By William E. Templin and Randall C. Schluter Sacramento, California 1990
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A WATER-RESOURCES DATA-NETWORK EVALUATION FOR MONTEREY COUNTY, CALIFORNIA, PHASE 3: NORTHERN SALINAS RIVER DRAINAGE BASIN By William E. Templin and Randall C. Schluter U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 89-4123 Prepared in cooperation with the MONTEREY COUNTY FLOOD CONTROL AND WATER CONSERVATION DISTRICT CM iH I CO O o Sacramento, California 1990 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information write to: Copies of this report may be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Books and Open-File Reports Section Federal Building, Room W-2234 Box 25425 2800 Cottage Way Building 810, Federal Center Sacramento, CA 95825 Denver, CO 80225 CONTENTS Page Abstract .................................................................. 1 Introduction .............................................................. 2 Purpose, scope, and objectives ....................................... 2 Approach ............................................................. 6 Location of study area ............................................... 6 Limitations .......................................................... 7 Acknowledgments ...................................................... 7 Well-numbering system ................................................ 8 Climate ................................................................... 9 Land use .................................................................. 10 Water use ................................................................. 12 Precipitation networks .................................................... 18 Precipitation-quantity networks ...................................... 18 Precipitation conditions ........................................ 18 Objectives ...................................................... 19 Factors affecting design ........................................ 34 Precipitation maps .............................................. 34 Description ..................................................... 35 Possible additional monitoring .................................. 37 Precipitation-quality networks ....................................... 37 Objectives ...................................................... 37 Possible problems ............................................... 38 Acid rain and acid fog ..................................... 38 Pesticides ................................................. 39 Design .......................................................... 39 Surface-water networks .................................................... 40 Surface-water conditions ............................................. 40 Streamflow networks .................................................. 40 Objectives ...................................................... 40 Method of evaluation ............................................ 41 Criteria for site selection ..................................... 41 Description of streamflow-gaging stations ....................... 44 Salinas River at Soledad ................................... 44 Salinas River near Gonzales ................................ 46 Salinas River near Chualar ................................. 46 Salinas River near Spreckels ............................... 47 El Toro Creek near Spreckels ............................... 47 Alisal Creek near Salinas .................................. 48 Gabilan Creek near Salinas ................................. 48 Reclamation Ditch near Salinas ............................. 49 Santa Rita Creek at Santa Rita ............................. 49 Contents III Page Surface-water networks Continued Surface-water-quality networks ....................................... 53 Surface-water quality conditions ................................ 53 Objectives ...................................................... 53 Method of evaluation ............................................ 54 Station location and sampling frequency ......................... 55 Description ..................................................... 55 Stream-reach rating system ...................................... 57 Ground-water networks ..................................................... 58 Ground-water conditions .............................................. 58 Occurrence of ground water ...................................... 58 Ground-water flow ............................................... 60 Flow barriers ................................................... 61 Water-level changes ............................................. 61 Ground-water-quality conditions ................................. 62 Ground-water-level networks .......................................... 63 Objectives ...................................................... 63 Method of evaluation ............................................ 63 Well and network classification ................................. 64 Well-classification system ................................. 64 Network-classification system .............................. 67 Description ..................................................... 67 Possible additional monitoring .................................. 72 Ground-water-quality networks ........................................ 74 Objectives ...................................................... 74 Description ..................................................... 75 Possible additional monitoring .................................. 89 Summary and conclusions ................................................... 90 References cited .......................................................... 92 ILLUSTRATIONS Page Figures 1-7. Maps showing: 1. Location of the study area .......................... 4 2. Land use and land cover in the northern Salinas River drainage basin .............................. 11 3. Point and regional sources of concern for possible water-quality degradation ................ 13 4. Mean annual precipitation in Monterey County ........ 20 5. Precipitation gages ................................. 36 6. Surface-water-quality monitoring sites and streamflow-gaging stations ........................ 45 7. Ground-water geographic areas ....................... 59 8. Graph showing mean changes in autumn ground-water levels, 1974-78 ........................................... 62 9. Map showing ground-water monitoring wells ................... 71 IV Contents TABLES Page Table 1. Generalized management and network objectives ................... 3 2. Major point-source dischargers to land .......................... 14 3. Ideal networks, priority, and pertinent data .................... 22 4. Precipitation gages ............................................. 32 5. Streamflow-gaging stations ...................................... 42 6. Surface-water-quality monitoring sites .......................... 50 7. Classification of ground-water networks ......................... 65 8. Inventory of ground-water-level networks ........................ 68 9. Network locations that presently do not have water-level wells monitored by the Monterey County Flood Control and Water Conservation District ................................... 73 10. Inventory of ground-water-quality monitoring networks ........... 76 11. Well summary and cross-reference to wells in ground-water networks ...................................................... 83 12. Network locations that presently do not have wells monitored for ambient water-quality conditions by the Monterey County Flood Control and Water Conservation District ................. 89 CONVERSION FACTORS For readers who prefer metric and International System (SI) units to inch-pound units, the conversion factors for the terms used in this report are as follows: Multiply By To obtain acre 0.4047 hectare cubic foot per second (ft 3 /s) 0.02832 cubic meter per second foot 0.3048 meter gallon per minute (gal/min) 0.06308 liter per second gallon per day 0.06308 liter per day inch 25.4 millimeter inch per year (in/yr) 25.4 millimeter per year mile 1.609 kilometer square mile (mi 2 ) 2.590 square kilometer Abbreviations; yg/L microgram per liter mg/L milligram per liter Degree Celsius (°C) can be converted to degree Fahrenheit (°F) by the following formula: °F = 1.8x°C+32. Sea level; In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929. Contents V A WATER-RESOURCES DATA-NETWORK EVALUATION FOR MONTEREY COUNTY, CALIFORNIA, PHASE 3: NORTHERN SALINAS RIVER DRAINAGE BASIN By William E. Templin and Randall C. Schluter ABSTRACT This report presents an evaluation of water-resources data-collection networks in the northern Salinas River drainage basin, Monterey County, California. The evaluation, done in cooperation with the Monterey County Flood Control and Water Conservation District, covers both quantity and quality monitoring by precipitation, surface-water, and ground-water networks. The report describes existing networks in the study area and possible additional data collection. The study identified 34 precipitation gages in the study area, of which 20 are active. The stations are concentrated in the northwestern part of the study area. Data are lacking for the eastern and southern parts of the study area, as well as the southwestern slopes of the Gabilan Range. No precipitation-quality networks