ISGS - Legend for the Water Well (ILH2O) Internet Map Service

Legend for the Illinois Water Well (ILH2O) Internet Map Service
Well Status
Symbol	Layer	Description	Metadata
	Dry	Dry well	none
	Engineering	Engineering boring	none
	Stratigraphic	Stratigraphic boring	none
	Water	Water well	none
Reference Data
	Interstates	Interstates and toll roads in Illinois	intstate.html
	US Highways	U.S. Highways in Illinois	ushways.html
	State Routes	Illinois state roads	stroutes.html
	Section	Section boundaries in the Illinois Public Land Survey System	re-state1.html
	Township	Township and Range boundaries in the Illinois Public Land Survey System	re-state1.html
	Quad	Index of U.S. Geological Survey 7.5-minute quadrangle map series for Illinois	quad75.html
	County	Illinois county boundaries	counties.html
	Lakes and Streams	Water bodies	streams.html
	Municipalities	Municipal boundaries in Illinois for incorporated places	municipal90.html
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.	bedtopo.html
	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.	aqmsg.html
	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.	aq50.html
	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.	driftthk.html
	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.	aqmb300.html
	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.	aqmb500.html
	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 units toward the center of the Illinois Basin in southeastern Illinois.	aqmbg500.html
	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.	karst.html
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.	doq_utm16_83.html
n/a	Western DOQ UTM Zone 15	Illinois Digital Orthophoto Quadrangle (DOQ) data in Universal Transverse Mercator, Zone 15, NAD83	doq_utm15_83.html
n/a	Statewide DRG	US Geological Survey Digital Raster Graphic (DRG) images for Illinois	drg_lam.html