The Hydrology division of the Arizona Department of Water Resources has published its research into water-supply conditions of a vast area of western Arizona known as the “Western Planning Areas.”

The Western Planning Area Hydrologic Monitoring Report summarizes water-level monitoring of the depth-to-groundwater within wells located throughout much of western Arizona as of December 2016.

Hydrologic Monitoring Reports are used to provide the public with important information on conditions both within and outside Arizona’s Active Management Areas, or AMAs.  To the extent possible, given the available information, these reports present surface water, groundwater, water-use, precipitation, recharge, and well information that has been compiled or developed by ADWR.

AMAs are the five regions of the State where the uses of finite groundwater resources are governed by the Groundwater Management Act of 1980.

The September 2020 report provides detailed analysis from five western Arizona groundwater basins: Butler Valley, Harquahala, McMullen Valley, Ranegras Plain, and Tiger Wash basins.

Among the findings: Water levels are generally declining across the five basins and larger declines are seen where there is a large farming presence.

Groundwater levels in the five basins were collected extensively in November through December 2004 and December 2016. Water levels collected during these two time periods – technically, water years 2005 and 2017 -- were then compared in order to observe water-level changes.

The report includes annual groundwater-level data collected at 92 index-well sites (wells that are measured by ADWR field-services personnel regularly), five automated sites (wells that electronically provide water-depth data on a daily basis), and groundwater levels collected at hundreds of non-index well sites during basin “sweeps.”

“Sweeps” are intensive data-collection efforts within the basins that are intended to give a comprehensive picture of the groundwater system.

The report includes data describing water-level elevation contours that are mapped and discussed to observe and interpret the direction of groundwater flow. In the report, researchers also discuss the lithology of the subsurface, as well as depth-to-bedrock.

Water use in each basin and crop-acreage data has also been compiled from information provided by the US Geological Survey for 2016. In conjunction with groundwater levels, water use helps us understand how pumping affects groundwater levels.

Precipitation and surface water data were also compiled for this report for the time period October 2016 - June 2017. The report also includes compilations of current water use data from USGS annual water-use reports, depth-to-bedrock data, and land subsidence/earth fissure monitoring data.

Arizona's hydrologic data collection activities are fundamental components of the state's Strategic Vision for Water Supply Sustainability.

New “Basin Sweep” report also released

In addition to the Hydrologic Monitoring Report of the state’s Western Planning Area, ADWR’s Hydrology division also has released a report detailing the “above average data collection” periods within groundwater basin and subbasins for a given year.

Above-average water level counts are commonly associated with basin sweeps.

The Department’s “Basin Sweeps and Bulk Data Collection Efforts By Subbasin and Calendar Year” report, released in September, can be found here.

In order to compile the tables within this report, ADWR Field Services staff reviewed over 40 years of ADWR-sourced groundwater level measurements within its Groundwater Sites Inventory database or GWSI.

To learn more about groundwater, click here to view Groundwater: Unlocking the Mystery of an Unseen Resource.