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Conceptual and Numerical Groundwater Flow Model of the Iowa River Alluvial Aquifer near Tama County, Iowa, 1980 through 2022

Scientific Investigations Report 2025-5086
Prepared in cooperation with the Sac & Fox Tribe of the Mississippi in Iowa
By:  and 
https://doi.org/10.3133/sir20255086

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Abstract

The Iowa River alluvial aquifer is an important source of water on the Meskwaki Settlement in Tama County, Iowa, which is land owned by the Sac & Fox Tribe of the Mississippi in Iowa (commonly known as the Meskwaki Nation). The U.S. Geological Survey constructed a groundwater flow model, including a conceptual and numerical model, of the Iowa River alluvial aquifer and underlying hydrogeologic units near the Meskwaki Settlement in Tama County, Iowa, for the period of January 1980–August 2022 to estimate the fraction of water pumped from the Iowa River alluvial aquifer by Meskwaki Settlement wells that is derived from streamflow depletion in the Iowa River and its tributaries. Streamflow depletion is a reduction in streamflow caused by groundwater pumping and includes the interception by groundwater production wells of water that otherwise would have been discharged to streams (called “captured groundwater discharge”) and induced infiltration of streamflow to the production wells. Calibrated model runs were performed with no simulated pumping and simulated pumping only at Meskwaki Settlement wells, and the change in simulated flow rates between the groundwater system and streams for the two model runs represents the amount of streamflow depletion in the Iowa River and tributary streams resulting from pumping at the Meskwaki Settlement wells. Streamflow depletion in the Iowa River and its tributaries as a percentage of simulated pumping at the Meskwaki Settlement wells was calculated by dividing this difference by the total simulated pumping rate for the Meskwaki Settlement wells. The model results demonstrate that the mean monthly streamflow depletion, including induced infiltration and captured discharge, in the Iowa River and its tributary streams as a percentage of mean monthly pumping at the Meskwaki Settlement wells was 97.4 percent and ranged from 65.4 to 112 percent. Of the total streamflow depletion, mean monthly induced recharge was 20.9 percent and ranged from 4.9 to 37.2 percent. Mean monthly captured discharge was 76.5 percent and ranged from 57.1 to 97.1 percent. These results indicate that most of the water pumped from the Meskwaki Settlement wells is the result of streamflow depletion, in the form of both induced infiltration and captured discharge.

Suggested Citation

Goldstein, K.M.F., and Davis, K.W., 2025, Conceptual and numerical groundwater flow model of the Iowa River alluvial aquifer near Tama County, Iowa, 1980 through 2022: U.S. Geological Survey Scientific Investigations Report 2025–5086, 55 p., https://doi.org/10.3133/sir20255086.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Conceptual Model of Groundwater Flow
  • Numerical Model of Groundwater Flow
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Conceptual and numerical groundwater flow model of the Iowa River alluvial aquifer near Tama County, Iowa, 1980 through 2022
Series title Scientific Investigations Report
Series number 2025-5086
DOI 10.3133/sir20255086
Publication Date December 08, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Nevada Water Science Center, Central Midwest Water Science Center
Description Report: viii, 55 p.; Data Release; Dataset
Country United States
State Iowa
County Tama County
Other Geospatial Iowa River alluvial aquifer
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Additional publication details