Flesch, T. K., Vergé, X. P. C., Desjardins, R. L. and Worth, D. 2013. Methane emissions from a swine manure tank in western Canada. Can. J. Anim. Sci. 93: 159-169. The emission rate of methane (CH₄) to the atmosphere was measured from a concrete manure tank at a farrow-to-finish swine facility in western Canada. Measurements were made during four seasonal campaigns using a bLS inverse-dispersion technique. Emission rates were highest in summer and lowest in winter, with intermediate rates in spring and fall. Annual emissions were estimated at 7600 kg CH₄, or 6.3 kg CH₄ m^-2 of tank surface area. Site-specific factors used for estimating CH₄ emissions were calculated from our measurements. A simple methane conversion factor, used by the Intergovernmental Panel on Climate Change to relate emissions to the volatile solids content of the manure, was calculated as 0.23. This value may be unrepresentatively high due to the long duration (15 mo) that manure was stored in the tank. A more sophisticated calculation methodology considers the influence of manure storage duration and temperature, and includes a critical management design practices (MDP) factor. The MDP factor was calculated as 0.31 for our tank. This MDP value implies that emissions from our manure tank were lower than expected given the results from other studies.