Allans Creek rises in the steep escarpment located to the west of the city of Wollongong. It is composed of three main tributaries; American, Byarong and Charcoal Creeks. The upper part of the catchment is steep wooded land while in the lower catchment is heavily urbanised. The Public Works Department (PWD) commissioned Cameron McNamara Pty Ltd to undertake a comprehensive flood study of Allans Creek and its tributaries. The investigation has three phases as follows:

1. Collection and review of all available data.
2. Development of numerical models to predict the behaviour of the creek system during the course of a flood.
3. Determination of the one, two and five percent of probability floods along designated tributaries of Allans Creek.