Construction of the Zeya hydraulic development was started in 1964. the river channel was closed off in 1972, and the first generating unit, with an installed capacity of 215,000 kW, was placed in operation in November 1975. The startup complex Included the following structures: the first stage of the massive buttress dam, two powerhouse sections together with the erection area, the central control desk, the transformer shop, the 220-kV switchyard together with the switchboard block and the compressor room, the trans-shippiag port. and the bridge across the Zeya River.The first start'up scheme for the units of the Zeya plant was worked out during the technical project stage. The periods for commissioning the units and readying the upstream front ( Fig. 1) were adopted on the basis of overall completion of the hydraulic development in 1978. It was assumed that during the first years the reservoir would be filled with an inflow having a 50% frequency of occurrence. The reduced construction ~rne (completion three years after commissioning the first units) and the rapid filing of the reservoir dictated large capital Investments (about 80%), which were necessary for commissioning the ~rst units. Subsequently, other alternatives were considered for placing the first units in operation with lower capital investments. The reduction in the volumes of the startup complex took place in three stages (1971, 1972, and 1973), in each of which optimal solutions compatible with the construction progress were found. The problem of the teehnieoeconomic indices of the startup complex for the first units was solved as part of the general startup scheme for all units, since the solution of this problem only within the limits of the minimal capital investments for commissioning the first units could lead to delays in commissioning the next units or to deterioration of the power-economy indices of the starmp period.The reduction in the capital investments for commissioning the first units was accomplished by the following means: a) Lowering of the startup head. The Francis turbines designed for the project could operate under a head of no less than 50 m" according to factory requirements, for this reason it was necessary to install in the first units temporary runners to be replaced by permanent runners, or to install diagonal turbines, capable of operating under heads of 40-35 m. The technicoeconomic analyses showed the expediency of the use of diagonal turbines. b) Limiting the rate of reservoir filling during the first years within the range of inflows having a 95% frequency. c) S tarring reservoir filling in the second half of the summer with a view to reducing the available storage for receiving the design storm flow. d) Making a detailed analysis of the dam behavior during the different construction stages in order to determine the sequence in dam construction and grouting for maximum reduction in the startup concrete volume while adhering to the minimum allowable stresses at the dam foundation level in the concrete on the upstrea...