This dataset has been collected thanks to the long-term partnership with Department of Agricultural Land Management (DALaM), Lao PDR, which granted the permission for field access, and to the financial, scientific, technical, and/or logistical support of the Multiscale TROPIcal CatchmentS (SNO M-TROPICS; https://mtropics.obs-mip.fr/) critical zone observatory (previously MSEC). The tabular data provided include water quality and environmental variables measured within and outside a set of 15 mesocosms installed from August 9 to August 16, 2019, across the main headwater wetland of the Houay Pano catchment, northern Lao PDR. Water quality variables are Escherichia coli concentrations (MPN 100 mL-1) for both total and free-living bacteria with upper and lower limits of the confidence interval, total suspended sediment concentration (g L-1), turbidity (NTU), and dissolved organic carbon concentration (µM C). Environmental variables are Rainfall (mm mn-1), temperature (°C) in the air, the water, and the sediment, and solar radiation (W m-2) in the surrounding vegetation at 380, 100, and 3 cm height above swamp bottom sediment, and inside mesocosms. Water volumes include initial and final water volumes (mL) in each one of the mesocosms. In the mesocosms, a control and four treatments were tested: resuspension-dark (RD), resuspension-light (RL), deposition-dark (DD), and deposition-light (DL). The authors acknowledge the financial support of the Institut de Recherche pour le Développement (IRD) and the French national grant EC2CO-Biohefect/Ecodyn//Dril/MicrobiEn (NARIBACT).