i ii Ambient Groundwater Quality of the Aravaipa Canyon Basin: A 2003 Baseline Study By Douglas C. Towne Maps by Jean Ann Rodine Arizona Department of Environmental Quality Open File Report 13-01 ADEQ Water Quality Division Surface Water Section Monitoring Unit 1110 West Washington St. Phoenix, Arizona 85007-2935 Thanks: Field Assistance: Elizabeth Boettcher and Angela Lucci. Special recognition is extended to the many well owners who were kind enough to give permission to collect groundwater data on their property. Photo Credits: ADEQ Monitoring Unit and Douglas Towne Report Cover: A perennial reach of Araviapa Creek is created by groundwater being brought to the surface by bedrock in Aravaipa Canyon. This segment of Aravaipa Creek was named one of Arizona’s Heritage Waters in 2007 based on the stream’s cultural, historical, political, scientific and social significance. 6 iii Other Publications of the ADEQ Ambient Groundwater Monitoring Program ADEQ Ambient Groundwater Quality Open-File Reports (OFR) and Factsheets (FS): Aravaipa Canyon Basin OFR 13-01, 46 p. FS 13-04, 4 p. Butler Valley Basin OFR 12-06, 44 p. FS 12-10, 5.p. Cienega Creek Basin OFR 12-02, 46 p. FS 12-05, 4.p. Ranegras Plain Basin OFR 11-07, 63 p. FS 12-01, 4.p. Groundwater Quality in Arizona OFR 11-04, 26 p. - Bill Williams Basin OFR 11-06, 77 p. FS 12-01, 4.p. San Bernardino Valley Basin OFR 10-03, 43 p. FS 10-31, 4 p. Dripping Springs Wash Basin OFR 10-02, 33 p. FS 11-02, 4 p. McMullen Valley Basin OFR 11-02, 94 p. FS 11-03, 6 p. Gila Valley Sub-basin OFR 09-12, 99 p. FS 09-28, 8 p. Agua Fria Basin OFR 08-02, 60 p. FS 08-15, 4 p. Pinal Active Management Area OFR 08-01, 97 p. FS 07-27, 7 p. Hualapai Valley Basin OFR 07-05, 53 p. FS 07-10, 4 p. Big Sandy Basin OFR 06-09, 66 p. FS 06-24, 4 p. Lake Mohave Basin OFR 05-08, 66 p. FS 05-21, 4 p. Meadview Basin OFR 05-01, 29 p. FS 05-01, 4 p. San Simon Sub-Basin OFR 04-02, 78 p. FS 04-06, 4 p. Detrital Valley Basin OFR 03-03, 65 p. FS 03-07, 4 p. San Rafael Basin OFR 03-01, 42 p. FS 03-03, 4 p. Lower San Pedro Basin OFR 02-01, 74 p. FS 02-09, 4 p. Willcox Basin OFR 01-09, 55 p. FS 01-13, 4 p. Sacramento Valley Basin OFR 01-04, 77 p. FS 01-10, 4 p Upper Santa Cruz Basin (w/ USGS) OFR 00-06, 55 p. - Prescott Active Management Area OFR 00-01, 77 p. FS 00-13, 4 p. Upper San Pedro Basin (w/ USGS) OFR 99-12, 50 p. FS 97-08, 2 p. Douglas Basin OFR 99-11, 155 p. FS 00-08, 4 p. Virgin River Basin OFR 99-04, 98 p. FS 01-02, 4 p. Yuma Basin OFR 98-07, 121 p. FS 01-03, 4 p. These publications are available at: www.azdeq.gov/environ/water/assessment/ambient.html iv Map 1. ADEQ Ambient Groundwater Monitoring Program Studies v Table of Contents Abstract .................................................................................................................................................................... 1 Introduction ............................................................................................................................................................. 2 Purpose and Scope ...................................................................................................................................... 2 Physical and Cultural Characteristics .......................................................................................................... 2 Surface Water Characteristics ..................................................................................................................... 2 Groundwater Characteristics ....................................................................................................................... 4 Investigation Methods ............................................................................................................................................. 4 Sample Collection ..................................................................................................................................... 10 Laboratory Methods .................................................................................................................................. 10 Data Evaluation ..................................................................................................................................................... 13 Quality Assurance ..................................................................................................................................... 13 Data Validation ......................................................................................................................................... 16 Statistical Considerations .......................................................................................................................... 16 Groundwater Sampling Results ........................................................................................................................... 17 Water Quality Standards / Guidelines ....................................................................................................... 17 Suitability for Irrigation ............................................................................................................................ 17 Analytical Results .................................................................................................................................... 17 Groundwater Composition ................................................................................................................................... 19 General Summary .................................................................................................................................... .23 Constituent Co-Variation .......................................................................................................................... 28 Oxygen and Hydrogen Isotopes ................................................................................................................ 30 Groundwater Quality Variation ................................................................................................................ 32 Discussion ............................................................................................................................................................... 38 References .............................................................................................................................................................. 38 Appendices Appendix A – Data for Sample Sites, Aravaipa Canyon Basin, 2003 ....................................................... 40 Appendix B – Groundwater Quality Data, Aravaipa Canyon Basin, 2003 ............................................... 41 vi Maps ADEQ Ambient Monitoring Program Studies .......................................................................................................... V Map 1. Aravaipa Canyon Basin .............................................................................................................................. 3 Map 2. Sample Sites ................................................................................................................................................ 5 Map 3. Water Quality Standards ............................................................................................................................ 18 Map 4. Radon ......................................................................................................................................................... 19 Map 5. Water Chemistry ........................................................................................................................................ 24 Map 6. Total Dissolved Solids ............................................................................................................................... 26 Map 7. Hardness .................................................................................................................................................... 27 Map 8. Isotope ....................................................................................................................................................... 31 Tables Table 1. Laboratory water methods and minimum reporting levels used in the study .......................................... 11 Table 2. Summary results of duplicate samples from the ADHS laboratory ....................................................... 14 Table 3. Summary results of split samples between the ADHS/Test America labs .............................................. 15 Table 4. Sampled sites exceeding aesthetics-based water quality guidelines or Secondary MCLs ...................... 20 Table 5. Alkalinity and salinity hazards for sampled sites .................................................................................... 20 Table 6. Summary statistics for groundwater quality data .................................................................................... 21 Table 7. Correlation among groundwater quality constituent concentrations ....................................................... 29 Table 8. Variation in groundwater quality constituent concentrations between two recharge groups .................. 33 Table 9. Summary statistics for two recharge groups with significant constituent differences ............................ 34 Table 9. Variation in groundwater quality constituent concentrations between two geologic types .................... 36 Table 10. Summary statistics for two geologic types with significant constituent differences ............................. 37 vii Diagrams Diagram 1. Aravaipa Canyon piper plot ............................................................................................................... 23 Diagram 2. Hardness concentrations of Aravaipa Canyon basin samples ........................................................... 25 Diagram 3. Calcium – pH-field relationship ....................................................................................................... 28 Diagram 4. Oxygen-18 – deuterium relationship ................................................................................................ 30 Diagram 5. Bicarbonate box plot using two recharge groups ............................................................................... 32 Diagram 6. Hardness box plot using two recharge groups ................................................................................... 32 Diagram 7. TDS box plot using two geologic types ............................................................................................. 35 Diagram 8. Calcium box plot using two geologic types ....................................................................................... 35 Figures Figure 1. Aravaipa Canyon basin from Klondyke Road ....................................................................................... 6 Figure 2. Irrigated field above Aravaipa Canyon................................................................................................... 6 Figure 3. Former windmill above Aravaipa Canyon ............................................................................................. 7 Figure 4. Aravaipa Creek below Aravaipa Canyon ............................................................................................... 7 Figure 5. Domestic well below Aravaipa Canyon ................................................................................................. 7 Figure 6. Elevated wellhead below Aravaipa Canyon ........................................................................................... 7 Figure 7. Brandenburg Ranger Station .................................................................................................................. 8 Figure 8. Orchard below Aravaipa Canyon ........................................................................................................... 8 Figure 9. Domestic well below Aravaipa Canyon ................................................................................................. 9 Figure 10. Araviapa Creek below Aravaipa Canyon ............................................................................................... 9 Figure 11. Aravaipa Wilderness kiosk ..................................................................................................................... 9 Figure 12. Perennial flow of Araviapa Creek .......................................................................................................... 9 viii Abbreviations amsl ac-ft af/yr ADEQ ADHS ADWR ARA ARRA AZGS As bls BLM CAP o C CI0.95 Cl EPA F Fe gpm GWPL HCl LLD Mn MCL ml msl ug/L um uS/cm mg/L MRL ns ntu pCi/L QA QAPP QC SAR SDW SC su SO4 TDS TKN USGS VOC WQARF * ** *** above mean sea level acre-feet acre-feet per year Arizona Department of Environmental Quality Arizona Department of Health Services Arizona Department of Water Resources Aravaipa Canyon Groundwater Basin Arizona Radiation Regulatory Agency Arizona Geological Survey arsenic below land surface U.S. Department of the Interior Bureau of Land Management Central Arizona Project degrees Celsius 95 percent Confidence Interval chloride U.S. Environmental Protection Agency fluoride iron gallons per minute Groundwater Protection List pesticide hydrochloric acid Lower Limit of Detection manganese Maximum Contaminant Level milliliter mean sea level micrograms per liter micron microsiemens per centimeter at 25° Celsius milligrams per liter Minimum Reporting Level not significant nephelometric turbidity unit picocuries per liter Quality Assurance Quality Assurance Project Plan Quality Control Sodium Adsorption Ratio Safe Drinking Water Specific Conductivity standard pH units sulfate Total Dissolved Solids Total Kjeldahl Nitrogen U.S. Geological Survey Volatile Organic Compound Water Quality Assurance Revolving Fund significant at p ≤ 0.05 or 95% confidence level significant at p ≤ 0.01 or 99% confidence level for information only, statistical test for this constituent invalid because detections fewer than 50 percent ix x Ambient Groundwater Quality of the Aravaipa Canyon Basin: A 2003 Baseline Study Abstract - In 2003, the Arizona Department of Environmental Quality (ADEQ) conducted a baseline groundwater quality study of the Aravaipa Canyon basin located approximately 120 miles southeast of Phoenix in southeastern Arizona. The basin comprises 517 square miles within Graham and Pinal counties and had an estimated 135 residents in 2000.5 Low-intensity livestock grazing is the predominant land use although there are some small parcels of irrigated pasture and orchards along Aravaipa Creek. Historic mining has resulted in the creation of the Klondyke Tailings Water Quality Assurance Revolving Fund (WQARF) site in 1998.2 Land ownership in the basin consists of federal lands (47 percent) managed by the U.S. Forest Service (26 percent) and the Bureau of Land Management (21 percent). The remainder of the basin consists of State Trust lands (38 percent), private land (14 percent), and Indian land (1 percent) owned by the San Carlos Apache Tribe. 4, 5 The basin is drained by Aravaipa Creek, which runs north until turning west to exit into the Lower San Pedro groundwater basin. The creek is intermittent in its upper reach but becomes perennial where groundwater is brought to the surface by bedrock at Aravaipa Spring.5 Perennial flow usually lasts for about 17 miles until the surface water infiltrates into the streambed alluvium about five miles above the creek’s confluence with the San Pedro River.5 The perennial segment of Aravaipa Creek was named one of Arizona’s Heritage Waters in 2007 based on the stream’s cultural, historical, political, scientific and social significance. 6 Groundwater occurs primarily in two aquifers: recent stream alluvium and basin-fill alluvium. Stream alluvium is the main aquifer and yields up to 1,500 gallons per minute.5 Fine-grained, lake-bed sediments separate the stream alluvium from the basin-fill alluvium, which causes confined conditions in the latter aquifer. Well yields in the basin-fill are variable but tend to be much less than the streambed alluvium.5 Minor amounts of groundwater are found in the surrounding bedrock, especially along faults, fracture zones, and/or localized perched aquifers. Most groundwater is used for irrigation, only minor amounts are used for stock or domestic purposes.5 Fifteen sites (13 wells and 2 springs) were sampled for the study. Inorganic constituents, radon, and isotopes (oxygen and deuterium) were collected from each site. The samples appear to consist of water from the streambed alluvium aquifer or fractured and/or faulted bedrock rather than the confined, basin-fill aquifer. Field data indicated none of the wells were flowing and well log information was not available for most sites. 5 Health-based, Primary Maximum Contaminant Levels (MCLs) were not exceeded at any site. These enforceable standards define the maximum concentrations of constituents allowed in water supplied for drinking water purposes by a public water system and are based on a lifetime daily consumption of two liters. 26 Aesthetics-based, Secondary MCLs were exceeded at 4 of the 15 sites (27 percent). These are unenforceable guidelines that define the maximum constituent concentration that can be present in drinking water without an unpleasant taste, color, or odor.26 Constituents exceeding Secondary MCLs include fluoride (3 sites) and manganese (1 site). Groundwater in the basin is typically slightly-alkaline, fresh, and moderately hard to hard, based on pH levels along with TDS and hardness concentrations.10, 14 Calcium was the dominant cation in half the samples while bicarbonate was the dominant anion composition in most samples. Oxygen and deuterium isotope values at most sites appear to consist of recently recharged winter precipitation. Two sites with more enriched isotope values appear to consist of recently recharged summer precipitation.11 Groundwater constituent concentrations were influenced by recharge source and geology.11, 18 Constituents such as temperature, specific conductivity (SC), TDS, bicarbonate, oxygen-18, and deuterium had significantly greater concentrations in recent summer precipitation than in recent winter precipitation (Kruskal-Wallis test, p ≤ 0.05). Constituents such as SC, TDS, calcium, bicarbonate, chloride, and oxygen-18 had significantly greater concentrations in sites located in consolidated rock than in unconsolidated alluvium (Kruskal-Wallis test, p ≤ 0.05). Groundwater in the basin is suitable for drinking water use based on the results of this ADEQ study. This conclusion is supported by limited data from prior studies conducted by the U.S. Geological Survey in 1975 and ADEQ’s WQARF program in 2001.2, 12 In the latter study, 15 wells sampled in the vicinity of the Klondyke WQARF site by ADEQ had “very good groundwater quality” although the report noted that mine tailings may be impacting surface water in Aravaipa Creek. 2 1 INTRODUCTION Purpose and Scope The Araviapa Canyon basin (ARA) comprises approximately 517 square miles within Graham and Pinal counties in southeastern Arizona (Map 1).5 The remote basin, located roughly 120 miles southeast of Phoenix, had an estimated population of 135 in 2000 with many living in the community of Klondyke.5 The basin is drained by Aravaipa Creek, which runs to the north until turning west and eventually exiting into the Lower San Pedro River basin. Groundwater is used for all domestic use within the basin and most irrigation, and stock water supply. The vast majority of water pumped in the basin is used for irrigation. 5 Sampling by the Arizona Department of Environmental Quality (ADEQ) Ambient Groundwater Monitoring program is authorized by legislative mandate in the Arizona Revised Statutes §49-225, specifically: “...ongoing monitoring of waters of the state, including...aquifers to detect the presence of new and existing pollutants, determine compliance with applicable water quality standards, determine the effectiveness of best management practices, evaluate the effects of pollutants on public health or the environment, and determine water quality trends.” 3 Benefits of ADEQ Study – This study, which utilizes accepted sampling techniques and quantitative analyses, is designed to provide the following benefits: • A characterization of regional groundwater quality conditions in the Araviapa Canyon basin identifying water quality variations between groundwater from different sources. • A process for evaluating potential groundwater quality impacts arising from mineralization, mining, livestock, septic tanks, and poor well construction. • A guide for determining areas where further groundwater quality research is needed. the land is used for low-intensity livestock grazing although there are small parcels of irrigated fields along Araviapa Creek. Retirees and commuters are increasingly relocating to the basin, attracted by its scenic qualities. The basin is bounded on the north by the Turnbull Mountains, on the northeast by the Santa Theresa and Pinaleno Mountains, and the Galiuro Mountains on the southwest. To the southeast, a subtle ridge forms the boundary between the Aravaipa Canyon and Willcox groundwater basins. Elevations in the basin range from a high of 7,540 feet above mean sea level (amsl) at Kennedy Peak in the Galiuro Mountains to a low of approximately 2,400 feet where Aravaipa Creek exits the basin into the Lower San Pedro groundwater basin. The Araviapa Canyon basin consists of federal land (47 percent) managed by the U.S. Forest Service (USFS) (26 percent) Bureau of Land Management (BLM) (21 percent). The remainder of the basin is composed of State Trust land (38 percent), private land (14 percent), and Indian land (1 percent) owned by the San Carlos Apache Tribe.4,5 Generally, tribal land is at the northernmost basin fringes, BLM lands are in the northwest portion, USFS lands are along the eastern and western portions, and State Trust and private land is interspersed throughout especially along Aravaipa Creek (Map 1). Climate – The Araviapa Canyon has an arid climate characterized by hot, dry summers and mild winters. Precipitation, which ranges annually from 14 inches in Araviapa Canyon to 28 inches in the Galiuro Mountains, occurs predominantly as rain in either late summer, localized monsoon thunderstorms or, less often, as widespread, low intensity winter rain that occasionally includes snow at higher elevations. 5 Surface Water Characteristics The basin is drained by Aravaipa Creek, a tributary to the San Pedro River which flows from the southeast to the northwest. The creek is intermittent in its upper reach but has perennial flow where groundwater is brought to the surface by bedrock at Araviapa Spring. Physical and Cultural Characteristics Geography – The Araviapa Canyon basin is a northwest-trending alluvial valley surrounded by blockfaulted mountains within the Basin and Range physiographic province. Vegetation is primarily semidesert grassland with small areas of chaparral and woodland. Riparian vegetation includes cottonwood, willow, mesquite and mixed broadleaf trees.5 Most of Perennial flow lasts for approximately 17 miles until the surface water completely infiltrates into the streambed alluvium about five miles above its confluence with the San Pedro River. The creek has a mean annual flow of over 26,000 acre-feet. Surface water diversions for agriculture average 97 acre-feet per year (af/yr).5 2 3 The perennial segment of Aravaipa Creek was named an Arizona’s Heritage Water based on the cultural, historical, political, scientific, and social significance.6 The segment is located within the 19,700-acre Aravaipa Canyon Wilderness Area, designated in 1984 and administered by the BLM. The 9,000-acre Aravaipa Canyon Preserve managed by the Nature Conservancy also helps maintain stream flows. The Nature Conservancy and the BLM have instream-flow rights that are used to maintain base flows for conservation purposes.5 Portions of three tributaries also have perennial flows: Parsons Creek, Turkey Creek and Virgus Canyon.5 Groundwater Characteristics Groundwater occurs primarily in two aquifers: recent stream alluvium and basin-fill alluvium under confined conditions. Limited groundwater may also be found in the surrounding bedrock. Total estimated recoverable groundwater in storage in the basin-fill sediments to a depth of 1,200 feet below land surface (bls) is estimated at 5.0 million acre-feet (af). 5 Streambed Alluvium Aquifer - The main aquifer is the streambed alluvium which varies in width from 0.5 to 1 mile, ranges in thickness from 25 to 300 feet deep, and is very permeable yielding up to 1,500 gallons per minute (gpm) in irrigation wells. Depth to water varies between less than 10 feet to 100 feet bls. 5 Groundwater Movement – Groundwater flow direction is generally from the surrounding mountains to the valley floor and then northwest towards Aravaipa Canyon. There, the valley narrows and bedrock brings groundwater to the surface at Aravaipa Spring. Through the gorge, Aravaipa Creek is perennial before becoming ephemeral upon exiting the canyon. 5 Groundwater Recharge – Total recharge in the basin is estimated to range from 7,000 to 16,700 af/yr. 5 This occurs through two major components: streambed infiltration of runoff which is the primary source of recharge for the streambed aquifer and mountain-front recharge which chiefly replenishes the basin-fill aquifer. Direct infiltration of rainfall is considered an insignificant contributor to recharge in the basin. 5 Groundwater Development – Groundwater discharge from the basin is estimated to be 16,700 af/yr. Base flow exiting the basin via Aravaipa Creek is estimated to be 11,000 af/yr. Groundwater pumping averages 3,100 af/yr; 2,400 af/yr from the streambed alluvium aquifer and 700 af/yr from the basin-fill aquifer. Most groundwater use is for irrigating small fields located along Aravaipa Creek. Only minor amounts are used for stock watering (45 af/yr) and domestic use (15 af/yr). 5 As of 2005, there has been modest groundwater development in the basin with 192 wells registered with a pumping capacity of less than 35 gpm and 50 wells with a pumping capacity greater than 35 gpm. 5 Basin-fill Aquifer - The lower, basin-fill aquifer is confined by fine-grained, lake-bed sediments that are continuous across the entire valley. There are additional deeper confining layers that are only continuous along the eastern and northern parts of the valley, yet some upward leakage into the streambed aquifer has been reported. Well yields from the basin-fill aquifer are dependable but tend to be small. Depth to water ranges from 25 to 500 feet bls. 5 Historic mining in the basin has resulted in the creation of the Klondyke Tailings Water Quality Assurance Revolving Fund (WQARF) site in 1998. Fifteen wells sampled by ADEQ WQARF program in the vicinity of the Klondyke site had “very good groundwater quality” although the report noted that mine tailings may be impacting surface water in Aravaipa Creek. 2 Bedrock Complex – Only minor amounts of groundwater are found in the surrounding bedrock and the Hell Hole Conglomerate. Most water produced from the complex consists of springs located along faults that drain fracture zones of consolidated rocks or localized perched water tables. 5 The U.S. Geological Survey (USGS) has identified 87 springs in the basin, 7 of which have a discharge rate of greater than 10 gpm.5 Springs support perennial flow in Aravaipa Creek and several streams tributary to it. A few low-yield stock wells have been drilled in the bedrock complex, tapping localized alluvial deposits or fractured consolidated rocks. 5 ADEQ collected samples from 15 sites to characterize regional groundwater quality in the Aravaipa Canyon basin (Map 2). Specifically, the following types of samples were collected: INVESTIGATION METHODS • • • oxygen and deuterium isotopes at 15 sites inorganic suites at 15 sites radon at 15 sites In addition, one isotope sample was collected from Aravaipa Creek. No bacteria sampling was conducted because microbiological contamination problems in groundwater are often transient and subject to a variety of changing environmental conditions including soil moisture content and temperature. 13 4 5 Figure 1 – The Aravaipa Canyon groundwater basin is shown above Araviapa Canyon from Klondyke Road. In this portion of the basin, Aravaipa Creek is an intermittent stream. Generally private land is found along the floodplain, State Trust lands are found higher up the slopes, and U.S. Forest Service manages lands at the highest elevations. The Galiuro Mountains, with snow remnants, are across the valley. Figure 2 – Above Aravaipa Canyon, groundwater is used to irrigate small fields along the floodplain to raise crops mainly for livestock feed. Groundwater pumping averages 3,100 acre-feet per year with the majority of water used for irrigation. 5 6 Figure 3 – Above Araviapa Canyon, a well formerly powered by a windmill now produces water via a submersible pump. The well is located in the floodplain of Aravaipa Creek. Figure 5 – ADEQ’s Elizabeth Boettcher examines a domestic well drilled in the floodplain just outside the Araviapa Canyon Wilderness Area. Figure 4 – ADEQ’s Elizabeth Boettcher stands alongside the perennial flow of Aravaipa Creek as it exits Aravaipa Canyon. Figure 6 – A domestic well completed in the floodplain of Aravaipa Creek has its casing extended almost four feet above surface to lessen the threat of contamination from flood flows. 7 Figure 7 – Access to the groundwater basin below Aravaipa Canyon is via the Aravaipa Road turnoff from Arizona Highway 77 which parallels the Lower San Pedro River. Figure 8 – Small orchards are found along in the lower reaches of Aravaipa Creek before it exits the basin to enter the Lower San Pedro groundwater basin. The lower elevations allow fruit trees such as apricots and citrus to grow in this part of the Aravaipa Canyon groundwater basin. 8 Figure 11 – A kiosk at the west entrance to the Aravaipa Canyon Wilderness explains the ecologic importance of the perennial flow of Aravaipa Creek. A permit system limits visitation to the wilderness area to 50 people per day. Figure 9 – A domestic well located just upgradient of the floodplain in the lower reaches of the basin is used to supply water to a horse property. Figure 10 – Aravaipa Creek is photographed from a bridge where the channel makes a hard bend near Brandenburg Mountain downstream of Aravaipa Canyon. Figure 12 – Perennial flow in Aravaipa Creek continues for approximately 17 miles until the surface water completely infiltrates into the streambed alluvium about five miles above its confluence with the San Pedro River. The creek has a mean annual flow of over 26,000 acre-feet. 5 9 Wells pumping groundwater for domestic, stock, and irrigation purposes were sampled for the study provided each well met ADEQ requirements. A well was considered suitable for sampling when the following conditions were met: the owner has given permission to sample, a sampling point existed near the wellhead, and the well casing and surface seal appeared to be intact and undamaged.1, 7 For this study, ADEQ personnel sampled 13 wells all served by submersible pumps except for one windmill. Of the 13 wells sampled, their primary purposes were domestic (6 wells), stock (5 wells), irrigation (1 well), and wildlife (1 well). Two springs were also sampled for the study, one primarily used for domestic purposes and the other used for stock watering. Additional information on groundwater sample sites is compiled from the Arizona Department of Water Resources (ADWR) well registry in Appendix A. 5 Sample Collection The sample collection methods for this study conformed to the Quality Assurance Project Plan (QAPP)1 and the Field Manual for Water Quality Sampling.7 While these sources should be consulted as references to specific sampling questions, a brief synopsis of the procedures involved in collecting a groundwater sample is provided. Radon, a naturally occurring, intermediate breakdown from the radioactive decay of uranium238 to lead-206, was collected in two unpreserved, 40 milliliter (ml) clear glass vials. Radon samples were filled to minimize volatilization and subsequently sealed so that no headspace remained.7, 21 The inorganic constituents were collected in three, one-liter polyethylene bottles: samples to be analyzed for dissolved metals were delivered to the laboratory unfiltered and unpreserved where they were subsequently filtered into bottles using a positive pressure filtering apparatus with a 0.45 micron (µm) pore size groundwater capsule filter and preserved with 5 ml nitric acid (70 percent). Samples to be analyzed for nutrients were preserved with 2 ml sulfuric acid (95.5 percent). Samples to be analyzed for other parameters were unpreserved.7, 19, 21 Oxygen and hydrogen isotope samples were collected in a 250 ml polyethylene bottle with no preservative.7, 25 All samples were kept at 4oC with ice in an insulated cooler, with the exception of the oxygen and hydrogen isotope samples.7,19,23 Chain of custody procedures were followed in sample handling. Samples for this study were collected during three field trips conducted during 2003. Laboratory Methods After obtaining permission from the well owner, the volume of water needed to purge the well three borehole volumes was calculated from well log and onsite information. Physical parameters—temperature, pH, and specific conductivity—were monitored at least every five minutes using either a Hach or YSI multi-parameter instrument. To assure obtaining fresh water from the aquifer, after three bore volumes had been pumped and physical parameter measurements had stabilized within 10 percent, a sample representative of the aquifer was collected from a point as close to the wellhead as possible. In certain instances, it was not possible to purge three bore volumes. In these cases, at least one bore volume was evacuated and the physical parameters had stabilized within 10 percent. Sample bottles were filled in the following order: 1. Radon 2. Inorganics 3. Isotopes The inorganic analyses for all inorganic samples, except three split samples, were conducted by the Arizona Department of Health Services (ADHS) Laboratory in Phoenix, Arizona. The inorganic analyses for the three split samples (ARA-7, ARA-11S, and ARA-16S) were conducted by Test America Laboratory in Phoenix, Arizona. A complete listing of inorganic parameters, including laboratory method, and Minimum Reporting Level (MRL) for each laboratory is provided in Table 1. Radon samples were submitted to Test America Laboratory and analyzed by Radiation Safety Engineering, Inc. Laboratory in Chandler, Arizona. All isotope samples were analyzed by the Department of Geosciences, Laboratory of Isotope Geochemistry located at the University of Arizona in Tucson, Arizona. 10 Table 1. Laboratory Water Methods and Minimum Reporting Levels Used in the Study Constituent Instrumentation ADHS / Test America Water Method ADHS / Test America Minimum Reporting Level Physical Parameters and General Mineral Characteristics Alkalinity Electrometric Titration SM 2320B / M 2320 B 2/6 SC (µS/cm) Electrometric EPA 120.1/ M 2510 B -- / 2 Hardness Titrimetric, EDTA Hardness Calculation pH (su) Electrometric TDS Turbidity (NTU) SM 2340 C / SM 2340B 10 / 1 SM 2340 B -- SM 4500 H-B 0.1 Gravimetric SM 2540C 10 Nephelometric EPA 180.1 0.01 / 0.2 Major Ions Calcium ICP-AES EPA 200.7 1/2 Magnesium ICP-AES EPA 200.7 1 / 0.25 Sodium ICP-AES EPA 200.7 1/2 Potassium Flame AA EPA 200.7 0.5 / 2 Bicarbonate Calculation Calculation / M 2320 B 2 Carbonate Calculation Calculation / M 2320 B 2 Chloride Potentiometric Titration SM 4500 CL D / E 300 5/2 Sulfate Colorimetric EPA 375.4 / E 300 1/2 Nutrients Nitrate as N Colorimetric EPA 353.2 0.02 / 0.1 Nitrite as N Colorimetric EPA 353.2 0.02 / 0.1 Ammonia Colorimetric EPA 350.1/ EPA 350.3 0.02 / 0.5 TKN Colorimetric EPA 351.2 / M 4500NH3 0.05 / 1.3 Total Phosphorus Colorimetric EPA 365.4 / M 4500-PB 0.02 / 0.1 All units are mg/L except as noted 19, 21 Source 11 Table 1. Laboratory Water Methods and Minimum Reporting Levels Used in the Study-Continued Constituent Instrumentation ADHS / Test America Water Method ADHS / Test America Minimum Reporting Level Trace Elements Aluminum ICP-AES EPA 200.7 0.5 / 0.2 Antimony Graphite Furnace AA EPA 200.8 0.005 / 0.003 Arsenic Graphite Furnace AA EPA 200.9 / EPA 200.8 0.005 / 0.001 Barium ICP-AES EPA 200.8 / EPA 200.7 0.005 to 0.1 / 0.01 Beryllium Graphite Furnace AA EPA 200.9 / EPA 200.8 0.0005 / 0.001 Boron ICP-AES EPA 200.7 0.1 / 0.2 Cadmium Graphite Furnace AA EPA 200.8 0.0005 / 0.001 Chromium Graphite Furnace AA EPA 200.8 / EPA 200.7 0.01 / 0.01 Copper Graphite Furnace AA EPA 200.8 / EPA 200.7 0.01 / 0.01 Fluoride Ion Selective Electrode SM 4500 F-C 0.1 / 0.4 Iron ICP-AES EPA 200.7 0.1 / 0.05 Lead Graphite Furnace AA EPA 200.8 0.005 / 0.001 Manganese ICP-AES EPA 200.7 0.05 / 0.01 Mercury Cold Vapor AA SM 3112 B / EPA 245.1 0.0002 Nickel ICP-AES EPA 200.7 0.1 / 0.01 Selenium Graphite Furnace AA EPA 200.9 / EPA 200.8 0.005 / 0.002 Silver Graphite Furnace AA EPA 200.9 / EPA 200.7 0.001 / 0.01 Strontium ICP-AES EPA 200.7 0.1 / 0.1 Thallium Graphite Furnace AA EPA 200.9 / EPA 200.8 0.002 / 0.001 Zinc ICP-AES EPA 200.7 0.05 Radionuclides Radon Liquid scintillation counter All units are mg/L Source EPA 913.1 varies 19, 21 12 DATA EVALUATION Quality Assurance Quality-assurance (QA) procedures were followed and quality-control (QC) samples were collected to quantify data bias and variability for the Aravaipa Canyon basin study. The design of the QA/QC plan was based on recommendations included in the Quality Assurance Project Plan (QAPP) and the Field Manual For Water Quality Sampling. 1, 7 Types and numbers of QC samples collected for this study are as follows: • • • Inorganic: (3 duplicates, 3 splits, and 2 equipment blanks). Radon: (none) Isotopes: (none) Based on the QA/QC results, sampling procedures and laboratory equipment did not significantly affect the groundwater quality samples. Blanks – Two equipment blanks for inorganic analyses were collected and delivered to the ADHS laboratory to ensure adequate decontamination of sampling equipment, and that the filter apparatus and/or de-ionized water were not impacting the groundwater quality sampling.7 Equipment blank samples for major ion and nutrient analyses were collected by filling unpreserved and sulfuric acid preserved bottles with de-ionized water. Equipment blank samples for trace element analyses were collected with de-ionized water that had been filtered into nitric acid preserved bottles. Systematic contamination was judged to occur if more than 50 percent of the equipment blank samples contained measurable quantities of a particular groundwater quality constituent. The equipment blanks contained specific conductivity (SC)-lab contamination at levels expected due to impurities in the source water used for the samples. Turbidity and nitrate were also each detected in one sample. For SC, the two equipment blanks had a mean value (3.7 uS/cm) which was less than 1 percent of the SC mean concentration for the study and was not considered to be significantly affecting the sample results. The SC detections may be explained in two ways: water passed through a de-ionizing exchange unit will normally have an SC value of at least 1 uS/cm, and carbon dioxide from the air can dissolve in de-ionized water with the resulting bicarbonate and hydrogen ions imparting the observed conductivity.19 For turbidity, one blank had a level of 0.02 nephelometric turbidity units (ntu) less than 1 percent of the turbidity mean level for the study. Testing indicates turbidity is present at 0.01 ntu in the deionized water supplied by the ADHS laboratory, and levels increase with time due to storage in ADEQ carboys.19 For nitrate, one blank had a concentration of 0.10 mg/L that is less than 1 percent of the nitrate mean level for the study. Duplicate Samples - Duplicate samples are identical sets of samples collected from the same source at the same time and submitted to the same laboratory. Data from duplicate samples provide a measure of variability from the combined effects of field and laboratory procedures.7 Duplicate samples were collected from sampling sites that were believed to have elevated or unique constituent concentrations as judged by SC-field and pH-field values. Two duplicate samples were collected and submitted to the ADHS laboratory for this study. Analytical results indicate that of the 40 constituents examined, 20 had concentrations above the MRL. The duplicate samples had an excellent correlation as the maximum variation between constituents was less than 4 percent except for turbidity (15 percent) and TDS (7 percent) (Table 2). Split Samples - Split samples are identical sets of samples collected from the same source at the same time that are submitted to two different laboratories to check for laboratory differences.7 Three inorganic split samples were collected and distributed between the ADHS and Test America labs. However, only one of the split sample results was available; the other two split sample results were missing and had not been entered into the ADEQ groundwater quality database. Partial split results entered into a spreadsheet accompanying the laboratory results were used in the analysis. The analytical results were evaluated by examining the variability in constituent concentrations in terms of absolute levels and as the percent difference. Analytical results indicate that of the 36 constituents examined, 16 had concentrations above MRLs for both ADHS and Test America laboratories (Table 3). The maximum variation between constituents was 12 percent; over half of the constituents had maximum variations below 5 percent. Split samples were also evaluated using the non-parametric Sign test to 13 Table 2. Summary Results of Duplicate Samples from ADHS Laboratory Parameter Number of Dup. Sites Difference in Percent Minimum Maximum Difference in Concentrations Median Minimum Maximum Median Physical Parameters and General Mineral Characteristics Alk., Total 2 0% 2% - 0 1 - SC (µS/cm) 2 1% 4% - 10 10 - Hardness 2 0% 3% - 0 2 - pH (su) 2 1% 1% - 0.1 0.1 - TDS 2 0% 7% - 0 11 - Turb. (ntu) 2 8% 15 % - 0.04 0.4 - Major Ions Calcium 2 0% 3% - 0 3 - Magnesium 2 0% 3% - 0 1 - Sodium 2 0% 0% - 0 0 - Potassium 2 2% 3% - 0.02 0.1 - Bicarbonate 2 0% 4% - 0 2 - Chloride 2 0% 1% - 0 0.1 - Sulfate 2 0% 0% - 0 0 - Nutrients Nitrate (as N) 2 1% 2% - 0.1 0.01 - Phosphorus, T. 1 0% 0% - 0 0 - TKN * 1 - - 3% - - 0.1 Trace Elements Barium 1 - - 0% - - 0 Copper 1 - - 14 % - - 0.004 Fluoride 2 0% 2% - 0 0.1 - Zinc 1 - - 13 % - - 0.17 All concentration units are mg/L except as noted with certain physical parameters. * = TKN was detected in one sample (ARA-11D) at a concentration of 0.078 mg/L and not detected in the duplicate (ARA-11) 14 Table 3. Summary Results of Split Samples between ADHS / Test America Labs Constituents Number of Split Sites Difference in Percent Difference in Levels Significance Minimum Maximum Minimum Maximum Physical Parameters and General Mineral Characteristics Alkalinity, total 3 0% 2% 0 10 ns SC (µS/cm) 3 0% 2% 0 10 ns Hardness 3 4% 9% 20 30 ns pH (su) 3 1% 2% 0.1 0.31 ns TDS 3 1% 9% 10 30 ns Turbidity (ntu) 1 9% 9% 1.1 1.1 ns Major Ions Calcium 3 0% 5% 2 9 ns Magnesium 3 2% 7% 1 1.4 ns Sodium 3 1% 5% 0 1 ns Potassium 3 4% 12 % 0.2 0.9 ns Chloride 3 1% 10 % 0.1 2.1 ns Sulfate 3 0% 3% 0 1 ns Nutrients Nitrate as N 1 1% 1% 0.58 0.58 ns Phosphorus, T. 1 8% 8% 0.12 0.12 ns Trace Elements Fluoride 3 0% 2% 0 0.01 ns Zinc 1 4% 4% 0.01 0.01 ns ns = No significant (p  ≤ 0.05) difference All units are mg/L except as noted 15 determine if there were any significant differences between ADHS laboratory and Test America laboratory analytical results.15 There were no significant differences in constituent concentrations between the labs (Sign test, p ≤ 0.05). by sampling and storage.16 The pH values measured in the field using a YSI meter at the time of sampling were not significantly correlated with laboratory pH values (regression analysis, r = 0.41, p ≥ 0.05). Statistical Considerations Based on the results of blanks, duplicate, and split samples collected for this study, no significant QA/QC problems were apparent with the study. Various statistical analyses were used to examine the groundwater quality data of the study. All statistical tests were conducted using SYSTAT software.28 Data Validation The analytical work for this study was subjected to four QA/QC correlations and considered valid based on the following results. 16 Cation/Anion Balances - In theory, water samples exhibit electrical neutrality. Therefore, the sum of milliequivalents per liter (meq/L) of cations should equal the sum of meq/L of anions. However, this neutrality rarely occurs due to unavoidable variation inherent in all water quality analyses. Still, if the cation/anion balance is found to be within acceptable limits, it can be assumed there are no gross errors in concentrations reported for major ions.16 Overall, cation/anion meq/L balances of Aravaipa Canyon basin samples were significantly correlated (regression analysis, p ≤ 0.01). Of the 15 samples, all were within +/-2 percent except for one sample with a 23 percent variation. Five samples had low cation/high anion sums; 10 samples had high cation/low anion sums. SC/TDS - The SC and TDS concentrations measured by contract laboratories were significantly correlated as were SC-field and TDS concentrations (regression analysis, r = 0.99, p ≤ 0.01). The TDS concentration in mg/L should be from 0.55 to 0.75 times the SC in µS/cm for groundwater up to several thousand TDS mg/L.16 Groundwater high in bicarbonate and chloride will have a multiplication factor near the lower end of this range; groundwater high in sulfate may reach or even exceed the higher factor. The relationship of TDS to SC becomes undefined with very high or low concentrations of dissolved solids.16 SC - The SC measured in the field at the time of sampling was significantly correlated with the SC measured by contract laboratories (regression analysis, r = 0.94, p ≤ 0.01). Data Normality: Data associated with 23 constituents were tested for non-transformed normality using the Kolmogorov-Smirnov onesample test with the Lilliefors option.8 Results of this test revealed that 17 of the 23 constituents (temperature, pH-field, SC-field, SC-lab, TDS, hardness, hardness-calculated, calcium, magnesium, sodium, potassium, total alkalinity, bicarbonate, chloride, sulfate, nitrate, and radon) examined were normally distributed. Spatial Relationships: The non-parametric KruskalWallis test using untransformed data was applied to investigate the hypothesis that constituent concentrations from groundwater sites having different aquifers were the same. The Kruskal-Wallis test uses the differences, but also incorporates information about the magnitude of each difference.28 The null hypothesis of identical mean values for all data sets within each test was rejected if the probability of obtaining identical means by chance was less than or equal to 0.05. The Kruskal-Wallis test is not valid for data sets with greater than 50 percent of the constituent concentrations below the MRL.15 Correlation Between Constituents: In order to assess the strength of association between constituents, their concentrations were compared to each other using the Pearson Correlation Coefficient test. The Pearson correlation coefficient varies between -1 and +1; with a value of +1 indicating that a variable can be predicted perfectly by a positive linear function of the other, and vice versa. A value of -1 indicates a perfect inverse or negative relationship. The results of the Pearson Correlation Coefficient test were then subjected to a probability test to determine which of the individual pair wise correlations were significant.28 The Pearson test is not valid for data sets with greater than 50 percent of the constituent concentrations below the MRL.15 pH - The pH value is closely related to the environment of the water and is likely to be altered 16 GROUNDWATER SAMPLING RESULTS Water Quality Standards/Guidelines The ADEQ ambient groundwater program characterizes regional groundwater quality. An important determination ADEQ makes concerning the collected samples is how the analytical results compare to various drinking water quality standards. ADEQ used three sets of drinking water standards that reflect the best current scientific and technical judgment available to evaluate the suitability of groundwater in the basin for drinking water use: • • • Federal Safe Drinking Water (SDW) Primary Maximum Contaminant Levels (MCLs). These enforceable health-based standards establish the maximum concentration of a constituent allowed in water supplied by public systems.26 State of Arizona Aquifer Water Quality Standards. These apply to aquifers that are classified for drinking water protected use. All aquifers within Arizona are currently classified and protected for drinking water use. These enforceable State standards are identical to the federal Primary MCLs except for arsenic which is at 0.05 mg/L compared with the federal Primary MCL of 0.01 mg/L. 3 Federal SDW Secondary MCLs. These nonenforceable aesthetics-based guidelines define the maximum concentration of a constituent that can be present without imparting unpleasant taste, color, odor, or other aesthetic effects on the water.26 Health-based drinking water quality standards (such as Primary MCLs) are based on the lifetime consumption (70 years) of two liters of water per day and, as such, are chronic not acute standards.26 Exceedances of specific constituents for each groundwater site is found in Appendix B. Aesthetics-based Secondary MCL water quality guidelines were exceeded at 4 of 15 sites (27 percent; Map 3; Table 4). Constituents above Secondary MCLs include fluoride (3 sites), and manganese (1 site). Potential impacts of these Secondary MCL exceedances are given in Table 4. Radon Results - Of the 15 sites sampled for radon none exceeded the proposed 4,000 picocuries per liter (pCi/L) standard that would apply if Arizona establishes an enhanced multimedia program to address the health risks from radon in indoor air. Seven (7) sites exceeded the proposed 300 pCi/L standard (Map 4) that would apply if Arizona doesn’t develop a multimedia program. 26 Suitability for Irrigation The groundwater at each sample site was assessed as to its suitability for irrigation use based on salinity and sodium hazards. Excessive levels of sodium are known to cause physical deterioration of the soil and vegetation. Irrigation water may be classified using SC and the Sodium Adsorption Ratio (SAR) in conjunction with one another. 27 Groundwater sites in the Aravaipa Canyon basin display a narrow range of irrigation water classifications. Samples from all 15 sites were within the “low” to “medium” for both alkalinity and salinity hazard categories (Table 5). Analytical Results Analytical inorganic and radiochemistry results of the Aravaipa Canyon basin sample sites are summarized (Table 6) using the following indices: MRLs, number of sample sites over the MRL, upper and lower 95 percent confidence intervals (CI95%), median, and mean. Confidence intervals are a statistical tool which indicates that 95 percent of a constituent’s population lies within the stated confidence interval.28 Specific constituent information for each sampled groundwater site is in Appendix B. Inorganic Constituent Results - Health-based Primary MCL water quality standards and State aquifer water quality standards were not exceeded at any of the 15 sites. 17 18 19 Table 4. Sampled Sites Exceeding Aesthetics-Based (Secondary MCL) Water Quality Standards Constituents Secondary MCL Number of Sites Exceeding Secondary MCLs Concentration Range of Exceedances Aesthetic Effects of MCL Exceedances Physical Parameters pH - field < 6.5 0 - - pH - field > 8.5 0 - - General Mineral Characteristics 500 TDS 0 2,100 hardness; deposits; colored water; staining; salty taste Major Ions Chloride (Cl) 250 0 800 salty taste Sulfate (SO4) 250 0 670 salty taste Trace Elements Fluoride (F) 2.0 3 5.0 tooth discoloration Iron (Fe) 0.3 0 - - Manganese (Mn) 0.05 1 0.10 black staining; bitter metallic taste Silver (Ag) 0.1 0 - - Zinc (Zn) 5.0 0 - - All units mg/L except pH is in standard units (su). Source: 26 Table 5. Alkalinity and Salinity Hazards for Sampled Sites Hazard Total Sites Low Medium High Very High Alkalinity Hazard Sodium Adsorption Ratio (SAR) Sample Sites 15 0 - 10 10- 18 18 - 26 > 26 15 0 0 0 Salinity Hazard Specific Conductivity (µS/cm) Sample Sites 15 100–250 250 – 750 750-2250 >2250 2 13 0 0 20 Table 6. Summary Statistics for Groundwater Quality Data Constituent Minimum Reporting Limit (MRL)* # of Samples / Samples Over MRL Median Lower 95% Confidence Interval Mean Upper 95% Confidence Interval Physical Parameters Temperature (oC) 0.1 15 / 15 21.2 19.6 21.8 24.1 pH-field (su) 0.01 15 / 15 7.65 7.48 7.66 7.83 pH-lab (su) 0.01 15 / 15 7.65 7.45 7.64 7.84 0.01 / 0.20 15 / 15 0.29 0.11 1.06 2.01 186 224 Turbidity (ntu) General Mineral Characteristics T. Alkalinity 2.0 / 6.0 15 / 15 190 148 Phenol. Alk. 2.0 / 6.0 15 / 0 SC-field (µS/cm) N/A 15 / 15 455 348 432 515 SC-lab (µS/cm) N/A / 2.0 15 / 15 410 348 434 520 Hardness-lab 10 / 6 15 / 15 180 121 159 197 TDS 10 / 20 15 / 15 260 216 264 312 > 50% of data below MRL Major Ions Calcium 5/2 15 / 15 53 35 48 60 1.0 / 0.25 15 / 15 11.0 8.3 11.3 14.3 5/2 15 / 15 28 22 30 39 Potassium 0.5 / 2.0 15 / 15 2.1 1.7 2.4 3.0 Bicarbonate 2.0 / 6.0 15 / 15 230 177 221 265 Carbonate 2.0 / 6.0 15 / 0 Chloride 1 / 20 15 / 15 6.8 5.2 8.4 11.7 Sulfate 10 / 20 15 / 15 20 15 25 36 0.3 0.6 0.9 Magnesium Sodium > 50% of data below MRL Nutrients Nitrate (as N) 0.02 / 0.20 15 / 14 0.6 Nitrite (as N) 0.02 / 0.20 15 / 0 > 50% of data below MRL TKN 0.05 / 1.0 15 / 6 > 50% of data below MRL Ammonia 0.02 / 0.05 15 / 1 > 50% of data below MRL T. Phosphorus 0.02 / 0.10 15 / 7 > 50% of data below MRL 21 Table 6. Summary Statistics for Groundwater Quality Data—Continued Constituent Minimum Reporting Limit (MRL)* # of Samples / Samples Over MRL Median Lower 95% Confidence Interval Mean Upper 95% Confidence Interval Trace Elements Aluminum 0.5 / 0.2 15 / 0 > 50% of data below MRL Antimony 0.005 / 0.003 15 / 0 > 50% of data below MRL Arsenic 0.01 / 0.001 15 / 0 > 50% of data below MRL Barium 0.1 / 0.001 15 / 2 > 50% of data below MRL 0.0005 / 0.001 15 / 1 > 50% of data below MRL 0.1 / 0.2 15 / 1 > 50% of data below MRL Cadmium 0.001 15 / 0 > 50% of data below MRL Chromium 0.01 / 0.001 15 / 0 > 50% of data below MRL Copper 0.01 / 0.001 15 / 2 > 50% of data below MRL Fluoride 0.2 / 0.4 15 / 15 Iron 0.1 / 0.05 15 / 1 > 50% of data below MRL Lead 0.005 / 0.001 15 / 0 > 50% of data below MRL 0.05 / 0.01 15 / 1 > 50% of data below MRL 0.0005 / 0.0002 15 / 0 > 50% of data below MRL 0.1 / 0.01 15 / 0 > 50% of data below MRL 0.005 / 0.002 15 / 0 >50% of data below MRL 0.001 15 / 0 > 50% of data below MRL 0.002 / 0.001 15 / 0 > 50% of data below MRL 0.05 15 / 5 > 50% of data below MRL Beryllium Boron Manganese Mercury Nickel Selenium Silver Thallium Zinc 0.5 0.4 1.0 1.6 Radiochemical Radon (pCi/L) Varies 15 / 15 264 184 307 430 Isotopes Oxygen-18 ** Varies 15 / 15 - 9.2 - 9.4 - 8.9 - 8.5 Deuterium ** Varies 15 / 15 - 65.0 - 66.7 - 64.7 - 62.6 * = ADHS MRL / Test America MRL All units mg/L except where noted or ** = 0/00 22 GROUNDWATER COMPOSITION General Summary The water chemistry at the 15 sample sites in the Aravaipa Canyon basin (in decreasing frequency) include calcium-bicarbonate (8 sites), mixedbicarbonate (4 sites), sodium-bicarbonate (2 sites), and mixed-mixed (1 site) (Diagram 1 – middle diagram) (Map 5). Of the 15 sample sites in the Aravaipa Canyon basin, the dominant cation was calcium at 8 sites and sodium at 2 sites; at 5 sites, the composition was mixed as there was no dominant cation (Diagram 1 – left diagram). The dominant anion was bicarbonate at 14 sites; at 1 site the composition was mixed as there was no dominant anion (Diagram 1 – right diagram). Diagram 1 – Groundwater in the Aravaipa Canyon basin is predominantly a calcium-bicarbonate chemistry which is reflective of recent local recharge occurring from both winter and summer precipitation. 23 24 At all 15 sites, levels of pH-field were all slightly alkaline (above 7 su) and 3 sites were above 8 su. 14 TDS concentrations were considered fresh (below 999 mg/L) at all 15 sites (Map 6).14 Hardness concentrations were soft (below 75 mg/L) at 1 site, moderately hard (75 – 150 mg/L) at 6 sites, hard (150 – 300 mg/L) at 8 sites, very hard (300 600 mg/L) at 0 sites (Diagram 2 and Map 7).10 Nitrate (as nitrogen) concentrations at most sites may have been influenced by human activities according to one source often cited. Nitrate concentrations were divided into natural background (3 sites at < 0.2 mg/L), may or may not indicate human influence (12 sites at 0.2 – 3.0 mg/L), may result from human activities (0 sites at 3.0 – 10 mg/L), and probably result from human activities (0 sites > 10 mg/L).17 Most trace elements such as aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium, silver, thallium, and zinc were rarely – if ever - detected. Only fluoride was detected at more than 33 percent of the sites. Diagram 2. Hardness Concentrations of Aravaipa Canyon Basin Samples 0% 7% Soft Moderately Hard 53% 40% Hard Very Hard Diagram 2 – In the Aravaipa Canyon basin hardness concentrations vary from 35 to 270 mg/L. The highest hardness concentrations tend to occur in samples collected from sites in consolidated bedrock and in downgraident areas along Aravaipa Creek. 25 26 27 Constituent Co-Variation The correlations between different chemical parameters were analyzed to determine the relationship between the constituents that were sampled. The strength of association between the chemical constituents allows for the identification of broad water quality patterns within a basin. The results of each combination of constituents were examined for statistically-significant positive or negative correlations. A positive correlation occurs when, as the level of a constituent increases or decreases, the concentration of another constituent also correspondingly increases or decreases. A negative correlation occurs when, as the concentration of a constituent increases, the concentration of another constituent decreases, and vice-versa. A positive correlation indicates a direct relationship between constituent concentrations; a negative correlation indicates an inverse relationship.28 Several significant correlations occurred among the 15 sample sites (Table 7, Pearson Correlation Coefficient test, p ≤ 0.05). Four groups of correlations were identified: • Fluoride was positively correlated with sodium; pH-field was negatively correlated with calcium (Diagram 3). • TDS was positively correlated with calcium, magnesium, sodium, bicarbonate, chloride, and sulfate. • Sodium was positively correlated with bicarbonate and chloride. TDS concentrations are best predicted among major ions by bicarbonate concentrations (standard coefficient = 0.84), among cations by calcium concentrations (standard coefficient = 0.65) and among anions, by bicarbonate concentrations (standard coefficient = 0.86) (multiple regression analysis, p ≤ 0.01). 90 80 Diagram 3 – The graph illustrates a negative correlation between two constituents; as pH-field values increase, calcium concentrations decrease. This relationship is described by the regression equation: y = -37x + 337 (r = 0.53). The pH-calcium relationship has been found in other Arizona groundwater basins and is likely related to precipitation of calcite in response to increases in pH. 20 Calcium (mg/L) 70 60 50 40 30 20 10 7.0 7.5 8.0 8.5 pH-field (su) 28 Table 7. Correlation Among Groundwater Quality Constituent Concentrations Constituent Temp pH-f pHlab SC-f TDS Hard Ca Mg Na K Bic Cl SO4 NO3 F Radon O D ** * + Physical Parameters Temperature pH-field pH-lab SC-field TDS Hardness Calcium Magnesium Sodium Potassium Bicarbonate Chloride Sulfate * + * ** * * ** ** ** * General Mineral Characteristics ** ** ** * ** ** Major Ions * ** ** ** ** * ** ** ** * ** * * ** ** * * ** * ** ** * * + ** + + * * Nutrients Nitrate Trace Elements Fluoride Radioactivity Radon Isotopes Oxygen Deuterium ** Blank cell = not a significant relationship between constituent concentrations * = Significant positive relationship at p ≤ 0.05 ** = Significant positive relationship at p ≤ 0.01 + = Significant negative relationship at p ≤ 0.05 ++ = Significant negative relationship at p ≤ 0.01 29 Oxygen and Hydrogen Isotopes The data for the Aravaipa Canyon basin roughly conforms to what would be expected in an arid environment, having a slope of 4.1, with the Local Meteoric Water Line (LMWL) described by the linear equation: δ D = 4.1 δ 18O – 27.7 (Diagram 4). The LMWL for the Aravaipa Canyon basin (4.1) is lower than other basins in Arizona including Dripping Springs Wash (4.4), Detrital Valley (5.2), Agua Fria (5.3), Bill Williams (5.3), Sacramento Valley (5.5), Big Sandy (6.1), Butler Valley (6.4), Pinal Active Management Area (6.4), Gila Valley (6.4), San Simon (6.5), San Bernardino Valley (6.8), McMullen Valley (7.4), Lake Mohave (7.8), and Ranegras Plain (8.3). 22 The most isotope samples plotted in a cluster that suggest much of the groundwater at these wells and springs consists of recent winter recharge stemming from precipitation originating in the Galiuro, Pinaleno, and/or Santa Theresa mountains. Two samples, ARA-12/12S and ARA-15, plot higher on the LWML and appear to consist of recent summer precipitation recharge (Map 8). Oxygen and Hydrogen Isotopes Groundwater characterizations using oxygen and hydrogen isotope data may be made with respect to the climate and/or elevation where the water originated, residence within the aquifer, and whether or not the water was exposed to extensive evaporation prior to collection.9 This is accomplished by comparing oxygen-18 isotopes (δ 18O) and deuterium (δ D), an isotope of hydrogen, data to the Global Meteoric Water Line (GMWL). The GMWL is described by the linear equation: δ D = 8 δ 18O + 10 where δ D is deuterium in parts per thousand (per mil, 0/00), 8 is the slope of the line, δ 18O is oxygen-18 0 /00, and 10 is the y-intercept.9 The GMWL is the standard by which water samples are compared and is a universal reference standard based on worldwide precipitation without the effects of evaporation. Isotopic data from a region may be plotted to create a Local Meteoric Water Line (LMWL) which is affected by varying climatic and geographic factors. When the LMWL is compared to the GMWL, inferences may be made about the origin or history of the local water.9 The LMWL created by δ 18O and δ D values for samples collected at sites in the Aravaipa Canyon basin plot mostly to the right of the GMWL. Meteoric waters exposed to evaporation are enriched and characteristically plot increasingly below and to the right of the GMWL. Evaporation tends to preferentially contain a higher percentage of lighter isotopes in the vapor phase and causes the water that remains behind to be isotopically heavier. In contrast, meteoric waters that experience little evaporation are depleted and tend to plot increasing to the left of the GMWL and are isotopically lighter. 9 Groundwater from arid environments is typically subject to evaporation, which enriches δ D and δ 18O, resulting in a lower slope value (usually between 3 and 6) as compared to the slope of 8 associated with the GMWL.9 Diagram 4 – The 15 isotope samples are plotted according to their oxygen-18 and deuterium values and form the Local Meteoric Water Line. Most samples consist of recent winter precipitation recharge; two outliers consist of recent summer precipitation recharge. 11 30 31 Groundwater Quality Variation Between Two Recharge Sources – Twenty (20) groundwater quality constituents were compared between two recharge types: recent winter precipitation (13 sites) and recent summer precipitation (2 sites). Significant concentration differences were found with seven constituents: temperature, SC-field, SC-lab, TDS, bicarbonate (Diagram 5), oxygen-18 and deuterium (Kruskal-Wallis test, p ≤ 0.05). In addition, hardness (Diagram 6), calcium, and magnesium just missed having significant differences. In all these instances, sites with recent summer precipitation recharge had significantly higher constituent concentrations than sites with recent winter precipitation recharge. Complete statistical results are in Table 8 and 95 percent confidence intervals for significantly different groups based on isotope recharge sources are in Table 9. Bicarbonate (mg/L) 400 Diagram 5 – Sample sites consisting of recharge from recent summer precipitation have significantly higher bicarbonate concentrations than sample sites consisting of recharge from recent winter precipitation (KruskalWallis, p ≤ 0.05). Elevated bicarbonate concentrations are often associated with recharge areas. 20 300 200 100 0 Summer Winter Recharge Precipitation Source Hardness (mg/L) 300 Diagram 6 – Sample sites consisting of recharge from recent summer precipitation just missed having statistically significantly higher hardness concentrations than sample sites consisting of recharge from recent winter precipitation (Kruskal-Wallis, p ≤ 0.05). Elevated hardness concentrations are often associated with recharge areas. 20 200 100 0 Summer Winter Recharge Precipitation Source 32 Table 8. Variation in Groundwater Quality Constituent Concentrations between Two Recharge Groups Constituent Significance Significant Differences Between Recharge Sources Temperature - field * Summer > Winter pH – field ns - pH – lab ns - SC - field * Summer > Winter SC - lab * Summer > Winter TDS * Summer > Winter Turbidity ns - Hardness ns - Calcium ns - Magnesium * - Sodium ns - Potassium ns - Bicarbonate * Summer > Winter Chloride ns - Sulfate ns - Nitrate (as N) ns - Fluoride ns - Radon ns - Oxygen * Summer > Winter Deuterium * Summer > Winter ns = not significant * = significant at p ≤ 0.05 or 95% confidence level ** = significant at p ≤ 0.01 or 99% confidence level 33 Table 9. Summary Statistics for Two Recharge Groups with Significant Constituent Differences Constituent Significance Summer Precipitation Winter Precipitation Temperature – field (oC) * 1.8 to 56.5 18.9 to 22.4 pH – field (su) ns - - pH – lab (su) ns - - SC - field (µS/cm) * 320 to 480 -213 to 1489 SC - lab (µS/cm) * 319 to 483 15 to 1,285 TDS * 287 to 478 199 to 294 Turbidity ns - - Hardness ns - - Calcium ns - - Magnesium * - - Sodium ns - - Potassium ns - - Bicarbonate * 217 to 408 161 to 253 Chloride ns - - Sulfate ns - - Nitrate (as N) ns - - Fluoride ns - - Radon ns - - Oxygen (0/00) * -7.59 to -6.32 -9.41 to -9.08 Deuterium (0/00) * -88.3 to -24.7 -66.9 to -65.0 ns = not significant * = significant at p ≤ 0.05 or 95% confidence level ** = significant at p ≤ 0.01 or 99% confidence level All units are mg/L except where indicated. 34 Between Two Geologic Types - Twenty (20) groundwater quality constituents were compared between two geologic types: consolidated crystalline and sedimentary rocks (6 sites) and unconsolidated sediments (9 sites).5, 18 Total Dissolved Solids or TDS (mg/L) Significant concentration differences were found with seven constituents: SC-field, SC-lab, TDS (Diagram 7), calcium, bicarbonate, chloride (Diagram 8) and oxygen-18 (Kruskal-Wallis test, p ≤ 0.05). Complete statistical results are in Table 10 and 95 percent confidence intervals for significantly different groups based on isotope recharge ages are in Table 11. 400 Diagram 7 – Sample sites collected from bedrock have significantly higher TDS concentrations than sample sites collected from sediment (KruskalWallis, p ≤ 0.05). Other groundwater basins in Arizona have also been characterized as having more mineralized groundwater in hardrock areas than the valley alluvium. Precipitation reactions could account for the decrease in TDS concentrations as water moves downgradient in the basin.20 300 200 100 0 Rock Sediment Geology 90 80 Diagram 8 – Sample sites collected from bedrock have significantly higher calcium concentrations than sample sites collected from sediment (Kruskal-Wallis, p ≤ 0.05). This pattern has occurred in other groundwater basins in Arizona. The spatial variation is probably due to calcium-dominated recharge occurring in upland areas. 20 Calcium (mg/L) 70 60 50 40 30 20 10 Rock Sediment Geology 35 Table 10. Variation in Groundwater Quality Constituent Concentrations between Two Geologic Groups Constituent Significance Significant Differences Between Geologic Types Temperature - field ns - pH – field ns - pH – lab ns - SC - field * Consolidated Rock > Unconsolidated Sediment SC - lab * Consolidated Rock > Unconsolidated Sediment TDS * Consolidated Rock > Unconsolidated Sediment Turbidity ns - Hardness ns - Calcium * Consolidated Rock > Unconsolidated Sediment Magnesium ns - Sodium ns - Potassium ns - Bicarbonate ** Consolidated Rock > Unconsolidated Sediment Chloride * Consolidated Rock > Unconsolidated Sediment Sulfate ns - Nitrate (as N) ns - Fluoride ns - Radon ns - Oxygen * Consolidated Rock > Unconsolidated Sediment Deuterium ns - ns = not significant * = significant at p ≤ 0.05 or 95% confidence level ** = significant at p ≤ 0.01 or 99% confidence level 36 Table 11. Summary Statistics for Two Geologic Groups with Significant Constituent Differences Significance Consolidated Rock Unconsolidated Sediments Temperature – field (oC) ns - - pH – field (su) ns - - pH – lab (su) ns - - SC – field (µS/cm) * 402 to 644 260 to 481 SC – lab (µS/cm) * 402 to 662 260 to 478 TDS * 258 to 384 162 to 291 Turbidity ns - - Hardness ns - - Calcium * 47 to 73 21 to 59 Magnesium ns - - Sodium ns - - Potassium ns - - Bicarbonate ** 238 to 315 123 to 245 Chloride * 3.7 to 20.2 4.2 to 7.9 Sulfate ns - - Nitrate (as N) ns - - Fluoride ns - - Radon ns - - Oxygen (0/00) * -9.57 to -7.19 -9.51 to -9.12 Deuterium (0/00) ns - - Constituent ns = not significant * = significant at p ≤ 0.05 or 95% confidence level ** = significant at p ≤ 0.01 or 99% confidence level All units mg/L except where indicated. 37 DISCUSSION Groundwater in Aravaipa Canyon basin appears to be suitable for irrigation, stock, and domestic uses based on the water quality sampling results of the ADEQ ambient study. Samples collected from 15 sites had no health-based standard exceedances and only four aesthetics-based standard exceedances. This determination is supported by the results of groundwater quality studies conducted by the agency in other southeastern Arizona basins. Groundwater quality in the Cienega Creek, Dripping Springs, Upper San Pedro, and Lower San Pedro basins also generally met water quality standards particularly in samples collected from unconfined aquifers.23 In addition, the Aravaipa Canyon basin is relatively pristine with minimal irrigation, domestic, and mining development to impact groundwater quality. In the Aravaipa Canyon basin, there is some tendency for constituent concentrations to be significantly higher in groundwater quality sites collected in bedrock areas and/or which consist of recharge from summer precipitation. These trends however, do not impact the acceptability of these sites for use as a drinking water source. Groundwater quality samples collected from three sites exceeded the 2.0 mg/L Secondary MCL for fluoride, though none had concentrations above the 4.0 mg/L Primary MCL. Fluoride concentrations in groundwater are often controlled by calcium through precipitation or dissolution of the mineral, fluorite. In a chemically closed hydrologic system, calcium is removed from solution by precipitation of calcium carbonate and the formation of smectite clays. Concentrations exceeding 5 mg/L of dissolved fluoride may occur in groundwater depleted in calcium if a source of fluoride ions is available for dissolution.20 The three sites however, are not depleted in calcium and appear to be controlled by processes other than fluorite dissolution. Hydroxyl ion exchange or sorption-desorption reactions have also been cited as providing controls on lower (< 5 mg/L) levels of fluoride. As pH values increase downgradient, greater levels of hydroxyl ions may affect an exchange of hydroxyl for fluoride ions thereby increasing the levels of fluoride in solution. 20 The pH levels of only one of the three sampled sites however, appears to follow this pattern so there may be yet other influences causing the elevated fluoride concentrations. The only other Secondary MCL exceedance was an elevated concentration of manganese in sample ARA-1. Groundwater in the Aravaipa Canyon basin would normally be expected to be oxidizing and have very low manganese concentrations. The sample site, ARA-1, however appears to be have a reducing environment as evidenced by not only the elevated manganese concentrations but also the only detections of iron and ammonia in the basin.20 Thus, the Secondary MCL for manganese appears to be site specific and not reflective of regional groundwater conditions. Some aspects of groundwater quality in the Aravaipa Canyon basin are however, still uncharacterized. Radionuclide samples were not collected at any of the sample sites and these constituents are often elevated by mining activity such as which created the Klondyke tailings piles. ADEQ’s WQARF program also did not collect radionuclide samples at any wells.2 Radionuclide constituents, such as gross alpha and uranium, are among the most common groundwater quality exceedances in Arizona. 22 Another uncharacterized aspect of groundwater quality in the Aravaipa Canyon basin is the confined, basin-fill aquifer. During sample collection, no effort appears to have been made to collect samples from wells known to be producing water from this aquifer. Although some sampled wells may be producing from the confined basin-fill aquifer, it is difficult to make this determination based on field notes and the lack of well logs.5 Samples from the confined, basinfill aquifer could potentially have groundwater quality issues as samples collected from wells producing water from confined aquifers in nearby basins often had water quality exceedances for fluoride, arsenic, and TDS. 23 REFERENCES 1 2 3 Arizona Department of Environmental Quality, 1991, Quality Assurance Project Plan: Arizona Department of Environmental Quality Standards Unit, 209 p. Arizona Department of Environmental Quality, 2009, Klondyke Tailings Water Quality Assurance Revolving Fund (WQARF) Site. ADEQ WQARF program, ADEQ Factsheet 09-16, 2 p. Arizona Department of Environmental Quality, 20112012, Arizona Laws Relating to Environmental Quality: St. Paul, Minnesota, West Group Publishing, §49-221-224, p 134-137. 38 4 Quality Issues: U.S. Geological Survey Water Supply Paper 2275, pp. 93-105. Arizona State Land Department, 1997, “Land Ownership - Arizona” GIS coverage: Arizona Land Resource Information Systems, downloaded, 4/7/07. 18 5 Arizona Department of Water Resources website, 2013, www.azwater.gov/azdwr/default.aspx, accessed 02/4/13. 6 Arizona Heritage Waters website, 2013, http://www.azheritagewaters.nau.edu/loc_aravaipa_cr eek.html, accessed 01/9/13. 7 Arizona Water Resources Research Center, 1995, Field Manual for Water-Quality Sampling: Tucson, University of Arizona College of Agriculture, 51 p. 8 Brown, S.L., Yu, W.K., and Munson, B.E., 1996, The impact of agricultural runoff on the pesticide contamination of a river system - A case study on the middle Gila River: Arizona Department of Environmental Quality Open File Report 96-1: Phoenix, Arizona, 50 p. 9 Richard, S.M., Reynolds, S.J., Spencer, J.E. and Pearthree, Pa, P.A., 2000, Geologic map of Arizona: Arizona Geological Survey Map 35, scale 1:1,000,000. 19 Roberts, Isaac, 2022, Personal communication from ADHS staff. 20 Robertson, F.N., 1991, Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California: U.S. Geological Survey Professional Paper 1406-C, 90 p. 21 Test America, 2012, Personal communication from Test America staff. 22 Towne, Douglas and Jones, Jason, 2011, Groundwater quality in Arizona: a 15 year overview of the ADEQ ambient groundwater monitoring program (19952009): Arizona Department of Environmental Quality Open File Report 11-04, 44 p. Craig, H., 1961, Isotopic variations in meteoric waters. Science, 133, pp. 1702-1703. 10 Crockett, J.K., 1995. Idaho statewide groundwater quality monitoring program–Summary of results, 1991 through 1993: Idaho Department of Water Resources, Water Information Bulletin No. 50, Part 2, p. 60. 23 Towne, D.C., 2012, Ambient groundwater quality of the Cienega Creek basin: a 2000-2001 baseline study: Arizona Department of Environmental Quality Open File Report 12-02, 46 p. 11 Earman, Sam, et al, 2003, An investigation of the properties of the San Bernardino groundwater basin, Arizona and Sonora, Mexico: Hydrology program, New Mexico Institute of Mining and Technology, 283 p. 24 Towne, D.C., 2012, Ambient groundwater quality of the Butler basin: a 2008-2012 baseline study: Arizona Department of Environmental Quality Open File Report 12-06, 44 p. 25 University of Arizona Environmental Isotope Laboratory, 2013, Personal communication with Christopher Eastoe. 26 U.S. Environmental Protection Agency website, www.epa.gov/waterscience/criteria/humanhealth/, accessed 3/05/10. 27 U.S. Salinity Laboratory, 1954, Diagnosis and improvement of saline and alkali soils: U.S. Department of Agriculture, Agricultural Research Service, Agriculture Handbook No. 60, 160 p. 28 Wilkinson, L., and Hill, M.A., 1996. Using Systat 6.0 for Windows, Systat: Evanston, Illinois, p. 71-275. 12 13 14 Gould, J.A. and Wilson, R.P., 1976, Maps showing ground-water conditions in the Aravaipa Valley area, Graham and Pinal counties, Arizona—1975: U.S. Geological Survey Water Resources Investigations 76107, 1 sheet, scale, 1:125,000. Graf, Charles, 1990, An overview of groundwater contamination in Arizona: Problems and principals: Arizona Department of Environmental Quality seminar, 21 p. Heath, R.C., 1989, Basic ground-water hydrology: U.S. Geological Survey Water-Supply Paper 2220, 84 p. 15 Helsel, D.R. and Hirsch, R.M., 1992, Statistical methods in water resources: New York, Elsevier, 529 p. 16 Hem, J.D., 1985, Study and interpretation of the chemical characteristics of natural water [Third edition]: U.S. Geological Survey Water-Supply Paper 2254, 264 p. 17 Madison, R.J., and Brunett, J.O., 1984, Overview of the occurrence of nitrate in ground water of the United States, in National Water Summary 1984-Water 39 Appendix A. Data for Sample Sites, Aravaipa Canyon Basin, 2003 Site # Cadastral / Pump Type Latitude Longitude ADWR # ADEQ # Site Name Samples Collected Well Depth Water Depth Geology 1st Field Trip, January 28-29, 2003 – Towne & Boettcher (Equipment Blank - ARA-5) ARA-1 D(6-17)24cbb submersible 32°53'45.346" 110°34'03.240" 619594 30461 HCN Well Inorganic, Radon O & H Isotopes - - Consolidated Rock ARA-2 D(6-19)28add submersible 32°52'59.000" 110°24'06.076" 619597 49052 HCN OfficeWell Inorganic, Radon O & H Isotopes 86’ 19’ Unconsolidated Sediments ARA -3 D(6-19) Aravaipa Creek - - - Aravaipa Creek O & H Isotopes - - - ARA -4 D(7-20)08cca submersible 32°50'10.720" 110°19'52.200" 577266 49095 Garwood Well Inorganic, Radon O & H Isotopes 120’ - Unconsolidated Sediments ARA -6/7 Split D(6-19)12cd submersible 32°55'12.772" 110°21'35.288" 608765 60558 Claridge Well Inorganic, Radon O & H Isotopes 120’ 90’ Unconsolidated Sediments ARA -8 D(7-17)09bcb submersible - 806141 61398 Newton IR Well Inorganic, Radon O & H Isotopes 65’ 18’ Consolidated Rock ARA -9 D(7-17)09bcb submersible - 806142 58652 Newton DM Well Inorganic, Radon O & H Isotopes 65’ 12’ Consolidated Rock 2nd Field Trip, May 5-6, 2003 –Boettcher & Lucci (Equipment Blank - Unnumbered) ARA-10 D(8-21)07abb submersible 32°45'25.648" 110°14'05.105" 624920 60983 Decker Well Inorganic, Radon O & H Isotopes 120’ 40’ Unconsolidated Sediments ARA-11/11D Duplicate D(7-19)26abb spring 32°47'26.274" 110°22'38.832" - 60985 Lackner Well Inorganic, Radon O & H Isotopes - - Unconsolidated Sediments ARA -12/12S Split D(8-19)01cad submersible 32°45'51.214" 110°21'15.319" 805043 60984 Holcomb Well Inorganic, Radon O & H Isotopes - 128’ Consolidated Rock ARA -13 D(9-22)19dcc submersible 32°37'53.438" 110°08'06.034" 627711 33998 ASLD Well #1 Inorganic, Radon O & H Isotopes 278’ 90’ Unconsolidated Sediments ARA -14 D(9-21)13acb submersible 32°39'17.319" 110°09'08.110" 627728 33993 ASLD Well #2 Inorganic, Radon O & H Isotopes 126’ 113’ Unconsolidated Sediments 3rd Field Trip, June 16-17, 2003 –Boettcher & Lucci ARA-15 D(8-22)20 submersible 32°43'48.150" 110°06'54.036" - 49136 Lindsey Well Inorganic, Radon O & H Isotopes - - Consolidated Rock ARA-16/16S Split D(8-20)1 submersible 32°46'19.479" 110°15'39.155" 624821 33220 Sollers Well Inorganic, Radon O & H Isotopes 85’ 50’ Unconsolidated Sediments ARA -17 D(9-20)10 spring 32°39'55.548" 110°17'08.446" - 33988 Deer Creek Spring Inorganic, Radon O & H Isotopes - - Consolidated Rock ARA -18/18D duplicate D(6-20)32 windmill 32°51'47.169" 110°19'47.862" 647920 49061 Dowdle Well Inorganic, Radon O & H Isotopes - - Unconsolidated Sediments 40 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003 Site # MCL Exceedances Temp (oC) pH-field (su) pH-lab (su) SC-field (µS/cm) SC-lab (µS/cm) TDS (mg/L) Hard (mg/L) Hard - cal (mg/L) Turb (ntu) ARA-1 Mn 21.3 7.95 7.9 562 600 350 210 210 1.2 ARA-2 F 16.8 8.08 7.8 386 410 260 90 87 0.15 ARA -4 - 20.5 7.47 7.6 533 360 220 210 210 4.4 ARA -6/7 - 17.2 7.36 7.75 593 635 375 270 290 5.85 ARA -8 - 19.3 7.71 7.5 465 440 270 190 200 0.24 ARA -9 - 19.0 7.63 7.6 464 490 300 180 180 0.56 ARA-10 - 17.4 7.65 7.6 231 250 180 85 91 0.68 ARA-11/11D - 21.2 7.27 7.65 455 485 310 190 195 0.25 ARA -12/12S - 27.0 7.06 7.55 571 600 375 245 250 0.24 ARA -13 - 20.6 7.86 8.0 339 360 230 83 86 0.34 ARA -14 - 25.1 8.01 8.1 349 370 210 140 150 0.13 ARA-15 F 31.3 7.48 7.8 705 700 390 220 240 0.17 ARA-16/16S - 26.4 7.7 7.45 323 325 175 110 130 0.29 ARA -17 - 22.4 8.18 7.8 372 360 240 130 140 0.08 ARA -18/18D F 21.6 7.47 6.55 126 125 81.5 35 39 1.3 italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 41 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003---Continued Site # Calcium (mg/L) Magnesium (mg/L) Sodium (mg/L) Potassium (mg/L) T. Alk (mg/L) Bicarbonate (mg/L) Carbonate (mg/L) Chloride (mg/L) Sulfate (mg/L) ARA-1 59 16 39 5.5 250 300 ND 13 42 ARA-2 30 2.8 54 1.4 160 195 ND 5.1 32 ARA -4 64 13 32 1.7 150 180 ND 6 16 ARA -6/7 89.5 13.5 17.5 2.05 255 280 ND 10.95 58 ARA -8 60 11 29 3.0 200 244 ND 9.3 34 ARA -9 56 11 28 2.8 210 260 ND 10 28 ARA-10 28 5.2 13 1.9 100 120 ND 3.7 14 ARA-11/11D 52.5 15.5 25 0.64 230 280 ND 6.75 12 ARA -12/12S 75 16.5 34 4.05 290 320 ND 8.15 19.5 ARA -13 22 7.5 46 2.9 160 200 ND 8.5 9.1 ARA -14 24 21 22 2.5 180 220 ND 4.9 4 ARA-15 70 16 64 1.4 250 305 ND 27 70 ARA-16/16S 35 6.6 16.5 2.3 140 155 ND 5.05 15 ARA -17 39 11 28 1.9 190 230 ND 4.3 3.8 ARA -18/18D 11 2.8 7.2 1.55 20.5 25 ND 3.5 21 italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 42 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003---Continued Site # Nitrate-N (mg/L) Nitrite-N (mg/L) TKN (mg/L) Ammonia (mg/L) T. Phos (mg/L) SAR (value) Irrigation Quality Aluminum (mg/L) ARA-1 ND ND 0.18 0.063 ND 1.2 C2-S1 ND ARA-2 0.58 ND ND ND ND 2.5 C2-S1 ND ARA -4 0.73 ND ND ND 0.048 1.0 C2-S1 ND ARA -6/7 0.062 ND ND ND ND 0.4 C2-S1 ND ARA -8 0.26 ND ND ND 0.046 0.9 C2-S1 ND ARA -9 0.24 ND 0.053 ND 0.021 0.9 C2-S1 ND ARA-10 1.4 ND 0.05 ND 0.15 0.6 C1-S1 ND ARA-11/11D 0.245 ND ND/ 0.078 ND ND 0.8 C2-S1 ND ARA -12/12S 1.6 ND ND ND 0.037 /ND 0.9 C2-S1 ND ARA -13 0.87 ND ND ND ND 2.2 C2-S1 ND ARA -14 0.79 ND ND ND ND 0.8 C2-S1 ND ARA-15 0.038 ND 0.2 ND ND 1.8 C2-S1 ND ARA-16/16S 0.62 ND ND ND 0.076 0.6 C2-S1 ND ARA -17 0.43 ND 0.089 ND 0.032 1.0 C2-S1 ND ARA -18/18D 0.895 ND 0.145 ND 0.037 0.5 C1-S1 ND italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 43 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003---Continued Site # Antimony (mg/L) Arsenic (mg/L) Barium (mg/L) Beryllium (mg/L) Boron (mg/L) Cadmium (mg/L) Chromium (mg/L) Copper (mg/L) Fluoride (mg/L) ARA-1 ND ND ND ND ND ND ND ND 0.75 ARA-2 ND ND ND ND ND ND ND ND 3.5 ARA -4 ND ND ND ND 0.12 ND ND ND 0.43 ARA -6/7 ND ND ND/0.024 ND ND ND ND ND 1.2 ARA -8 ND ND ND ND ND ND ND ND 0.86 ARA -9 ND ND ND ND ND ND ND ND 0.73 ARA-10 ND ND ND 0.0016 ND ND ND ND 0.21 ARA-11/11D ND ND 0.63 ND ND ND ND ND 0.245 ARA -12/12S ND ND ND/0.052 ND ND ND ND ND 0.465 ARA -13 ND ND ND ND ND ND ND ND 0.32 ARA -14 ND ND 0.16 ND ND ND ND ND 0.21 ARA-15 ND ND ND ND ND ND ND 0.011 3.0 ARA-16/16S ND ND ND ND ND ND ND ND 0.295 ARA -17 ND ND ND ND ND ND ND ND 0.29 ARA -18 ND ND ND ND ND ND ND 0.014 2.1 italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 44 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003---Continued Site # Iron (mg/L) Lead (mg/L) Manganese (mg/L) Mercury (mg/L) Nickel (mg/L) Selenium (mg/L) Silver (mg/L) Thallium (mg/L) Zinc (mg/L) ARA-1 0.19 ND 0.18 ND ND ND ND ND ND ARA-2 ND ND ND ND ND ND ND ND 0.083 ARA -4 ND ND ND ND ND ND ND ND ND ARA -6/7 ND ND ND ND ND ND ND ND 0.135 ARA -8 ND ND ND ND ND ND ND ND ND ARA -9 ND ND ND ND ND ND ND ND ND ARA-10 ND ND ND ND ND ND ND ND ND ARA-11/11D ND ND ND ND ND ND ND ND ND ARA -12/12S ND ND ND ND ND ND ND ND ND ARA -13 ND ND ND ND ND ND ND ND ND ARA -14 ND ND ND ND ND ND ND ND 0.069 ARA-15 ND ND ND ND ND ND ND ND 0.062 ARA-16/16S ND ND ND ND ND ND ND ND ND ARA -17 ND ND ND ND ND ND ND ND ND ARA -18 ND ND ND ND ND ND ND ND 0.68 italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 45 Appendix B. Groundwater Quality Data, Aravaipa Canyon Basin, 2003---Continued Radon-222 (pCi/L) ∗18 O (0/00) ∗D (0/00) Type of Chemistry Ion Balance % Difference Pass / Fail ARA-1 124 -9.5 -67 mixed-bicarbonate Low cation - 0.65 - Yes ARA-2 782 -9.2 -68 sodium-bicarbonate Low cation - 1.42 - Yes ARA-3 - -9.6 -68 - - ARA -4 214 -9.6 -68 calcium-bicarbonate Low anion - 22.97 - No ARA -6/7 188 -9.5 -67 calcium-bicarbonate Low anion - 0.76 - Yes ARA -8 306 -9.1 -66 calcium-bicarbonate Low anion - 1.97 - Yes ARA -9 338 -9.0 -65 calcium-bicarbonate Low cation - 1.91 - Yes ARA-10 123 -9.1 -64 calcium-bicarbonate Low cation – 0.71 - Yes ARA-11/11D 132 -8.9 -64 calcium-bicarbonate Low cation – 1.28 - Yes ARA -12/12S 264 -6.9 -54 calcium-bicarbonate Low anion - 0.44 - Yes ARA -13 327 -9.2 -64 sodium-bicarbonate Low anion - 0.03 - Yes ARA -14 117 -9.3 -65 mixed-bicarbonate Low anion - 0.67 - Yes ARA-15 <31 -7.0 -59 mixed-bicarbonate Low anion - 1.68 - Yes ARA-16/16S 400 -9.7 -68 calcium-bicarbonate Low anion - 1.32 - Yes ARA -17 570 -8.8 -65 mixed-bicarbonate Low anion - 1.23 - Yes ARA -18 693 -9.3 -66 mixed-mixed Low anion - 1.46 - Yes Site # LLD = Lower Limit of Detection italics = constituent exceeded holding time bold = constituent concentration exceeded Primary or Secondary Maximum Contaminant Level 46