Constituent Council(s):Ryde City Council, Hunters Hill Council

Constituent stream(s):Buffalo Creek

Strangers Creek

Rainfall Station(s):R12

Sewerage Overflows: 14

Stormwater outlets: 43

Water Quality sampling points: WQ019, WQ061

Pollution Control Device Numbers: D010, D011, D013

Overview:

Landuse:

Period of sampling records: August 1989 - March 1998 % wet days: 0

Number of sampling occasions (N):4

Compliance of key indicators to ANZECC guidelines

Summary: Water quality in this sub-catchment is poor. There is evidence of both sewerage and nutrient pollution. The data is only taken for dry conditions indicating that in wet weather, overflows of sewerage will be even greater.

Issues: The possibility of algal blooms in Buffalo creek are likely given the eutrophic conditions. The sewerage system is clearly incapable of dealing with dry weather flows of sewage so the situation in wet weather will be considerably worse. The sub-catchment is large with a high proportion of residential land so the problem is widespread.

Knowledge Gaps: Sewerage, stormwater and water quality data is adequate for the sub-catchment. Water quality sampling sites are spread across the catchment giving information on the upper and lower reaches.

Recommendations: The sewerage system in this sub-catchment is ineffective and needs to be upgraded. Three PCDs exist in the sub-catchment. GPTs at Ryde Park and Pains road and a trash rack in Blaxland road. Their effectiveness needs to be assessed and methods for trapping nutrients in runoff such as wetlands need to be considered