Before the nineteenth century, a substantial portion of the Hungarian Great Plain consisted of seasonally or permanently waterlogged habitats, which underwent radical transformation following large-scale water regulation interventions in the Tisza Valley. As a result, extensive wetlands were converted into arable land, causing a major loss of natural vegetation. We surveyed the Eastern (Ke­leti), Western (Nyugati), and Nagykunság Irrigation Main Canals and selected tributaries to map the distribution of six native wetland species (Carex pseudocyperus, Nymphaea alba, Nymphoides peltata, Trapa natans, Salvinia natans, and Stratiotes aloides). Field surveys were conducted in summer 2022 along the full length of the main canals using 50-m transects spaced ~300–900 m apart (depending on accessibility and vegetation visibility); all sampling locations were recorded in WGS84. To evaluate the potential contribution of water flow to dispersal, we (i) counted drifting individuals of three predomi­nantly free-floating species (S. natans, T. natans and S. aloides) during 60-min observation periods at 26 sites, and (ii) measured surface drift velocity at 24 bridges using 20-cm Phragmites stem fragments (10 replicates per site). All six target species occurred along the Western Main Canal, five along the Eastern Main Canal and three along the Nagykunság Canal. Salvinia natans was the most widespread species, whereas Nymphaea alba was recorded only rarely; Nymphoides peltata was detected exclusively along the Western Main Canal. Surface drift velocity differed markedly among canals, with the highest mean values in the Eastern Main Canal (0.34 ± 0.18 m/s) compared with the Western (0.17 ± 0.03 m/s) and Nagykunság (0.15 ± 0.03 m/s) canals. During drift counts, S. natans was observed at all sites (often >1,000 individuals per hour), T. natans at eight sites (118 individuals in total), and S. aloides as a single drifting specimen. Based on measured drift speeds, a small free-floating macrophyte could be trans­ported up to ~29 km per day in the Eastern Main Canal; order-of-magnitude extrapolations from hour­ly counts suggest that millions of individuals, particularly S. natans, may be dispersed downstream during the summer vegetation period. Our results indicate that irrigation canals can support native aquatic plant populations and may facilitate downstream dispersal in the Great Plain, highlighting their potential conservation value in an otherwise habitat-poor agricultural landscape.