Improper mining activities cause various environmental problems. A major problem is the heavy metal pollution. Can-Etili Basin (Northwest Turkey) has been subjected to intense mining activities with open/underground mining operations in several locations within the basin. Acid mine lakes have been also created at the abandoned mining sites. This study was conducted to investigate physical and chemical characteristics of the mine tailings and sediments and the types of contaminants present in them. Further, the leachability and associated environmental risk of the contaminants present was also investigated. Two locations of the basin were selected for this study, and several representative samples of mine tailings, rock outcrops, and lake sediments were collected. These samples were tested for physical properties such as moisture content, particle size, specific gravity and hydraulic conductivity and for chemical properties such as organic content and pH. The metal contamination in each of the samples was also determined. Subsequently, batch and column experiments were conducted to quantify the leachate/bioavailable toxic metals. The results showed that the sediments, mine tailings and outcrops contain several toxic metals at elevated concentrations. The most dominant metal contaminants found were: Pb (79 mg/kg), Ba (190 mg/kg) and Ni (470 mg/kg) in mine tailings; Pb (64 mg/kg), Ba (310 mg/kg) and Ni (570 mg/kg) in lake sediments; and Pb (96 mg/kg), Ba (279 mg/kg) and Ni (760 mg/kg) in outcrop rocks. The extent of leachable/bioavailable metals was dependent on the physical and chemical characteristics of the media, and the toxic metals such as Pb, Cu, Zn, and Ni were found to leach in the amounts ranging from 5 to 15 mg/kg. The total and leachable toxic metals found in the materials at the basin have potential to impact the public health and surrounding environment. Additional research is being conducted to quantify the risk as well as to develop practical green and sustainable methods to mitigate the environmental risk.