The European eel (Anguilla anguilla L.) population has experienced a severe decline in recent decades, with restricted upstream migration of glass eels identified as a major contributing factor. In Flanders, glass eel potential entries are located at the IJzer (Nieuwpoort), the “Sas Slijkens” sluice complex (Ghent-Ostend Canal), and the complex in Zeebrugge (Afleidingskanaal van de Leie and Leopoldkanaal). To facilitate migration, adjusted tidal barrier management - slightly opening sluice gates during incoming tide - was evaluated between 2016 and 2025. This dataset contains monitoring results of electrical conductivity, discharge and precipitation and sluice management practices at these sites, providing insight into the effectiveness of adjusted sluicing measures and the trade-off between eel migration opportunities and salinization risks. The data currently stored is from 2020 to August 2025. The folder data is subdivided in: conductiviteit (conductivity data collected by VMM as provided at waterinfo.be) KGO: VMM conductivity data of the Kanaal Gent-Oostende (KGO) NE: VMM conductivity data of the Noordede (NE) Ijzer: VMM conductivity data of the Ijzer CTD (conductivity data collected by INBO) 2019 to 2025 (per canal further subdived in date that divers were read out; 1 file per site) AKL (Afleidingskanaal van de Leie) Ijzer KGO (Kanaal Gent-Oostende) LK (Leopoldkanaal) ND (Kanaal Nieuwpoort-Duinkerke) NE (Noordede) NP (Kanaal Nieuwpoort-Plassendale) debiet (discharge data collected by VMM as provided at waterinfo.be) One file per site intern (all data that was created within the R project) ctd (all INBO conductivity data brought together and standardized) ctd_vmm (all VMM conductivity data brought together and standardized) debiet ((all VMM discharge data brought together and standardized) metadata (treshold values, coordinates and links between stations) conductiviteitslimieten (tresholds for terminating the adjusted tidal barrier management and returning to regular tidal barrier management) coordinaten_ctd (coordinates of all INBO ctd divers) link_conductiviteit_debiet_neerslag (which VMM conductivity data is connected to which discharge and precipitation data) link_ctd_debiet_neerslag (which INBO conductivity data is connected to which discharge and precipitation data) neerslag (precipitation data collected by VMM as provided at waterinfo.be) One file per site spuibeheer (adjusted tidal barrier management records) extern ruw (as provided by the operators of the sluices) verwerkt_in_excel (corrections were made) intern