Koto Panjang reservoir has the main function as a hydroelectric power plant, besides it is used as a place to catch fish and cultivate fish in floating cages, as well as being a tourist area. The study aims to understand the concentration of organic matter in the dam site Koto Panjang reservoir. This study was conducted May-June 2018.Samplings were conducted 3 times, once/week. There were 3 sta…