John P Hoffmann
John Hoffmann is the Director of the Pacific Islands Water Science Center in Honolulu, Hawaiʻi.
John Hoffmann joined the USGS in 1984 as a geologist at the Hawaiian Volcano Observatory to help monitor Kīlauea Volcano on Hawaiʻi Island. Following graduate school in Honolulu, John joined the Pacific Islands Water Science Center in 1988, where he worked on groundwater issues in Hawaiʻi and Micronesia. By 1995, John transferred to the USGS Arizona Water Science Center where he served many roles, including six years as Center Director. From 2013 to 2020 John held several positions with the USGS Water Mission Area in Reston, Virginia. His interests are in groundwater availability, groundwater/surface-water interaction, and the application of geophysical methods for hydrological studies. John earned a Bachelor’s degree in Geology from Michigan Technological University and a Master’s degree in Geology and Geophysics from the University of Hawaiʻi at Mānoa.
Science and Products
Estimated infiltration, percolation, and recharge rates at the Rillito Creek focused recharge investigation site, Pima County, Arizona
Ground-water recharge in the arid and semiarid southwestern United States
Hydrogeology of the upper and middle Verde River watersheds, central Arizona
Simulated water-level responses, ground-water fluxes, and storage changes for recharge scenarios along Rillito Creek, Tucson, Arizona
Geologic, hydrologic, and chemical data from the C aquifer near Leupp, Arizona
Numerical ground-water change model of the C aquifer and effects of ground-water withdrawals on stream depletion in selected reaches of Clear Creek, Chevelon Creek, and the Little Colorado River, northeastern Arizona
Heat as a tool for studying the movement of ground water near streams
Characteristics of shallow deposits beneath Rillito Creek, Pima County, Arizona
Quality of water and estimates of water inflow, northern boundary area, Fort McDowell Indian Reservation, Maricopa County, Arizona
Hydrogeology, water quality, and stormwater-sediment chemistry of the Grande Wash area, Fort McDowell Indian Reservation, Maricopa County, Arizona
Geology, Ground-Water Occurrence, and Estimated Well Yields from the Mariana Limestone, Kagman Area, Saipan, Commonwealth of the Northern Mariana Islands
Geochemical analyses of ground-water ages, recharge rates, and hydraulic conductivity of the N aquifer, Black Mesa area, Arizona
Science and Products
- Publications
Estimated infiltration, percolation, and recharge rates at the Rillito Creek focused recharge investigation site, Pima County, Arizona
A large fraction of ground water stored in the alluvial aquifers in the Southwest is recharged by water that percolates through ephemeral stream-channel deposits. The amount of water currently recharging many of these aquifers is insufficient to meet current and future demands. Improving the understanding of streambed infiltration and the subsequent redistribution of water within the unsaturated zAuthorsJohn P. Hoffmann, Kyle W. Blasch, Don R. Pool, Matthew A. Bailey, James B. CallegaryGround-water recharge in the arid and semiarid southwestern United States
Ground-water recharge in the arid and semiarid southwestern United States results from the complex interplay of climate, geology, and vegetation across widely ranging spatial and temporal scales. Present-day recharge tends to be narrowly focused in time and space. Widespread water-table declines accompanied agricultural development during the twentieth century, demonstrating that sustainable grounHydrogeology of the upper and middle Verde River watersheds, central Arizona
The upper and middle Verde River watersheds in central Arizona are primarily in Yavapai County, which in 1999 was determined to be the fastest growing rural county in the United States; by 2050 the population is projected to more than double its current size (132,000 in 2000). This study combines climatic, surface-water, ground-water, water-chemistry, and geologic data to describe the hydrogeologiAuthorsKyle W. Blasch, John P. Hoffmann, Leslie F. Graser, Jeannie R. Bryson, Alan L. FlintSimulated water-level responses, ground-water fluxes, and storage changes for recharge scenarios along Rillito Creek, Tucson, Arizona
A local ground-water flow model is used to simulate four recharge scenarios along Rillito Creek in northern Tucson to evaluate mitigating effects on ground-water deficits and water-level declines in Tucson's Central Well Field. The local model, which derives boundary conditions from a basin-scale model, spans the 12-mile reach of Rillito Creek and extends 9 miles south into the Central Well Field.AuthorsJohn P. Hoffmann, Stanley A. LeakeGeologic, hydrologic, and chemical data from the C aquifer near Leupp, Arizona
No abstract available.AuthorsJ.P. Hoffmann, D. J. Bills, J. V. Phillips, K. J. HalfordNumerical ground-water change model of the C aquifer and effects of ground-water withdrawals on stream depletion in selected reaches of Clear Creek, Chevelon Creek, and the Little Colorado River, northeastern Arizona
No abstract available.AuthorsS. A. Leake, J.P. Hoffmann, Jesse E. DickinsonHeat as a tool for studying the movement of ground water near streams
Stream temperature has long been recognized as an important water quality parameter. Temperature plays a key role in the health of a stream’s aquatic life, both in the water column and in the benthic habitat of streambed sediments. Many fish are sensitive to temperature. For example, anadromous salmon require specific temperature ranges to successfully develop, migrate, and spawn [see Halupka andCharacteristics of shallow deposits beneath Rillito Creek, Pima County, Arizona
Characteristics of the stream-channel and basin-fill deposits beneath a 12-mile reach of Rillito Creek, Pima County, Arizona, were obtained to describe the geohydrologic system. The findings presented here are part of a larger project to improve the understanding of recharge processes beneath ephemeral streams. The stream-channel deposits, which range in thickness from 15 to 40 feet, generally arAuthorsJohn P. Hoffmann, Marcella A. Ripich, Kevin M. EllettQuality of water and estimates of water inflow, northern boundary area, Fort McDowell Indian Reservation, Maricopa County, Arizona
Increased agricultural and recreational activities and recent growth of population centers within the Verde River basin have led to concerns about the quality and quantity of water flowing onto the Fort McDowell Indian Reservation. The purpose of this study was to determine the quality and quantity of water in the Verde River and in the shallow stream-channel deposits in the vicinity of the northeAuthorsJohn P. Hoffmann, Christie M. O'DayHydrogeology, water quality, and stormwater-sediment chemistry of the Grande Wash area, Fort McDowell Indian Reservation, Maricopa County, Arizona
Grande Wash is a tributary of the Verde River and drains an area of 13 square miles within the McDowell Mountains and the Town of Fountain Hills in Central Arizona. The wash enters the Fort McDowell Indian Reservation at the eastern boundary of Fountain Hills and is incised in coarse-grained alluvium that is contiguous with the alluvial aquifer along the Verde River. The aquifer is used by the ForAuthorsJohn P. HoffmannGeology, Ground-Water Occurrence, and Estimated Well Yields from the Mariana Limestone, Kagman Area, Saipan, Commonwealth of the Northern Mariana Islands
A study of the geology, ground-water occurrence, and estimated well yields from the Mariana Limestone was done to investigate ground-water availability in the Kagman area, Saipan. The Mariana and Tagpochau Limestone formations form the major aquifer in the Kagman drainage basin. The Mariana Limestone, which is the major water-bearing unit in the Kagman area, ranges in thickness from 300 to 500 feeAuthorsJohn P. Hoffmann, Rob Carruth, William MeyerGeochemical analyses of ground-water ages, recharge rates, and hydraulic conductivity of the N aquifer, Black Mesa area, Arizona
The Navajo Nation and Hopi Tribe of the Black Mesa area, Arizona, depend on ground water from the N aquifer to meet most tribal and industrial needs. Increasing use of this aquifer is creating concerns about possible adverse effects of increased ground-water withdrawals on the water resources of the region. A thorough understanding of the N aquifer is necessary to assess the aquifer's response toAuthorsThomas J. Lopes, John P. Hoffmann