A case study of the upper and middle reaches of the Oka river from Kaluga to the settlement of Polovskoe in Ryazan oblast demonstrated the consequences of anthropogenic disturbances of the river channel. The study revealed that a dominant role in the disturbance of the channel was played by the extraction of building materials from in-streammines which continues for nearly 60 years now. The study section is divided into two parts in accordance with the morphology and resistance of the channel as well as with the response of the channel to disturbances. Analysis of the minimum low-water flows revealed development tendencies of the channel prior to the start and at the time of anthropogenic disturbances. We estimated the volume of non-renewable sand-and-gravel bed material that was removed from the riverbed, and identified the magnitude and rate of directional deformations. Recommendations are proposed for the regulation of the extraction operations on the river, and for the consequences mitigation in respect of the hydrological regime, infrastructure and navigation.Keywords: channel processes, fluvial sediments, technogenic disturbances of channels.