  Abundance of fecal coliform (FC) is widely used to indicate the potential
presence of pathogens, the No.1 cause of water impairments in the U.S. Despite
extensive monitoring efforts, assessing and modeling FC pollution still faces
challenges, largely owing to the uncertainties in estimation of overall removal
rate (K). This study proposes an alternative method to estimate in situ K by
combining observational data, hydrodynamic simulation, and analytical solution.
The method requires the observed spatial distribution of FC concentration along
an estuarine channel and the numerically-simulated transit time, and converts
the K estimation from a temporal problem into a spatial problem, potentially
reducing survey duration, effort, and cost. Application of the method gave an
estimation of K = 0.5 d-1 on average for the Nassawadox Creek in Chesapeake
Bay. The numerical and analytical model results with the estimated K agreed
well with the observation, demonstrating the credibility of the method.
