The present article assessed the self-depuration capacity of Jordão River, considering the real contributions of Brejo Alegre stream in a drought period and two scenarios regarding the estimated polluting loads of a waste treatment plant and the low dilution capacity of the river for the Q7,10 critical flow by using the QUAL-UFMG model. The simulation for the drought period presented acceptable calibration by adjusting coefficients, evidencing the deoxygenation by carbon demand over nitrification and the importance of natural re-aeration in the self-depuration process. Only the biochemical oxygen demand (BOD5) parameter did not respect the limits recommended by the CONAMA Resolution 357:2005, in which all the river extension was outside the regulations due to the pollution loads received from Brejo Alegre stream. For the simulated scenarios, polluting loads of a population of 13.300 people for scenario 1 and 20.500 for 2 guaranteed the self-depuration capacity, considering a critical flow 3.2 times lower than the lowest flow measured in the drought period.
self-depuration; QUAL-UFMG model; Jordão River; Brejo Alegre stream
