In 2003 the Resource Assessment Section started production of a new series of aquifer systems maps for the purpose of assessing Indiana’s groundwater resources. There are two maps per county; one for unconsolidated aquifer systems and one for bedrock aquifer systems. Mapping of the aquifer systems rely heavily on the DNR/DOW digital water well record database (about 400,000 records available online) along with other useful digital information (see Indiana Map) where available (e.g. seismic data, bedrock topography maps, soil surveys, oil and gas wells). In addition, publications by the U.S. Geological Survey, Indiana Geological and Water Survey, and other entities were very helpful. Relatively uniform characteristics are the basis for the naming of an aquifer system. However, some variation between counties is possible. See a particular county of interest for specific details.
Unconsolidated Aquifer Systems
The maps, with accompanying text and tables, describe characteristics such as geologic materials, thickness of confining units, aquifer thickness, static water levels, well yield, typical well depths, and depth to the aquifer resource. The counties within the northern Basin Studies were adapted from that series to complete statewide coverage in a uniform style. The basin study aquifer system names are unique and are described on those county map adaptations, and in more detail within the cited publication. All of the unconsolidated mapping is intended for use at a scale of 1:48,000 or smaller.
Unconsolidated Aquifer Systems names (2003-2011 series)
Dissected Till and Residuum Aquifer System, Till Veneer Aquifer System, Unglaciated Southern Hills and Lowlands Aquifer System These systems are similar in composition and have little potential for groundwater production. The Dissected Till and Residuum Aquifer System includes areas where pre-Wisconsin and/or Wisconsin till is thin and dissected due to deep down-cutting by streams and other areas where soils have formed directly from bedrock due to weathering. The Till Veneer Aquifer System encompasses areas where the unconsolidated material is predominantly thin till overlying bedrock; chiefly the product of the deposition of glacial till over an uneven, eroded bedrock surface rather than erosion of till by younger streams. The Unglaciated Southern Hills and Lowlands Aquifer System is mapped within areas of nonglaciation, beyond the southern limit of older glacial deposits. This system name was adapted from the Physiographic Divisions of Indiana (H.H. Gray, 2000). Also included in these three aquifer systems are relatively thin deposits of alluvium and colluvium in many stream valleys. Total thickness of unconsolidated materials overlying bedrock is generally less than 50 feet.
| Aquifer type | residual, intertill, or basal fine-grained sand and gravel and/or weathered bedrock |
|---|---|
| Unconsolidated thickness | varies widely; commonly less than 50 feet |
| Number of aquifer units | typically none |
| Aquifer thickness | individual units, if present, are generally less than 3 feet (almost all of the wells started in these systems are completed in bedrock) |
| Aquifer depth | varies widely but commonly less than 50 feet |
| Static water level | varies widely; typically less than 25 feet |
| Yield | generally less than 5 gallons per minute; dry holes common |
| Overlying materials | predominantly clay-rich material; alluvium in places |
| Susceptibility to contamination | typically low |
Alluvial, Lacustrine, and Backwater Deposits Aquifer System The Alluvial, Lacustrine, and Backwater Deposits Aquifer System is mapped along minor tributaries primarily in southern Indiana where the floodplain is greater than one-eighth mile in width and total thickness of deposits are greater than 25 feet. The materials in this aquifer system come from two major sources. One source is alluvium deposited by the streams along with colluvium eroded from the valley walls and upland areas. The second source is glaciolacustrine sediment, which accumulated in bodies of relatively stagnant lake water. These silts and clays were deposited when the valleys of the White, Wabash, and Ohio rivers were choked with coarser material carried by glacial meltwater that effectively dammed tributary streams, creating lakes. Few wells are completed in this system. However, where conventionally drilled wells would not be successful, large-diameter bored (bucket-rig) wells could be adequate in places to meet the needs of some domestic users.
| Aquifer type | alluvial and/or lacustrine fine sand and gravel |
|---|---|
| Unconsolidated thickness | varies widely; commonly less than 50 feet |
| Number of aquifer units | typically none |
| Aquifer thickness | individual units, if present, are generally less than 5 feet (almost all of the wells started in this system are completed in bedrock) |
| Aquifer depth | varies widely but commonly less than 50 feet |
| Static water level | varies widely; typically less than 25 feet |
| Yield | generally less than 5 gallons per minute; dry holes common |
| Overlying materials | alluvial and lacustrine sand, silt, and clay |
| Susceptibility to contamination | typically low to moderate |
Till Aquifer System The till aquifer system primarily consists of glacial till with intertill sand and gravel layers. The geographic names are from the Physiographic Divisions of Indiana (H.H. Gray, 2000).
| Aquifer type | regionally discontinuous intertill or basal sand and/or gravel |
|---|---|
| Unconsolidated thickness | varies widely; commonly 80 to 200 feet |
| Number of aquifer units | typically one but may have a second thin layer with potential |
| Aquifer thickness | individual units are commonly 5 feet to 15 feet but are absent in some areas (generally about 40% of the wells started in this system are completed in bedrock) |
| Aquifer depth | varies widely but typically 60 to150 feet |
| Static water level | varies widely; commonly less than 50 feet |
| Yield | generally 10 to 25 gallons per minute (domestic); typically 200 gallons per minute for large-diameter high-capacity wells (defined as 70 gallons per minute or greater) |
| Overlying materials | predominantly clay-rich till |
| Susceptibility to contamination | commonly low |
Till Aquifer Subsystem This subsystem is mapped within glaciated areas where unconsolidated materials are generally greater than 50 feet in thickness, yet have limited aquifer potential. The till aquifer subsystem is similar to the till aquifer system except the aquifer thickness and yield are less. The geographic names are from the Physiographic Divisions of Indiana (H.H. Gray, 2000).
| Aquifer type | locally discontinuous intertill or basal sand and/or gravel |
|---|---|
| Unconsolidated thickness | varies widely; generally 50 to 200 feet |
| Number of aquifer units | in places one; typically none |
| Aquifer thickness | individual units are commonly 5 feet to 10 feet but are absent in many areas (generally about 80 percent of the wells started in this system are completed in bedrock) |
| Aquifer depth | varies but typically greater than 50 feet |
| Static water level | varies but commonly less than 50 feet |
| Yield | generally less than 10 gallons per minute (domestic only); extremely limited high-capacity potential |
| Overlying materials | predominantly clay-rich till |
| Susceptibility to contamination | typically low |
Complex Aquifer System This system is typically mapped in areas of multiple glacial sequences. The complex aquifer system commonly occurs adjacent to a till aquifer system, however, the number of aquifers, thickness, and yield are greater than till aquifer systems. The geographic names are from the Physiographic Divisions of Indiana (H.H. Gray, 2000).
| Aquifer type | multiple, intertill and basal sand and gravel or buried outwash sands and gravels |
|---|---|
| Unconsolidated thickness | varies widely; typically 100 to 200 feet |
| Number of aquifer units | commonly two or more, occasionally one thick unit |
| Aquifer thickness | individual units utilized are generally 10 feet to 20 feet (however, about 10 percent of the wells started in this system are completed in bedrock) |
| Aquifer depth | varies widely but typically 60 to150 feet |
| Static water level | varies widely; commonly less than 50 feet |
| Yield | generally 10 to 50 gallons per minute (domestic); typically 400 gallons per minute for large-diameter high-capacity wells |
| Overlying materials | predominantly clay-rich till |
| Susceptibility to contamination | commonly low |
Outwash Aquifer System (Wabash River and Tributaries Outwash Aquifer System, White River and Tributaries Outwash Aquifer System, Ohio River Outwash Aquifer System, Whitewater Valley Aquifer System) In places, meltwater streams deposited large volumes of sand and gravel in the stream valleys. These areas are mapped as the outwash aquifer system, and are characterized by excellent groundwater availability.
| Aquifer type | outwash sand and gravel or valley-train sand and gravel |
|---|---|
| Unconsolidated thickness | varies widely; commonly 100 to 150 feet |
| Number of aquifer units | typically one |
| Aquifer thickness | generally greater than 20 feet |
| Aquifer depth | varies widely but commonly near the surface |
| Static water level | varies widely; typically less than 10 feet |
| Yield | generally 50 gallons per minute (domestic); commonly 1000 gallons per minute for large-diameter high-capacity wells |
| Overlying materials | typically a thin silt and clay layer or unsaturated sand and gravel |
| Susceptibility to contamination | generally high |
Outwash Aquifer Subsystem (Wabash River and Tributaries Outwash Aquifer Subsystem, White River and Tributaries Outwash Aquifer Subsystem, Ohio River Outwash Aquifer Subsystem, Whitewater Valley Aquifer Subsystem) The outwash aquifer subsystem is mapped similar to the outwash aquifer system. However, potential aquifer materials are thinner, overlying silt and clay materials are generally thicker, and potential yield is less in the outwash aquifer subsystem than in the outwash aquifer system.
| Aquifer type | outwash sand and gravel or valley-train sand and gravel |
|---|---|
| Unconsolidated thickness | varies widely; commonly 50 to 150 feet |
| Number of aquifer units | typically one |
| Aquifer thickness | generally less than 20 feet |
| Aquifer depth | varies widely but commonly near the surface |
| Static water level | varies widely; typically less than 25 feet |
| Yield | generally 20 gallons per minute (domestic); commonly 300 gallons per minute to large-diameter high-capacity wells |
| Overlying materials | typically a silty clay layer |
| Susceptibility to contamination | generally moderate, high if overlain by surficial sand and gravel |
Till Aquifer System, Till Aquifer Subsystem, Complex Aquifer System, Outwash Aquifer System, Outwash Aquifer Subsystem (over buried valley with some potential) These areas consist of a known bedrock valley that underlies a shallower mapped system, with supporting data showing some deep aquifer potential; although the deep aquifer is not typically used as the main aquifer source because of overlying aquifers.
Till Aquifer System, Till Aquifer Subsystem, Complex Aquifer System, Outwash Aquifer System, Outwash Aquifer Subsystem (over buried valley with no or unknown potential) These areas consist of a known bedrock valley that underlies a shallower mapped system, with supporting data showing that potential as a deep aquifer resource is extremely limited or there is no information available.
Buried Valley Typically mapped in areas where a known bedrock valley is present with a deep aquifer, and little or no information showing a shallower aquifer system above the deep aquifer.
| Aquifer type | deep intertill sand and gravel or sand and gravel resting on bedrock |
|---|---|
| Unconsolidated thickness | varies widely; typically greater than 110 feet |
| Number of aquifer units | one |
| Aquifer thickness | individual units are generally 10 feet or greater |
| Aquifer depth | varies widely but typically greater than 100 feet |
| Static water level | varies widely |
| Yield | in southern Indiana, there is limited aquifer potential and most wells are completed in bedrock; in the central and northern regions, well yields are generally 10 to 20 gallons per minute (domestic) and typically 300 gallons per minute for high-capacity wells |
| Overlying materials | predominantly clay-rich till |
| Susceptibility to contamination | low |
Coal Mine Spoil Aquifer System (digital coverage is from the Indiana Geological Survey Indiana Coal Mine Information System) This aquifer system primarily consists of select areas of southern Indiana where coal mine spoil was used to fill excavated mined areas above an underlying aquitard. Where extensive, these spoil areas contain considerable amounts of groundwater.
Bedrock Aquifer Systems
The maps, with accompanying text and tables, describe characteristics such as geologic materials, aquifer system thickness, depth to bedrock, static water levels, well yield, amount of rock penetrated, and typical well depths. For the purpose of assessing groundwater availability, the bedrock aquifer system mapping is intended for use at a scale of 1:48,000 or smaller.
Bedrock Aquifer Systems names
Bedrock aquifer systems are attributed to the aquifer systems category from the Indiana Geological Survey shapefile: BEDROCK_GEOL_MM48_IN: Bedrock Geology of Indiana (Indiana Geological Survey, 1:500,000, Polygon Shapefile). The shapefile can be viewed and downloaded from Indiana Map. The digital shapefile was derived with minor modifications from a preexisting published paper map (Gray, H.H., Ault, C.H., and Keller, S.J., 1987, Bedrock Geologic Map of Indiana, Indiana Department of Natural Resources, Geological Survey, Miscellaneous Map 48). The bedrock aquifer systems are shown below. Following that is a description of the Underground Coal Mine Aquifer System, which is also shown where applicable on bedrock aquifer systems maps.
Underground Coal Mine Aquifer System (digital coverage is from the Indiana Geological Survey Indiana Coal Mine Information System) The Underground Coal Mine Aquifer System consists chiefly of select areas of southern Indiana where various coal seams within bedrock have been removed by underground mining methods. Approximately 50 percent of the coal seam was typically removed, leaving the potential for storage of substantial amounts of groundwater in the larger mines.
