Water quality of urban watershed Cancela-Tamandaí, Santa Maria/RS

Abstract

Inadequate release of sewage and solid waste in water resources promotes gradual contamination of water. This study aimed to evaluate the quality of surface waters of Cancela-Tamandaí Creek in dry period. The basin is located in urban area of Santa Maria city, in Rio Grande do Sul, with 2.7 km² area, predominating impervious areas. The water quality parameters were statistically analyzed and evaluated according to Pearson correlation coefficient. The use and land occupation influenced negatively the quality of water, exceeding the limits from Class IV of CONAMA 357/2005 Resolution. The heavy metal concentrations found showed that the use and land occupation in drainage area of watershed are introducing negative impacts on stream. Mitigating measures should be adopt, preventing these impacts become more and more significant. Strong correlations between DO and nitrate (r=0.85), BOD and COD (r=0.78), E. coli and turbidy (r =0.63) are illustrating the degradation of water quality in the Creek. The high variability obtained for the evaluated parameters was due to interference of environment.