Stormwater Planning Data Inventory

Stormwater Planning Data Inventory

Local and regional analysis of flooding issues relies upon regularly-updated geospatial information about a variety of indicators – including land cover/use characteristics, topography, and soils. The Stormwater Planning Data Inventory, a list of useful datasets, is shown below. Some of these datasets are used in the Guide to Flood Susceptibility and Stormwater Planning. Each record includes the most recently available vintage and provides a link to download or request the data. For additional information on available datasets, contact Kate Evasic ( or 312-386-8782).

Source Data Download / Request Vintage Description
CMAP ArcHydro modeling outputs 2017 Includes hydrologically-corrected DEM, flow direction, flow accumulation, drainage lines, catchments, and depressions.  See data packages for additional information.


Elevation differential between property and nearest Base Flood Elevation (BFE)            

2017 Identifies properties within a 1,500-foot buffer whose mean parcel elevation is within six feet of the nearest BFE. 
CMAP Impervious cover summarized by watershed catchment 2017 Summarizes percent imperviousness from the 2011 National Land Cover Database by watershed catchments contained in the 2012 National Hydrography Dataset “Plus.” 
CMAP Land Use Inventory 2013 Comprehensive parcel-based Land Use Inventory, containing 59 different use classes for over 2.5 million parcels.

Regional Flood Susceptibility Index

2017 Urban and riverine flooding susceptibility indexes (FSI) to identify priority areas across the region for flooding mitigation activities. Raw FSI values available upon request. 
CMAP Topographic Wetness Index (TWI) 2017 Identifies flat areas with high flow accumulation where water is likely to pond using flow accumulation, slope, and various other geometric functions. CMAP's TWI is a simplified version of an Illinois State Water Survey effort for a portion of the region. 
Counties Streams and waterbodies, Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will Various Hydrographic lines and polygons created and/or hosted by County GIS departments.
Counties; Municipalities Building footprints, Chicago, DuPage, Lake, Will Various Overhead extent of building footprint as extracted or digitized from aerial photos.  Footprints are known to exist for those areas with download/request links.  For other areas, contact counties or municipalites to determine availability.
EPA National Hydrography Dataset "Plus" 2012 Hydrologic data framework which incorporates the National Hydrography Dataset, the National Elevation Dataset, and the National Watershed Boundary Dataset.  Includes HUC12 boundaries.
FEMA National Flood Hazard Layer (NFHL) Various Database that includes location/extent of FEMA 100 and 500 year floodplains, including Base Flood Elevation lines.
ISGS; Counties Light Detection and Ranging (LiDAR) Digital Elevation Model (DEM) data Various High-resolution LiDAR-derived elevation grids.
MWRD 100-year Inundation Maps Various Modeling results from MWRD detailed watershed plans that delineate areas where flooding is expected to occur during a 100-year rainfall event.
MWRD Combined Sewer Area Boundary Various Regulatory limits of unseparated sewer system, which conveys both wastewater and stormwater in the same pipes.  Contact munipalities for availability outside of MWRD's jurisdiction.
NOAA NOAA Atlas 14 2013 Precipitation frequency estimates for selected durations and frequencies with 90% confidence intervals and supplementary information on temporal distribution of heavy precipitation, analysis of seasonality and trends in annual maximum series data, etc.
USGS Historic Topographic Maps 1889-1949 Historic maps, including the location of streams and water bodies, created via field surveys or aerophotogrammetry.
USGS Age of First Development 2012 Summarizes USGS National Water-Quality Assessment (NAWQA) Wall-to-Wall Anthropogenic Land Use Trends (NWALT) 1974-2012 land cover datasets into six categories: Prior to 1974; 1975 to 1982; 1983 to 1992; 1993 to 2002; 2003 to 2012; and Undeveloped/post-2012.
USGS National Land Cover Database 2011 Medium-resolution land cover grid, including percent imperviousness and percent tree canopy.