<p>Laguna de Bay, the largest lake in the Philippines and third in Southeast Asia, is constantly challenged by anthropogenic activities. Hydrochemistry was investigated to understand its spatial and seasonal dynamics in terms of anthropogenic and natural influences. Water sampling campaigns were done during dry and wet seasons from the western, southern, and eastern parts of the bay representing residential and industrial areas, agricultural and residential areas, and agricultural area in the catchment, respectively. Sites include crucial waterbody spots such as important tributaries, i.e.<i>,</i> rivers and lakeshores. Major ions, Cl⁻, Na⁺, Ca²⁺, Mg²⁺, K⁺, and NO₃⁻, were analyzed. Using Canonical Correspondence Analysis (CCA) and ion molar ratios assessments, water origin was traced using the major ions, land cover, and geological characteristics. In general, results showed that in terms of concentration the dominance of the ions is as follows: Cl⁻ &gt; Na⁺ &gt; Ca²⁺ &gt; Mg²⁺ &gt; K⁺ &gt; NO₃⁻ whether wet or dry season. However, this varies when looking at the individual river. In terms of the total ion concentrations at each site, the highest contributors were the tributaries in the western part and the lakeshore in the southern part. In general, all the measured major ions are influenced by the anthropogenic origins mainly by built-up at the same time geogenic sources were identified, Cl⁻, Ca²⁺, Mg²⁺ are inclined to the Pliocene Quaternary volcanic area whereas Cl⁻, K⁺ and Na⁺ are associated from seawater discharges. In terms of tendencies, south and east bays showed vulnerability to both anthropogenic and magmatic influences. West bay showed the dominance of anthropogenic influence. The results presented the geogenic and anthropogenic origins of Laguna de Bay’s hydrochemistry that can help in coming up with better management programs to improve the water quality.</p>