Evaluation of faecal contamination in Bahía Blanca estuary (Argentina) using a numerical model

The need for techniques and appropriated sites for sewage discharge has been long time acknowledged. The most common place to discharge wastewater treated or not, is usually a nearby body of water. In September 2008 began operating a sewage treatment plant in Bahía Blanca that dumps poorly treated wastewater in the area near Municipal public recreational pool (Balneario Maldonado). Due to proximity, there is a potential health risk because a significant part of this sewage could reach the Municipal pool. The purpose of this study is to assess the health of the marine water bodies along the inner part of Bahía Blanca estuary using a numerical model (MOHID), with special attention to a specific indicator of faecal contamination, Escherichia coli. We validated the dispersion model of faecal contamination, so that we can use it as a decision support tool in coastal areas. MOHID model used the concept of lagrangian tracers to evaluate the spatial-temporal evolution of the pollution plume, determined by tidal regime, winds and local circulation. The fate models accurately predicted both variability and means indicator organism counts at most stations (r > 0.9) and show the environmental impact over the Municipal pool. It is expected that the model results described herein be a useful tool and thereby generate an effort by environmental authorities to reduce pollution in the Bahía Blanca estuary.