2023 Status of the High Plains Aquifer in Kansas

Introduction

The High Plains aquifer (HPA), which includes the Ogallala aquifer, is the primary source of water for western Kansas and economically is the most important groundwater resource in the state. This aquifer and the river-reservoir systems located principally in eastern Kansas are identified as the two most critical water resource components of the state’s Long-Term Vision for the Future of Water Supply in Kansas (Kansas Water Office, 2015). Two of the keys to implementing the long-term vision are clearly defining the resource conditions and issues, and reviewing and evaluating progress toward achieving the vision’s goals. The Kansas Water Office updated the Kansas Water Plan in 2022 (Kansas Water Office, 2022). The first of the plan’s guiding principles is “Conserve and extend the High Plains aquifer.” In December 2022, the Kansas Water Authority (KWA) voted to place statements in its 2023 Annual Report to the Governor and Legislature (Kansas Water Authority, 2023) concerning the “critical depletion of the Ogallala aquifer.” The first of these is “The policy of planned depletion of the Ogallala aquifer is no longer in the best interest of the State of Kansas.” The statements also indicate that a “collaborative process is needed to establish data-driven goals, metrics, and actions to halt the” aquifer decline and that the process should engage state agencies, committees, stakeholders, and the KWA. This Kansas Geological Survey (KGS) publication addresses key elements of the long-term vision goals, updated water plan, and annual report to the governor by providing an assessment of the recent and current resource conditions of the HPA that can be used to evaluate progress toward sustaining or prolonging the life of the aquifer. 

The KGS published a previous report on the status of the HPA in 2018 that was based on groundwater use data for 1996–2016 and groundwater-level data to winter 2017 (Whittemore et al., 2018). This report is an update of the aquifer status that evaluates water-use data to 2022 and water levels to winter 2023. 

The HPA in Kansas covers most of the western third and much of the south-central portion of the state (fig. 1). The area in the western third of the state is known as the Ogallala part of the aquifer; three groundwater management districts (GMDs) operate in this area: Western Kansas GMD1, Southwest Kansas GMD3, and Northwest Kansas GMD4. In the south-central, or Quaternary region, Big Bend GMD5 and Equus Beds GMD2 encompass the Great Bend Prairie and Equus Beds portions of the aquifer, respectively. Although the Ogallala and Quaternary region aquifers are both composed of sand and gravel interbedded with silt and clay, differences in climatic conditions, overlying soil types, and depth to water translate into large differences in the prospects for sustainability. The range in average annual rainfall over the Ogallala region is 17–23 inches compared to 23–35 inches over the Quaternary region.

The availability of high-quality water-level and water-use data for the HPA in Kansas during the last two and a half decades makes it possible to provide a sound assessment of the aquifer status. The KGS and the Division of Water Resources in the Kansas Department of Agriculture (KDA-DWR) each winter measure groundwater levels in approximately 1,400 wells (primarily irrigation wells) (fig. 2). The KGS has been leading the water-level program since 1996. Kansas has more than 35,600 wells with active water rights; most of these (27,613) overlie the HPA, and 24,179 (approximately 88%) of them are used for irrigation (as of September 10, 2023) (fig. 3). Not all of the wells overlying the HPA produce only from the HPA. Based on an analysis of KDA-DWR information for the wells, 88% of the wells are estimated to yield water from the HPA and 8% from both the HPA and underlying bedrock units such as the Dakota aquifer; the rest produce from the bedrock units.

Each water right is required to report water use yearly. In 2022, 99.6% of the wells in the GMDs that reported some amount of water usage did so using totalizing flow meters. Both water-level and water-use data are reviewed for quality to ensure accurate data.