Sandra J. Owen-Joyce and C. K. Bell

During recent years, the Verde Valley has experienced a rapid growth in population and a concurrent increase in water-resources development. The increase in population is closely associated with the growing interest in this area as a retirement location. The Verde River, numerous lakes, Indian ruins, and spectacular scenery make this a popular tourist and recreation area. Surface water is used primarily for irrigation and recreation, but surface-water use is limited in the area owing to downstream water rights. Ground water serves as the major source of public and domestic water, and future development probably will depend on this water supply. The increasing demand for water prompted an appraisal of the water resources in the upper Verde River area. The study was made by the U.S. Geological Survey in cooperation with the Arizona Department of Water Resources.

Ground-water and surface-water resources cannot be considered separately in the upper Verde River area. Discharge from the regional aquifer maintains the flow of the perennial streams in the area. Large-scale ground-water development would ultimately decrease the low-flow surface outflow from the basin.

Purpose of the Investigation and Scope of the Report

The purpose of the investigation was to define the groundwater system, determine the low-flow characteristics of streams in the area, evaluate the relation between ground water and surface water, and determine the extent of development and its effects on the ground-water system. The report describes: (1) the distribution, structure, and lithology of the geologic units that underlie the area and their relation to the occurrence, movement, availability, and chemical quality of ground water; (2) the base flow, low-flow frequency, flow duration, and chemical quality of water in the Verde River and its perennial tributaries; and (3) a ground-water budget for the regional aquifer.

Location of the Area

The upper Verde River area is in north-central Arizona and overlaps the Central highlands and the Plateau uplands water provinces (fig. 1). This area occupies about 2,600 mi2 of Yavapai and Coconino Counties. The main population centers are in the Verde Valley near Cottonwood, Camp Verde, Clarkdale, and Sedona.

Physiography and Climate

The study area includes the northern valley of the Verde River; the valley is bounded by the escarpment of the Mogollon Rim to the north and northeast and by the Black Hills to the southwest. The Mogollon Rim escarpment, which is the boundary between the Plateau uplands province and the Central highlands province, is a steeply sloping cliff that rises 1,000 to 2,000 ft from the Verde Valley floor to altitudes of 5,500 to 7,500 ft above the National Geodetic Vertical Datum of 1929 at the upper edge of the escarpment (fig. 1). The rim is cut by steepened canyons, and south of the rim is a landscape of buttes and mesas. The plateau altitudes are about 6,000 ft near the rim to 9,256 ft at Bill Williams Mountain. The Black Hills, part of the Central highlands province, rise to 7,834 ft in the north at Woodchute Mountain and to 6,525 ft in the south at Squaw Peak (fig. 1).

The Verde River is the main stream that drains the study area and enters the area in T. 17 N., R. 1 W. The river flows along the foot of the Black Hills eastward to Perkinsville then southeastward where it leaves the study area at its confluence with Fossil Creek. Altitudes along the Verde River range from about 4,240 ft where the Verde River enters the study area to about 2,540 ft where the river flows out of the study area.

The major perennial tributaries to the Verde River are Sycamore Creek, Oak Creek, Beaver Creek, West Clear Creek, and Fossil Creek. These tributaries drain the region north and east of the Verde River and flow in a southwesterly direction toward the Verde River. Most streams that drain the Black Hills and the northwestern part of the study area flow only in response to rainfall or snowmelt. Perennial flow in the Verde River and its major tributaries is maintained by ground-water discharge.

The Mogollon Rim and the Black Hills influence the climate of the area. Moisture-laden airmasses, on encountering these topographic features, rise, cool, and precipitate moisture. Annual precipitation ranges from 18 to 26 in. near the rim and in the Plateau uplands, the highest values occur along the rim (Sellers -and Hill, 1974). Annual snowfall is about 40 to 85 in. (Sellers and Hill, 1974, p. 208 and 276). Jerome, the only weather station in the Black Hills, receives about 18 in. of precipitation and 25 in. of snowfall per year. In the Verde Valley precipitation ranges from 12 to 17 in. per year, and snowfall is negligible. The average annual temperature ranges from 43°F at Happy Jack Ranger Station to 62°F at Cottonwood (Sellers and Hill, 1974).

Precipitation is seasonal; during the winter, storms associated with frontal systems bringing moisture from the Pacific Ocean traverse the area from west to east. These storms spread rainfall of light to moderate intensity across large parts of the southwestern United States from late October through April. Precipitation often occurs as rain at the lower elevations in the Verde Valley and as snow at higher elevations along the Mogollon Rim, on the plateau, and on the Black Hills. Winter storms have been the cause of many of the major floods in this area, particularly when warm rain falls on snow. The highest runoff during a year commonly occurs in March and April as a result of snowmelt. High flows are less common in May and early June between the winter and summer storm seasons than during any other part of the year. The second precipitation season is during the summer when moist tropical air sweeps in from the south. Precipitation at this time of year often occurs as short-duration, locally intense thunderstorms that are common from late June through early October and often cause local flash flooding.

Methods of Investigation

The fieldwork on which this report is based was done in 1976-80. Hydrologic data collected prior to this investigation and selected data collected by other agencies are included in the hydrologic data tables at the end of the report. An inventory was made of wells and springs, and water levels in wells were measured where possible (tables 10, 11, and 12). Well and spring locations are described in accordance with the well-numbering system used in Arizona, which is explained and illustrated in figure 2. The altitudes of wells and springs were obtained from U.S. Geological Survey topographic maps at scales of 1:24,000 or 1:62,500. Water samples were collected from selected wells, springs, and streamflow sites (tables 13 and 14). Drill cuttings were collected and analyzed for arsenic in areas where large concentrations of arsenic occurred in water samples.

The geologic map is generalized from existing geologic maps (pl. 1). In areas of intense faulting only the major faults are shown. In the upper Verde River area many of the individual rock units or formations are hydraulically connected and function as a single waterproofing unit; therefore, they were grouped for mapping in order to reflect this relation.

Precambrian metamorphic and granitic rocks were mapped as a single unit. Paleozoic and Mesozoic rocks were divided into three map units on the basis of hydrologic and lithologic characteristics and mappable size. The rocks of the regional aquifer were grouped into two map units. The Coconino Sandstone, Supai Formation, and Naco Formation were grouped as the first map unit; the Redwall Limestone, Martin Formation, and Tapeats Sandstone were grouped as the second map unit. The rocks that lie above the regional aquifer-the Toroweap Formation, Kaibab Limestone, and Moenkopi Formation-are the third map unit. Rocks of Tertiary age are divided into sedimentary rocks, volcanic rocks, and the Verde Formation. Sedimentary rocks include the sedimentary rocks of Krieger (1965; 1967a, b), the Hickey Formation (Anderson and Creasey, 1958), and the Perkinsville Formation (Lehner, 1958). Volcanic rocks include the basalts, cinders, and associated volcanic sediments of the Hickey Formation, Perkinsville Formation, Verde Formation, and the intermediate basalt of Lehner (1958). The Verde Formation is a significant part of the regional aquifer and is mapped as a separate unit. Two Quaternary units, alluvium and gravel, are shown. The alluvium along the Verde River is hydraulically connected to the regional aquifer. The gravel does not contain water but crops out over a large area.

Lithologic and drillers' logs of wells were examined to determine the thickness, physical characteristics, and water-yielding potential of the rock units. Selected drillers' logs are listed in table 15. Additional drillers' logs have been published for southern Coconino County (McGavock, 1968), for the Verde Valley (Twenter and Metzger, 1963), and for the Sedona area (Levings, 1980), and deep stratigraphic test-hole information appears in Peirce and Scurlock (1972).

Streamflow records were collected at 11 existing gaging stations, and the Verde River near Camp Verde gaging station was reactivated as a base-flow station from July 1, 1976, to October 1, 1979. The base-flow data from a gaging station on the Verde River below Camp Verde was not used because irrigation ditches on both sides of the river often carry more water than the river, which makes the data meaningless. Floods isolated the below Camp Verde gage, and since January 1, 1979, it has been operated as a high-flow station.

A seepage investigation was made along the Verde River from Clarkdale to the confluence with Fossil Creek on June 11-13, 1979. Discharge measurements were made at 20 sites on the main stem of the Verde River and at 35 sites on tributary streams and irrigation diversions and returns (pl. 3). A previous low-flow investigation (not part of this study) had been made along the Verde River from Paulden to Camp Verde on June 20-22, 1977, but did not include the irrigation diversions and returns between Clarkdale and Camp Verde.

Previous Investigations

The initial hydrologic study of the Verde Valley was made by Twenter and Metzger (1963) in which they reported on the ground-water resources and geology of the region. Ground water of the Mogollon Rim region was studied by Feth and Hem (1963) during their investigation of springs. Ground-water basic data for southern Coconino County is available in McGavock (1968). Geohydrologic studies on specific sections of the study area include Lake Mary (Harshbarger and Associates, 1976; 1977) and Sedona (Levings, 1980). The Verde Valley was studied as a potential geothermal-resource area using the chemical character of ground water as an indicator (Ross and Farrar, 1980). Basic data have been compiled as maps showing the ground-water conditions in the upper Verde River area (Levings and Mann, 1980). Evapotranspiration losses were determined from flood-plain areas of central Arizona (Anderson, 1976). Water-quality data are available for Oak Creek (Obr and others, 1970) and West Clear Creek (Sommerfeld and others, 1976). The U.S. Forest Service has published information on the hydrology of the Beaver Creek watershed (Brown and others, 1974). Flood studies and high-flow information are available for the study area (U.S. Geological Survey, 1973; U.S. Army Corps of Engineers, 1976; Roeske, 1978; and Anderson and White, 1979).

Geologic studies were made of the ore deposits located in the region (Anderson and Creasey, 1958; Lehner, 1958; Krieger, 1965), the geologic history of the basin and the lake deposits (Blake, 1890; Jenkins, 1923; Mears, 1948; Mahard, 1949; Wadell, 1972), and stratigraphy (McKee, 1938; McKee and Gutschick, 1969; Nations, 1974).

Acknowledgments

The authors gratefully acknowledge the cooperation of the many residents of the area who granted permission to work on their property and supplied information about their wells. Special appreciation is extended to the well drillers, water companies, and State agencies who furnished information for the study. Special thanks are due to Mr. Richard E. Lewis of the California Institute of Technology for furnishing a copy of his unpublished geologic map of the area between the Verde River and Hackberry Mountain, Mr. J. E. Alam of the Soil Conservation Service for the estimate of consumptive use of water on irrigated acreage for the area, and Mr. Timothy D. Love of the Arizona Department of Health Services for the water-quality information on Bitter Creek.