Hydrogeologic framework and characterization of the Truxton Aquifer on the Hualapai Reservation, Mohave County, Arizona

Abstract

to and guiding our initial trips to study areas on the reservation. The Hualapai Game and Fish Department manager Scott Crozier made sure that access permits were available for our work. A special thanks is extended to Ruth Thayer (Bureau of Reclamation), who facilitated a number of meetings with the Department of Interior Federal Indian Water Rights Negotiation Team that negotiated the objectives of this study. George Billingsley, U.S. Geological Survey (USGS) emeritus geologist, provided valuable insight into the geology of the southern Hualapai Reservation and the Truxton basin. The authors also thank the field crews from the USGS Arizona Water Science Center for their hard work during winter conditions in helping to collect the geophysical data for this study; specifically, Joel Unema, Jon Mason, Cory Sannes, Curt Crouch, and Lucien Bucci.

Gravity surveys and depth to bedrock in the Truxton basin, northwestern Arizona

“…The gravity data show a clear southwest-northeast gravity low consistent with a previously hypothesized paleochannel (Young, 1999;Bills and Macy, 2016). Subparallel to this trend, to the southeast, is a steep gravity gradient indicative of the Hurricane Fault.…”

“…The southwest-northeast trending gravity low is consistent with a hypothesized paleochannel incised into the Proterozoic basement rocks (Young, 1999;Bills and Macy, 2016). To the southwest, this gravity low extends into the gravity low associated with the Hualapai Valley.…”

Major hydrostratigraphic contacts of the Truxton basin and Hualapai Plateau, northwestern Arizona, developed from airborne electromagnetic data

“…The survey encompassed an area of 3,070 square kilometers (km 2 ) and included most of the area hydrogeologically upgradient of the Colorado River along the southern side of the reach described above. The region receives relatively low precipitation (<50 centimeters per year [cm/yr]) and high evapotranspiration (>160 cm/yr), and there is slightly greater rainfall at higher elevations and greater evapotranspiration potential at lower elevations (Bills and Macy, 2016). Regional aquifers are primarily recharged by precipitation at higher elevations in the western and southern parts of the survey area, and groundwater is conceptualized to generally flow northeast following the regional geologic dip.…”

“…In the northeastern part of the Truxton basin, well logs indicate that basin-fill sediments overlie the lower Paleozoic sequence of Muav Limestone, Bright Angel Shale, and Tapeats Sandstone . In the rest of the basin, the primary aquifer consists of Paleocene and younger alluvial and lacustrine sediments that are overlying Proterozoic crystalline basement and interbedded with volcanic flows (Billingsley and others, 2006;Bills and Macy, 2016).…”

Groundwater availability in the Truxton basin, northwestern Arizona

“…Three reports document the findings from these comprehensive groundwater studies conducted from 2015 through 2018. The first report published in 2016 described the hydrologic framework and characterization of the Truxton aquifer on the Hualapai Indian Reservation (Bills and Macy, 2016). The second report described the hydrogeologic characterization of the Hualapai Plateau part of the reservation (Mason, Macy, and others, 2020).…”