Ground-Water Quality Classification and Recommended Septic Tank Soil-Absorption- System Density Maps, Castle Valley, Grand County, Utah
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GROUND-WATER QUALITY CLASSIFICATION AND RECOMMENDED SEPTIC TANK SOIL-ABSORPTION- SYSTEM DENSITY MAPS, CASTLE VALLEY, GRAND COUNTY, UTAH by Mike Lowe, Janae Wallace, Charles E. Bishop, and Hugh A. Hurlow View to the northeast of Castle Valley, Grand County, Utah. The foreground shows part of the River Ranchos Community, where most of the population in the valley resides. The lone spire of Castle Rock is on the end horizon of Parriott Mesa. ISBN 1-55791-714-0 SPECIAL STUDY 113 UTAH GEOLOGICAL SURVEY a division of Utah Department of Natural Resources 2004 STATE OF UTAH Olene S. Walker, Govenor DEPARTMENT OF NATURAL RESOURCES Robert L. Morgan, Executive Director UTAH GEOLOGICAL SURVEY Richard G. Allis, Director PUBLICATIONS contact Natural Resources Map/Bookstore 1594 W. North Temple telephone: 801-537-3320 toll-free: 1-888-UTAH MAP website: http://mapstore.utah.gov email: [email protected] THE UTAH GEOLOGICAL SURVEY contact 1594 W. North Temple, Suite 3110 Salt Lake City, UT 84116 telephone: 801-537-3300 website: http://geology.utah.gov Although this product represents the work of professional scientists, the Uah Department of Natural Resources, Utah Geological Survey, makes no warranty, expressed or implied, regarding its suitability for any particular use. The Utah Department of Natural Resources, Utah Geological Sur- vey, shall not be liable under any circumstances for any direct, indirect, special, incidental, or consequential damages with respect to claims by users of this product. The Utah Department of Natural Resources receives federal aid and prohibits discrimination on the basis of race, color, sex, age, national origin, or disability. For information or complaints regarding discrimination, contact Executive Director, Utah Department of Natural Resources, 1594 West North Temple #3710, Box 145610, Salt Lake City, UT 84116-5610 or Equal Employment Opportunity Commission, 1801 L. Street, NW, Wash- ington DC 20507. Printed on recycled paper 1/04 CONTENTS ABSTRACT . .1 INTRODUCTION . .1 Purpose and Scope . .3 Ground-Water Quality Classification . .3 Septic-Tank Density/Water-Quality Degradation Analysis . .4 Well-Numbering System . .4 Location and Geography . .4 Population and Land Use . .4 Climate . .4 PREVIOUS INVESTIGATIONS . .6 GEOLOGIC SETTING . .6 GROUND-WATER CONDITIONS . .6 Introduction . .6 Valley-Fill Aquifer . .6 Occurrence . .6 Thickness . .9 Ground-Water Depth, Volume, and Flow Direction . .9 Recharge and Discharge . .11 Relationship of Geology to Ground-Water Quality . .11 GROUND-WATER QUALITY CLASSIFICATION . .11 Introduction . .11 Results . .11 2000-2003 Data for Valley-Fill Aquifer . .11 Data sources . .11 Total-dissolved-solids concentrations . .12 Nitrate concentrations . .12 Other constituents . .12 Resulting Ground-Water Quality Classification . .12 Class IA- Pristine ground water . .14 Class II- Drinking Water Quality ground water . .14 Unclassified part of valley-fill aquifer in Castle Valley . .14 Land-Use Planning Considerations . .15 Current beneficial uses of ground water . .15 Potential for ground-water quality degradation . .15 Possible land-use planning applications of this ground-water quality classification . .15 SEPTIC-TANK DENSITY/WATER-QUALITY DEGRADATION ANALYSIS . .15 Introduction . .15 Ground-Water Contamination from Septic-Tank Systems . .16 Pathogens . .16 Household and Industrial Chemicals . .16 Phosphate . .16 Nitrate . ..