Provides guidance for the construction and use of the Secchi disc. Outlines a procedure for determining the Secchi depth which is useful for monitoring changes in water clarity.RECONFIRMATION NOTICETechnical Committee EV-008 has reviewed the content of this publication and in accordance with Standards Australia procedures for reconfirmation, it has been determined that the publication is still valid and does not require change.Certain documents referenced in the publication may have been amended since the original date of publication. Users are advised to ensure that they are using the latest versions of such documents as appropriate, unless advised otherwise in this Reconfirmation Notice.Approved for reconfirmation in accordance with Standards Australia procedures for reconfirmation on 15 September 2017.The following are represented on Technical Committee EV-008:Australasian Land and Groundwater AssociationAustralian Contaminated Land Consultants AssociationAustralian Nuclear Science