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Groundwater Age Estimates for the Mississippi River Valley Alluvial Aquifer Based on Tracer Data Collected During 2018–20

Scientific Investigations Report 2024-5127
Water Availability and Use Science Program
By: , , , , , and 
https://doi.org/10.3133/sir20245127

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Abstract

This study characterized groundwater age across the Mississippi River Valley alluvial aquifer (MRVA). Groundwater samples from 69 MRVA wells and 19 wells in Tertiary units of the Mississippi embayment aquifer system (MEAS) were analyzed for sulfur hexafluoride (SF6), tritium (3H), helium (He), and (or) carbon-14 of dissolved inorganic carbon (14C). The age distributions of 89 samples were estimated by fitting lumped parameter models to processed tracer concentrations with the U.S. Geological Survey software TracerLPM. Mean ages of MRVA groundwater samples ranged from 12 to 22,000 years, with a median of 140 years. Mean ages of MEAS groundwater samples ranged from 230 to 52,000 or more years, with a median of 13,500 years. The spatial distribution of MRVA groundwater ages was found to be influenced by depth, inflow of groundwater from deeper units, and soil saturated hydraulic conductivity. In parts of the MRVA, the spatial distribution of MRVA groundwater ages was found to be influenced by annual recharge and (or) annual groundwater pumpage.

Suggested Citation

Gratzer, M.C., Solder, J.E., Knierim, K.J., Kingsbury, J.A., O’Reilly, A.M., and Davidson, G.R., 2025, Groundwater age estimates for the Mississippi River Valley alluvial aquifer based on tracer data collected during 2018–20: U.S. Geological Survey Scientific Investigations Report 2024–5127, 34 p., https://doi.org/10.3133/sir20245127.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Hydrogeology
  • Methods
  • Results
  • Discussion
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater age estimates for the Mississippi River Valley alluvial aquifer based on tracer data collected during 2018–20
Series title Scientific Investigations Report
Series number 2024-5127
DOI 10.3133/sir20245127
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description Report: viii, 34 p.; Data Release
Country United States
State Alabama, Arkansas, Illinois, Kentucky, Louisiana, MIssissippi, Missouri, Tennessee
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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