Trophic State Index (TSI) of the Reservoir of the Itaipu Binacional Hydroelectric Power Plant, Brazil

3. Itaipu Binacional, Directorate of Coordination Division reservoirs (MARR.CD), Brazil

Abstract: In order to evaluate the water quality of the reservoir of the Itaipu Binacional hydroelectric power plant, the present study classifies the Itaipu Dam using the Trophic State Index (TSI) of Carlson (1977) modified by Toledo-Jr et al. (1983), considering the period from 2008 to 2014. From the limnological data of analyzes carried out by the Environmental Institute of Paraná (IAP), provided by the Itaipu Environmental Monitoring Program, the TSI of the reservoir was calculated for the period 2008 to 2014, considering the quarterly averages of the sampling stations grouped according to the hydrological regime (averages of fluvial, transition and lacustrine zones). The limnological variables used in the calculation were the chlorophyll-α and total phosphorus concentrations and the depth of transparency, measured with the Secchi disk. The Itaipu Dam can be classified as ultraoligotrophic (TSI = 39.41). From the ANOVA and the Tukey test, it was verified that the lacustrine zone differs significantly from the transition and fluvial zones (and these do not differ from each other). The residuals presented normal distribution, confirmed by the Lilliefors test, whose probability value was p = 0.873. The reservoir is classified as ultra-lithotrophic and the quality of its waters may be considered adequate for the purposes for which they are intended.