Water Quality Assessment of Ex-Mining Lakes Converted Man-made Wetlands in Paya Indah Wetlands, Selangor, Malaysia

This study assessed the spatial variations of water quality and trophic state of the ex-mining lakes converted into man-made wetlands in Paya Indah Wetlands, Selangor, Malaysia. The variations of the parameters were referred to the National Water Quality Standard (NWQS) to determine the water quality index (WQI) and Carlson's Trophic State Index (CTSI), guided by the National Lake Water Quality Standard (NLWQS) to assess the quality and trophic state of lake water. Water sampling was carried out at 13 stations within the Main Lake, Sendayan Lake and Teratai Lake through the DotS sampling method. The potential pollution sources affecting water quality were quantified using a statistical approach, including Pearson's correlation and principal component analysis/factor analysis (PCA/FA). The results show that the water quality parameters in some stations exceeded the NLWQS. Pearson analysis shows that nutrients flow with the organic and inorganic matter in the lake. Average WQI values ranged from 62 to 77, indicating slightly polluted to clean water quality in Paya Indah Wetlands. Two factors were found to account for over 82% of the total variation in the dataset when PCA was used to compare the compositional patterns among the samples that were analysed. This suggests that the point source (open areas for development) and non-point source (agriculture-oil palm estate) as well as the natural processes are the main causes of fluctuations in the concentration of the water components. Organic matter and nutrient regimes mainly affect water quality. Even though the lakes at the studied stations are currently hypertrophic, the overall water quality assessment categorises Paya Indah Wetlands as Class III. Hence, Paya Indah Wetlands has great potential to be an alternative water source supplying water to surrounding areas which require extensive water treatment.