Geology topics
J. P. Sottilare
Publications and source records attributed to J. P. Sottilare.
Progress report on the ground-water, surface-water, and quality-of-water monitoring program, Black Mesa area, northeastern Arizona— 1988-89
The Black Mesa monitoring program in Arizona is designed to determine long-term effects on the water resources of the area resulting from withdrawals of groundwater from the N aquifer by the strip-mining operation of Peabody Coal Company. Withdrawals by Peabody Coal Company increased from 95 acre-ft in 1968 to 4 ,090 acre-ft in 1988. The N aquifer is an important source of water in the 5,400-sq-mi Black Mesa area on the Navajo and Hopi Indian Reservations. Water levels in the confined area of the aquifer declined as much as 19.7 ft near Low Mountain from 1988 to 1989. Part of the decline in the measured municipal wells may be due to local pumping. During 1965-88, water levels in wells that tap the unconfined area of the aquifer have not declined significantly and have risen in many areas. Chemical analysis indicate no significant changes in the quality of water from wells that tap the N aquifer or from springs that discharge from several stratigraphic units, including the N aquifer, since pumping began at the mine. The groundwater flow model developed for the study area in 1988 was updated using pumpage data for 1985-88. The model simulated a steady decline in water levels in observations wells developed in areas of unconfined groundwater. Measured water levels in these wells did not show this trend but indicated that water levels remained the same or increased. The model accurately simulated water levels in most observation wells developed in areas of confined groundwater.
Progress report on the ground-water, surface-water, and quality-of-water monitoring program, Black Mesa area, northeastern Arizona, 1987
The N aquifer is an important source of water in the 5,400 sq-mi Black Mesa area on the Navajo and Hopi Indian Reservations. The Black Mesa monitoring program is designed to monitor long-term effects on the groundwater resources of the mesa as a result of withdrawals from the aquifer by the strip-mining operation of Peabody Coal Company. Withdrawals from the N aquifer by the mine increased from 95 acre-ft in 1968 to more than 4,480 acre-ft in 1986. Water levels in the confined area of the aquifer declined as much as 90 ft from 1965 to 1987 in some municipal and observation wells within about a 15-mi radius of the mine well field. Part of the drawdown in municipal wells is due to local pumpage. Water levels have not declined in wells tapping the unconfined area of the aquifer. Chemical analyses indicate no significant changes in the quality of water from wells that tap the N aquifer or from springs that discharge from several stratigraphic units, including the N aquifer, since pumping began at the mine. (USGS)