The Orava Water Work was planned after construction of the first channel level on the river Vah – the Dolne Kockovce weir and the Ladce water power station, at the time of an existing plan to use the river Vah on a complex basis. In order that the cascade of planned water power stations don't depend on the weather conditions, it was necessary to have a sufficient large reservoir in the upper flow, which would allow seasonal and also yearly regulation of flows according to the needs of the main consumers.
The industrialisation should have been accompanied by intensification of agricultural production in the central river Vah – mainly in the Trnava lowland – which required sufficient volume of water not only for industry, but also for irrigation.
The evaluation of the economic efficiency was made by analysing the cash flow in respect of the prices in the year 1970, in three areas:
- in the area of the Water Power Station,
- in the area of the Water Management Operator
- in the area of the Water Work as a whole.
For up-dating the cash flow items, the values constant until 1970 were modified by three different summary inflation coefficients: - Coefficient of costs was determined according to the increased operational costs and the value of basic funds of the water management operator.
- Coefficient of contributions for water supply was determined according to the increased prices for surface water.
- Coefficient of energetic contributions was calculated by multiplying the official inflation rate coefficients determined according to the investment costs for the Slatinka Water Work, calculated on two different price levels.
By correcting some overestimated contributions of the water management part of the Work, the efficiency of the water power station was closer to the efficiency of the whole Water Work, and thus in both areas of evaluation, the Work is adequately effective. From the evaluation of power it is evident that the contributions created by the Orava reservoir for the Vah cascade are realised on higher levels, and thus the yields in this area are significantly higher than in the Water Work taken as a whole. The power engineering which invested only less than 12 % of the initial costs for the Work, or having a 19 % share in the calculated costs for the Work, actually earns more than one half of the contributions created by the Water Work, and especially from its water management object – the Orava reservoir.
Up-dating of the individual cash flow items significantly increased the contributions in the last years of operation, but the period of return of the initial costs by the yields (less than 12 years) has practically remained the same in spite of the fact that currently, the contribution of the water power station is five times higher, and more than twice the Water Work.
(See table No. 1 – download)
