This seminal work is designed to serve as a textbook for advanced undergraduate and graduate students, as well as a working reference for specialists in stream ecology and related fields. This new edition is extensively rewritten, with hydrology and geomorphology now accorded chapter-length discussion. Coverage includes a considerably improved and updated treatment of abiotic factors, organized around the habitat template concept. Additional new material outlines important advances in microbial ecology. The book presents vital new findings on human impacts, and new work in pollution control, flow management, restoration and conservation planning that point to practical solutions. All told, the book is expanded in length by some twenty-five percent, and includes hundreds of figures, most of them new. Thoroughly updated and expanded, this edition reflects the enormous growth in our understanding of stream metabolism and nutrient processes, which are the core of ecosystem functioning.