In collaboration with the U.S. Geological Survey (USGS), McHenry County maintains a network of 37 groundwater monitoring wells that are distributed across the county. These wells monitor water levels in near "real time", taking water level measurements every fifteen minutes and transmitting the data to the USGS satellites.

The USGS collects the data and makes it publicly available (see links below).  The monitoring wells have been collecting data since 2009 and have been able to capture two periods of extreme drought (2012 and 2020-2022) and a period of record rainfall (2017-2020).  This data improves our understanding of how our groundwater aquifers react and recover from climatic events. 

The monitoring wells have also been used for two water quality studies (in 2010 and 2020) that helps track potential changes in water quality over time.  The results of the 2020 study were recently published by the USGS (see link to report below).

USGS Groundwater levels in McHenry County

The link above leads to a U.S. Geological Survey (USGS) webpage where you can look up water level data from McHenry County's Groundwater Monitoring Well Network. 

After opening the website, a map of McHenry County showing the locations of each of the 37 wells that are part of the county's Groundwater Monitoring Network.  locations will appear. The colored dots are single wells and the gray circles are locations with multiple wells that extend down to different aquifer depths (i.e. Shallow, Intermediate, or Deep).  Click once on the gray circle to show the individual wells. 

Each well is color coded to show if water levels are below normal, normal, or above normal relative to long-term averages.  Generally speaking, green represents normal water levels, red represents low water levels, and blue represents high water levels.

Click on an individual well to pull up a graph that shows water levels since the wells were installed in 2009.  The vertical axis on the left of the graph shows the depth of water below land surface, and the horizontal axis at the bottom shows the years.  

USGS 2020 Water Quality Report

Every ten years the USGS conducts water quality analysis on groundwater from wells in McHenry County, including the 37 wells in the monitoring well network.  Samples are collected from each of the wells and tested for a wide range of pollutants.  In 2020 additional samples were collected from 12 wells and analyzed for pharmaceuticals and wastewater indicator compounds commonly referred to as "contaminates of emerging concern" (CEC's).  These studies enable us to track changes in water quality over time and take corrective action if needed.  The first study was conducted in 2010 and the second study was in 2020.  The findings of the the 2020 study were published in a report by the USGS (link above).

Please visit our Water Forum webpage to view videos of past events, download copies of presentations, and learn about the guest speakers.

Water Forum Webpage

The McHenry County Water Forum is an annual event hosted by the McHenry County Department of Planning and Development that provides a festive atmosphere where residents, businesses and elected officials can learn what makes the regions water supplies special and how water resources can be protected into the future. 

This free, catered program is held every Fall at the McHenry County College Auditorium and features fascinating presentations by scientists, planners, and engineers who specialize in water resources. 

The WRAP is a comprehensive look at the county's water resources that was updated in 2020 following the latest scientific information and has been adopted by the McHenry County Board.  It serves as a Guide to help empower communities to protect water by providing detailed information about water resources in McHenry County, identifies the threats to those resources, and recommends best management practices to address the threats.

The 2020 WRAP is available online (link above) and consists of 18 chapters broken into 4 separate sections that focus on different aspects of McHenry County's water. Each Section features bookmarks that let users go directly to the subjects of most interest to them.

WRAP Update

McHenry County 3D Map Viewer
https://maps.isgs.illinois.edu/vxs4/mchenry/

This interactive map enables you to see Cross-Section views (side views) of the subsurface geology across McHenry County.  You can also create your own maps anywhere in the county by simply drawing a line over your area of interest, then the 3D viewer will generate a Cross-Section view of the geology below that line.

Directions:

Upon opening the website, a map of McHenry County with a colored overlay will appear. This overlay map includes black lines (transect lines) that run from West to East and North to South.  When you click on any of these transect lines, a pop-up menu with a “Cross Section Name” will appear.  Click on the underlined Name to view the cross-section of the geology under that transect line.

The cross-section map uses different colors to represent the various geologic layers.  The lighter colors (yellow, gold, brown) are areas of permeable sand and gravel that can serve as groundwater aquifers, or areas that help recharge groundwater aquifers by allowing rainfall to infiltrate through soil.  The darker colors (blue, green) are areas of less permeable silts or clays that restrict the flow of water. The thick pink layer at the bottom is the limestone/dolomite bedrock.  

You can also create your own cross-section maps of any area in McHenry County.  To create a new cross-section map, first turn off the colored overlay by clicking on “Layer” widget near the top right corner of the screen. 

Next click on the “eye” icon to turn the colored layer off. 

The colored layer will disappear, and a map of McHenry County will then be visible.

To create a new geologic map, first zoom in on your area of interest in the county.  You will then trace a transect line across the area you are interested in. Follow these steps:

1. Click on the “Draw a Polyline” widget (zig zag shape) at the top right corner of the map.

    

2. Move your cursor to the start of the area of interest and click once to place marker.

    

3. Drag your cursor across the area of interest to create your transect line.

    

4. Once finished, double click to place the end marker.  A cross-section view will then be generated for the transect area.

Zoom in to your area of interest (note that you have to select the Pan/hand icon to be able to click and drag the map).  Once zoomed in you will see blue dots with numbers next to them.  The blue dots represent wells and the numbers indicate the well depth. Click on a blue dot to open a window with basic well information, then click on the blue numbers at the top of the window to open the actual “well log”. The “well log” typically includes detailed information including descriptions of geologic material encountered during drilling and water levels and the type of aquifer (e.g. sand/gravel, limestone, sandstone).

Illinois Water and Related Wells Interactive Map

Our use of chloride-based road salt and other de-icing chemicals to manage roads, parking lots, and sidewalks in winter is polluting water resources.  While we need to manage snow and ice to maintain safety, current practices regularly apply excessive amounts of these chloride-based products.  Since there are no viable alternatives to these products, the best option is to eliminate the application of any excess material, using only what is really necessary to maintain safety, and implement practices that use deicing chemicals efficiently.  This is often referred to as Sensible Salting, Salt Smart Practices, Smart Salting, or other similar titles.  This presentation provides an overview of the problems associated with pollution from de-icing chemicals and the Sensible Salting practices that can be used to maintain safety while minimizing impacts to the environment and infrastructure.