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.

Hiwakloy Sulfur Spring River, physicochemical analysis, water quality, dissolved oxygen, freshwater ecosystem, Camarines Sur

1. Allan, J. D. (2004). Landscapes and riverscapes: The influence of land use on stream ecosystems. Annual Review of Ecology, Evolution, and Systematics, 35, 257–284. https://doi.org/10.1146/annurev.ecolsys.35.120202.110122 [Google Scholar] [Crossref]

2. Besagas, R. L., Asoy, A. T., Ceniza, M. S., Leopoldo, G. D., Dael, N. T., & Del Rosario, R. M. (2015). Upland and coastal freshwater sources in Misamis Oriental, Philippines: A comparison of water quality. Mindanao Journal of Science and Technology, 13(1), 1–13. [Google Scholar] [Crossref]

3. Chapman, D. (Ed.). (1996). Water quality assessments: A guide to the use of biota, sediments and water in environmental monitoring (2nd ed.). E & FN Spon. [Google Scholar] [Crossref]

4. Davies-Colley, R. J., & Smith, D. G. (2001). Turbidity, suspended sediment, and water clarity: A review. Journal of the American Water Resources Association, 37(5), 1085–1101. https://doi.org/10.1111/j.1752-1688.2001.tb03624.x [Google Scholar] [Crossref]

5. Department of Environment and Natural Resources. (2016). DENR Administrative Order No. 2016-08: Water Quality Guidelines and General Effluent Standards of 2016. [Google Scholar] [Crossref]

6. Department of Environment and Natural Resources. (2021). DENR Administrative Order No. 2021-19: Updated Water Quality Guidelines for Selected Parameters. [Google Scholar] [Crossref]

7. Hem, J. D. (1985). Study and interpretation of the chemical characteristics of natural water (3rd ed.). U.S. Geological Survey Water-Supply Paper 2254. [Google Scholar] [Crossref]

8. Intergovernmental Panel on Climate Change. (2023). Climate change 2023: Synthesis report. [Google Scholar] [Crossref]

9. Laud, Noel & Rosel, Hanah & Bungabong, Jonal & Resada, Terence & Alonsagay, Kenler & Taer, Carl & Tinampay, Fransric. (2016). Physical and chemical parameters of selected river waters in Davao City. UIC Research Journal. 19. 10.17158/524. [Google Scholar] [Crossref]

10. Magbanua, F. S., Velasco, A. B., Mendoza, S. S., Naling, C. S., Ramos, M. T., Ilano, A. S., & Pepito, C. C. (2025). Multivariate statistics and Water Quality Index (WQI) approach for water quality assessment in tropical streams and wadeable rivers in Cagayan Valley, Central Visayas, and Caraga, Philippines. Philippine Journal of Science, 154(6A), 1453–1465. (Philippine EJournals) [Google Scholar] [Crossref]

11. Martin, T. T. B., Lobredo, G. G., Leaño, E. P., Aljibe, M. C., & Oconer, E. P. (2018). Physico-chemical and bacteriological water quality evaluation of the four tributaries in Mt. Matutum Protected Landscape, South Cotabato, Philippines. Journal of Engineering, Environment and Agriculture Research, 1, 24–33. https://doi.org/10.34002/JEEAR.2018.01.15 (Philippine EJournals) [Google Scholar] [Crossref]

12. Philippine Statistics Authority. (2020). 2020 Census of Population and Housing (2020 CPH): Camarines Sur. [Google Scholar] [Crossref]

13. United Nations. (2023). The Sustainable Development Goals Report 2023. [Google Scholar] [Crossref]

14. United Nations Educational, Scientific and Cultural Organization. (2024). The United Nations World Water Development Report 2024: Water for Prosperity and Peace. [Google Scholar] [Crossref]

15. United Nations Environment Programme. (2021). Measuring progress: Water-related ecosystems and SDG indicator 6.6.1. [Google Scholar] [Crossref]

16. Vörösmarty, C. J., McIntyre, P. B., Gessner, M. O., Dudgeon, D., Prusevich, A., Green, P., Glidden, S., Bunn, S. E., Sullivan, C. A., Liermann, C. R., & Davies, P. M. (2010). Global threats to human water security and river biodiversity. Nature, 467(7315), 555–561. https://doi.org/10.1038/nature09440 [Google Scholar] [Crossref]

17. Wetzel, R. G. (2001). Limnology: Lake and river ecosystems (3rd ed.). Academic Press. [Google Scholar] [Crossref]

18. World Health Organization. (2022). Guidelines for drinking-water quality (4th ed., incorporating the first and second addenda). [Google Scholar] [Crossref]