GROUND-WATER HYDROLOGY AND SIMULATED EFFECTS OF DEVELOPMENT IN THE MILFORD AREA, AN ARID BASIN IN SOUTHWESTERN UTAH l * ! \ PROFESSIONAL PAPER 14Q9-G USGS science for a changing world AVAILABILITY OF BOOKS AND MAPS OF THE US. GEOLOGICAL SURVEY Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the current- year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey publica­ tions released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that may be listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability List" may be no longer available. Order U.S. Geological Survey publications by mail or over the counter from the offices given below. 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Subscriptions to Preliminary Determination of Epicenters can RESTON, Virginia USGS National Center, Rm. 1C402, be obtained ONLY from the 12201 Sunrise Valley Dr. SALT LAKE CITY, Utah 2222 West 2300 South Superintendent of Documents Government Printing Office SPOKANE, Washington U.S. Post Office Bldg., Rm. 135, Washington, DC 20402 West 904 Riverside Ave. WASHINGTON, D.C. Main Interior Bldg., Rm. 2650, 18th (Check or money order must be payable to Superintendent of and C Sts., NW. Documents.) Maps Only Maps Maps may be purchased over the counter at the following For maps, address mail orders to U.S. Geological Survey office: U.S. Geological Survey, Information Services Box 25286, Federal Center, Denver, CO 80225 ROLLA, Missouri 1400 Independence Rd. Ground-Water Hydrology and Simulated Effects of Development in the Milford Area, an Arid Basin in Southwestern Utah By JAMES L. MASON REGIONAL AQUIFER-SYSTEM ANALYSIS GREAT BASIN NEVADA AND UTAH U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1409-G 1998 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Thomas J. Casadevall, Acting Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Government. Library of Congress Cataloging-in-Publication Data Mason, James L. Ground-water hydrology and simulated effects of development in the Milford area, an arid basin in southwestern Utah / by J.L. Mason. p. cm. - (Regional aquifer-system analysis-Great Basin, Nevada and Utah) (U.S. Geological Survey professional paper ; 1409-G) Includes bibliographical references Supt. of Docs, no.: I 19. 16: 1409-G 1. Ground-water flow--Utah--Milford Region. I. Title. II. Series. III. Series: Regional aquifer-system analysis-Great Basin, Nevada-Utah. GB1197.7.M374 1996 551.49'09792'4-dc21 97-13890 CIP ISBN 0-607-86818-X For sale by U.S. Geological Survey, Branch of Information Services Box 25286, Federal Center Denver, CO 80225 FOREWORD THE REGIONAL AQUIFER-SYSTEM ANALYSIS PROGRAM The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which, in aggregate, underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and, accordingly, tran­ scend the political subdivisions to which investigations have often arbi­ trarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabili­ ties that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities and to provide a means of predicting the regional effects of future pumping or other stresses. The final interpretive results of the RASA Program are presented in a series of U.S. Geological Survey Professional Papers that describe the geology, hydrology, and geochemistry of each regional aquifer system. Each study within the RASA Program is assigned a single Professional Paper number beginning with Professional Paper 1400. L Thomas J. Casadevall Acting Director CONTENTS Page Page Foreword............................................................................................. iii Simulation of ground-water flow Continued Abstract............................................................................................... Gl Initial conditions Continued Introduction........................................................................................ 1 Water levels........................................................................... G15 Purpose and scope ..................................................................... 2 Recharge................................................................................. 15 Previous studies.......................................................................... 2 Discharge............................................................................... 16 Well-numbering system used in Utah..................................... 4 Description of study area.......................................................... 4 Hydraulic conductivity........................................................ 16 Physiography........................................................................ 4 Storage coefficients............................................................... 17 Geology.................................................................................. 4 Steady-state calibration.............................................................. 17 Climate................................................................................... 6 Transient calibration................................................................... 20 Vegetation.............................................................................. 6 Sensitivity analysis..................................................................... 21 Surface water........................................................................ 7 Limitations of model.................................................................. 32 Ground-water hydrology................................................................. 8 Short-term predictive simulations............................................ 32 Consolidated rocks..................................................................... 8 Simulation of hypothetical development alternatives.................. 39 Unconsolidated basin fill........................................................... 8 Criteria.......................................................................................... 39 Description............................................................................ 8 Development alternative Al..................................................... 40 Movement............................................................................. 8 Development alternative A2..................................................... 40 Recharge................................................................................ 10 Development alternative A3..................................................... 44 Discharge............................................................................... 11 Development alternative Bl...................................................... 48 Hydraulic properties........................................................... 11 Development alternative B2...................................................... 52 Storage................................................................................... 11 Simulation of ground-water flow.................................................... 13 Development alternative B3...................................................... 52 Model design............................................................................... 13 Evaluation of development alternatives.................................. 61 Model grid and layers......................................................... 13 Need for future studies..................................................................... 65 Boundary conditions........................................................... 14 Summary............................................................................................. 67 Initial conditions......................................................................... 15