This research developed and applied a GIS-based modelling framework that integrated a hydrologic model and a farm economic model to examine the environmental and economic implications of land management changes in terms of potential crop rotation in the Fairchild Creek watershed in southwestern Ontario. Model simulations that incorporated annual object-oriented landuse/landcover classifications revealed that both sediment loads and cropping returns are variable across space and time and that these patterns are not comparable. Furthermore, the spatial distribution of sediment load to economic output ratios are relatively stable and concentrated in areas with high sediment delivery or low crop-based economic output. These results provide practical references for watershed management agencies to understand the spatial and temporal dimensions of the tradeoffs between environmental impacts of agricultural nonpoint source pollution and economic output. Therefore, based on identifying high damage to benefit ratios, decision makers may prioritize areas to implement agricultural conservation practices such as conservation tillage and riparian buffer strips.