This article analyzes the hydraulic processes in the spillway tunnels of high-pressure hydraulic units. The conducted studies involve the examination of the spatial model of the Pskom HPP production spillway tunnel section and address one of the issues that arise during the efficient operation of high-pressure facilities: hydraulic processes in the spillway tunnel. Based on the observed studies, it can be stated that calculated values of hydraulic resistances in the diaphragms are presented. These diaphragms are designed to reduce the energy of the flow while ensuring the permeability and hydraulic efficiency of the operational discharge of water. As a result of the calculations, resistances along the length of the operational spillway and the head loss on local resistances in the diaphragm were computed, and resistance coefficients were also estimated.