Upper North Chickamauga Creek in Hamilton and Sequatchie Counties, Tennessee, is severely impacted by acid mine drainage (AMD) emanating from more than 15 abandoned coal mines in headwater tributaries. AMD is formed when pyrite and other sulfide minerals are exposed to air and water during coal mining. It is characterized by low pH (<2.8) and elevated concentrations of acidity, iron, aluminum, sulfate, and other pollutants. These attributes tend to be toxic to most aquatic life and result in reduced aesthetics and potential uses of the water. The North Chickamauga Creek Watershed Restoration Project is a multi-organizational effort to restore the upper 18 miles of the North Chickamauga Creek watershed to a level that will support a warm-water fishery. Several passive treatment systems (PTS) have been installed at abandoned mining sites in the North Chickamauga Creek watershed where AMD is generated and is flowing into surface waters. PTS is the engineered use of natural and enhanced geological, biological, chemical, and physical processes to prevent pollutant generation or to remove pollutants from aqueous discharges. PTS include technologies such as constructed wetlands, anoxic limestone drains, mine seals and flooding, successive alkalinity-producing systems, limestone trenches, and other components. During this field trip to the upper reaches of the North Chickamauga Creek watershed, we will visit several of the operational systems and observe untreated AMD. Participants will gain an understanding of how AMD is generated, its impacts and characteristics, and how it can be prevented or treated. This field trip requires extensive hiking over moderate slopes and sometimes vegetated terrain.