The textual material for a unit on facultative lagoons is presented in this student manual. Topic areas discussed include: (1) loading; (2) microbial theory; (3) structure and design; (4) process control; (5) lagoon start-up; (6) data handling and analysis; (7) lagoon maintenance (considering visual observations, pond structure, safety, odor, recordkeeping, and preventative maintenance); and (8) lagoon troubleshooting (considering causes and solutions to such problems as high loading, decreasing trend in pH, effluent high in biological oxidation demand, insects, and odor problems). A list of unit objectives, a glossary of key terms, a short list of references, and student worksheet are included. (JN)