Use of parameter-method code pairs in the National Water Information System (NWIS) and the process for requesting parameter codes and method codes

In Reply Refer To:
Mail Stop 412


March 27, 2003


  Office of Water Quality Technical Memorandum 2003.01

  Subject: Use of parameter-method code pairs in the National Water
           Information System (NWIS) and the process for requesting
           parameter codes and method codes

  Purpose:

  The purpose of this memo is to describe the way parameter code-method
  code pairs are used for rounding purposes in National Water-Quality
  Information System (NWIS), an enhancement that was added in NWIS version
  4.2.  The process for assigning new and/or updating existing parameter
  and method codes is also described.

  Use of parameter-method code pairs in NWIS water-quality software:

  The NWIS water-quality software (QWDATA) uses a reference table of
  parameter-method code pairs for most rounding scenarios and, during data
  entry, performs a check against the reference table for valid
  parameter-method code pairs.  Batch entry of an invalid parameter-method
  code pair causes the assignment of a 'blank' method code for that result
  in the database.  During the transfer to the NWIS 4.2 software, invalid
  method codes were allowed to exist in historical records.  Invalid
  parameter?method code pairs are rounded using rounding specifications
  associated with a 'blank' method code.  The rounding specifications
  associated with the 'blank' method are typically less precise than recent
  methods and, consequently, the use of 'blank' method rounding may not be
  appropriate for newer, more precise methods.  Therefore, the reference
  table maintained within NWIS and used for validation must contain all
  legitimate parameter-method code combinations, and their associated
  rounding arrays, in order for data to be properly rounded in tables and
  other output.

  Method code descriptions are currently not an integral part of the NWIS,
  so this information will be maintained externally until it can be added
  to the software.  The external file can be obtained from:
  http://wwwok.cr.usgs.gov/nawqa/phoenix/www/references.html

  Process for requesting new and updated parameter codes and method
codes:

  The process for requesting new and updated parameter codes, as described
  in Office of Water Quality (OWQ) Technical Memorandum 96.08, has become
  obsolete.  The current process for requesting new codes is outlined
  below.

  1.  Requests for new and/or updated parameter codes and method codes are
  to be submitted to the Office of Water Quality by completing the
  information listed in a spreadsheet named "pcode.request.xls."  The
  spreadsheet can be obtained via ftp as follows:

        ftp disftp.er.usgs.gov
        [login as] anonymous
        cd pub/owq/parameters
        get pcode.request.xls
        bye

        These instructions can also be found on the internal Office of
        Water Quality (OWQ) home page at:
        http://water.usgs.gov/usgs/owq/parm_request.html.

        Mandatory information for the assignment of new parameter codes
        includes:

        
Constituent name.
        
Sample medium (e.g., water, biota, etc.), or matrix, or biological
      tissue type or body part.
        
Reporting units.
        
Lowest reporting level at which at least one significant figure is
      shown.
        
Maximum number of significant digits to be shown in output.
               
        Mandatory information for the assignment of new method codes includes:

        
Parameter code(s) associated with the method.
        
Method short name.
        
Method citation.
        
Identification as a field or a lab method.
        
Lowest reporting level at which at least one significant figure is shown.
        
Maximum number of significant digits to be shown.
               
        Additional information can be entered if it is known.  This same
        spreadsheet is used to request updates to existing parameter and
        method codes.

  2.  The completed spreadsheet should be sent via electronic mail to Ken
  Pearsall, New York District (pearsall@usgs.gov).  Ken will assign new
  parameter codes, update existing parameter codes, forward requests for
  new and updated method codes to Pete Rogerson (senior chemist, OWQ), and
  maintain the parameter-method code reference list for NWIS.

  3.  Pete Rogerson will assign new method codes and make any requested
  updates to the method codes and will forward these codes to Ken for
  inclusion in the parameter-method code pair reference table.

  4.  Ken will submit the revised Parameter Code Dictionary (PCD), method
  code reference list, and parameter-method code pair reference table to
  the NWIS team.

  5.  To keep data processing as up-to-date as possible, the NWIS team will
  release the updated PCD, method code reference list, and parameter-method
  code pair reference table at least quarterly for the Districts to install
  on their NWIS systems.


  Questions should be directed to Yvonne Stoker (ystoker@usgs.gov).  Errors
  and requests for changes to NWIS other than a parameter code-method code
  request should be entered into the NWIS 'Gnats Problem Report Management
  System' at:

             http://wwwnwis.er.usgs.gov/cgi-bin/gnats_home.pl



                                                           Timothy L.
                                 Miller /s/
                                                           Chief, Office of
                                 Water Quality

  This memorandum supercedes OWQ Technical Memo 96.08.

  Distribution:  All WRD Employees

  (See attached file: OWQ 03.01 pcode-method_management.doc)
*******************************************************
Timothy L. Miller, Chief, Office of Water Quality
U.S. Geological Survey
412 National Center
Reston, VA  20192
703/648-6868
703/648-6693 (fax)
tlmiller@usgs.gov
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