Book excerpt: Water Quality Data emphasizes the interpretation of a water analysis or a group of analyses, with major applications on ground-water pollution or contaminant transport. A companion computer program aids in obtaining accurate, reproducible results, and alleviates some of the drudgery involved in water chemistry calculations. The text is divided into nine chapters and includes computer programs applicable to all the main concepts presented. After introducing the fundamental aspects of water chemistry, the book focuses on the interpretation of water chemical data. The interrelationships between the various aspects of geochemistry and between chemistry and geology are discussed. The book describes the origin and interpretation of the major elements, and some minor ones, that affect water quality. Readers are introduced to the elementary thermodynamics necessary to understand the use and results from water equilibrium computer programs. The book includes a detailed overview of organic chemistry and identifies the simpler and environmentally important organic chemicals. Methods are given to estimate the distribution of organic chemicals in the environment. The author fully explains all accompanying computer programs and presents this complex topic in a style that is interesting and easy to grasp for anyone.