Technical Abstract: Microbiological quality of surface water sources can be affected by microbial load in runoff from grazing lands. This effect depends, among other factors, on survival of microorganisms in animal waste deposited at pastures. Temperature is one of leading environmental parameters affecting the survival. The Q10 model is a widely used tool to simulate the effect of temperature on rates of biological processes. The objective of this work were (i) to evaluate the applicability of the Q10 model to the E. coli inactivation in bovine animal waste deposited at grazing land as cowpats, and ii) to identify a set of parameters that could reproduce the previously reported E. coli die-off dynamics in cowpats. The database included published data on E. coli concentrations in natural and repacked cowpats were analyzed in experiments in Virginia, USA, Maryland, USA, New Zealand, and United Kingdom. Inspection of the datasets led to the conceptualizing the field E. coli survival as a two-stage process where the first stage could be growth, inactivation or stationary state of the population, and the second stage was the approximately first-order inactivation. Application of the Q10 model showed the remarkable similarity in inactivation rates defined by using the thermal time. The reference inactivation rate constant of 0.042 (thermal days)-1 at 20°C gave a good approximation (R2=0.88) of all inactivation stage data with Q10 = 1.48. The reference inactivation rate constants in individual experiments were not different from the one obtained using all data pooled together (P < 0.05). The rate of logarithm of E. coli concentration change during the first stage depended on temperature. The duration of the first stage until the first order inactivation started and the initial concentration of E. coli in cowpats could not be predicted from data collected during experiments. Diet and age are probable factors affecting these