Version 1.0 (June 2007) - Database includes anion concentrations from 12 sampling sites. For some sites data is available from water year 2002 and for other sites data is available from when sampling was initiated.

Version 2.0 (May 2008) - The revised database includes data from water water year 2007 and data from from two new sites: Firehole River at Old Faithful (USGS station# 06036805) and Yellowstone River near Tower Junction (currently no operating gauge).

Version 3.0 (April 2009) - The revised database includes data from water water year 2008. Added Dan Mahony and Mark A. Huebner as a co-authors. Updated references.