Hans C. Claassen 1982 <p>Obtaining ground-water samples that accurately represent the water chemistry of an aquifer is a complex task. Before a ground-water sampling program can be started, an understanding of the kind of chemical data needed and the potential changes in water chemistry resulting from various drilling, well-completion, and sampling techniques is needed. This report provides a basis for such an evaluation and permits a choice of techniques that will result in obtaining the best possible data for the time and money allocated.</p> application/pdf 10.3133/ofr821024 en U.S. Geological Survey Guidelines and techniques for obtaining water samples that accurately represent the water chemistry of an aquifer reports