Constituent Council(s):Ku-ring-gai Municipal Council

Constituent stream(s):Blackbutt Creek Falls Creek DeBurghs Creek

Honeysuckle Creek Links Creek

Rainfall Station(s):R07

Sewerage Overflows: 2

Stormwater outlets: 89

Water Quality sampling points: WQ014, WQ042

Pollution Control Device Numbers: none

Overview:

Landuse:

Period of sampling records: August 1989 - September 1996 % wet days: 31

Number of sampling occasions (N):31

Compliance of key indicators to guidelines - % of time guidelines met under all conditions.

Summary: Water quality in this sub-catchment is moderate. Sewage pollution and nutrient loadings are evident. The failure of DO and total phosphorus measurements to meet ANZECC guidelines suggest eutrophication and algal blooms.

Issues: The sub-catchment contains Gordon and Killara golf courses which may be large sources of nutrients for the five creeks which make up this catchment. The upper reaches of Blackbutt creek are within a narrow reserve which backs on to residential land. Riparian vegetation and the bushland of the reserve may be under threat from weed species and the water quality of the creek may suffer from nutrient loadings and propagules which are washed from household gardens.

Knowledge Gaps: This is one of the larger sub-catchments on the east side of Lane Cove River but is only served by 2 designed overflows. Sewage pollution may be coming from these points or from as yet undiscovered leaks. Further investigation is required.

Recommendations: Investigate the loads of nutrients and water coming from golf courses. Find the sources of additional pollution and if from designed overflows suggest an increase in the size of on site storage especially to cater for wet weather events.