Evaluation of Water Quality in the Nenggiri River, Kelantan using Water Quality Index (WQI)

Abstract

Abstract The Nenggiri River, located in the District of Gua Musang, Kelantan, Malaysia, is an essential water resource that plays a crucial role in the local ecosystem and community life. Spanning a catchment area of 3,703 km 2 , the river is situated approximately 30 km from the town of Gua Musang. Despite its importance, the Nenggiri River’s forest ecosystem is increasingly threatened by uncontrolled and unsustainable development. In particular, the upper Nenggiri basin, including the Loging Highlands, has witnessed the transformation of mountain forests into large-scale agricultural farms. This deforestation and land conversion have led to severe sedimentation issues downstream, significantly impacting water quality. Additionally, lowland forests are being replaced by plantations, further compromising the river’s ecological balance. The objective of this study is to assess the water quality of the Nenggiri River by calculating the Water Quality Index (WQI) and classifying the river based on the National Water Quality Standards (NWQS) of Malaysia. Key parameters monitored include Dissolved Oxygen (DO), pH, Temperature, Ammoniacal Nitrogen (AN), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), and Biological Oxygen Demand (BOD). The sampling was conducted at several strategically identified locations, using the APHA 2005 method. The findings indicate that the WQI values for all sampling locations place the Nenggiri River in Class II, which corresponds to a water quality status of ‘Slightly Polluted’ under the NWQS. Three measured parameters DO, BOD, and COD were below the acceptable limits for Class IIB, while pH was within the acceptable range, indicating relatively good water quality in these aspects. However, TSS and AN concentration exceeded the permissible limits set by the NWQS, highlighting areas of concern. These results underscore the urgent need for effective management and conservation efforts to protect the Nenggiri River from further degradation. Sustainable practices and stricter regulations on land use and agricultural expansion in the region are essential to preserve the river’s health and ensure it continues to support the local environment and community.