Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2018–2019

First posted October 17, 2022 For additional information, contact: Director,Arizona Water Science CenterU.S. Geological Survey520 N. Park AvenueTucson, AZ 85719 The Navajo (N) aquifer is an extensive and the primary source of groundwater in 5,400-square-mile Black Mesa area northeastern Arizona. availability important issue because arid climate, past industrial water use, continued requirements for municipal use by a growing population. Precipitation typically ranges from less than 6 to more 16 inches per year depending on location.The U.S. Survey water-monitoring program began 1971 provides information about long-term effects withdrawals N uses. This report presents results data collected as part monitoring calendar 2019, additionally uses streamflow statistics November December 2018. includes measurements (1) (pumping), (2) levels, (3) spring discharge, (4) surface-water (5) chemistry.In total were estimated be 3,070 acre-feet (acre-ft), 670 acre-ft, 2,400 acre-ft. Total during 2019 58 percent 2005 Peabody Western Coal Company’s discontinued transport coal slurry pipeline after cessation mining operations 2019.Water levels measured wells completed unconfined areas within showed decline 10 when compared with prestress period (prior 1965). changes across all ranged +8.2 feet (ft) −40.0 ft, median change was −1.7 ft. also 18 confined period. −38.8 ranging +12.9 ft −185.0 ft.Spring flow at four springs 2019. Flow fluctuated record Burro Spring Pasture Canyon Spring, but decreasing trend statistically significant (p<0.05) Moenkopi School Unnamed near Dennehotso. Discharge has remained relatively constant since it first 1980s discharge record.Continuous records streamflow-gaging stations following sites: Wash 09401260 (1976 2019), Dinnebito Sand Springs 09401110 (1993 Polacca Second 09400568 (1994 09401265 (2004 2019). Median winter flows (November through February) each used estimate amount above-named sites. record, have generally Springs, whereas indicated Wash.In samples three analyzed selected chemical constituents. Results previous analyses same springs. Concentrations dissolved solids, chloride, sulfate increased 30 years that site. not varied significantly (p>0.05) early 1980s, there no increasing or those data. Dennehotso statistical solids chloride data; however, concentrations now show towards lower concentrations. No tests performed sampled historical water-quality available comparison.