Mining, and particularly diamond exploitation, is one of the most ancient human economic activities and even today plays a crucial role in the economy of many countries. Our study aimed to inventory and map mining activities in the northeastern provinces of Angola (Lunda Norte and Lunda Sul) to enable the subsequent assessment of their impact on the natural environment and on water resources. To achieve this aim, we carried out several field campaigns. Various effects on the environment have been observed, ranging from visual impact to deforestation, soil depletion, and changes in topography. Water resources are the most affected part of the ecosystem, resulting in pollution of lakes and rivers, changes in river courses, silting of streams, and the dry-up of some watercourses. As a whole, our observations show that the effects of mining activities on water pollution in rivers impact large parts of the northeastern provinces of Angola and reach the border areas of the inner Congo Basin.