The Bodri River is one of the main rivers in Kendal regency, Central of Java. This river flows through three regencies, namely Temanggung, Semarang, and Kendal, with anthropogenic conditions such as agricultural areas, settlements, and fish ponds. Human activities have caused high concentrations of suspended solids (TSS) to enter the Bodri River estuary, carrying nutrients such as phosphate. This study aims to investigate the relationship between dissolved inorganic phosphate (DIP or phosphate) with chlorophyll-a (Chl-a) and TSS at the Bodri River estuary in Kendal, Central Java. Water quality parameters, including turbidity, temperature, dissolved oxygen (DO), and salinity, were measured in the field. Meanwhile, Chl-a, phosphate, and TSS analyses in the laboratory. Based on Pearson correlation analysis, phosphate showed a strong positive correlation with chl-a (p=0.000; r=0.959) and TSS (p=0.000; r=0.872). The high correlation between phosphate and Chl-a is related to the role of phosphate as a nutrient that influences the growth of green phytoplankton (Chl-a), while phytoplankton itself is also a component of TSS. This study shows that phosphate nutrients play an important role in aquatic fertility, and when their concentrations are too high, they can cause eutrophication and increased TSS, which may negatively impact DO levels. Therefore, the presence of phosphate in water bodies requires continuous monitoring.