The object of this study was to determine long-term temporal and spatial patterns of nutrients (nitrogen and phospho­rus), suspended solids, and chlorophyll (Chl) in Chungju Reservoir, based on the dataset of 1992 – 2013, and then to develop the empirical models of nutrient-Chl for predicting the eutrophication of the reservoir. Concentrations of total nitrogen (TN) and total phosphorus (TP) were largely affected by an intensity of Asian monsoon and the longitudinal structure of riverine (Rz), transition (Tz), and lacustrine zone (Lz). This system was nitrogen-rich system and phosphorus contents in the water were relatively low, implying a P-limiting system. Regression analysis for empirical model, however, showed that Chl had a weak linear relation with TP or TN, and this was mainly associated with turbid, and nutrient-rich inflows in the system. The weak relation was associated with non-algal light attenuation coefficients (Kna), which is in­versely related water residence time. Thus, values of Chl had negative functional relation (R2 = 0.25, p < 0.001) with non-algal light attenuation. Thus, the low chlorophyll at a given TP indicated a light-limiting for phytoplankton growth and total suspended solids (TSS) was highly correlated (R2 = 0.94, p < 0.001) with non-algal light attenuation. The relations of Trophic State Index (TSI) indicated that phosphorus limitation was weak [TSI (Chl) – TSI (TP) < 0; TSI (SD) – TSI (Chl) > 0] and the effects of zooplankton grazing were also minor [TSI (Chl) – TSI (TP) > 0; TSI (SD) – TSI (Chl) > 0].