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D.W.R HYDROLOGIC MAP SERIES REPORT NO. 34 PREPARED IN COOPERATION WITH THE UNITED STATES GEOLOGICAL SURVEY THE ARIZONA DEPARTMENT OF WATER RESOURCES DEPTH TO WATER AND ALTITUDE OF THE WATER LEVEL SHEET 1 OF 2 114 113 112 111 110 109 Based on 1968 data, a small elliptical cone of depression was first described by Roeske and Werrell, (1973, p.16). The 37 37 With the exception of the Pantano (?) Formation, all of the previously mentioned basin-fill units are also present in Allen Flat, depression was enclosed within the 4,150 foot contour. It encompassed about 5 square miles and was centered in section 33, however, the units are not as thick (Putman and others, 1988, p. 65). Depth to bedrock in the Allen Flat sub-basin has been Township 21 South, Range 20 East. The major axis of the elliptical cone was northeast-southwest in orientation. Data col- estimated to be from 1,600 to 3,200 feet (Oppenheimer and Sumner, 1980, map). lected by the U. S. Geological Survey in the winter of 1977-78 supports Konieczki’s (1980, sheet 1) reference to the small depression centered within the 4,150 foot contour near Sierra Vista-Fort Huachuca. Putman and others (1988, p.98), using GROUNDWATER OCCURRENCE data collected in the winter of 1985-86, stated that the cone of depression within the 4,150 foot contour still extended in a northeast-southwest direction, and had increased areally to the east and southeast of Sierra Vista, to about 7.5 square miles. A T R 21 E The predominant aquifers in the Upper San Pedro Basin are the basin-fill deposits and the floodplain alluvium (Roeske and maximum decline of 9.2 feet was observed between 1985 and 1990 at well (D-21-21) 31CAC, while the minimum observed 36 36 decline was 2.2 feet at well (D-21-20) 35CBC for this period. 11 Werrell, 1973, p. 24). Groundwater occurs under unconfined conditions in the flood-plain alluvium and under both confined and unconfined conditions in the basin-fill deposits. S COCONINO In 1990, the cone was centered or deepest in section 33, Township 21 South, Range 20 East. The deepest part of the cone Basin-Fill Deposits could be encircled by the 4,100 foot water-level altitude contour. Water levels in wells within the influence of the depression were generally declining at approximately 0.5 to 1.0 foot per year. The depression was generally expanding in an east-south- Flagstaff KINGMAN The basin-fill deposits, consisting of the upper and lower units and the (Pantano (?) Formation), form the principal aquifer in easterly direction from the deepest part of the cone. APACHE R 22 E NAVAJO the Upper San Pedro Basin. The basin-fill deposits are stratigraphically complex. Locally, some areas exhibit confined condi- 35 35 tions, but regionally the basin-fill aquifer is unconfined (Freethey, 1982, p. 49). In Dec.2001-Jan.2002, the cone was still centered in section 33, Township 21 South, Range 20 East and the deepest part of the cone can still be encircled by the 4100 foot water-level contour. MOHAVE Holbrook T YAVAPAI Unconfined 12 Declines for 1990-Dec.2001-Jan.2002 became less pronounced north of Sierra Vista. Between Sierra Vista and Huachuca S Both the upper and lower units are good sources of groundwater, and together they produce most of the water pumped from the City declines in the 5.0 to 7.0 foot range are common, (see hydrograph J). North of Huachuca City declines are in the 1.0 to 5.0 4 foot range for the 1990-Dec.2001-Jan.2002 period, (see hydrograph I). One exception was public supply well (D-20-19) 5076 Prescott regional aquifer. Yields of 100 to 2,800 gallons per minute have been reported from wells completed in the upper and lower 2 14ADD, which declined 13.4 feet (1.2 ft/yr) since 1990. N 5080 units (Roeske and Werrell, 1973, p. 13). The Pantano (?) Formation is generally well cemented and not a reliable aquifer, but well yields up to several hundred gallons per minute have been reported (Roeske and Werrell, 1973, p. 10). In Dec.2001- Jan.2002, measured depths to water in the unconfined areas of the regional aquifer ranged from less than 100 feet to nearly 600 South of Sierra Vista toward Nicksville a wide range of declines, as well as rises, were recorded on either side of State Route W E 34 34 28 92. The largest declines occur in public supply wells, ranging from 26.4 to 35.4 feet since 1990. The closer the proximity to the 5002 feet below land surface. LA PAZ Huachuca Mountains foothills, the more varied the water levels become, ranging from a decline of 8.7 feet to a rise of 16.6 196 GILA 4223 feet. Many of the wells in the area are completed in either the pediment aquifer or in fractured hardrock. In either case, these S 13 PHOENIX Confined 5 5097 136 5095 wells are more susceptible to rainfall or drought conditions than those completed in the regional aquifer. T 4234 10 13 5315 The Upper San Pedro Basin has long been recognized as an area with hundreds of artesian wells. Nearly all of these wells are MARICOPA located in two geographically small areas along the San Pedro River, where silt and clay layers restrict vertical movement of Tombstone S groundwater. The larger of the artesian areas is located roughly between Land and Pomerene, and is about 12 miles long and 2 Declines are common in the Tombstone area, ranging from less than 1 foot to as much as 23 feet. Many of the declines are in 33 33 to 3 miles wide. This area includes Benson and St. David. The confined area near Benson may be more laterally extensive than shallow wells (windmills) located in or near washes. These declines clearly reflect the drought conditions which have persisted YUMA 722 PINAL GRAHAM 4250 GREENLEE previously thought (Fluid Solutions, Inc, 2000). A second area, about 10 miles long and 1 mile wide, is located between in recent years. Three deep (600-890 feet) public supply wells exhibit declines ranging from 3.3 feet to 23.1 feet. Hereford and Palominas. In these two areas, deep wells drilled in or adjacent to the flood plain of the San Pedro River encounter 4200 Yuma confined waters (Heindl, 1952, p. 70). Gravel beds of the lower basin fill are overlain by up to several hundred feet of silt and Naco clay. Depths to the confined waters vary depending upon location. The shallowest is in the Hereford-Palominas area, where Among the sharpest declines in the basin, are those having occurred in the Naco area. These declines are consistently in the TUCSON well depths of about 200 feet are required (Roeske and Werrell, 1973, p. 12). At St. David, and south to Land, well depths of mid-20 foot range. The range of declines was from 9.8 feet to 32.1 feet. However, farther west, toward the San Pedro River, T 300 feet and deeper are required to reach the confined aquifer. The deepest confined waters are found between Benson and changes ranged from a rise of 1.0 to a decline of 4.1 feet, which are more consistent with those observed in the rest of the PIMA Pomerene, at depths of 500 to 1,000 feet. Confined groundwater has also been encountered in the upper unit of the basin fill, basin. 14 32 32 where sand and gravel beds are locally overlain by clay and silt lenses. Flowing discharges from these wells are much less than S COCHISE the flowing wells completed in the lower basin fill. In December of 1990, approximately 150 artesian wells were visited while United States Border to State Route 90 (including Palominas-Hereford) 114 collecting data for HMS 31. Of that group, 47 flowing wells were observed. Many other flowing wells were not accessible, and The reach of the San Pedro River from the United States-Mexico Border, to State Route 90 has shown no remarkable change SANTA 113 CRUZ some wells flow only seasonally. Of the artesian wells that were not flowing, depth to water ranged from a few inches to as since 1990. This area, which includes the communities of Palominas and Hereford, reflects water level changes ranging from declines of 4.9 feet, and rises to 7.0 feet. Most of the wells show a change of plus or minus 3 feet. When considered over an 11 Nogales much as 50 feet below land surface. In Dec.2001-Jan. 2002, 16 flowing wells were visited in the Benson/Pomerene area and 17 in the St. David/Land area. This is not intended to imply that there are less flowing wells now than in 1990, just that the year period, these changes are quite small. Hydrograph (S) shows stable water table conditions in the Palominas area. West of 112 R 18 E R 19 E emphasis of the Dec.2001-Jan.2002 data collection was to obtain water levels from wells that had previously been measured. the San Pedro River in the eastern half of T22S, R21E, wells show declines in the 2.0 to 7.0 foot range. However, Hydrograph R 20 E 4100 111 110 109 No effort was made to seek-out flowing wells. (P) shows that no drastic change has taken place. 43 3304 4000 T 0 50 100 MILES In 1903, a maximum discharge of 80 gallons per minute was observed in the artesian wells of the Upper San Pedro Basin.

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