Legend for the Illinois Water Well (ILH2O) Internet Map Service
Well Status
Symbol
Layer
Description
Metadata
Dry
Dry well
Engineering
Engineering boring
Stratigraphic
Stratigraphic boring
Water
Water well
Reference Data
Interstates
Interstates and toll roads in Illinois
US Highways
U.S. Highways in Illinois
State Routes
Illinois state roads
Section
Section boundaries in the Illinois Public Land Survey System
Township
Township and Range boundaries in the Illinois Public Land Survey
System
Quad
Index of U.S. Geological Survey 7.5-minute quadrangle map series
for Illinois
County
Illinois county boundaries
Lakes and Streams
Water bodies
Municipalities
Municipal boundaries in Illinois for incorporated places
Geologic Data
Symbol
Layer
Description
Metadata
Bedrock Topography
Buried bedrock surface of Illinois. Useful for the regional and
statewide studies
such as groundwater resource planning and geologic mapping because some
of the most extensive and productive aquifers in the state are located in thick
glacial sediments of major buried bedrock valleys.
such as groundwater resource planning and geologic mapping because some
of the most extensive and productive aquifers in the state are located in thick
glacial sediments of major buried bedrock valleys.
Sand and Gravel
Major sand and gravel aquifers in Illinois. Distribution of
major sand and gravel
aquifers at any depth. Generally, the tops of such aquifers lie within 300 feet of the
surface and the bases occur within 500 feet.
aquifers at any depth. Generally, the tops of such aquifers lie within 300 feet of the
surface and the bases occur within 500 feet.
Aquifer < 50 feet
Coarse-grained materials within 50 feet of the ground surface in
Illinois. This
includes bedrock, sand and gravel, and alluvial units with characteristics that
suggest a potential to store or conduct groundwater.
includes bedrock, sand and gravel, and alluvial units with characteristics that
suggest a potential to store or conduct groundwater.
Drift Thickness
Glacial drift in Illinois: thickness and character.
Unconsolidated deposits, mainly
glacial drift, overlie the bedrock surface in most of Illinois. The thickest drift occurs
in major preglacial valleys cut into the bedrock and filled with glacial sediments.
glacial drift, overlie the bedrock surface in most of Illinois. The thickest drift occurs
in major preglacial valleys cut into the bedrock and filled with glacial sediments.
Aquifer < 300 feet
Major bedrock aquifers within 300 feet of ground surface. Cover
most of northern
Illinois; commonly overlain by thin layers of less permeable silts and clays.
Illinois; commonly overlain by thin layers of less permeable silts and clays.
Aquifer < 500 feet
Major bedrock aquifers within 500 feet of ground surface. Cover
most of northern
Illinois; many are directly overlain by shallow or major sand and gravel aquifers.
Illinois; many are directly overlain by shallow or major sand and gravel aquifers.
Aquifer > 500 feet
Major bedrock aquifers greater than 500 feet below ground
surface. Groundwater
quality with in deep major bedrock aquifers degrades from northwest to
southeast in the northern portion of Illinois, due to the regional inclination of
geological unit toward the center of the Illinois Basin in southeastern Illinois.
quality with in deep major bedrock aquifers degrades from northwest to
southeast in the northern portion of Illinois, due to the regional inclination of
geological unit toward the center of the Illinois Basin in southeastern Illinois.
Karst Areas
Sinkhole areas (an indicator of karst terrain) in Illinois.
Areas that contain
sinkholes are susceptible to aquifer contamination and may also lack the stability
required for certain land uses.
sinkholes are susceptible to aquifer contamination and may also lack the stability
required for certain land uses.
Base Data
Symbol
Layer
Description
Metadata
n/a
Eastern DOQ
UTM Zone 16
UTM Zone 16
Illinois Digital Orthophoto Quadrangle (DOQ) data in Universal
Transverse
Mercator, Zone 16, NAD83.
Mercator, Zone 16, NAD83.
n/a
Western DOQ
UTM Zone 15
UTM Zone 15
Illinois Digital Orthophoto Quadrangle (DOQ) data in Universal
Transverse
Mercator, Zone 15, NAD83
Mercator, Zone 15, NAD83
n/a
Statewide DRG
US Geological Survey Digital Raster Graphic (DRG) images for
Illinois
Updated 11/22/2010 SKB