The importance of mining companies in the national economic development as well as the role of the source and the potential impact of silts to the environment for the development and expansion of mining companies is briefly discussed to gain the knowledge of how these two parties are inter-related. Also, most mining companies in Rwanda experience siltation problems during mineral processing. Those problems include the change in river direction, soil erosion, increase flooding in the river, disturbance of aquatic animals, and also the most issues of those silts damage hydroelectric power station build on NYABARONGO River. The result in an unnaturally large accumulation of silt that stays in that particular area of that river. This book comes as a result to those problems by designing a silt dam to capture those silt from mineral processing in order to prevent those negative impact caused by silts. This book provides recommendations how to build silt dams in order to reduce environment degradation caused by silts.