Biodiversity Strategy - Gosford City Council - NSW Government

• appropriately timed collection of litter in Council bins; and
• on-site containment and appropriate disposal.
While source controls (non-structural and structural) should be considered as the first option for
stormwater impact reduction, these measures would generally not be sufficient to completely
halt the transport of most pollutants. Measures to treat stormwater and remove pollutants instream
will inevitably be required. This is the Treatment Train Approach to stormwater
management described in the Gosford City Council Stormwater Management Plan (GCC,
1999).
In general, the treatment of stormwater should, where possible, reduce the quantity of
stormwater entering receiving water bodies and allow filtration to remove particulates and
dissolved pollutants. This is a significant change in approach from the long-held concept of
rapid removal of stormwater to reduce the potential for flooding, however there is an obvious
need to balance stormwater velocity retarding approaches with the potential of the approach to
increase flooding. The approach can be taken at any point in the drainage line however the
process is most efficient (in terms of pollutant reduction/removal) when implemented on a small
scale where there is also likely to be less likelihood of increased flooding. Some of the
approaches that can be used to this end include:
• collection of rainwater where it falls;
• top of catchment infiltration;
• structural options for top of catchment removal/capture;
• in-line/end of line capture/treatment; and
• management of receiving water bodies.
The NSW Department of Infrastructure, Planning and Natural Resources has produced the
Geomorphic Categorisation of streams within the Central Coast Catchment Management Board
Area (Cook, 2004). The objective of the Geomorphic Assessment was to provide an appraisal of
geomorphic condition and a prioritisation of management efforts based upon a whole of
catchment assessment. It was based on the River Styles® Framework, which is procedure that
aims for consistent and comparable assessment of a river’s biophysical health.
This approach is recognised Australia wide as an effective simple step-by-step procedure to
achieve consistent and comparable results:
• it assesses river character and behaviour and most importantly allows for the
developmentof a rating based around a stream’s recovery potential; and
• it categorises stream reaches based on the biophysical characteristics such as the
planform, channel geometry and the surrounding assemblage of vegetation and
landforms (recognising that fluvial systems are zones of biological, physical and
chemical interaction between terrestrial and aquatic ecosystems).
The most dominant stream type in the Gosford area is the meandering sand bed stream that
occurs generally around the mid to lower reaches of the catchment and is very sensitive to
change. In sand bed streams riparian vegetation and large woody debris or snags play a very
important role in both the physical and ecological functions of the river system. Riparian
vegetation assists in stabilizing stream channels and often represents the only mechanism
contributing to the formation and maintenance of pools and riffles via scouring of the bed and
sediment trapping and retention. The loss of these natural controls could result in dramatic
changes to channel structure and the loss of
habitat essential for the functioning of a healthy stream.
Biodiversity - Technical Report Page 150