The Reston Groundwater Dating Laboratory

NWIS Parameter Codes for GW Dating

Most if not all of the analyses conducted by the USGS GW Dating Lab have NWIS (National Water Information System) parameter codes and associated method codes. The downloadable spreadsheet available here provides a summary of these codes. This sheet is a work in progress. It incorporates comments and suggestions from previous users. If you use the sheet and see parameter codes or method codes that need to be updated please send an email to

Also available for download is Water Quality Information Note 2011.06 which describes procedures relevant to entering GW dating data into NWIS.