The overall objective of this study is to determine the influence of landscape and hydrological characteristics on sub-catchment variability of total phosphorus (TP), soluble reactive phosphorus (SRP), the ratio of SRP and TP (SRP/TP), and total suspended solids (TSS). Fourteen longitudinal synoptic surveys were conducted for 13 sampling sites over a variety of flow conditions in the Innisfil Creek watershed located in southern Ontario. The surveys were split into baseflow and stormflow and partial least squares regression (PLSR) was used to analyze the relationship between watershed and hydrological characteristics, median concentrations of phosphorus, and TSS. The PLSR models indicate that buried tile drainage might be a major source of SRP in Innisfil Creek, while bank erosion is likely a dominant source of TSS. The results of this study can serve as the basis for future adaptive management experiments that seek to improve water quality in Innisfil Creek and beyond.