Credible intervals (CIs) for thermotolerant coliforms (A), enterococci (B), coliphages (C), and enterophages (D) in the Rio Grande de Arecibo watershed. Results represent the means of the sampling period (n = 13), and credible intervals, representing positive values, were drawn as well. Except for enterophages, CIs could not be calculated for site 10 since most data are zeros.