Access ISWS’ detailed data on Illinois’ water wells and the groundwater sources that supply them.
Well Records
ISWS has maintained a collection of well documents and reports for over 100 years, amassing over 370,000 paper and electronic records.
Well Construction Reports
A large portion of our collection consists of well construction reports submitted by drillers via county health departments. Visit the Illinois State Geological Survey’s ILWATER map service to access transcriptions of many of these documents.
Domestic Wells Database
Users can view listings of private well records through our Domestic Wells Database. (The ISWS well records inventory database also describes other types of wells, including those used for irrigation, community supplies, parks, schools, and industrial and commercial facilities; however, these records are not available online at this time.) Please email the ISWS Well Records team for more information.
Historic Records
Looking for older wells? While we have some historical records, ISWS does not maintain a comprehensive archive of every well in Illinois. If you need documentation for a specific property, email the ISWS Well Records team with your property details to request a custom search.
Additional Water Well Resources
Responsible for managing a well? Explore our educational resources on well care.
Aquifers
Explore Illinois’ shallow and deep aquifer systems through our aquifer maps and datasets.
Illinois Groundwater Resources Map
This interactive map shows Illinois’ three major aquifer systems — sand and gravel, shallow bedrock, and Cambrian-Ordovician sandstone — along with the public water supply wells drawing from them, as of 2013. Featured data includes withdrawal amounts in gallons per year, as reported to the Illinois Water Inventory Program.
Access the interactive Illinois groundwater resources map or download aquifer data and maps from the Illinois State Geological Survey. You can also view and download an Illinois community water supply wells map showing wells active as of 2003. For questions, please email Daniel Hadley.
Sand and Gravel Aquifers’ Estimated Potential Yield Map
Originally published in ISWS Contract Report CR-2004-11, this map displays estimated potential yields from Illinois’ sand and gravel aquifers in gallons per day per square mile.
View and download the sand and gravel aquifers’ estimated potential yield map.
Northeastern Illinois Shallow Bedrock Aquifer Map
This online map depicts the shallow carbonate bedrock aquifer’s potentiometric surface, or the groundwater elevation (head) in feet above mean sea level. It is a composite of 1,461 water level measurements in wells taken between 1990 and 2006 as part of various ISWS studies, and an additional 231 surface water elevations along rivers and creeks that have a hydraulic connection to the shallow bedrock aquifer.
View the northeastern Illinois shallow bedrock aquifer map or download potentiometric surface data. For questions, please email Daniel Hadley.
Cambrian-Ordovician Sandstone Aquifer System Map
This interactive map contains the latest data and model results for Illinois’ Cambrian-Ordovician Aquifer System. This system includes three major aquifers — the St. Peter Sandstone, Ironton-Galesville Sandstone, and Mt. Simon Sandstone — and one minor aquifer, the New Richmond Sandstone, which is primarily used where the St. Peter Sandstone is absent. Data and model results will be updated as newer data becomes available and are subject to change. Results outside of Illinois have not been verified for accuracy.
View the Cambrian-Ordovician Sandstone Aquifer System map. For questions, please email Devin Mannix.
Well & Aquifer Tests
Our staff can conduct well production and aquifer tests on municipal and other large-supply wells for a fee. We typically partner with drilling contractors and consultants to run these tests and analyze the resulting data, helping well owners accurately estimate their long-term safe water yield.
For more information, email Daniel Hadley or call 217-300-0402.
Groundwater Monitoring
ISWS monitors groundwater levels across Illinois using more than 370 monitoring wells. These wells are classified by major geologic unit and distributed according to the locations of major aquifers.
We are actively measuring over 270 of these monitoring wells, either during periodic site visits or in real time using transducers and telemetry stations. Roughly 90 historic wells were measured for specific projects, but are now sealed.
Learn more about our groundwater monitoring networks or explore well network locations and data with our interactive Illinois Groundwater Monitoring Network map.
Groundwater Information Requests
We provide information and technical assistance to agencies and individuals regarding:
- groundwater resource availability and quality,
- water well design and potential yields, and
- hydraulic properties of regional aquifers.
ISWS maintains extensive files of well records, well and aquifer production tests, water quality analyses, and reports.
To request information or technical assistance, email Daniel Hadley or call 217-300-0402. Depending on your inquiry, we will respond by phone, letter, or written report.