A DELWAQ nutrient model coupled to a Delft3D hydrodynamic model was set up for Tauranga Harbour and surrounding shelf, and run for three months during summer and three months during winter for 5 years. Model results were summarised in 34 different regions, aligned to the BoPRC reporting of sensitive receiving environments in Tauranga Harbour. Prior to undertaking the 5-year DELWAQ modelling, a sensitivity analysis was undertaken to tune key modelling parameterisations (primarily sediment denitrification). Nutrient and salinity outputs from the 5-year runs were compared against BoPRC monitoring data to assess performance. Salinity was generally over 30 ppt even in winter, except very near freshwater input zones. Flushing time varied substantially across the harbour from less than one day to 9 days.