32 Hydrogeology

Added due to amount of discipline abstracts submitted.

Tuesday, 10 March 2026
1:30 PM - 5:30 PM
RCC, 106

Groundwater Nutrient Concentrations in the Principal Aquifers of Tennessee

Paper number: 32-1
Program: Technical Sessions
Time: 1:45 PM – 2:00 PM

Authors

  • Kristi Hill Presenting Author
    Lower Mississippi Gulf - Water Science Center, Nashville, Tennessee
  • Laura Ruhl-Whittle
    Lower Mississippi Gulf - Water Science Center, Fayetteville, Arkansas
  • Amy Hourigan
    Lower Mississippi Gulf - Water Science Center, Nashville, Tennessee
  • Spencer Smith
    Lower Mississippi Gulf - Water Science Center, Memphis, Tennessee
  • Brian Ham
    Division of Water Resources, Nashville, Tennessee

Abstract

The U.S. Geological Survey, in collaboration with the Tennessee Department of Environment and Conservation (TDEC), is developing a groundwater quality network across the principal aquifers of Tennessee. The network will characterize groundwater quality in major aquifers used for supply and assess their suitability for potential future demands. To date, 68 sites in western and middle Tennessee have been sampled for major and trace inorganics, nutrients, and volatile organic compounds; as well as pesticides, radionuclides, and fecal indicator bacteria at a subset of sites. Nutrient data collected between 2023 and 2025, along with approximately 350 previously sampled wells (1989–2022), were evaluated considering general land use, well depth, geology, and redox conditions, with variability observed between principal aquifers across Tennessee. In western Tennessee, which includes the Mississippi River Valley alluvial, Mississippi embayment, and Southeastern Coastal Plain aquifer systems, total nitrogen levels ranged from undetectable (<0.05 mg/L) to 25.9 mg/L and orthophosphate levels ranged from undetectable (<0.02 mg/L) to 0.52 mg/L. In middle Tennessee, which includes aquifers in Ordovician, Silurian-Devonian, Mississippian, and Pennsylvanian ages units, total nitrogen levels ranged from undetectable (<0.05 mg/L) to 8.6 mg/L and orthophosphate levels ranged from undetectable (<0.02 mg/L) to 0.63 mg/L. In eastern Tennessee, which includes aquifers in structurally altered Precambrian to Mississippian aged units, total nitrogen levels ranged from undetectable (<0.05 mg/L) to 11.0 mg/L and orthophosphate levels ranged from undetectable (<0.02 mg/L) to 0.08 mg/L. Seven sites exceeded the U.S. EPA maximum contaminant level (MCL) for nitrate (10 mg/L), all of which were shallow wells (≤100 feet deep) near agricultural activity with relatively high dissolved oxygen, with saturations >50%. These data enhance understanding of nutrient occurrence in groundwater and how concentrations vary along regional flow paths in Tennessee, supporting water-resource managers in planning and protecting the state’s groundwater resources.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411677

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