Identification_Information:
  Citation:
    Citation_Information:
      Originator: Terri Arnold
      Publication_Date: Unpublished Material
      Publication_Time: 2008
      Title: Hydrochemical regions of the glacial aquifer system -- Maximum Likelihod Classification
      Geospatial_Data_Presentation_Form: Fgdb raster digital data
      Series_Information:
      Publication_Information:
      Other_Citation_Details: 
      Online_Linkage: none
      Larger_Work_Citation:
        Citation_Information:
          Publication_Date: 2008
          Title: From SIR2008-5015, Hydrochemical regions of the glacial aquifer system and their environmental and water quality characteristics
          Series_Information:
            Series_Name: USGS SIR
            Issue_Identification: 2008-5015
  Description:
    Abstract: 
        This data set was created for SIR2008-5015 to map hydrochemical regions of the glacial aquifer system.  It was created from unsupervised and supervised classificaitons of water quality and environmental explanatory variables.  See published report for detailed description of process and regions.  There are 5 hydrochemical regions. Maximum Likelihood Classification (MLC) was used to make the extrapolation from clusters defined by points to areas of hydrochemical regions. Maximum Likelihood Classification is a geostatistical method of supervised classification, commonly used in remote sensing, in which characteristics of the clusters are known in some locations before the analysis begins. This set of known characteristics and locations is called a training sample and is used to define a range of characteristic values for each cluster. The MLC algorithm classifies spatial areas based on the maximum probability of an area being similar to a particular cluster based on the training sample. As a result of the previously described unsupervised classification, 1,316 wells were assigned to clusters. Each cluster represented a different hydrochemical region into which the glacial aquifer system would be classified. For the analysis described in this report, the environmental characteristics were spatially combined in the GIS. Environmental characteristics of each cluster were identified when the wells were spatially overlaid with the combined layers of environmental characteristics, creating the training sample. Multivariate statistics describing environmental characteristics for the training sample were stored in a text file called a signature or index file (mlcalt30sig.gsg) that the MLC then used to classify the glacial aquifer system into hydrochemical regions. The hydrochemical regions have the highest probability of matching the environmental characteristics of the corresponding cluster groups (the training sample). The result of the MLC is a map showing five hydrochemical regions of the glacial aquifer system (listed in the order of corresponding cluster groups 1 through 5): (1) Midwestern Agricultural Region (MAR), (2) Urban-Influenced Region (UIR), (3) Northern and Great Lakes Forested Region (NGLFR), (4) Western Agriculture and Grassland Region (WAGR), and (5) Mountain and Coastal Forested Region (MCFR). The hydrochemical region for 1,660 wells was identified when the wells were spatially overlaid with the hydrochemical regions map. This spatial overlay allowed an extrapolation of information to 400 wells not originally included in the classifications because the wells lacked spatial and/or chemical data. The hydrochemical region could not be identified for 56 of the 1,716 wells in the glacial aquifer system because these wells overlaid areas that could not be classified by the MLC. Thirty-three wells were in Alaska, and 23 wells were in the Puget Sound area (10 wells in Washington and 13 wells in Canada).
    Purpose: This data set was created for SIR2008-5015 to map hydrochemical regions of the glacial aquifer system.
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 2008
        Time_of_Day: unknown
    Currentness_Reference: publication date
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -142.169385
      East_Bounding_Coordinate: -52.098856
      North_Bounding_Coordinate: 55.424004
      South_Bounding_Coordinate: 17.378117
  Keywords: hydrochemical region, glacial aquifer system
    Theme: hydrochemical regions, glacial aquifer system
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: 
      Theme_Keyword: 
      Theme_Keyword: 
    Place:
      Place_Keyword: United States
  Access_Constraints: For internal use only.
  Use_Constraints: For internal use only.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Terri Arnold
        Contact_Organization: US Geological Survey
      Contact_Position: Cartographer/GIS Specialist
      Contact_Voice_Telephone: 217-328-9702
      Contact_Facsimile_Telephone: 217-344-0082
      Contact_Electronic_Mail_Address: tlarnold@usgs.gov
  Data_Set_Credit: 
  Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.4.1420
Data_Quality_Information:
  Lineage:
    Source_Information:
      Source_Citation: result of SIR2008-5015
        Citation_Information:
          Originator: USGS
          Publication_Date: 2008
          Publication_Time: Unknown
          Title: Hydrochemical regions of the glacial aquifer system and their environmental and water quality characteristics 
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name:  USGS Scientific Investigations Report
            Issue_Identification: 2008-5015
          Publication_Information:
            Publication_Place: Urbana, IL
            Publisher: USGS
          Other_Citation_Details: 
          Online_Linkage: 
    Process_Step:
      Process_Description:
        See methods described in USGS SIR 2008-5015
      Process_Date: 2008
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Terri Arnold
            Contact_Organization: USGS
          Contact_Position: GIS Specialist
          Contact_Voice_Telephone: 217-328-9702
          Contact_Electronic_Mail_Address: tlarnold@usgs.gov
    Process_Step:
      Process_Description: import into geodatabase
      Process_Date: 2008
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Pixel
    Row_Count: 7276
    Column_Count: 13024
    Vertical_Count: 1
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Map_Projection:
        Map_Projection_Name: Albers Conical Equal Area
        Albers_Conical_Equal_Area:
          Standard_Parallel: 29.500000
          Standard_Parallel: 45.500000
          Longitude_of_Central_Meridian: -96.000000
          Latitude_of_Projection_Origin: 23.000000
          False_Easting: 0.000000
          False_Northing: 0.000000
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 500.000000
          Ordinate_Resolution: 500.000000
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137.000000
      Denominator_of_Flattening_Ratio: 298.257222
Entity_and_Attribute_Information:
  Detailed_Description:
    Attribute:
      Attribute_Label: value
      Attribute_Definition: integer designation of hydrochemical region
      Attribute_Definition_Source: SIR2008-5015, result of ESRI Maximum likelihod classification
      Attribute_Domain_Values: (1) Midwestern Agricultural Region (MAR), (2) Urban-Influenced Region (UIR), (3) Northern and Great Lakes Forested Region (NGLFR), (4) Western Agriculture and Grassland Region (WAGR), and (5) Mountain and Coastal Forested Region (MCFR)
Distribution_Information:
  Resource_Description: By Request to Terri Arnold (tlarnold@usgs.gov)
Metadata_Reference_Information:
  Metadata_Date: 20080827
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Terri Arnold
        Contact_Organization: USGS
      Contact_Position: GIS Specialist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 1201 W University Ave, Suite 100
        City: Urbana
        State_or_Province: IL
        Postal_Code: 61801
        Country: USA
      Contact_Voice_Telephone: 217-328-9702
      Contact_Electronic_Mail_Address: tlarnold@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Extensions:
    Online_Linkage: http://www.esri.com/metadata/esriprof80.html
    Profile_Name: ESRI Metadata Profile
