Creeks are interlinked with estuaries, wetlands, lagoons and beaches and affected by the surrounding catchment land use. 

A Creek Management Study was undertaken to 2004. It classified creeks according to their ecological value,  and provides a basis for deciding how best to go about protecting and repairing them.

Creek condition throughout Warringah varies. The non-urban catchments of near pristine catchments of Wheeler and Deep Creeks have very high ecological value and are classified as Group A creeks. The heavily degraded catchments such as South Creek in Dee Why and Greendale Creek in Brookvale are classified as Group C creeks and are generally of low to moderate ecological value with moderate to highly developed catchments.

All of Warringah’s creeks are under threat from development that results in poor water quality, increased sediment loads and weed infestations. The increase in hard surfaces means that more water runs off the catchment into the creeks via stormwater pipes at higher speeds and may cause flooding and erode creek banks and beds.

One of the biggest threats to our creeks is weeds. They choke creek lines and can smother native creek vegetation which is important habitat for native animals. In some circumstances, they can also pose a flooding risk.