The objective was to estimate pesticide concentrations in the Azul stream (Buenos Aires province, Argentina), using representative values ​​for this type of data series and to evaluate the health risk of recreational use. The substances that allowed the estimation of the 95% Upper Confidence Limit (95% UCL, or UCL) were selected. The UCL was computed using ProUCL 5.1 software. The program estimates the UCL using methods such as Kaplan-Meier and regression on order statistics, in data sets containing censored. The risk calculation was made from chronic exposure to substances in water during recreational bathing by accidental ingestion and dermal contact (USEPA 1992 and 2004). The probabilistic USEPA model was used with Crystal Ball 11.1 by Monte Carlo, for non-carcinogenic and carcinogenic effects. The concentrations of the pesticides ranged between 9.41E-06 and 1.71E-01. The aggregate RNC values, considering the intake and dermal route simultaneously, were not significant, except cypermethrin, which presented significant but low aggregate risk values. The aggregate CR presented non-significant values, even considering both ways simultaneously. The work allowed to know representative values ​​of concentrations of pesticides by means of methods that allow their estimation in data series that includes observations not detected under reasonable maximum conditions of exposure.