The Ohio Department of Natural Resources (ODNR) Division of Geological Survey has released new groundwater maps that will serve as important tools for land-use planning and development. The maps offer a highly detailed assessment of Ohio’s aquifers and how vulnerable they are to pollution. 

“The new groundwater vulnerability maps were three years in the making,” Division Chief and State Geologist Mark Jones said. “These are the culmination of a decades-long effort to create a statewide, seamless map of Ohio’s hydrogeology.”

Thanks to modern advances in data gathering and mapping technology, the Division of Geological Survey was able to develop maps with greater detail that evaluate the groundwater resources across county lines and throughout the state.

“Past authors used varied mapping methods and scales for assessing the groundwater vulnerability of an area,” lead hydrogeologist on the mapping project Craig Nelson said. “For this project, we came to a consensus on our methods and criteria of Ohio’s groundwater vulnerability.”

The new maps replace older pollution potential maps created by ODNR, collaborating consultants, and universities between 1987 and 2016.  Thanks to funding from the Ohio Water Development Authority, the new mapping began in January 2019 and was completed in January 2022, with the new products made available to the public on March 31.

The Groundwater Vulnerability Index Map of Ohio depicts an area’s vulnerability to groundwater contamination based upon its hydrogeologic, topographic and soil characteristics. It does not consider the presence of contaminant sources nor specific kinds of pollutants. The map is based only on the geology of the area in question and how it plays a role in that area’s vulnerability to contamination.

The Hydrogeologic Settings of Ohio map depicts the hydrogeology of the state’s aquifer systems. Forty hydrogeologic settings have been identified and distinguished based on their geologic nature, such as type of bedrock in an area and whether and how an area was glaciated. In contrast to previous groundwater maps, the new map provides a very systematic breakdown of Ohio’s hydrogeologic settings.

When combined, the new maps provide important tools to better inform land-use planners and government agencies conducting site assessments for new development. The maps also are useful to Ohioans who seek a greater understanding of groundwater resources and aquifers in their area.

The groundwater vulnerability maps, GIS data, shapefiles and additional information are available at https://ohiodnr.gov/discover-and-learn/safety-conservation/about-odnr/geologic-survey/groundwater-resources/groundwater-vulnerability-map. High-resolution versions of the maps are available for purchase as print-on-demand products for $15 each (plus tax and shipping). Please contact the Geological Records Center at 614-265-6576 or geo.survey@dnr.ohio.gov to order.