Odour-related complaints are a major concern of pork producers. Open manure storage and treatment facilities such as uncovered anaerobic treatment lagoons are a major contributor to odour nuisance. Repeatable and valid field measurement techniques are needed for evaluating baseline odour emissions from existing livestock facilities and the effectiveness of odour abatement technologies. A buoyant convective flux chamber (BCFC) for measuring odour flux from liquid surfaces of dilute waste waters was designed, constructed, and tested. Odour flux from a surface-aerated stratified facultative lagoon at a 6000-head swine finishing facility was measured with the BCFC. The swine buildings at this facility contained recirculation flush pits initially charged with approximately 0.5-m depth of effluent from the second cell of a two-stage lagoon system and discharged weekly to the first cell. The first cell was overloaded by 23% as an anaerobic lagoon with an estimated daily loading rate of approximately 118 g of volatile solids per m3 of lagoon volume. To mitigate odour nuisance in the surrounding neighbourhood, a static-tube aeration system was installed in the first cell in an attempt to create an oxygenated surface layer on an otherwise anaerobic lagoon. Odour flux measurements with the new BCFC appeared to exhibit good repeatability based on a limited number of tests. Odour flux of the stratified lagoon measured using a simulated wind speed of 1.1 m/second in the BCFC averaged 1.72 odour units per second per m2 of lagoon surface area. The results are preliminary in terms of representing annual odour emission rates because odour flux is affected by wind and weather characteristics, results were based on only one constant wind speed that was simulated in the BCFC, and there were relatively few data points. The data was compared with odour flux measured at two unaerated anaerobic lagoons.