The Surface Water & Floodplain Information program at the Illinois State Water Survey offers a wide range of information services related to the management and study of the state's surface water resources. Public service activities include dissemination of general and technical information, and data collection.
Note: Charges for some data retrieval and analytical services do apply. Please see our Policy Statement and Itemization of Charges for additional details.
General Surface Water Information and Technical Services
Requests for information regarding surface water are directed to the information services staff. Professional and technical staff are available to answer questions from the general public, engineers, realtors, developers, and other government agencies; to provide information and data; or to perform engineering analyses. Staff use the Water Survey's collection of surface water data, reports, and maps to answer questions regarding Illinois water resources. Program staff may make referrals to other Water Survey offices or agencies as appropriate.
Data Collection and Reporting
Surface water conditions in Illinois are summarized by Surface Water & Floodplain Information in the monthly Illinois Water and Climate Summary newsletter available from the State Water Survey. Data collection activities include monitoring daily stage data from telemetered river and stream gaging stations. Month-end water surface elevations for more than 40 reservoirs are obtained through a network of cooperating reservoir operators in Illinois.
A complete set of National Wetlands Inventory (NWI) maps for Illinois are available for public review. NWI maps are annotated 7.5-minute USGS quadrangles (1:24,000) compiled by the U.S. Fish and Wildlife Service. When provided with a property description or location map of a specific location, staff will send a photocopy of the relevant portion of the NWI map, with legend.
The Floodplain Information Repository, established in 1978, maintains a complete library of Federal Emergency Management Agency (FEMA) documents: Flood Insurance Studies, Flood Insurance Rate Maps, Floodway Boundary and Floodway Maps, Flood Hazard Boundary Maps, and engineering data and supportive studies related to flooding. By providing information and technical assistance to individuals, professionals, and communities, the floodplain information service facilitates compliance with the provisions of the National Flood Insurance Program, thereby encouraging responsible floodplain management. Floodplain information services available include:
- Base Flood Elevations from published profiles for specific sites
- Estimated 100-year flood elevations for sites not previously studied, on the basis of best available information (some limitations may apply)
- Photocopies of portions of FEMA maps or Flood Insurance Studies
- Copies of Flood Insurance Study engineering model data archived after publication (as available).
The Repository's knowledgeable staff provide accurate, up-to-date information about floodplain management and regulations in Illinois and the National Flood Insurance Program. Staff participate in continuing education programs and maintain regular contact with agencies and organizations involved in floodplain management and regulation.
Note: Charges for some services do apply.
Flood Discharge Database. The State Water Survey maintains a database of streamflow flood discharges that includes:
- Discharges certified by the Illinois Department of Natural Resources, Office of Water Resources (IDNR OWR)
- Discharges published in all current FEMA Flood Insurance Studies (FISs) for Illinois
- Database fields include river basin, stream name, drainage area, location description, Township-Range-Section coordinates, and source document.
- Updates are made as new and revised FISs are published. The Illinois Department of Natural Resources, Office of Water Resources provides the Repository with copies of their discharge certifications, which are added to the database.
This database may be searched online. Please note, however, that it is presently being updated.
Floodplain Model Inventory. The State Water Survey maintains a collection of floodplain hydraulic models as part of its Floodplain Information public service program. An inventory list of the models in the collection is posted online for technical users, who may order copies. The primary source of the model data at ISWS is the Federal Emergency Management Agency (FEMA) archives for Flood Insurance Studies (FISs); however, please note that this database is not a list of the most current regulatory models nor all FIS models that exist.
This database may be searched online.
Other materials distributed
- 7-Day 10-Year (Q7,10) Low Flow Maps
Maps list stream low flows at various point sources and stream gage locations. Eleven (11) B&W maps cover all regions of Illinois. Each map covers one or more major basins. Data is 1984 edition for all regions, except Northeastern Illinois Region (1990). Call Floodplain Information to purchase or request a photocopy of single location, or obtain an electronic version of the map from the 7-Day 10-Year Low Flow Maps Web site.
For price and availability of all other State Water Survey publications, including bulletins and reports, contact Publications at (217) 333-8888. To search for a State Water Survey publication title or author, see SWS Publication Search.
Floodplain Information Staff
Associate Supportive Scientist
Contact for floodplain information.