Revision History for U.S. Geological Survey Techniques and Methods; Book 9, Handbooks for Water-Resources Investigations; Section A, National Field Manual for the Collection of Water-Quality Data; Chapter 6.3, Specific Conductance U.S. Geological Survey Specific Conductance ----------------------------------------------------- Posted online - first release: 1998, as Techniques of Water-Resources Investigations (TWRI), book 9, chapter A6.3, version 1.0 ----------------------------------------------------- Revised: 2005, online as TWRI, book 9, chapter A6.3, version 1.2 The authorship was changed and the report was updated. ----------------------------------------------------- Revised and reposted February 8, 2019, online as Techniques and Methods (T&M), book 9, chapter A6.3 U.S. Geological Survey, 2018, Specific conductance: U.S. Geological Survey Techniques and Methods, book 9, chap. A6.3, 15 p., https://doi.org/10.3133/tm9A6.3. [Supersedes USGS Techniques of Water-Resources Investigations, book 9, chap. A6.3, ver. 1.2.] The personal authors were changed to the agency, U.S. Geological Survey. The report series was changed as indicated above. The layout was revised to match the current style and format of a USGS series report, and the text was set in two columns. A back cover was added, and the front cover, title page, back-of-title page, and abstract were revised to include the following: the change of series (to a T&M), the change in authorship, and a statement that this 2018 release of chapter A1 in the T&M series supersedes TWRI, book 9, chapter A1, version 2.0. The layout was revised 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 2018 release of chapter A6.3 in the T&M series supersedes TWRI, book 9, chapter A6.3, version 1.2. Substantive changes made in book 9, chapter A1, in 2018 are summarized below. Added: Section on measurement of specific conductance in water having low or high pH Section on applications of specific conductance in surface water and groundwater Discussion of differences between one-point and multipoint calibrations Procedure change: Calibration in the laboratory prior to field measurement is now recommended, and at a standard solution temperature between 5 and 35 degrees Celsius. The former procedure specified calibrating the meter with standards that were at the same temperature as the sample to be measured. Expanded and updated: Discussion of temperature-compensation factors and equations and their use in different types of environmental sample matrices Discussion of types of cells and probes and their construction Data reporting requirements, including discussion of uncertainty