NOVELTY - The building of the hydroelectric station has a light upper structure, feeding and discharge flow channels of the horizontal hydroelectric unit with a straight-axis draught tube, the discharge chamber and the foundation plate under the hydroelectric unit make up a rigid spatial construction serving as a deepened foundation of the hydroelectric unit. The discharge chamber represents a built-up reinforced-concrete prefabricated construction consisting of several separate members mounted and monolithic finished on the workplace. Conjugation of the discharge chamber outlet and the discharge channel is made by a reinforced- concrete pipe of square section assembled of two or more separate standard prefabricated members. The conjugating pipe is equipped at the outlet with a bottom wall providing the necessary sinking of the discharge pipe outlet section, and standard built-up reinforced-concrete lean-to members for conjugation with the slopes of the discharge channel. The u pper lightened structure represents a built-up construction: of a separate strip foundation that is not coupled to the foundation of the hydroelectric unit, and a metal framework mounted on it, wall panels of section plate material with a warmth-keeping jacket mounted on the metal framework, and slabs with an assembly hatch and a detachable hatch door. The method for erection consists in examination of the hydrology of rivers, conducting of geological and geodetic surveyings of river range lines, construction of the headwork and diversion canals, first selected are one, two or more standard sizes of hydraulic turbines of different power, consumption ranges and operating heads. After that differential selection of the river range lines is accomplished in accordance with the parameters of the selected standard sizes of hydraulic turbines. All the river range lines are divided into groups. At construction of the hydraulic electric station the rated head is provided by selection of the l engths of the diversion canals. The main and auxiliary equipment is built up and unified by groups. Modular hydroelectric unit and electric block-sections assembled of unified constructions unified by these groups are developed. After fabrication of the unified constructions and transportation of the hydroelectric unit block-sections and their mounting are accomplished, after that arrangement of the building of the hydroelectric station consisting of 1,2 and more hydroelectric units and the respective number of electrical block-sections is accomplished.    USE - Hydraulic engineering, in particular, construction of diversion small hydroelectric stations on mountain rivers.    ADVANTAGE - Reduced material costs for designing and construction of hydroelectric stations and the term of putting the stations into operation. 2 cl, 2 dwg