Shallow Aquifer Conditions In The Greater Barrington Region: Assessing Groundwater Elevations And Municipal Water Use (2014-2024)

Iordache, Vlad; Hadley, Daniel R.

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https://hdl.handle.net/2142/128860 Copy

Description

Title

Shallow Aquifer Conditions In The Greater Barrington Region: Assessing Groundwater Elevations And Municipal Water Use (2014-2024)

Author(s)

• Iordache, Vlad
• Hadley, Daniel R.

Issue Date

2025-06-24

Keyword(s)

• Groundwater
• Shallow aquifer
• Bedrock aquifer
• Private wells
• Sustainability
• Water management
• Monitoring
• Municipal water
• Seasonal Mann-Kendall
• Standardized Precipitation Index
• Illinois Water Inventory Program
• Potentiometric surfaces
• Fox River
• Deer Park
• Climate Change
• Water use
• Water quality

Date of Ingest

2025-06-17T12:40:24-05:00

Geographic Coverage

Illinois

Abstract

Groundwater in the Greater Barrington area is sourced from shallow “sand and gravel” (Henry Formation) and “bedrock” (Silurian dolomite) aquifers. Because the area has a high reliance on private wells tapping these sources, their sustainable management is critical. The Barrington Area Council of Governments (BACOG) maintains a comprehensive monitoring network to track groundwater levels. This report updates a previous analysis (2014–2019) by incorporating data through 2024 to assess recent changes in groundwater levels and municipal water use. Methods include analyzing municipal withdrawal data from the Illinois Water Inventory Program (IWIP), analyzing hydrographs from United States Geological Survey (USGS) monitoring wells, performing Seasonal Mann-Kendall (SMK) tests for statistical trends, calculating the Standardized Precipitation Index (SPI) for precipitation context, and developing annual potentiometric surfaces using geographic information system (GIS) interpolation tools. Groundwater levels in the study area from 2020–2024 showed stabilization or decline, shifting from the generally increasing trends observed up to 2019. While the overall configuration of the potentiometric surface remained consistent — with a groundwater high west of the Fox River and lower levels east of the Fox River, where the aquifer system is confined — SMK analysis revealed statistically significant decreasing trends over the last five years at the South Barrington (approx. -1.25 to -1.5 ft/yr) and Deer Park (approx. -0.5 to -0.75 ft/yr) USGS wells. This recent shift towards stabilization or decline coincided with moderately to severely dry conditions indicated by SPI analysis, suggesting climate variability is a significant factor influencing recent groundwater levels. This hypothesis is supported by the fact that regional municipal withdrawals from shallow aquifers continued along the generally declining trend observed since 2010. Potentiometric change maps reveal complex patterns influenced by climate and measurement protocols. Specifically, within the BACOG boundary, groundwater levels declined, on average, by approximately 3 feet over the 2019-2024 period due to contrasting wet and dry end-year conditions. Over a seven-year static comparison (2017-2024), groundwater levels increased, on average, by 0.8 feet. The ten-year comparison yielded a mean apparent increase approaching 4 feet. However, this value is significantly biased by the comparison of initial pumping levels to later static levels at municipal wells, therefore limiting definitive conclusions about the true decadal trend. The findings highlight the shallow aquifer system's sensitivity to climatic fluctuations. Continued comprehensive monitoring is crucial to differentiate climate-driven changes from potentially unsustainable water demand trends. Recommendations include continuing to maintain BACOG’s planned consistent static water level measurements, prioritizing water quality investigations, further analysis of localized declining trends, enhancing data coverage, and considering the development of a numerical groundwater flow model to better understand system dynamics and future outcomes under varying conditions.

Publisher

Illinois State Water Survey

Series/Report Name or Number

ISWS Contract Report 2025-02

Type of Resource

text

Genre of Resource

report

Language

eng

Sponsor(s)/Grant Number(s)

The Barrington Area Council of Governments (BACOG)

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