Movimiento superficial de contaminantes biológicos de origen ganadero en la red de drenaje de una cuenca de Pampa Ondulada

runoff water and sediments from crop and cattle production fields of the rolling pampas accumulate in small depressions along the drainage network. we studied the concentration of biological contamination indicators in these small sinks located in bottomlands devoted to cattle production of the tala river basin. the stocking rate was closely related to the concentration of microorganisms in the depressions. the intensity of rainfall events previous to each sampling date and the time between the last significant runoff event and each sampling date proved to be sensible variables for predicting the concentration dynamic of total coliforms and faecal enterococci and streptococci, respectively. our results show a close relationship between runoff, soil erosion and surface water biological contamination in the studied area. we propose a simple conceptual model of inputs and outputs of potential contaminants in the depressions which may constitute the base for a future early warning program of regional surface water contamination.