Effect of waste disposal on nitrate and phosphate levels in Raleting Dam, Lesotho
| dc.contributor.author | Moeti, Lepekola | |
| dc.contributor.supervisor | Mahamo, Tebello | |
| dc.date.accessioned | 2026-07-08T08:44:31Z | |
| dc.date.available | 2026-07-08T08:44:31Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | Surface water quality in urban areas is consistently declining due to the indiscriminate disposal of both liquid and solid wastes. Identifying waste sources and factors increasing nitrate and phosphate levels in potable water bodies is crucial for water resource managers to mitigate nutrient pollution. This study evaluates the effect of waste disposal on nitrate and phosphate levels in Raleting Dam, located in Mafeteng, Lesotho. Fifty-four water samples were collected from nine sampling locations from March to May 2025. All samples were analysed using a HACH DR6000 spectrophotometer. The results indicated that domestic waste and industrial effluents are the primary contributors of nitrate and phosphate in this reservoir, respectively. Results revealed that all water samples had nitrate concentrations that are within the WHO acceptable contamination threshold of 50 mg/L, with an average value of (4.200 ± 1.083) mg/L. Results also revealed that all samples had phosphate levels exceeding the WHO acceptable contamination threshold of 0.03 mg/L, with an average value of (1.620 ± 0.740) mg/L. Higher nitrate concentration levels were exhibited during the wet season compared to the dry season, yielding mean values of 1.987 mg/L and 1.694 mg/L, respectively. In contrast, higher phosphate concentrations were observed during the dry season, compared to the wet season, yielding the mean values of (1.026 ± 0.114) mg/L and (1.003 ± 0.081) mg/L, respectively. There is, however, no positive correlation between nitrate and phosphate levels, hence suggesting a weak relationship between these two parameters. Historically, nitrate and phosphate levels revealed a gradual increase over time. Extensive investigations are further required around the identified pollution hotspots to ascertain the particular sources and facilitate the implementation of corrective actions. Findings from this study raise awareness among water resource managers and policymakers about the significant harm caused by the indiscriminate disposal of waste in this reservoir. The study can therefore serve as a basis from which local authorities and policymakers can formulate and implement waste management strategies in this area. Future research should explore public perceptions of illegal dumping and involve larger sample sizes over different periods for accurate analysis. Prioritizing physico-chemical parameters in future studies is essential for assessing water quality for domestic use. | |
| dc.description.sponsorship | ReNOKA, GIZ, National Manpower Development Secretariat | |
| dc.identifier.uri | https://hdl.handle.net/20.500.14155/2370 | |
| dc.language.iso | en | |
| dc.publisher | National University of Lesotho | |
| dc.title | Effect of waste disposal on nitrate and phosphate levels in Raleting Dam, Lesotho |