Introduction

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide (fig. 1). The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift (Thorn and others, 1993). The basin is approximately bisected by the southward-flowing Rio Grande, the only perennial stream extending through the length of it. The study area, which includes the Albuquerque Basin and adjacent areas, extends from just upstream from Cochiti Lake south to San Acacia and from near Tijeras Canyon west to near the intersection of Interstate 40 and the Bernalillo-Cibola County line.

In 2000, the population of the Albuquerque Basin was about 690,000 (Bartolino and Cole, 2002). According to 2010 U.S. Census Bureau data, the 2010 population was about 840,000 (U.S. Census Bureau, 2019; calculated as the sum of population for census tract centers within the basin). The basin population increased about 20 percent from 1990 to 2000 (Thorn and others, 1993; Bartolino and Cole, 2002) and about 22 percent from 2000 to 2010 (U.S. Census Bureau, 2019). The majority of the population is concentrated within the city limits of Albuquerque, which had a population of 448,607 in 2000 and 545,852 in 2010 (U.S. Census Bureau, 2012). Prior to 2008, drinking water in the Albuquerque Basin was primarily sourced from groundwater, resulting in an increase in groundwater withdrawals as population increased (Albuquerque Bernalillo County Water Utility Authority [ABCWUA], 2016). Since 2008, groundwater sourced for drinking water has been supplemented with surface water by the San Juan-Chama Drinking Water Project, along with water reuse and reclamation projects (ABCWUA, 2016). The San Juan-Chama Drinking Water Project is a diversion project that imports surface water from the headwaters of the San Juan River in the Colorado River Basin to the Rio Grande Basin (ABCWUA, 2016).

An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this groundwater monitoring network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. Since the initial installation, additional wells and piezometers¹ have been added to the network; as of the 2021 water year,² there are 54 locations with 120 measuring points (tables 1, 2, and 3). Of the wells and piezometers, 60 are equipped with continuously recording data loggers (table 2); 55 are measured discretely semiannually, quarterly, or every 2–3 months with a steel or electric tape (table 1); and 5 are measured using both types of measurements (table 3). Discrete measurements are also collected at sites equipped with data loggers but are not shown in this report with the exception of those from sites 42–45, which have more than 10 years of discrete measurements prior to the installation of continuously recording data loggers, and those from site 229 (table 3). Discrete measurements collected at sites equipped with data loggers are generally used for calibration and correction of inaccuracies in water levels resulting from drift, hysteresis, temperature effects, and offsets (Cunningham and Schalk, 2011).

The USGS, in cooperation with the ABCWUA, the New Mexico Office of the State Engineer (NMOSE), and Bernalillo County, measures water levels in the wells and piezometers in the groundwater monitoring network (tables 1, 2, and 3); this report, prepared in cooperation with the ABCWUA, presents water-level data collected by USGS personnel at the sites through water year 2021 (October 1, 2020, through September 30, 2021). The locations of the active monitoring wells in the Albuquerque Basin and adjacent areas are shown in figure 1, and the locations of those within the Albuquerque metropolitan area are shown in figure 2. The data presented in this report are available in the USGS National Water Information System (USGS, 2022).

Well-Numbering System

The system of numbering wells and piezometers in New Mexico is based on the common subdivision of public lands into sections (fig. 3). Each well number, in addition to designating the well, locates the position to the nearest 10-acre tract in the Public Land Survey System. This number (referred to as “local identifier” in tables 1, 2, and 3) is divided into four segments. The first segment denotes the township (“T.”) north or south of the New Mexico base line, the second denotes the range (“R.”) east or west of the New Mexico principal meridian, and the third denotes the section. The fourth segment of the well number, which consists of three digits, denotes the 160-, 40-, and 10-acre tracts in which the well is located. Each section is divided into quarters, which are numbered 1, 2, 3, and 4 for the northwest, northeast, southwest, and southeast quarters, respectively. The first digit of the fourth segment gives the quarter section, which is a tract of 160 acres. Each quarter section is then subdivided into four 40-acre tracts numbered in the same manner, and the second digit denotes the 40-acre tract. Finally, each 40-acre tract is further subdivided into four 10-acre tracts, and the third digit denotes the 10-acre tract. The fourth segment of the well number can further denote subdivisions of the 10-acre tract by including more than three digits; each additional digit further subdivides the tract by quarters in the same manner as shown in figure 3. Letters A, B, C, and so on are added to the end of the last segment of the well number to designate the second, third, fourth, and succeeding wells in the same tract. For example, well 09N.03E.07.131A is the first subsequent well in the northwest quarter (NW 1/4) of the southwest quarter (SW 1/4) of the northwest quarter (NW 1/4) of section 7, T. 09 N., R. 03 E. (Bureau of Land Management, 2009).

Methods

Water-level measurements were collected from the groundwater monitoring network during the 2021 water year by following standard USGS protocols for discrete and continuous water-level measurements using steel or electric tapes and continuously recording data loggers (Cunningham and Schalk, 2011). Discrete measurements are collected at 55 of the sites (table 1); of these, 49 sites (2, 4, 9, 10, 12–20, 24–30, 32–41, 46–51, 53–55, 68, 70–73, 76, 81, 83, 87, and 237) are monitored semiannually, 2 sites (230 and 231) are monitored quarterly, and 4 sites (218 and 222–224) are monitored every 2–3 months. At 60 of the sites (64, 165–184, 189–194, 196–203, 205–217, 219–221, 225–228, and 232–236; table 2), pressure transducers and data loggers are used to collect continuous (hourly) water-level data. At 5 of the sites, (42–45 and 229; table 3), discrete and continuous data are both collected, with discrete data being collected at a frequency of every 2–3 months.

Water-Level Data

The continuous and discrete water-level data collected from the groundwater monitoring network in the Albuquerque Basin and adjacent areas during the 2021 water year are published online through the National Water Information System (USGS, 2022). Descriptive data for the groundwater monitoring network are listed in tables 1, 2, and 3 and include site number, number of the figure on which the well location is shown, USGS site number, local identifier, other identifier (if applicable), latitude and longitude, well depth, and screened interval. In figure 4, hydrographs presenting discrete and (or) continuous water-level data collected by the USGS at these sites include water level in feet below land surface and water level in feet above the North American Vertical Datum of 1988 (NAVD 88). Data in hydrographs from wells that have continuous (hourly) recorders are shown by solid lines that represent daily mean water levels. Data gaps that are evident in some of the continuous hydrographs may be caused by equipment malfunction or removal of spurious data during the review and approval process. In hydrographs that present data from discretely measured wells, dashed lines connect symbols (“+”) that represent the discrete measurements. In hydrographs showing discretely measured piezometers that are nested (more than one trace per graph), the symbols were removed to make the hydrographs easier to read.

There are two hydrographs presenting data for sites 42–45 and for site 229 (table 3), one showing continuous water-level data and one showing discrete water-level measurements (fig. 4). The period of record for discrete measurements is much longer than that of continuous data in some locations, such as sites 42–45, which have more than 10 years of discrete measurements prior to the installation of continuously recording data loggers. For those wells, both hydrographs have been included to ensure that all data are presented. Continuous data were collected for part of the 2021 water year at site 229 before the transducer was removed on February 11, 2021, after which continuous data collection was halted and discrete data collection continued.

Continuous data were collected for part of the 2019 water year at site 218 before the transducer was removed on July 16, 2019, after which continuous data collection was halted and discrete data collection continued at a frequency of every 2–3 months.

The transducers and data loggers were removed from sites 222–224 in 2014, but discrete measurements continue to be collected at those sites since that time.