The kinetic and potential energy of water discharged from a hydraulic retention structure can cause erosion in the zone immediately downstream and adjacent to the structure. Therefore, special erosion protection is necessary in the downstream discharge zone of these structures. A protection type that has given satisfactory results in Perú is the use of rock block pavements. The blocks effectively form a plate to resist the impact and abrasive action of the discharge flow. This paper details the construction process of one particular hydraulic structure that used rock blocks for erosion protection. The blocks were installed after the structure had experienced significant erosion of the stilling basin below its inflatable dam. This work was performed at the Hydroelectric Power Station Maria Auxiliadora del Quiroz located on the river Quiroz in northern Perú.