The Pato Branco river basin, which supplies water to Pato Branco city (70,000 inhabitants) in southwestern Paraná State, was monitored during two hydrological cycles, totaling 22 campaigns at two monitoring stations on the Conrado river: the Conrado station upstream (RC01) and the Conrado station downstream (RC02). The main characteristics of the basin here: area - 29.69 km², length - 9,300 m, height difference - 170 m, declivity - 18.62 m km-1, and concentration time - 102 min. Physico-chemical variables were analyzed, using samples collected after a minimum three-day period without rain. The data set comprising seven variables yielded the following averages respectively for monitoring stations RC01 and RC02: variables that characterized the organic matter: BOD5 (5.2 - 4.31mg L-1 O2) and COD (11.04 - 11.2 L-1 O2), and variables that characterized the eutrophication processes: ammoniacal N (0.16 - 0.09 mg L-1 N); nitrate (0.67 - 0.78 mg L-1 N); nitrite (0.06 - 0.029 mg L-1 N); total N (0.48 - 0.33 mg L-1 N), and total phosphorous (0.13 - 0.07 mg L-1). The lowest and the highest variation coefficients for data downstream and upstream corresponded to: nitrate and nitrite (46.1 and 166%); phosphorous and nitrite (56.8 and 229.6%).
Water quality; environment; anthropic influence
