The owners of Tatogga Lake Resort informed geologists of persistent flammable natural gasseepage into Tatogga Lake, British Columbia.. The gas seep was sampled from anomalously unfrozen, openings (UTM zone 440378/6396983, NAD27) when the ice cover was generally 15 to 20 cm thick. Samples-of this gas are compose&of methane:(98.2 %) and carbon dioxide (1.8 %). The stable carbon isotopic composition of both gases is consistent with biogenic- generation and possibly slight- microbial oxidation. The biogenic origin of this natural petroleum seepage suggests that the gas is not associated. with crude oil stains and. thermogenic petroleum systems in the Bowser Basin and underlying rocks. The seepage source strata and economic potential remain unidentified and obscured by its underwater occurrence.