EPA Research Partner Support Story: Impacts of Enhanced Aquifer Recharge (EAR) on groundwater quality and quantity
Partner: City of Ada (OK), Chickasaw Nation, Oklahoma Water Resources Board, East Central University-Oka’ Institute, U.S. Geological Survey
Challenge: Enhancing limited local groundwater supplies
Resource: Investigating the impacts of Managed Aquifer Recharge (MAR) on groundwater quality/quantity
Project Period: 2020 – Present
In south central Oklahoma, the Arbuckle-Simpson Aquifer is a critical water source which is increasingly being stressed by growing water demands and shifting weather patterns. The aquifer, a store of groundwater within the underground rock layers, is the primary source of drinking water for tens of thousands of people, including the Chickasaw Nation. Additionally, the aquifer provides water for agriculture, mining and other industries. It is also the source of many springs, lakes and rivers—providing important recreational and tourism resources to the area. The aquifer is designated as a “sole-source aquifer,” a recognition that there are no reasonably available alternative drinking water sources. The aquifer relies solely on precipitation to recharge the groundwater supply, as no other water source enters the aquifer.
“Enhanced (or managed) aquifer recharge represents a process, once scientifically proven, that will provide a practical solution to rising demand for additional water resources, and potentially a definitive resource management approach to aquifer sustainability.” – Chickasaw Nation’s Natural Resources Office Director Kris Patton
The challenge of studying groundwater, however, is that it is not readily observable, like a stream or lake. Scientists from EPA ORD have been working with federal, Tribal, state and academic partners, including the City of Ada, Oklahoma and the Chickasaw Nation, whose headquarters are in Ada, to understand the impacts of human activities (like pumping water from the aquifer) on the aquifer’s water quality and quantity. EPA and its partners are also conducting research to understand the geological controls on groundwater flow, its underground “plumbing system.” Scientists have developed conceptual models of how rainfall percolates through the ground to recharge the aquifer. To check these models, they have installed monitoring wells, water autosamplers, soil water sensors, and weirs at a site within the aquifer to measure changes in water levels and water quality. Other EPA research includes electrical resistivity imaging to map the subsurface to “see” the apparent water movement through the subsurface, and changes with the use of enhanced aquifer recharge (EAR) approaches. EAR uses small dams and weirs to capture water from significant rainfall events, allowing it to infiltrate into the ground, rather than run off the surface.
The studies EPA scientists are conducting and the concepts and the techniques they are using at the Arbuckle-Simpson Aquifer can be applied in other aquifers facing similar resource management issues. This research will inform the City of Ada, EPA regions, states and other partners of the risks and potential impacts to groundwater quality from the use of EAR in rural settings to recharge aquifers. This research will allow water managers to establish initial best management practices and policies on the use and maintenance of EAR systems; and identify the types of characterization and monitoring necessary for the implementation and long-term monitoring and maintenance at MAR sites.