These are very common around many of our lakes and other water courses in Perth and if you catch them at the right times it's easy to come across several in a very short period of time.
The introduced grasses, reeds, melaleuca and a diet of frogs keeps them around in abundance and If need be they have no problem diving in the water and seeking refuge in submerged tree roots etc to escape predation.
The average jogger would be amazed at how many they must pass unnoticed if somebody took the time to show them just how many there are and how easy to find if your looking for them.