The purpose of this interagency manual is to document/compile field water-sample-collection methods (water column only) commonly used by various participating agencies for assessing the water quality of international and transboundary rivers. These agencies include the USEPA-Regions VI and IX, IBWC, USGS, BOR, and State regulatory agencies. This document is intended to provide an objective assessment of the benefits and limitations associated with each sampling method to enable the collector to select the field procedure that is most appropriate for the respective agencys needs or individual projects DQOs. This manual covers only water-column sampling of ambient waters of rivers, streams, lakes, and reservoirs. This manual also is not intended to replace agency-specific,detailed guidelines or sampling instructions provided by the USEPA, IBWC, USGS,BOR or State agencies for various water-quality projects. Users of this manual are advised to contact water-quality personnel within their agency for final determinations on sampling procedures, techniques, and protocols.