Reports & Publications

The ODNR Groundwater Program joined the Division of Geological Survey in 2017, but the group has been mapping the state's groundwater resources since 1949. During this time, the group has published a variety of publications and maps to aid in the protection and use of Ohio's groundwater resources, including:

• Groundwater vulnerability map
• Groundwater resource maps
• Pollution potential maps
• Statewide aquifer maps
• Potentiometric surface maps
• Technical bulletins and reports
• Monthly Water Inventory Report
• Fact sheets
• Hydrologic Atlas for Ohio

Use our Publications Catalog to locate and download reports, fact sheets, and other publications related to Ohio's groundwater resources. For assistance or to order printed publications, contact the Geologic Records Center.

Monthly Water Inventory Report

The Monthly Water Inventory Report for Ohio is a compilation of current precipitation data, stream flow data, reservoir levels, groundwater levels, and Lake Erie levels. Click here to access the most recent and past editions of the Monthly Water Inventory Report.  

Groundwater Maps

Read more below to learn about the various groundwater maps available.

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 viewing  and download via the Ohio Geology Interactive Map. County-based shapefiles are also available here.

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 (pdf) include explanations of mapping methodology and descriptions of Ohio’s 40 hydrogeologic settings.

Groundwater Resources Maps

Created between 1978 and 1996, these maps are intended to aid in the development of reliable groundwater supplies throughout Ohio.

Groundwater resources maps show the expected yield to a drilled well at any location in a county. All maps use a consistent color coding system to represent well yields. For example, properly constructed wells drilled in areas colored blue on any map can be expected to yield 100 to 500 gallons per minute. Areas colored yellow would yield 25 to 100 gallons per minute. In all, there are six colors used to identify well yield categories.

Use our Publications Catalog to locate and download groundwater resources maps. Use the search term "WGWR."

Pollution Potential Maps

Pollution Potential Maps have been superseded by the Groundwater Vulnerability Map of Ohio (see above).

In 1987, the Groundwater Program began mapping the groundwater pollution potential, or groundwater vulnerability, within the aquifers of Ohio. This mapping program uses the DRASTIC mapping process. The system consists of two major elements:

1. The designation of mappable units, termed hydrogeologic settings.
2. The superposition of a relative rating system to determine the pollution potential.

Hydrogeologic settings form the basis of the system and incorporate the major hydrogeologic factors that affect and control groundwater movement and occurrence. These seven factors are:

• 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 pollution potential index. Hydrogeologic settings are combined with the pollution potential indices to create units that can be graphically displayed on a map. A report accompanies each map and includes general geologic and hydrogeologic information and describes the mapping process used to determine the groundwater pollution potential.

Use the status map below to identify what DRASTIC maps are available for each Ohio county. Use our Publications Catalog to locate and download groundwater resources maps. Use the search term "WGWPP."

Potentiometric Surface Maps

In 2006, the Groundwater Program started mapping the potentiometric surface of the unconsolidated (sand-and-gravel) and consolidated (bedrock) aquifers in the state. These maps show the contour of the water surface in the different aquifers. From the contours, the direction of groundwater flow can be determined. The potentiometric surface maps do not indicate where water table conditions may exist.

Use the status map below to identify what maps are available for each Ohio county. Use our Publications Catalog to locate and download groundwater resources maps. Use the search term "WGWPS."

Statewide Aquifer Maps

Completed in 2001, the Statewide Aquifer Mapping Program (SAMP) mapped the extent of 31 bedrock aquifers and all of the unconsolidated or glacial aquifers within Ohio. Aquifer delineations were completed at a scale of 1:24,000, using standard USGS 7.5-minute quadrangles as a base. The primary product is a series of GIS coverages that delineate aquifer boundaries and thicknesses, quantify yields, and standardize naming for all of the significant bedrock (consolidated) and glacial (unconsolidated) aquifers in Ohio. The 32 individual shape files (coverages) that comprise the SAMP data have been grouped into eight downloadable sets by geologic system including supporting documents. Some sets may contain only one coverage.

Bedrock (Consolidated) Aquifers
Bedrock aquifers were mapped as separate coverages and overlap each other in some areas of the state. The following four attributes are assigned to each coverage: aquifer name, boundaries, thickness, and yield. Yields for the bedrock aquifers are divided into four categories: 0-5 gallons per minute (gpm), 5‒25 gpm, 25‒100 gpm, and greater than 100 gpm. Aquifer thicknesses fall into one of two categories: less than 100 feet or greater than 100 feet. In portions of eastern and southeastern Ohio where relief is extremely high, the 100-foot thickness line is not drawn.

• Statewide Bedrock Aquifer Coverage: Download 1 Shape File [zip 109Mb]
• Permian Bedrock Aquifer Files: Download 1 Shape File [zip 11Mb]
• Pennsylvanian Bedrock Aquifer Files: Download 5 Shape Files [zip 62Mb]
• Mississippian Bedrock Aquifer Files: Download 11 Shape Files [zip 18Mb]
• Devonian Bedrock Aquifer Files: Download 5 Shape Files [zip 8Mb]
• Silurian Bedrock Aquifer Files: Download 8 Shape Files [zip 13Mb]
• Ordovician Bedrock Aquifer Files: Download 1 Shape File [zip 3Mb]

Glacial (Unconsolidated) Aquifers
Glacial aquifer boundaries were mapped using the lithologies (e.g. till, silt, sand, gravel, etc.) present. The complex nature of glacial deposits does not allow mapping multiple distinct aquifers at most locations. Yields are divided into five categories: 0‒5 gallons per minute (gpm), 5‒25 gpm, 25‒100 gpm, 100‒500 gpm, and greater than 500 gpm. Aquifer thicknesses fall into one of three categories: less than 25 feet, 25 to 100 feet, and greater than 100 feet. One file is available for all unconsolidated aquifers in the state.

• Statewide Unconsolidated Aquifer Coverage: Download Shape File [zip 22Mb]

Interactive Geologic Maps

The ODNR Division of Geological Survey has created an interactive, GIS-based mapping application that allows the user to navigate anywhere in the state and see Ohio’s geology. The Ohio Geology Interactive Map includes numerous groundwater and water well datasets, as well as surficial/glacial geology, geohazards, coal and industrial minerals, and more. Click here to access the Ohio Geology Interactive Map.

For other interactive maps, please visit our Interactive Maps web page.