This site provides access to the old data and its associated manual:
Kunapo, J., Walsh, C.J., Sammonds, M.J. (2020) The Melbourne Water Stream Network. Version 1.1. Melbourne Waterway Research-Practice Partnership Report 19.4a. School of Ecosystem and Forest Sciences, The University of Melbourne, Melbourne.
See the version 1.2 manual at tools.thewerg.unimelb.edu.au/mwstr/ for a description of the improvements in version 1.2.

You can access the version 1.1 manual via the pdf button below.

Table 1 of the version 1.1 manual provides links to download the old version 1.1 data in various formats.

This web page provides an interface for exploring the dataset by stream name.

Checking the 'Show catchment' option calculates and plots the catchment boundary of the selected stream, and provides an option to download the output as a GIS file.

Clicking on a reach will show its details. Selecting 'Plot only upstream of clicked reach' allows calculation of catchment area for that reach.

Select base layers and choose to show the stream, its trib and catchment using 'Layers', bottom left.

See this page for tips on using the app, including dealing with the curious case of the Yarra River.

You can find the mwstr version 1.1 app here It is less accurate in parts of the region, but retained to allow access to old reach codes.