oj fr TO 172 7 0 296 59 .03 P4 11 29 4.4 0 172 17 6.0 1.2 2.1 .40 9U8 106 0 5/C 18-52 -7aab ...... Oct. 12 IPfi [-7*6- 376 -57- 1*7 37 la JiO 5.0 o 208 28 15 .4 4.6 .30 318 134 0 3ft 19-53-15bba...... Oct. 13 180 9 0 261 61 .03 13 3.1 48 5.6 1? 136 11 7.0 .4 1.0 .30 254 0 67 19-54-30aab...... Oct. 13 7 C 54 .04 42 8.5 24 4.7 0 ifift 21 9.0 ,4 5.7 30 270 140 0 P6 19-55 -4bbc...... Oct. 13 160 8.4 429 66 .06 2.0 .2 106 4.2 1ft 218 24 7.0 1.2 4.0 .40 356 6 0 95 19-55 -SOadc...... July 13 100 374 57 TJ 7.3 36 5.6 6 192 14 7.0 .4 8.6 276 11? 0 40 Chadron formation 20-50-26edd iHov. 17, 1949 1870 17.81 541 I 64 To.04 I 32 17.7 I 74 I 8.81 0 I 242 I 63 I 13 10.4 1 12 le.40 I 412 I 112 I 0 I 57 Lance formation (V»+ 19 1 OllO 925 6.0 1 75O 14 1 *7 5.0 1.9 llTfi 4.8 0 r\£j\ 5.0 ion l.P 0.7 1,170 PI 0 oft 19-48-30b 1 ...... Sept. 15 518 8.1 1,360 15 12 3-2 POO 4.8 0 432 106 169 .4 .2 834 43 0 93 19-50-llcad...... [Aug. 18 454 8.1 i ^4o 25 /\c 4.0 1.6 292 2.4 0 41 ft 62 182 1.0 .0 812 17 0 97 Aw. 7. 1950 454 7.7 1.430 * * * * 6.0 .5 293 3.2 0 412 * * 191 0.70 97 3prjIngs IB-50 -19ccc ...... Sept. 16, 1949 S.o 305 62 40 7 n 17 2 1. 0 180 8.0 4.0 0.4 2.4 232 129 0 2P TrQ l8-50-28dba...... Sept. 15 7.5 313 45 42 9.0 5.5 3.2 0 9.6 2.2 .4 *.5 228 142 0 "\?ft l8-51-28dbd...... Sept .16 8.1 3O4 53 40 7.7 8.8 10 0 172 6.4 3.0 .4 6'1 22k 132 0 18-53 -22acd ...... Oct. 12 7-9 331 51 0.03 47 8.9 14 3.6 0 208 2.0 6.0 ,4 2.4 ©.20 258 15* 0 16 19-54-33abb...... Sent. 16 7-9 495 H 3.4 4.5 67 8.0 0 2^4 34 18 .6 3.3 * * 352 104 0 56 &urfac ftft .07 ko Lawrence Fork, 2 miles south of Redington, Nebr ...... 2 ko 7k 77 07 3.35 P7 PI Middle Creek near confluence 2.48 .81 Uo .12 > kk .10 .27 Greenwood Creek south of Courthouse Rock Canal...... 1.61 .82 .k2 .23 2.81 .07 .20 1 Outside immediate area of investigation. The percentage of sodium for samples of moderately low mineral content and is hard. water in the alluvium ranges from 17 to k8; The dissolved-solids content is rather uni­ in the Brule formation, from 18 to 95. The form, ranging from 288 to 338 ppm. The depth percentage of sodium for water in the Lance of wells ranges from 25 to 83 ft, with one formation is remarkably uniform, ranging from depth not known. The water from all wells is 93 to 98. quite siliceous, a characteristic of ground water in many western areas of the Great Plains region. In addition to silica, the Alluvium dissolved solids consist largely of calcium, sodium, and bicarbonate ions. Ground water in the alluvium, as repre­ sented by four samples from drilled wells The water sample from one of the wells adjacent to Pumpkin Creek (see fig. 6), is of (l9-5U-7bab) had an iron content of 0.6k ppm, 19 Table 5 --Range in mineral constituents, in parts per million, of samples of water from several geologic sources

Constituent Alluvium Brule formation Lance formation Maximum Minimum Maximum Minimum Maximum Minimum Silica...... 55 k& 66 M 25 Ik Calcium + magnesium 76 k3 50 2.2 15 5.6 Sodium + potassium. 62 26 110 18 483 29k 266 22k 218 136 960 k!2 Chloride...... 9.0 5.0 15 6.0 191 169 Dissolved solids... 338 288 356 236 1,170 812 Total hardness..... 20k 119 iko 6 *3 17 Percent sodium..... U8 17 95 18 98 93 which was the highest obtained in the area area of investigation) for the purpose of com­ sampled. This quantity of iron is reportedly paring the character of this water with that sufficient to give a rust color to the water of the Brule and Lance formations. This prior to clearing the pump. water, sampled from a well 870 ft deep, is similar in most respects to the high sodium The percentage of sodium is not uniform in water that is encountered frequently in the water from the alluvium and is probably in­ Brule formation. The dissolved solids con­ fluenced to some extent by the mineral char­ tent is Ul2 ppm and is composed largely of acter of the Brule formation. sodium and calcium bicarbonate. Although the percentage of sodium is 57, total hardness as Only two boron analyses were made, and both CaC03 is 112 ppm. The water has a high silica results for this element are low and about content of 6k ppm, and the sulfate concentra­ the same as that found in water from the tion of 63 ppm is higher than that found in Brule. samples from the Brule formation. High sul­ fate water in the Brule formation in other adjacent areas in Nebraska has been reported Brule formation by Wenzel (Wenzel, Cady, and Waite, pp. 128-129). Eight samples were obtained from wells that are in the Brule formation and that range in depth from ^5 to 330 ft. (See fig. 6.) As Lance formation in water from the alluvium, the concentra­ tions of dissolved solids are moderately low Water, thought to be from the Lance forma­ and range from 236 to 356 ppm. The percent­ tion (see fig. 6), is a distinctly different age of sodium is more variable, with a range type than found in other formations of this from 18 to 95. region. The differences can readily be seen in table 5« Compared to water obtained from Although higher in ratio of sodium (95 and the overlying Tertiary and Quaternary 67 percent, respectively) and softer than deposits, water from the Lance formation is water from other wells in the Brule formation, lower in silica and total hardness and is samples of water from wells 19~55-4bbc and much higher in sodium and potassium, bicar­ 19-53-15bba are similar in respect to the bonate, chloride, dissolved solids, and per­ other acid constituents, sulfate, chloride, centage of sodium. The percentage of sodium fluoride, and nitrate. This suggests that is relatively constant, ranging from 93 to 98 encroachment by chloride-bearing waters from percent. The high content of chloride is the Lance has not occurred, and that the evidence of the marine origin of some of the changes in the character of the water were material through which water in the Lance brought about through base exchange. Evi­ formation has percolated. dently the Brule formation differs in various areas with respect to mineral matter capable The water from one well (l8-56-2cca) had of entering into base exchange reactions. 960 ppm bicarbonate and only 5*0 ppm sulfate. The sulfate-bicarbonate relationship in water The iron and boron contents were generally from the Lance formation has been previously low in samples of water in which these con­ observed in other ground-water studies in stituents were determined. Wyoming and Montana. Riffenburg (1925, p. ^7) in reviewing the work of the other investi­ gators, has suggested that the relation of Chadron formation sulfate and bicarbonate in water from the Lance and Fort Union formations may be ex­ One sample (20-50-26cdd) was obtained from plained as due either directly or indirectly the Chadron formation (outside, the immediate to the reducing action of lignite, 20 carbonaceous shale, or natural gas in these Montana, particularly those in the lever- formations. In this reduction, an equivalent rierite group, have been described by Renick amount of bicarbonate is formed for the sul- (1929, p. 28). He points out that the ex­ fate reduced. Hydrogen sulfide is an end change of calcium and magnesium in the water product in this reaction. In view of the for the sodium in the base exchange silicate vide range in the concentration of sulfate is rapid and that the exchange may be com­ (5.0 - 106 ppm) in water from the Lance for­ plete after the water has percolated through mation, it might be postulated that complete­ a few feet of rock material that contains ness of reduction of the sulfate is a function leverrierite. of time or existing quantities of carbona­ ceous materials. Also, the sulfate content in the water, as represented here, originally Springs must have been substantially larger than that found in the water in overlying deposits. Five springs issuing either through open- Otherwise, only nominal differences in the Ings in the Brule formation or from gravels bicarbonate content of the water from the that overlie the Brule were sampled. (See several formations would be expected. If the fig. 6.) As shown in table 3 and illustrated source of recharge to the Lance formation is in figure 7, the water from springs is similar derived principally from the overlying Ter­ to that from the Brule formation and the tiary formations, then appreciable solution alluvium. Water from all the springs has a of sulfate must occur in the water as it moderately low mineral content and is hard. moves through the Lance formation. Renick Water from spring 19>5^-33abb differs from (1929, p. k8 ), reports the chemical analyses the water from other springs in having a of several samples of materials obtained from relatively high sodium ratio (56) and in con­ tiie Lance formation. A summary of the major taining more sulfate and chloride--an occur­ water- and acid-soluble substances follows: rence often associated with waters from the Brule formation. Analyses of water- and acid-soluble constitu­ ents, in percent of air-dried sample, of rock materials from Lance formation, Rose­ Quality of water in relation to drainage bud County, Mont. Water samples were obtained from several Mate­ To­ Ca Na+K points on Pumpkin Creek and its principal rial Mg HC03" SOIT Cl N03 tal tributaries from the south. (See fig. 6.) Sand. 0.01 0.00 0.26 0.03 0.58 T I/ T l] 0.91 There is little increase in dissolved solids Shale .05 .02 32 .05 .85 T I/ T I/ 1.29 downstream, probably because the tributary Shale .03 .01* 3* .05 .8? 0.03 0.01 1.36 waters are all of lower mineral content than Sand­ the main stream. (See table 3*) The dis­ stone .00 .00 .01 .02 .02 T I/ T I/ .05 solved solids concentration of Pumpkin Creek water ranges from 206 to 1*02 ppm. Hardness I/ T = Trace as calcium carbonate ranges from 121 to l8l ppm. Most of the water-soluble minerals in the shales and sands consist of sodium sulfate Pumpkin Creek water has a higher concentra­ (NagSOU), though there are noticeable amounts tion of sodium than the tributary streams; to of calcium and magnesium, largely as car­ some extent this is attributable to diversion bonate (reported as bicarbonate). As the in Courthouse Rock Canal and subsequent irri­ materials collected would be near the ground gation return flows. Also, there is a sig­ surface, the insignificant amount of chloride nificant increase in the ratio of equivalents is an indication that substantial leaching of sulfate to total equivalents of anions in occurred in the Rosebud County samples. Un­ the main stream at the gaging station on High­ doubtedly, there must be considerable varia­ way 26, as compared to other samples taken tion in the types and amounts of water- upstream. (See fig. 6.) soluble substances in different parts of the formation. To date, irrigation has had no adverse effect on the chemical quality of the ground Reference is again made to the trilinear water in the area. diagram in figure 7. All the plotted points for samples of water -from the Lance formation are found near the lower right vertex (Na+K) Quality of water in relation to use of the triangle. Similar high sodium ratios were found by Wenzel (Wenzel, Cady, and Waite, Except for being somewhat hard, water from 19^6, pp. 128-129) in the analyses of water the alluvium, Brule formation, and springs, as from the Lance formation in Scotts Bluff represented by samples collected during this County. Base exchange properties of some investigation, is of satisfactory quality for minerals found in the Lance formation in most domestic needs. The mineral content of 21 all the water, with exception of that from Flowing well 19-50-Head supplies water for the Lance formation, is considerably lower irrigation. Because of the very high per­ than the upper limit of 500 ppm suggested by centage of sodium (97) the water is classi­ the U. S. Public Health Service (19^6). An fied as unsuitable. However, the owner excerpt of these standards, which also in­ reports no evidence to date of damage to the clude specifications for biological, sanita­ farm soils, which are sandy and well-drained. tion, and other cheat!cal substances, is given below. CONCLUSIONS Constituent Maximum parts per million Unconfined ground water in sufficient Iron and manganese quantities for irrigation supplies is con­ (together)...... 0.3 tained in the Quaternary alluvium that under­ Magnesium...... 125 lies the flood plains of Pumpkin Creek and Sulfate...... 250 some of its major tributaries. Wells that Fluoride...... 1.5 yield 1,000 to 2,000 gpm probably could be Chloride...... 250 developed from this material in most places. Dissolved solids.. 500 (1,000 permitted) Ground water also can be obtained in suffi­ cient quantities for irrigation from frac­ Undesirable quantities of iron may be tures in the Brule formation in places where present in some places in water from the the fracturing is extensive or where the alluvium, but for the most part, this con­ fractures are overlain by saturated alluvium. stituent is found only in negligible quanti­ ties . This reconnaissance was not designed to give the detailed data required for the Although in many places the water from the proper location and construction of wells; Lance formation is soft and therefore suit­ hence, more detailed studies of the water­ able for domestic supplies, the water in some bearing properties of the alluvium should be areas may contain undesirable quantities of made prior to the construction of irrigation chloride. All the analyzed samples of water wells. The selection of sites for irrigation from the Lance formation are of satisfactory wells should be preceded by adequate test quality for most domestic needs. drilling in order to determine the most favor­ able places for development in the alluvium. With respect to use for irrigation, the Also, additional pumping tests are desirable to samples of water from the alluvium and firule determine the yield and proper spacing of the formation for the most part rate "excellent wells and the safe yield of the aquifer. to good" by the method of rating proposed by Such pumping-test data obtained should be Wilcox (19^8, p. 27). These ratings are con­ supplemented by laboratory tests on the tingent upon normal soil, crop growth, and hydrologic properties of the water-bearing drainage conditions. In Wilcox*s method, the materials. criteria of total concentration (expressed as micromhos per cm. at 25°C) and percentage of It is estimated that about 21,000 acre-ft sodium (ratio of equivalents of sodium to of additional ground water is available annu­ total cation equivalents and multiplied by ally for development from the alluvium. If 100) in the water are used for classification* sufficient ground water were developed to The expression of the results in various cause a decline of the water table, additional classes or groups is more easily seen in water would be salvaged from loss by evapo­ figure 8, in which specific conductance and ration and transpiration and would be avail­ percent sodium are shown on the abscissa and able for irrigation use. Also, some of the ordinate, respectively. water pumped for irrigation would percolate into the ground--water reservoir. Part of As the conductivity or mineral concentra­ this "return flow" could be re-used; however, tion of the water increases, the water is part of this water should be allowed to leave given a lower quality classification. Like­ the area in order to prevent the accumulation wise, the quality classification becomes of salts in the soil. If an extensive pro­ poorer when the percentage of sodium in­ gram of ground-water development is under­ creases above 50. Thus water of low dis­ taken in the area, records should be kept of solved solids content but of high sodium the amount of water pumped and the changes in ratio may not be satisfactory for irrigation. water levels, and samples of water should be Because of its high percentage of sodium, one collected periodically from selected wells of the samples of water from the Brule forma­ for chemical analysis. tion (19-55-lj-bbc) falls into the unsuitable category. All of the samples of water from In parts of the area, wells of small yield the Lance, by reason of high percentage of probably could be developed from the sand­ sodium and relatively high mineralization, stones that are thought to be in the Lance are not satisfactory as irrigation supplies. formation. Considerable test drilling would 22 100

500 1000 «~- ISpO 2000 2500 3OOO 35OO 4OOO Specific conductance in micromhos per cm at 25 C

Figure 8. Classification of waters in the Pumpkin Creek area for irrigation use.

23 be necessary to determine the extent and Darton, N. H., 1903&, Description of the Camp thickness of the sandstones* Water in the Clark quadrangle, Nebr.: 'U. S. Geol. Sur­ sandstones is confined under artesian vey Geol. Atlas 87, ^ pp. pressure; hence, it will rise appreciably above the point at which it is encountered Darton, N. H., 1903b, Description of the and, in some parts of the area, will flow at Scotts Bluff quadrangle, Nebr.: U. S. the surface. Geol. Survey Geol. Atlas, 88, 5 PP» Results of analyses of 31 water samples Hayes, F. A., and Bedell, H. L., 1921, Soil from ground and surface locations depict survey of Banner County, Nebr.: U. S. water that ranges from moderately mineral­ Dept. Agr. in cooperation with Nebraska ized, hard water in the alluvium to more Univ., 62 pp. highly mineralized, soft water in the deeper Lance formation. Water in the Brule forma­ Hayes, F. A., and others, 1921, Soil survey tion, though similar in mineral content, of Morrill County, Nebr.: U. S. Dept. Agr. differs widely in the degree of hardness. in cooperation with Nebraska Univ., 69 PP. These differences imply that base exchange materials may be present in some parts of Meinzer, 0. E., 1923, The occurrence of the Brule formation. Water obtained from the ground water in the United States, with a water-bearing sandstones in the Lance forma­ discussion of principles: U. S. Geol. tion is characterized by percentages of Survey Water-Supply Paper ^89, 321 pp. sodium exceeding 90, low degree of hardness, and high concentrations of bicarbonate and Renick, B. C., 1929, Geology and ground-water dissolved solids. The water is further iden­ resources of central and southern Rosebud tified with chloride concentrations of more County, Mont., with chemical analyses of than 150 ppm. The content of sulfate varies water: U. S. Geol. Survey Water-Supply considerably, depending on the extent of Paper 600, lJ*0 pp. reduction to bicarbonate that has occurred. Riffenburg, H. B., 1925, Chemical character Although somewhat harder than is desirable, of ground waters of the northern Great water from the alluvium and from the Brule Plains: U.S. Geol. Survey Water-Supply formation is of satisfactory quality for most Paper 560-B, pp. 31-52. domestic needs. However, there may be a problem of high iron in some supplies from Theis, C. V., 1935, The relation between the these sources. The percentage of sodium in lowering of the piezometric surface and the water from the Brule in some places is the rate of duration of discharge of a well relatively high, but water from this source using ground-water storage: Am. Geophys. as well as from the alluvium is as a rule of Union Trans., vol. 16, pp. 519-52U. satisfactory quality for irrigation. Turner, S. F., and others, 19*H> Water The chloride content of water in the Lance resources of Safford and Duncan-Virden formation in some places may be undesirable, Valleys, Ariz. and N. Hex.: U. S. Geol. particularly in the supplies from the very .Survey (mimeographed report), 58 pp. deep wells. Otherwise, the water is very soft and will meet the requirements for most U. S. Public Health Service, 19^6, Drinking domestic needs. Conversely, by virtue of the water standards: Public Health reports, high sodium percentages, water from the Lance vol. 61, no. 11, pp. 371-38U. formation is not satisfactory for irrigation. Wenzel, L. K., 19U2, Methods for determining permeability of water-bearing materials, REFERENCES CITED with special reference to discharging-well methods, with a section on direct laboratory Babcock, H. M., and Visher, P. N., 1950, methods and bibliography on permeability Geology and ground-water resources of the and laminar flow, by V. C. Fishel: U. S. Dutch Flats area, Scotts Bluff and Sioux Geol. Survey Water-Supply Paper 887, 192 pp. Counties, Nebr., with a section on the chemical quality of the ground water by Wenzel, L. K., Cady, R. C., and Waite, H. A., W. H. Durum: U= S. Geol. Survey Circ. 126, 19^6, Geology and ground-water resources of 51 pp. Scotts Bluff County, Nebr.: U. S. Geol. Survey Water-Supply Paper 9^3, 150 pp. Bluhm, F. I., and Wolcott, H. N., 19^9, Ground-water resources of Deer Valley, Wilcox, L. V., 19^8, The quality of water for Maricopa County, Ariz.: U. S. Geol. Survey irrigation use: U. S. Dept. Agr. Tech. (mimeographed report), 3*4- pp. Bull. 962, ko pp. LOGS OF WELLS 18-54-lbbd Logs of veils obtained from veil drillers Thickness Depth and veil owners are presented in table 6. It (feet) (feet) vas not possible to verify the logs by exam­ Soil...... Ik 14 ination of the drill cuttings; consequently, 9 23 the logs are presented with the drillers' Hardpan (Brule formation). 10 33 terminology largely unchanged. It is be­ 27 60 lieved that the logs are reasonably accurate and give a fairly good description of the materials penetrated. 19-50-Head

199 1QQ Table 6.--Logs of veils in the Pumpkin Creek Hardpan (Brule formation). 101 300 area, Kebr. Chalk rock and limestone.. 125 425 29 454 l8-50-5add Thickness Depth 19-50-23ddd (feet) (feet) 35 35 Soil...... 6 6 2 37 2 8 Hardpan (Brule formation). 26.5 63.5 17 "5 Sand, clean, and gravel... 12 37 l8-50-6aaa 19-50-30cdd Loam, sandy (no gravel)... 30 30 Hardpan (Brule formation}. 40 70 20 20 61 81 l8-51-3dcb 19-51-25dcc Sand, fine; some gravel... 40 40 Clay (Brule formation).... 50 90 oo 23 39 62 Hardpan (Brule formation). 2 64 l8-51-23baa 31 95 Soil...... 10 10 50 60 19-51-35aaal Clay (Brule formation).... 112 172 Soil, fine, 15 15 n«v 15 30 18-52-llccc 10 40 Soil and gravel, coarse... 35 35 Clay (Brule formation).... 8 43 19-52-25bbd Soil...... 30 30 l8-52-12bbc 13 43

Soil...... 10 10 £.£ 7oid 19-52-26ddc2 Harduan (Brule formation). k 80 Soil...... 12 12 71 83 l8-52-13acc 24 2k 19-52-34abb Clay...... 58 82 Soil...... 5 5 Clay...... 10 15 Ik 29

25 Table 6.--Logs of wells in the Pumpkin Creek 19-55-20adc Continued area, Nebr. Continued Thickness Depth 19-52-36bbd (feet) (feet) 72 100 Thickness Depth (feet) (feet) 28 28 19-55-33aaa 22 50 15 65 Soil...... 8 8 22 30 Hardpan, yellow (Brule 19-53-22bcb 370 *oo 65 *65 11- 11 Mud, yellow (clay)...... 10 *75 9 20 20 *95 *0 60 Shale, light blue ...... 25 520 Shale, sandy...... 10 530 15 5*5 19-53-26aclb 85 630 10 6*0 Soil...... 11 11 175 815 9 20 20 835 38 58 ?...... 25 860 f T o v 6^4 /*tv Vil 11 A 60 920 60 980 19-53-26cdi31 6*0 1,620 Shale , gray...... 160 1,780 28 28 r 70 1,850 Clay (Brule formation).... 72 100 Shale, sandy, light gray.. 120 1,970 Uo 2,010 Shell...... 3 2 m 3 19-5*-15bbl3 177 2 1OA 30 2,220 19 19 70 S oon 3 22 180 2 k7n 26 *8 3 2 k77 Brule formation...... 2 50 3*7 2,820 ?...... 180 3,000 *5 3,0*5 19-5*-15bc c *16 3,*61 1 a ]i£p 18 18 Shale, limy, light gray... 263 3,725 22 kn 100 3,825 23 63 Shale, sandy, dark gray... 115 3,9*0 2 65 ?...... 100 k nlio Shale, dark blue; contains 120 M6G 19-55-lcda Shale, light blue; contains *15 h CtfK Soil...... 16 16 Shale, light blue, and 8 2* shale, white; contains Hardpan (Brule formation). 56 80 25 *,6oo 3 *,603 0157 4,86o 19-55-2cbd Slate...... 190 5,050 30 5,o8o Soil...... 1* 1* Lime and shale , broken. . . . 10 5,090 6 20 *5 5 1 Vi Clay (Brule formation).... 80 100 15 5,150 10 5,160 10 5,170 19-55-2Qadc 30 5 POO flo 5,280 Soil.., 20 20 Slate, contains hard Gravel, 8 28 70 5,350 26 Table 6. Log* of wells in the Pumpkin Creek RECORDS OF WELLS AMD SPRINGS area, Kebr. Continued Records of 83 veils ana springs la the 19-55 -33«*»"Continued Pumpkin Creek area were obtained during the investigation and are given in table 7* The Ibiekness Depth location of them veils is shown on plate 1. (feet) (feet) All information classed as reported was 95 « kkc obtained from the owner or driller. 5 5,^0 105 5,555 Shale, bentonitlc, white.. 5 5,560- 15 5 ^f*i Shale, bentouitic, white.. 20 5,595 07fn 5 ,OO2&£a i 5.663 ik 5 ,«77£ftt Shale soft* brown...... 20 5.697

27 Table 7.--Records of wells and springs in the Pumpkin Creek area, Nebr. Well number: See text for description of well-numbering operated; W, windmill. system. Use of water: D, domestic; I, irrigation; N, none; 0, Type of well: Dr, drilled well; Du, dug well; Sp, spring. observation; S, stock. Depth of well: Measured depths are given in feet and Measuring point: Bpb, bottom of pump base; Ls, land tenths below measuring point; reported depths are surface; Tbc, top of board cover; Tc, top of casing; given in feet below land-surface datum. Tpb, top of pump base; Tpc, top of pipe clamp. Type of casitg: P, iron or steel pipe; W, wood. Depth to water: Measured depths to water level are given Character of water-bearing material: G, gravel; S, sand; in feet, tenths, and hundredths; reported depths are SI, siltstone; Ss, sandstone. given in feet. Geologic source of ground water: Kl, Lance formation; Qa, Remarks': Ca, sample collected for chemical analysis; D, alluvium; Ta, Arikaree sandstone; Tb, Brule formation. discharge in gallons a minute (E, estimated; M, meas­ Method of lift (first letter): C, cylinder; Cf, centrifu­ ured; R, reported); DD, drawdown in feet while dis­ gal; F, natural flow; J, Jet; N, none; T, turbine. charging at the preceding rate; L, log of well given Type of power (second and third letter): B, butane; E, in table 6; T, temperature in degrees Fahrenheit. electric motor; G, gasoline or diesel engine; H, hand - - Measuring ' 45 13 5-3 0 point $ « to ^ 0) o) tt) § ^, M) u to ^ 0) I oJ S *"^* H g£0) i-f H a 03 H co is 4^ 3 5 -H Remarks cn u to ft 0) O a to o 0 S 4^ W ft Pi 4-4 o « S3 a P. stl- 4-4 O 4-" -H o 0 -H 4-4 ft O |~ 03 fc O 1^1* 5^ ** 0} -» H 1 b IJ^g 0) Qj PI 8 Ql 03 w O w 4^ (D CO CD + * 0| 10 W to +> ft fi 1" 0) to H ^-''^ **

Uvn-t- /i /i -22bcb P Dr 60 6 P S On C D o Ls 20 191*9 L -25acc Dr TO 12 P S,G T,G I Tpb 0 23.9^ 6-27-1*9 D600H -26acb A. F. Burnett... Dr 58 11* P S,G Qa T,G I Ls .... 11 191*9 D900R, DD3T, L -26cda .... .do ...... Dr 100 6 P SI Tb C,W D fS Ls .... 60 191*9 T55, L -3l*bcd Dr 6 P SI Tb C u Tpc 4O U 36.12 6-28-1*9

19-5^-7bab D . Croathouse . . . Dr 25 6 P S,G Qa C,W D Ls 13 191*9 Ca -15bbb Bert Rodgers.... Dr 50 18 P S,G Qa T,G I Tc t |l 23.12 5-16-1*9 D580M, DDll*.5,L -15bcc .... .do ...... Dr 65 18 P S,G Qa T,G I Tpb + .2 32.70 5-16-1*9 Dl*20M, DD21.5, L -15ddd Dr k P 0.1 Tb C,N N Tc o n 52.07irrt iC*7 5-16-1*9 -22daa M. Farrell...... Dr 1* P 01 Tb C u D Tc +1.0 66.00 5-16-4Q

T. Muhr...... Dr 60 18 P S n QA T fl I Ls 30 191*9 TlftfVTR -30aab Dr 1*5 6 P SI Tb C.E D Ls 22 191*9 Ca 19-5l*-33abb Sp SI Tb F S D2E, Ca -3l*aaa E. J. Whipple... Du 50+ 1*8 W SI Tb C,G D Ls 50 19-55-lcda F. L. Johnson... Dr 80 21* p G,S1 Qa,Tb T,G I Ls 19 191*1 D2,300R, L -2cbd Dr 100 18 p S.G Qa N N Tc +.7 10.97 6-29-1*9 L -l*bbc Dr 160 6 p SI Tb C,W D,S Ca -20adc Mr . Stauff er .... Dr 100 18 p G,S1 Qa,Tb T,G I Ls 20 T53, D1,200E, DD13.5, Ca,L -29acb Du,Dr 80 18 p S,G Qa N 0 Tpb +1.1* 31.64 6-21-1*9 Prairie Oil Co.. Dr 5*697 p N N Ls 105 1917 L Morrill County 18-50-lbcd C. B. & Q. RR... Dr 6 p Si Tb C,H D,S Tbc + .2 25.80 5-19-1*9 T55 -5add Dr 63-5 6 p SI Tb N N Tc +.3 1*6.18 5-19-49 L -6aaa D. C. Hutchinson Dr 70 6 p SI Tb C,W,G D Ls 58 1949 L -19ccc Sp SI Tb F S D10E, Ca -21bbb W. Earless ...... Dr 65 i* p SI Tb C,E D,S Tc -6.7 12.02 8-19-1*9 -28dba Sp SI Tb F I T56, D560M, Ca 18-51-lccc Sp G Qa F S -2ddd Dr 20 6 p 8,0 Qa C,W S Tpc +1.8 8.87 5-19-49 5-20-49 -3dcb vdO * Dr 90 6 p SI Tb C,W S Bpb +1.6 39.95 L -l6ccb County School... Dr 75 6 p SI Tb T,G I Ls * 53 1949 D1,200R, DD8 -23baa Dr 172 5 p SI Tb C,W S Tpc +1.6 5-19-49 L, Ca -2l*bcc H. S. Welker.... Du 1*8 SI Tb c,w D,S Ls * 50 -28dbd J. Miller...... SP G Qa F I T6l, D900E, Ca 18-52 -Ibcc Dr 71* 18 p S,G Qa T,G I Bpb 0 16.18 5-18-49 D1,200R -7aab Walter A. Lease. Dr 128 6 p SI Tb C,W S Ls 68 1949 Ca -8ddb Guy Seckles ..... Dr ll*0 6 p SI Tb c,w D,S Ls 85 1949 -llcca Fred Wright..... Dr 23.5 6 p SI Tb N N Tc 22.68 5-19-49 -llccc Dr 6 p SI Tb C,G D Ls '+".5 22 1949 L -llddd Dr 18 p S,G Q» T,G I Tpb 2l*.l6 5-18-49 -12bbc Dr 80 18 p S,G Qa T,G I Tpb +.5 10.20 5-18-49 D1,800R, DD24, L -12ccc J. Barden...... Dr 18 p S,G Qa T,G I Tpb +.2 21*. 02 5-18-49 -IJacc G. Mewkirk...... Dr 82 6 p SI Tb C,W S T56, L -28bda Sp G Qa F D900E 19-50-llcad John Thompson ... Dr p Ss Kl? F I T60, D200E, Ca, L -23ddd P. Hutcheson.... Dr 37 6 p S,G Qa C,H D Tc + .5 13.32 5-19-49 L -25bcc N, G. Beskas.... Dr 1*1* 6 p S,G Qa C,H D T53 -29aad Dr 1*0+ 6 p S,G Qa C,W D Tpb +.7 32.50 5-20-49 T56 -30cdd Dr 81 21* p S,G Qa T,G I Tc *+is 23.61 5-18-49 D1,500R, L -33baa Dr 25 6 p S,G Qa C,W D Tc 16.08 5-l8249 Dr 28 6 p S,G Qa C,G D Ls * 20 1949 -36bbb R. Hart...... Dr 36 6 p S,G Qa C,W D,S Ls 15 1949 T56 19-51-19CCC ,V. E. Eckert.... Dr 68 18 p S,G Qa T,G I Tpb +1.0 16.76 5-23-49 D1,450R, DD8 Table 7.--Records of wells and springs in the Pumpkin Creek area, Nebr. Continued Measuring point 1ofDiameterwell Characterofwater­ Geologicofsource levelbelowmeas­ (feet)uringpoint Dateofmeasurement -I materialbearing groundwater Distancetowater §PU |(inches) l-lS o it u Well no. Owner or tenant n 3o Description Remarks <*-( o ! o !l I o OtS O *C$ 4) EH Morril L County Cor tinued 19-51-21dad Emeric Nerud I.. Dr Ss Kl? F N D20OR -25dcc 1C. Chris-tens en.. Dr 95 18 P S,G Qa T,G I Ls * * 23 191*9 D2,1*OOR, DD15.5,L -26dda L. Coulter...... Dr 30+ S,G Qa C,W S Tpc +2.0 17.70 5-20-1*9 T55 -28aac Du S,G Qa C,H D Ls * * 12 191*9 -28ddd County School... Dr 30 6 P S,G Qa C,H D Ls * * * 20 191*9 T52, Ca

-30daa Mr. Smith...... Dr 6 P S,G Qa C,W S Tc ^2.90 19.20 5-23-1*9 -31aac Dr 68 P S Qa C,G S Ls * 20 19^9 -31acd .... .do ...... Dr 120 6 P SI Tb N N Ls 30 191*9 -3l*aba Dr 55 18 P S,G Qa T,G I Ls * 20 19^9 -35aal Dr 1*0 6 P S,G Qa C,W D Ls * * * 26 19l*9 L

-35aa2 .... .do ...... Du,Dr 50 * S,G Qa Cf,G I Ls * » 26 19^9 19-52-23cdd L. Eckert...... Dr 6 P S,G Qa C,W S Tpc +1.5 20.52 5-23-^9 Ca -25bbd C. W. Schneider. Dr *3 6 P S,G Qa C,H D Ls 25 191*9 L -25cbc Du 25 1*8 W S Qa C,W D Tpc *+!2 18.86 5-23-1*9 -25dcb .... .do ...... Dr 35 6 p S,G Qa C,G S Tpc +1.7 29.1*7 5-23-1*9 -26ccc C. Rice...... Dr S,G Qa C,W D,S Ls 0 5.1*0 6-27-1*9 -26ddcl J. Schneider.... Dr 1*0+ 1* p S,G Qa N 0 Tc -.5 18.72 5-18-1*9 -26ddc2 .... .do ...... Dr 83 18 p S,G Qa T,B I Tpb +.7 19.69 5-18-1*9 T54, D1,1*80M DD17, Ca, L -28aba Dr 100 6 p SI Tb C,W D -29add .... .do ...... Dr 30 *6 S,G Qa c,w S Ls 6 191*9 -30aad V. A. Nielsen... Dr 13 p S,G Qa C,E D Le .... 5 191*9 -31bbb Dr 6 p SI Tb C,W S -31ccb Dr 6 p SI Tb C.W S Tbc +.2 81.12 6-28-1*9 G. Williams..... Dr 29 7 p S,G Qa C,W D,S LB '+'.7 13 191*9 L -35aaa County School... Dr 30+ 6 p S,G Qa C,H D,0 Tpb 19.67 7- 6-1*9 -36bbd Dr 65 18 p S,G Qa T,G I Tc +.1* 27.85 5-18-1*9 D900R, DD20, L