Methanogenic potential (MP) was found to be significantly higher in the upper sediment layer compared to that from deeper sediment layer. Generally, average MP varied between 0.74-158.6 pM CH4 mL-1 WW hour-1 with the highest values found at site IV. Average methanotrophic activity (MA) varied between 0.02- 31.3 nM CH4 mL-1 WW hour-1 and the highest values were found to be at the downstream localities while sediment from sites located upstream showed much lower or even negative activity. Similar to MP, values of MA were significantly higher in sediments from upper layers compared to those from deeper layers (e. g. Figs. 3c, 3d).