This handbook provides information on developing and implementing watershed management plans that help to restore and protect water quality. A watershed is the area of land that contributes runoff to a lake, river, stream, wetland, estuary, or bay. A watershed management plan defines and addresses existing or future water quality problems from both point sources and nonpoint sources of pollutants. Experience over the past decade has shown that effective watershed management includes active participation from stakeholders, analysis and quantification of the specific causes and sources of water quality problems, identification of measurable water quality goals, and implementation of specific actions needed to solve those problems. This handbook is intended to serve as the basis for developing and implementing watershed plans to meet water quality standards and protect water resources. Although watershed plans are useful for all watersheds to protect and restore water resources, as well as to meet other community resource goals, they are critical for impaired or threatened waterbodies.