Data from: Seasonal Variation in Methane Ebullition in a Temperate Hydropower Reservoir Related to Drawdown

Estimates of methane (CH4) emissions from freshwaters, including hydropower reservoirs, are highly uncertain, often based on annualization or upscaling from snapshot sampling events during the summer when water levels are high. Some uncertainty in these estimates exists because CH4 emissions, particularly via the ebullition (bubbling) pathway, are highly variable, and are sensitive to hydrostatic pressure and oxidation potential that varies with water depth. However, reservoir-wide estimates of CH4 ebullition often do not account for water depth variability or the size of the “ebullition zone”, potentially contributing to high uncertainty in CH4 emissions. In a case study of Douglas Reservoir, Tennessee, USA, we conducted a monthly sampling campaign March 2023 to March 2024 to capture annual temporal variation in CH4 ebullitive fluxes and the size of the ebullition zone due to seasonal fluctuations in reservoir water levels. This dataset includes the approximately monthly CH4 ebullition rates measured at 20 sites across Douglas Reservoir, along with the corresponding water depth at each site which fluctuated throughout the year due to seasonal drawdown. Additional information and data on drawdown at Douglas Reservoir can be found here: https://www.tva.com/environment/lake-levels/Douglas/Operating-Guide.