Physicochemical Assessment and Water Quality Classification of the Hiwakloy Sulfur Spring River, Camarines Sur, Philippines

Freshwater ecosystems are essential for sustaining biodiversity, supporting human health, and promoting socioeconomic development. However, increasing anthropogenic activities have contributed to the deterioration of river water quality, highlighting the need for continuous monitoring and assessment. This study evaluated the physicochemical water quality of the Hiwakloy Sulfur Spring River in Goa, Camarines Sur, Philippines, and determined its classification based on the Department of Environment and Natural Resources (DENR) Administrative Order No. 2016-08. A descriptive-quantitative research design was employed using water samples collected from three designated sampling stations representing the head, body, and foot of the river during the wet season in November 2022. Six physicochemical parameters were analyzed, namely turbidity, pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and salinity. The results revealed distinct descriptive differences among the sampling stations. Turbidity increased downstream, with the highest value recorded at the river foot, indicating greater sediment accumulation from surface runoff and nearby human activities. In contrast, pH remained stable within the slightly basic range, while dissolved oxygen levels consistently exceeded the minimum standard required to support aquatic life. The measured TDS, EC, and salinity values remained within acceptable freshwater limits, with relatively higher concentrations observed at the headwaters due to the river's natural sulfur spring characteristics. Based on DENR standards, the average values for pH, dissolved oxygen, and total dissolved solids met the criteria for Class AA inland waters, indicating excellent water quality suitable as a source of public water supply requiring only disinfection. The remaining parameters could not be classified because corresponding regulatory limits are not specified in the current DENR guidelines. Overall, the measured physicochemical parameters remained within acceptable ranges during the wet-season sampling period, with pH, dissolved oxygen, and total dissolved solids meeting the Class AA criteria under DENR Administrative Order No. 2016-08. The study provides baseline information for future monitoring and may support future watershed conservation planning, environmental monitoring, and evidence-based water resource management in Camarines Sur.