During a four-month stay at the Desert Ecological Research Unit (DERU) of Namibia, Central Namib Desert, an approximately 30 km long stretch of the Kuiseb River was monitored to assess the impact caused by the domestic stock owned by the indigenous Topnaar people. By estimating the conditions of the most common tree species in the area, Tamarix usneoides, Euclea pseudebenus, Salvadora persica and Acacia albida, the impact could be quantified for the first time. Assigning "Impact Indication Points", permitted a quantification of the impact on individual tree species, as well as providing an overview of the varying extent of impact along the monitored stretch of the river. This paper presents the results of the survey and also discusses the method in question in terms of its applicability. Keywords: Namibia, Namib Desert, Kuiseb River, Kuiseb Canyon, Topnaar community, riverine vegetation, human impact, livestock grazing.