Major Bedrock Aquifers at Depths Greater Than 500 Feet Below Ground Surface

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Frequently-anticipated questions:


What does this data set describe?

Title:
Major Bedrock Aquifers at Depths Greater Than 500 Feet Below Ground Surface
Abstract:
This map shows the distribution of major bedrock aquifer units at depths greater than 500 feet below ground surface in Illinois. Major aquifers are capable of yielding 70 gallons of water per minute. The data are sub-divided into (1) aquifers yielding potable water (containing less than 2,500 milligrams per liter of total dissolved solids), (2) aquifers yielding water containing from 2,500 to 10,000 milligrams per liter of total dissolved solids, and (3) aquifers yielding water containing greater than 10,000 milligrams per liter of total dissolved solids. The map indicates that groundwater quality within deep major bedrock aquifers degrades from northwest to southeast in the northern portion of Illinois. This degradation in water quality is due to the regional inclination of geological units toward the center of the Illinois Basin in southeastern Illinois. Stratigraphic units considered to be major bedrock aquifers are:

Hunton Limestone Megagroup Ancell Group Prairie du Chien Group Ironton-Galesville Sandstone Elmhurst-Mt. Simon Sandstone

The scale of these data is 1:500,000.

Supplemental_Information:
In April 2004 the source coverage was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated edition 20040401.

The source coverage (edition 2.0) was entirely reconstructed from the source hand-drafted map, making the previous version (coverage edition 1.0) obsolete. This edition retains the edition 2.0 data.

Some information used to compile this map was obtained from well log data on file at the Illinois State Geological and Water Surveys. A variety of well/boring data were used, including:

water wells oil wells (active and abandoned) gas wells (active and abandoned) Secondary and Tertiary oil recovery wells air injection wells service wells waste disposal wells observation wells (disposal sites) observation wells (water resources) gas storage operational wells water test holes coal test holes mineral test holes structure test holes stratigraphic test holes engineering test holes

  1. How should this data set be cited?

    Miller, Jerry, 1994, Major Bedrock Aquifers at Depths Greater Than 500 Feet Below Ground Surface: ISGS GIS Database GISDB_HYDRO.IL_Maj_Bedrock_Aq_Gt_500_Ft_Py, Illinois State Geological Survey, Champaign, Illinois.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.4244
    East_Bounding_Coordinate: -87.3840
    North_Bounding_Coordinate: 42.4951
    South_Bounding_Coordinate: 36.9540

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 1986
    Currentness_Reference: publication date of sources

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • G-polygon (7)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    Attribute items are in typical SDE feature class format. Those requiring explanation are:

    CODE - Discriminates polygon on basis of water quality 0 - Major bedrock aquifers containing more than 10,000 mg/L total dissolved solids 1 - Major bedrock aquifers containing from 2,500 to 10,000 mg/L total dissolved solids 2 - Major bedrock aquifers containing less than 2,500 mg/L total dissolved solids


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Contact_Instructions: Please refer to the Distribution Information section.


Why was the data set created?

This feature class is intended to identify areas of Illinois where major bedrock aquifers exist.

These data are appropriate for use in regional thematic analysis. The data are not appropriate as a geodetic, legal or engineering base. The datasets were not and are not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS, the data have no legal basis in the definition of boundaries or property lines.


How was the data set created?

  1. From what previous works were the data drawn?

    none (source 1 of 10)
    Miller, J.R., R.C. Berg, T.M. Johnson, A. Weh, 1985 (not published), Siting a Low-Level Radioactive Waste Disposal Facility in Illinois: Statewide Criteria - Description of maps: Compilation, Database, and Intended Use.: Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: ISGS internal document
    Type_of_Source_Media: paper
    Source_Contribution: attribute and data description

    none (source 2 of 10)
    Berg, R.C., and J.P. Kempton, 1984, Potential for contamination of shallow aquifers by land burial of municipal wastes: Illinois State Geological Survey Map same as title, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: unknown

    none (source 3 of 10)
    Bergstrom, R.E., K. Cartwright, K. Piskin, and M, 1968, Groundwater resources of the Quaternary deposits of Illinois; in the Quaternary of Illinois - a symposium in observance of the centennial of the University of Illinois: Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: Bergstrom, R.E. (ed.); p. 157-159
    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 4 of 10)
    Bergstrom, R.E., and A.J. Zeizel, 1957, Ground-water geology in western Illinois, south part - A preliminary geologic report: Illinois State Geological Survey Circular 232, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 5 of 10)
    Kempton, J.P., W.H. Johnson, P.C. Heigold, and, 1991, Mahomet bedrock valley in east-central Illinois; topography, glacial drift stratigraphy, and hydrology: Geological Society of America Special Paper 258.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 6 of 10)
    Pryor, W.A., 1956, Groundwater geology in southern Illinois - A preliminary geologic report: Illinois State Geological Survey Circular 212, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 7 of 10)
    Selkregg, L.F., and J.P. Kempton, 1957, Groundwater geology in south-central Illinois - A preliminary geologic report: Illinois State Geological Survey Circular 225, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 8 of 10)
    Selkregg, L.F., and J.P. Kempton, 1958, Groundwater geology in east-central Illinois - A preliminary geologic report: Illinois State Geological Survey Circular 248, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 9 of 10)
    Visocky, A.P., M.G. Sherrill, and K. Cartwrigh, 1985, Geology, hydrology, and water quality of the Cambrian and Ordovician systems in northern Illinois: Illinois State Geological Survey Cooperative Groundwater Resources Report 10, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

    none (source 10 of 10)
    Willman, H.B., E. Atherton, T.C. Buschback, C., 1975, Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Contribution: unknown

  2. How were the data generated, processed, and modified?

    Date: 1985 (process 1 of 3)
    This coverage was originally digitized in ARC/INFO circa 1985 from hand-drafted map compiled by Jerry Miller of the ISGS. The map is pencil on paper in good condition, at a scale of 1:500,000.

    Date: 1994 (process 2 of 3)
    In 1994 the coverage underwent extensive Quality Assurance/ Quality Control review. As a result of the QA/QC review, the existing coverage was replaced. The new coverage was digitized from the original paper map, with a maximum RMS of 0.004. The .PAT ITEMS and values were copied from the existing coverage and then manually verified. This processing was subsequently reviewed and verified by ISGS staff.

    Date: 01-Apr-2004 (process 3 of 3)
    Source coverage (aqmbg500) converted to double precision and reprojected to GCS_NAD83 using Workstation ArcInfo 7.2.1.

    The features were imported into the ISGS SDE enterprise database following steps outlined in ISGS procedure GISDB_0009.

    Attributes COUNT-FED-FIPS and SYMBOL were dropped. They were unnecessary items leftover from previous processing.

    Metadata updated.

    Person who carried out this activity:

  3. What similar or related data should the user be aware of?

    , ISGS Terms of Use.

    Online Links:

    , University of Illinois Web Privacy Notice.

    Online Links:

    , University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).

    Online Links:

    , Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Attributes were extracted from source hand-drafted maps in 1994 and verified by three individuals. Attribute codes are believed to fully representative of the source data. Source data were derived through contouring and interpretation.

  2. How accurate are the geographic locations?

    Horizontal positional accuracy of this data with respect to the source maps was verified by three individuals by visual comparison (manual overlay) of source maps and hard-copy plots. Arcs within one line-width of source mylars were deemed acceptable. Consult the sources for information on the derivation of aquifer boundaries.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    This data set contains major bedrock aquifers as defined in the abstract. There exist other aquifers (associated with other geologic formations or aquifer definitions) not identified on this map. Some examples are sand and gravel aquifers, shallow aquifers, and other aquifers between 50 and 300 feet that are not identified as "major aquifers". Because these data are generalized over a large areal extent, the user needs a good working knowledge of the geologic formations used here in order to derive valid and useful interpretations.

  5. How consistent are the relationships among the observations, including topology?

    When in coverage format, this data set was checked for complete chain-node topology (no dangling arcs, except where appropriate), polygon labels (one per polygon, except for universal polygon), boundary values appropriate for map projection and map units, and appropriate "fuzzy" tolerances. There are no known polygon attribute values outside the appropriate value domains.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current.

Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice.

Links to these are provided in the Cross References section.

Use_Constraints:
ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved.  University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section.

Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage.

Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section.

Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data.  Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.

The data do not replace the need for detailed site-specific studies.

  1. Who distributes the data set? (Distributor 1 of 1)

    Information Office, Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

    217-333-4747 (voice)
    isgs@isgs.illinois.edu

    Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following:

    Disclaimer of Liability Disclaimer of Warranties and Accuracy of Data Disclaimer of Endorsement Disclaimer for External Links Disclaimer of Duty to Continue Provision of Data Security Choice of Law

    By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, ESRI formats can be imported into many different GIS software packages. It is expected that customers who obtain these data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.


Who wrote the metadata?

Dates:
Last modified: 24-Feb-2009
Metadata author:

Contact_Instructions: Please refer to the Distribution Information section.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Illinois Natural Resources Geospatial Data Clearinghouse

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