Influence of Fundão Tailings Dam Breach on Water Quality in the Doce River Watershed

ABSTRACT The Fundão dam (Minas Gerais, Brazil) breach resulted in the transport and deposition of Fe mine tailings and debris for approximately 670 km along the Doce River watershed. Following the event, an extensive water quality monitoring program was implemented. The results generated by this program were used to assess the temporal and spatial impacts of the event on water quality. Data from several sampling sites situated along affected watercourses collected from 6 November 2015 to 27 September 2017 were evaluated. The sampling area was grouped into 4 zones delineated by hydropower plant dams located along the Doce River watershed and divided into 5 distinct time periods related to hydrological seasonality. Data were also compared to the Brazilian standards of water quality and available pre‐event conditions. Principal component analysis followed by analysis of variance (ANOVA) tests were performed to evaluate the observed temporal and spatial trends and patterns. The results indicated that concentrations of 58 water quality parameters increased with the arrival of the tailings wave released by the breach, generally exceeding pre‐event and regulatory levels. Persistent or seasonally recurring concentrations were observed for 30 water quality parameters. Concentrations of total and dissolved forms of Fe, Al, Mn, total P, total suspended solids, and turbidity tended to increase during the wet season and decrease during the dry season, this trend being more pronounced close to the dam. The water quality changes were more pronounced immediately after the arrival of the tailings wave, gradually decreasing over time and returning prebreach conditions, but fluctuated seasonally in response to the natural variation in river flow. Integr Environ Assess Manag 2020;16:583–595. © 2020 SETAC RESUMO O rompimento da barragem de Fundão (Brasil‐Minas Gerais) resultou no transporte e deposição de rejeitos de mineração de ferro e detritos por aproximadamente 670 km ao longo da bacia do rio Doce. Após o evento, um extenso programa de monitoramento da qualidade da água foi implementado. Os resultados gerados por este programa foram utilizados para avaliar os impactos temporais e espaciais do evento na qualidade da água. Dados de vários locais de amostragem situados ao longo dos cursos de água afetados coletados de 6 de novembro de 2015 a 27 de setembro de 2017 foram avaliados. As áreas de amostragem foram agrupadas em quatro zonas delineadas por barragens de hidrelétrica