Legend for the Illinois Water Well (ILH2O) Internet Map Service

  Well Status


Symbol

Layer

  Description

  Metadata


Dry Well
Dry
  Dry well
Engineering boring
Engineering
  Engineering boring

Stratigraphic boring
Stratigraphic
  Stratigraphic boring
Water Well
Water
  Water well

  Reference Data


Interstates
Interstates
  Interstates and toll roads in Illinois

U.S. Highways
US Highways
  U.S. Highways in Illinois

State Routes
State Routes
  Illinois state roads

PLSS Section Boundaries
Section
  Section boundaries in the Illinois Public Land Survey System

PLSS Township and Range Boundaries
Township
  Township and Range boundaries in the Illinois Public Land Survey System

USGS 7.5 Minute Quadrangle Index
Quad
  Index of U.S. Geological Survey 7.5-minute quadrangle map series for Illinois

County Boundaries
County
  Illinois county boundaries

Lakes and Streams
Lakes and Streams
  Water bodies

Municipal Boundaries
Municipalities
  Municipal boundaries in Illinois for incorporated places

  Geologic Data


Symbol

Layer

  Description

  Metadata

Bedrock Topography, Elev 0 ft above Mean Sea Level
Bedrock Topography, Elev 200 ft above Mean Sea Level
Bedrock Topography, Elev 400 ft above Mean Sea Level
Bedrock Topography, Elev 600 ft above Mean Sea Level
Bedrock Topography, Elev 800 ft above Mean Sea Level
Bedrock Topography, Elev 1000 ft above Mean Sea Level
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.
Major sand and gravel aquifers in Illinois
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.

Coarse-grained Materials within 50 feet of ground surface
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.

no Glacial Drift
Glacial Drift less than 25 feet thick
Glacial Drift 25 to 50 feet thick
Glacial Drift 50 to 100 feet thick
Glacial Drift 100 to 200 feet thick
Glacial Drift 200 to 300 feet thick
Glacial Drift 300 to 400 feet thick
Glacial Drift 400 to 500 feet thick
Glacial Drift greater than 500 feet thick
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.

Major bedrock aquifers within 300 feet of ground surface.
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.

Major bedrock aquifers within 500 feet of ground surface.
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.

Major bedrock aquifers greater than 500 feet below ground surface, TDS less than 2,500 mg/L, Potable Water.
Major Bedrock Aquifers Greater than 500 feet Below ground surface, TDS 2,500 to 10,000 mg/L.
Major Bedrock Aquifers Greater than 500 feet Below ground surface, TDS greter than 10,000 mg/L.
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.

Karst Areas
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.

  Base Data


Symbol

Layer

  Description

  Metadata


n/a
Eastern DOQ
UTM Zone 16
  Illinois Digital Orthophoto Quadrangle (DOQ) data in Universal Transverse
  Mercator, Zone 16, NAD83.

n/a
Western DOQ
UTM Zone 15
  Illinois Digital Orthophoto Quadrangle (DOQ) data in Universal Transverse
  Mercator, Zone 15, NAD83

n/a
Statewide DRG
  US Geological Survey Digital Raster Graphic (DRG) images for Illinois



Updated 11/22/2010 SKB

ILLINOIS STATE GEOLOGICAL SURVEY
615 E. Peabody
Champaign, IL 61820
217-333-4747
info@isgs.illinois.edu

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