Ground Water in the Prineville Area Crook County, Oregon

Ground Water in the Prineville Area Crook County, Oregon s f GEOLOGICAL SUR'VEY WATER-SUPPLY PAPER 1619-P t i Prepared in cooperation with the Office of the Oregon State Engineer Ground Water in the Prineville Area Crook County, Oregon By J. W. ROBINSON and DON PRICE CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1619-P Prepared in cooperation with the Office of the Oregon State Engineer UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. CONTENTS Page Abstract___________________________________________________ P 1 Introduction..____________________________________________________ 2 Purpose and scope of the investigation.__________________________ 2 Location and extent of the area_--_----__----_--_--_-__--_-__--_ 2 Previous in vestigations___ _________ _____________________________ 3 Acknowledgments.. _________________________________________ 4 Well-numbering system________________________________-______- 4 Geography____________________________________________________ 5 Surface features and drainage___________________________._______ 5 Climate_____________________________________________________ 7 Culture and industry____________________________________ 7 Geologic setting.__________________________________________________ 8 Summary of stratigraphy______________________________________- 8 Geologic history_____________________________________________ 10 Ground water____________________________________ ________ 11 Occurrence.__________________________________________________ 11 General features_____-__-_______-________-_________-__-___- 11 Bedrock um'ts_____________________________________________ 13 Fluviolacustrine deposits__________________________________ 14 Unconfined aquifers__________________________________ 14 The artesian aquifer_______________________________ 15 Alluvium__ _____________________________________ 18 Landslide debris__________________________ ________ 19 Water-level fluctuations and long-term trends.____________________ 19 Chemical character of the ground water__________________________ 27 Withdrawal from the artesian aquifer______________________ 30 Present development___________________________________ 30 Effects of present withdrawals______________________ _ 32 Possible effects of increased withdrawals____________________ 33 Conclusions_____________________________________________________ 35 References______________________________________________________ 36 in IV CONTENTS ILLUSTRATIONS PLATE 1. Geologic map of the Prineville ares, Oregon, showing location of wells and contours on the artesian pressure surface, Novem ber 1953______________________________ In pocket Page FIGURE 1. Map of Oregon showing location of the Prineville area ____ P3 2. Annual precipitation and cumulative departure from average. 6 3. Hydrographs of wells_____-________________-___-_-___-__ 20 4. Hydrographs of wells___________________________________ 21 5. Map showing decline of pressure head in the aquifer._______ 25 6. Hydrograph of well 14/16-32N1 showing fluctuations caused by pumping of nearby wells__________________________ 26 7. Diagram for the classification of irrigation waters_________ 31 TABLES TABLE 1. Summary of rock units exposed in the Prineville area, Oregon_________________________________ P9 2. Records of selected wells in the Prineville area, Oregon_____ 38 3. Logs of wells in the Prineville area____________________ 42 4. Chemical analyses of typical waters from the Prineville area, Oregon.._______________________________________ 49 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES GROUND WATER IN THE PRINEVILLE AREA CROOK COUNTY, OREGON BY J. W. ROBINSON and DON PRICE ABSTRACT The area studied includes about 60 square miles of the valleys of Ochoco Creek and Crooked River in semiarid central Oregon, the city of Prineville, and the surrounding agricultural district. The principal source of ground water in the area is a single artesian aquifer of sand and gravel locally more than 30 feet thick, which occurs at the base of the unconsolidated valley fill deposits. This artesian aquifer yields as much as 1,000 gallons per minute to wells in the area, and at places contains water under sufficient pressure to rise 50 feet or more above the land surface. Shallower aquifers, which contain unconfined water, generally yield less than 20 gpm; the bedrock underlying the artesian aquifer does not yield appreciable amounts of water to wells. The ground water is of generally good chemical quality, although that from some wells is harder than desirable or contains iron in amounts that are troublesome for some uses. Since the artesian aquifer was first tapped by wells in 1912, there has been both a progressive increase in the number of wells producing water from it and a general lowering of artesian pressures in the aquifer. Sharp declines of the pres sures at some wells in the summer of 1944 caused local concern about the continued availability of the artesian water, and led to the present study. Between October 1944 and November 1953, the decline in artesian pressure was less than 20 feet throughout most of the area, but was more than 30 feet in localities of intensive pumping. At Prineville, the relatively great drawdown is caused largely by mutual interference between large-capacity wells. The long-term decline of artesian pressures was caused by the progressively greater withdrawals from wells. It represents chiefly an increase in the rate at which ground water moves through the aquifer from the principal recharge area to points of discharge rather than the permanent removal of water stored in the aquifer. Increased withdrawal from the artesian aquifer would tend to cause further decline of artesian pressures, but it also might result in some increase in recharge to the aquifer, salvage of some water presently discharging from the aquifer by leakage to shallower zones, and possibly, some local increase in the concentrations of dissolved minerals in the artesian water in districts of greatest decline of artesian levels. The additional water that might be available for withdrawal, owing to increased recharge and decreased natural discharge from the aquifer, would tend to counteract the decline of artesian levels owing to the increased withdrawal. In 1953, the recharge to the aquifer may have been about 2,000 acre-feet. PI P2 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES INTRODUCTION PURPOSE AND SCOPE OF THE INVESTIGATION The principal source of ground water in the Prineville area is a single artesian aquifer or water-bearing zone that underlies the valley floor in the vicinity of, and downstream from, Prineville. Since it was first tapped by wells in 1912, there has been a progressive increase in the number of wells producing water from this aquifer. In the summer of 1944, owners and operators of wells in the area became concerned when large withdrawals from the aquifer caused the water levels in some of the artesian wells to decline rapidly to new low levels. Thus, it became apparent that a better understanding of the extent and water-bearing properties of the aquifer would be necessary in order to guide future development and management of ground water in the area. The principal purposes of this investigation were to determine the extent of the aquifer, the source and the approximate amount of water that moves through the aquifer, and the possible effects of increased withdrawals from the aquifer. This investigation was made in cooperation with the Oregon State Engineer as part of a continuing program of appraisal of the ground- water resources of Oregon. Most of the fieldwork for this report was done from October 1944 to November 1946 by the senior author. The fieldwork during that period included reconnaissance geologic mapping and collection of basic ground-water data. Additional information on wells, ground-water levels, and chemical quality of the ground water have since been obtained, mostly during fieldwork in the area in November 1953 and November 1959. In May 1960, the earlier geologic mapping was checked and revised in the field by the junior author and E. R. Hampton. A preliminary version of the report, based on data collected through 1946, was prepared by the senior author and was released to the open file for public inspection in April 1947. LOCATION AND EXTENT OF THE ABBA The area of this study is in Crook County in central Oregon (fig. 1). It lies between lat 44°15/ and 44°22/ N., and long 120°43' and 120°58/ W., and it covers about 60 square miles. The area is about 15 miles long (in a northwest direction), and about 7 miles at its widest point. It comprises the valleys of Ochoco Creek downstream from the Ochoco Reservoir, and of Crooked River from the vicinity of Prineville downstream for about 7 miles (pi. 1). GROUND WATER IN THE PRINEVILLE AREA, OREGON P3 123° 122° 121' 120' 119" FIGURE 1. Map of Oregon showing the location of the Prineville area. PREVIOUS INVESTIGATIONS Although the Prineville area has been included in larger areas of general geologic studies, no detailed investigation of the ground-water resources of the area was made prior to this study. The geology and water resources of the Prineville area were men tioned briefly in a report by I. C. Russell (1905, p. 82-86) that de scribes a reconnaissance trip through central

Load more