Small freshwater reservoirs are ubiquitous and likely play an important role in global greenhouse gas (GHG) budgets relative to their limited water surface area. However, constraining annual GHG fluxes in small freshwater reservoirs is challenging given their footprint area and spatially and temporally variable emissions. To quantify the GHG budget of a small reservoir, we deployed an eddy covariance system in a small (0.1 km²) reservoir located in southwestern Virginia, USA for a full year to measure carbon dioxide (CO₂) and methane (CH₄) fluxes near-continuously. Fluxes were coupled with in situ sensors measuring multiple environmental parameters. Throughout the year, we found the reservoir to be a substantial source of CO₂ (~600 g CO₂-C m^-2 yr^-1) and CH₄ (~1.0 g CH₄-C m^-2 yr^-1) to the atmosphere, with significant sub-daily, daily, weekly, and approximately monthly timescales of variability. Importantly, we found annual GHG emissions estimated using eddy covariance were over an order of magnitude greater than diffusive GHG fluxes measured weekly to biweekly. During the winter, we found GHG fluxes during partial ice-on and open-water conditions were not statistically different, suggesting reservoirs may play an important role in freshwater GHG budgets throughout the year, not just during the open-water period. Finally, we identified several key environmental variables that may be driving GHG fluxes, specifically, surface water temperature and dissolved oxygen concentrations. Overall, our novel year-round eddy covariance data from a small reservoir indicate that these freshwater ecosystems likely contribute a substantial amount of CO₂ and CH₄ to global GHG budgets.