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Groundwater Vulnerability Map of Ohio

Groundwater Vulnerability Map of Ohio

In 2022, the Groundwater Program updated and replaced its existing Groundwater Pollution Potential maps with a new statewide, seamless Groundwater Vulnerability map. The new map uses a highly modified DRASTIC model consisting of two major elements:

  1. The designation of mappable units, termed hydrogeologic settings.
  2. The superposition of a relative rating system to determine each area’s vulnerability to groundwater contamination.

Hydrogeologic settings form the basis of the system and incorporate seven major hydrogeologic factors affecting the movement and occurrence of groundwater:

  • Depth to Water
  • Net Recharge
  • Aquifer Media
  • Soil Media
  • Topography
  • Impact of the Vadose Zone Media
  • Hydraulic Conductivity of the Aquifer

These factors, which form the acronym DRASTIC, are incorporated into a relative ranking scheme that uses a combination of weights and ratings to produce a numerical value called the groundwater vulnerability index. Hydrogeologic settings are combined with the groundwater vulnerability indices to create units that can be graphically displayed on the map. A statewide digital coverage of this map is available for download and viewing via the Ohio Geology Interactive Map. County-based shapefiles are also available.

Two 1:500,000-scale wall maps were created—one for Groundwater Vulnerability Index and another for Hydrogeologic Setting—and are available for download here or through the Publications Catalog. Printed copies may be purchased from the  Geologic Records Center. These wall maps and the Guide to the Groundwater Vulnerability Map of Ohio (see Attachments section to right) include explanations of mapping methodology and descriptions of Ohio’s 40 hydrogeologic settings.

The old Pollution Potential maps are still available for download through the Publications Catalog using the search term “WGWPP”; however, Pollution Potential maps should be considered historical products that have been superseded by the new Groundwater Vulnerability map.

Statewide & County Shapefiles

To access the complete statewide and county GIS metadata and download the shape files, surf to the GIS Metadata Downloads web page here.

  1. In the By County dropdown, select either “STATEWIDE” or the county of interest.
  2. In the By Category dropdown, select “Hydrologic.”
  3. Click the “SELECT” button. 
  4. When the results appear, scroll down to find metadata entry and click the radial button. Then click the “VIEW RECORD” button. The metadata entry should appear on screen.  
  5. To download the shape file, scroll down the entry to find the link to the .zip file. 

Symbology/Layer Files

Maps & Other Downloads