Understanding the cumulative impact of a suite of simultaneously occurring environmental stresses on stream water quality is essential for developing effective management and restoration strategies at the watershed scale. Although it is well known that land use and geology are the most important factors regulating nutrient concentrations in streams ecosystems, most of the variation in stream chemistry cannot be explained by one of these factors alone, suggesting that these systems are influenced by multiple factors acting at multiple spatial and temporal scales. Furthermore, the combined effect of land use and geology on stream water quality produces more than simply additive impacts and such dynamic is still poorly understood. In [...]