Early in the 1970's, the Division of Water, now the Division of Soil and Water Resources, realized the need to distribute basic ground water availability information to the general public in an easy to use, semi-technical format. To meet this need, the Division began producing a series of maps which describe Ohio's ground water resources on a county by county basis. Generally referred to as "Ground Water Resource Maps", these maps are intended to aid homeowners, industries, municipalities, and regional water systems in developing reliable ground water supplies.
Ground water 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 ranging from purple (greater than 500 gpm) to orange (less than 3 gpm).
Information to Plan Your Water Supply:
In addition to yield information, Ground Water Resources Maps show several other types of data which can be used to aid in the development of a water supply. All maps show selected well log data for locations throughout the county. These data include total well depth, well yield, aquifer type, and depth to bedrock if encountered. Many of the maps also include data for some of the most common, naturally occurring, inorganic chemicals such as iron and total hardness. Each map includes a brief written description of the ground water geology within the county. These descriptions usually contain information on the type of aquifer or aquifers present in an area (e.g. sandstone, limestone, sand and gravel, etc.), typical well depths, and any known unusual conditions a well driller may encounter when drilling.
Producing a Ground Water Resources Map:
Ground water resources maps are printed on a United States Geological Survey topographic map base which shows significant natural and man-made features such as roads, streams and rivers, lakes, and buildings. County political subdivisions are also illustrated on the base map including township borders, and city and village limits. Ground Water Resource Maps are produced at a scale of 1:62,500 or approximately 1 inch = 1 mile.
Ground water resources maps are constructed using well log and drilling reports on file at the Division, bedrock and glacial information published by the Division of Geological Survey, and unpublished geologic and hydrogeologic data including consultants reports, test borings, sieve analyses, and pumping tests.