Version History for U.S. Geological Survey Techniques and Methods 9-A6.8 By U.S. Geological Survey Use of Multiparameter Instruments for Routine Field Measurements ----------------------------------------------------------------------------- First posted online August 2007 as Techniques of Water-Resources Investigations (TWRI), book 9, chapter A6.8, version 1.0 ----------------------------------------------------------------------------- Revised and reposted March 2012 as version 1.1 ----------------------------------------------------------------------------- Revised and reposted November 28, 2023, as Techniques and Methods, book 9, chapter A6.8, version 1.0 U.S. Geological Survey, 2023, Use of Multiparameter Instruments for Routine Measurements: U.S. Geological Survey Techniques and Methods, book 9, chap. A6.8, 13 p., https://doi.org/10.3133/tm9A6.8. [Supersedes USGS Techniques of Water-Resources Investigations, book 9, chap. A6.8.] The personal authors were changed to the agency, U.S. Geological Survey. The report series was changed as indicated above. The layout was changed to match the current style and format of a USGS series report, and the text was set in two columns. A front cover, back cover, title page, and back-of-title page were added and show the following: the change of series (to a T&M), the change in authorship, and a statement that this 2023 release of chapter A6.8 in the T&M supersedes TWRI, book 9, chapter A6.8, version 1.1. Substantive changes made in book 9, chapter A6.8, in 2023 are summarized below: Calibration procedures were generalized with references made to NFM field parameter chapters A6.1 through 6.7 for specific procedures. The calibration order for parameters was reordered to reflect an emphasis on the importance of zero checks for dissolved oxygen. Stabilization criteria for specific conductance was changed to match NFM A6.3 Specific Conductance. Stabilization criteria for pH was changed to match NFM A6.4 Measurement of pH. ----------------------------------------------------------------------------- Revised and reposted June 12, 2025, as version 1.1. U.S. Geological Survey, 2023, Use of Multiparameter Instruments for Routine Measurements (ver. 1.1, June 2025): U.S. Geological Survey Techniques and Methods, book 9, chap. A6.8, 13 p., https://doi.org/10.3133/tm9A6.8. [Supersedes USGS Techniques of Water-Resources Investigations, book 9, chap. A6.8, version 1.1; and USGS Techniques and Methods, book 9, chap. A6.8, version 1.0.] On page 1, added the chapter to the title. On page 3, under Tables in the Contents, table 6.8—7: changed title from "USGS guidelines for reporting field parameter values" to "USGS guidelines for recording and storing field parameter values". On page 7, the first bullet point of 4.1 Surface Water, the second sentence: changed "through a transect" to "through the water column". On page 8, under 6.0 Reporting, first paragraph, the last sentence: changed "Reporting guidelines" to "Recording and storage guidelines" On page 10, table 6.8—7, table title: changed from "USGS guidelines for reporting field parameter values" to "USGS guidelines for recording and storing field parameter values". On page 10, table 6.8—7, table headnote: changed "ppt, parts per trillion" to "ppt, parts per thousand" On page 11, moved Acknowledgements to the page 10 before Selected References. On page 11, Hydrolab reference: changed "24 p. accessed accessed November 2, 2023" to "24 p., accessed November 2, 2023". On page 12, Appendix title: changed from "Appendix 6.8–1." to "Appendix 6.8–1. Example of a U.S. Geological Survey Field Form for Recording Sensor Calibrations and Field Measurements" On page 12, Appendix 6.8–1: the first sentence was deleted. On page 12, Appendix 6.8–1, the second sentence: changed "version of this and other field forms" to "version of the form shown in figure 6.8-01.01 and other field forms". On page 13, figure 6.8-01.01: added period to the end of the caption.