This report summarises the data set compiled for the project “PRW and Lake Wivenhoe modelling update”. Most of the data were collected by Seqwater over several years of regular monitoring, and other data were collected during event-based sampling or for specific projects. Parameters that were not measured locally, but are required by the model as input, are indicated in the individual data sections of this report. The report includes data used for the catchment model and the lake model used in the project. It summarises data sources, QA/QC procedures, and assumptions that were made to fill gaps in the data sets. The focus is on the lake model, while the catchment model data are summarised briefly here and described in detail in the final project report (Yu et al. 2020).