<p>Cattle grazing near and inside watercourses may potentially contribute fecal coliform (FC) to surface water (streams, lakes, etc.), posing risks to both ecosystems and public health. This study presents a novel approach for estimating the impact of grazing cattle on watercourses under diverse conditions and to assess the effects of mitigation measures. The approach is based on a conceptual framework integrating field observations, long-term laboratory analysis, and FC fate and transport prediction modeling. The field survey revealed uniform distribution of dung across the plots, irrespective of distance to water. Microbial fate in the cattle dung over time under varying temperatures describes growth followed by a decline. The developed predictive process-based model showed that indirect FC load reaching the stream after dry grazing days (~10¹⁰ CFU per cow per rain event) was approximately two orders of magnitude higher than FC load by direct in-stream deposition (~10⁸ CFU per cow per day). These loads were significantly reduced by creating a buffer zone of 50&#xa0;m between the watercourse and grazing areas or by cattle exclusion from the watercourses for a limited time - at least during sensitive periods, i.e., when heavy rain is expected after several dry weeks and especially during the tourist period. The model results can help policy makers to quantify the effectiveness of management practices and will assist in identifying ways of revising existing measures to improve this effectiveness. The developed model can be adapted to different cases, considering the conditions prevailing on the sites.</p>