The valley of Muddy Creek where it passes through Rockdale is potentially at hazard from flooding, even though there have not been any major floods for a number of years. Significant recent floods were in 1975, 1983, 1993 and 1998.

Rockdale City Council, through the Rockdale Floodplain and Stormwater Management Committee, is developing a floodplain management strategy and plan for the Muddy Creek floodplain in Rockdale.

The Muddy Creek stormwater channel extends from Kogarah through the Main Southern Railway viaduct, through the centre of Rockdale and downstream to beyond Bestic Street. The study also includes Spring Street Drain, which is a tributary of Muddy Creek, and the adjacent Scarborough Ponds catchment. The study also considers the full range of flooding issues including some local stormwater drainage, but it does not consider stormwater quality.

The floodplain which this study covers, extends to the estimated limit of the Probable Maximum Flood (PMF) This study uses an extreme flood which, for all practicable purposes is equal to the PMF. The study area is shown in Figure 1 in the report.

Historical data is assembled and modelling. A one-dimensional hydrodynamic model was used by AWACS to derive design flood levels along Muddy Creek. The model used MIKE-11 software from DHI. This software is a well known and recognised program which is widely used for flood modelling.