Out in the field: ADWR hydrologists conducting “basin sweep” in vast northwest region
For the next several months, ADWR’s Field Services team will be out “sweeping” for groundwater-level data in an enormous area of northwestern Arizona.
Starting March 11, the team began collecting water-level measurements in the Virgin River, Grand Wash, Shivwits Plateau, Kanab Plateau, Paria, and Coconino Plateau groundwater basins.
This survey of wells – or basin “sweep,” as it is known – was last conducted by the USGS in 1976 for the Grand Wash, Shivwits Plateau, Kanab Plateau, Paria Basins.
ADWR last conducted a sweep in the Virgin River Basin in 1991 and Coconino Plateau Basin in 2004.
Geographically speaking, this northwestern Arizona basin sweep covers an area generally from the Virgin River and Virgin River Mountains, including the Grand Canyon – Parashant National Monument, north and south rims of the Grand Canyon National Park, extending east to Paria Canyon and southeast to the Colorado River region west of Page, and, finally, south to the San Fransisco Mountains just northwest of Flagstaff, including Williams.
The “Arizona Strip” area of the sweep has been identified as a critical area that has not had a basin sweep conducted recently.
A basin sweep is an intensive effort to measure as many wells as necessary in a specific basin or subbasin in order to provide a comprehensive picture of the groundwater system. ADWR’s objective on this mission is to measure water levels at hundreds of wells in these groundwater basins.
The data collected will be analyzed and used to obtain a comprehensive overview of the groundwater conditions and used to support scientific and water management planning efforts. Data collected will be used for several purposes, including:
• Analysis of water-level trends
• Groundwater modeling
• Water-level change maps
• Hydrologic reports
• Water resource planning and management
The department’s Field Services staff, part of the Hydrology Division, is responsible for collecting the data. This includes measuring water levels in wells, collecting water quality samples, measuring discharge from pumping wells, and conducting well inventories. Staff from the Field Services Basic Data Unit, as it is formally known, conducts basin sweeps to measure water levels for all accessible wells within a specific basin or sub-basin.
Basin sweeps are conducted throughout the state on a rotational basis with priority given to Active Management Areas (AMAs), Irrigation Non-Expansion Areas (INAs), and other basins based on ADWR data-collection needs.
The department uses the information from the basin survey to develop water level maps to support scientific, planning and management studies of the basin’s aquifer system. Data collected also support hydrologic studies such as groundwater modeling and water budget development.