Groundwater Monitoring

The BACOG area is almost entirely reliant on the shallow aquifer system for all its water needs, and there is growing concern about the sustainability of this resource.  Water consumption due to growth and development has increased around and within the BACOG area and will continue.  For the BACOG area, there is currently no alternate water supply. Even if another source of water were to become available, there is very little piped infrastructure to distribute such a supply.  The cost to build distribution systems throughout over 80 square miles would be prohibitive.

Most areas have individual residential private wells or subdivision wells. Over 7,800 shallow aquifer system wells provide supply for a population of approximately 35,000.  A significant drop in water levels could pose a financial impact as well owners might need to drill deeper or relocate wells.

A significant drop in water levels could also mean changes to the thousands of acres of natural areas in the BACOG area if groundwater discharge were no longer adequate to sustain waterways and natural areas such as woods and wetlands.  If the natural areas that define the BACOG area and quality of life were to deteriorate, property values could be negatively affected.

State studies predict there will be a downward trend in water levels in the coming decades, so monitoring those conditions has become more critical.  BACOG initiated its “Groundwater Monitoring Program” in November 2013.  The program established a baseline of water levels and will assess changes and trends over time.  Water level data can provide an indication of “what we need to do” in upcoming years to protect the shallow aquifer system that is virtually the sole water supply for the region.


Continuous Water Level Monitoring

Click here for REAL-TIME data from BACOG’s three wells in Deer Park, Lake Barrington and South Barrington.

Click here for REAL-TIME data from wells in Illinois


Groundwater Monitoring Reports

Illinois State Water Survey (ISWS) report on the analysis of groundwater level changes, surface water conditions, and water use in the greater Barrington region, 2014-2019

Groundwater levels presentation by Dan Hadley, June 2020

BACOG’s July 2016 interim report on our shallow aquifer water levels monitoring program

BACOG’s January 2015 baseline report on surface and groundwater levels


Science & Methodology

The methodology for the science portion of the BACOG groundwater resources initiative defined the processing and classification of well log descriptions into simplified units of bedrock, aquifer, aquitard, and aquiclude. These procedures are described in detail in the reports and articles under the “Resources” tab.

Well Classification

The science portion has been heavily advised by Dr. Kurt O. Thomsen,Ph.D., P.G., a professional hydrogeologist with many years of experience in hydrological and environmental consulting. His work with BACOG’s groundwater has been invaluable to this project. The science and methodology have also been reviewed and advised by various other academic and State and U.S. governmental sources.

A Rapid Method for Analyzing Well Log Records in Preparation for Water Resource Mapping


GIS: Mapping and Visualization

GIS, or a Geographic Information System, is used to create the layer maps for the 3 dimensional stratigraphic model as well as other important maps that define the shallow aquifer system.

Aquifer Diagram

BACOG has used GIS in many ways and it has been an integral part of analyzing the groundwater resources and communicating that information to officials and community members. Creating the model has allowed BACOG to apply and query information from this data for applications at local and regional scales.

Online video shows the representative model produced using GIS software.

Depth to Bedrock

In the BACOG area, the shallow aquifer system is composed of unconsolidated glacial soil materials and the shallow dolomite bedrock. The unconsolidated soils, including gravel, sand, clay and other sediments, contain underground pockets of water that supply water to the vast majority of BACOG-area wells. Bedrock is a unit of consolidated rock that lies beneath the glacial soils. Bedrock is also considered aquifer because it contains fractures, cracks, and void spaces that contain and transmit water. Though less common, a number of wells in the area are drilled into the upper portion of this bedrock unit.

Depth to bedrock is the distance from the ground surface to the top of the shallow bedrock unit.

BACOG Groundwater Recharge Areas

Recharge characteristics were mapped in the BACOG area from the research undertaken in the water resource initiative. Recharge is the process by which rain, snow melt and stormwater move downward from the surface to groundwater aquifers. Recharge is the primary method through which water enters an aquifer.

BACOG analyzed the soil materials from ground surface down to the first aquifer encountered to establish hydro-conductivity, that is, the relative time of travel of water through the soils. Hydro-conductivity was used to classify area recharge characteristics as highly sensitive, sensitive, moderately sensitive, poor, or very poor.

In the highly sensitive areas, the travel times of water are measured in days. In sensitive areas, recharge times range from days to several years. Poor to very poor recharge areas exhibit travel times from 40+ years to hundreds of years or more.

Click Here for Legend Recharge Descriptions

Identification of Groundwater Recharge Areas Using Readily Available Data


Planning, Analysis & Education

Planning, analysis, and public education are critical components to BACOG’s groundwater programs. BACOG has used the groundwater research findings in practical environmental planning applications with its member governments and local conservation organizations and will continue to provide support for regional and local issues with regard to groundwater and planning.

BACOG has a Water Resources Committee comprised of appointed government and community representatives and technical advisors that provides input to program initiatives and policy development.  The BACOG Executive Director and Water Resources Committee continue to work on translating the groundwater science into local policies, ordinances, and best practice guidelines for groundwater and recharge area protection.