This report contains information about all the sub-catchments in the lane Cove River Valley.
In relation to Chatswood West,there are two sub-catchments identified. These are:
Water Quality Ranking: 32 / 43
Data Reliability Ranking: 31 / 43
Constituent Council(s):Ku-ring-gai Municipal Council
Constituent stream(s):Blue Gum Creek
Rainfall Station(s): R09
Sewerage Overflows: 2
Stormwater outlets: 16
Water Quality sampling points: WQ018
Pollution Control Device Numbers: none
Landuse | Area (ha) | % sub-catchment | % LCR catchment |
Open space | 53 | 43 | 2.7 |
Residential | 60 | 49 | 1.3 |
Business | 2 | 2 | 1.5 |
Industrial | 0 | 0 | 0 |
Special Uses | 8 | 7 | 0.9 |
Special Zones | 0 | 0 | 0 |
Total | 123 | 100 | 1.5 |
Period of sampling records: August 1989 - March 1998 % wet days: 16
Number of sampling occasions (N):33
Parameter
pH | Faecal Coliforms | % Diss. Oxygen | Diss. Solids | Total P | Total N | Ammonia | Chl. - A |
87 | 10 | 23 | 0 | 10 | 3 | 10 | 0 |
Water quality in this sub-catchment is very poor. A large number of samples have been taken including those on
wet days and has shown faecal contamination, nutrient loads and deoxygenation of the water to be high. Old
sewerage infrastructure is one possible cause of this.
Only 2 designed overflows exist in this sub-catchment. It is clear that sewage is present much of the time in
Blue Gum creek. Exfiltration may be a contributing factor.
Information on exfiltration rates is available from SWCs Licensing Sewerage Overflows EIS but rates suburbs
as high, medium or low. It does not provide details on where specific problems arise but the Sewerage and
Stormwater overlay may be of some assistance in identifying the location of sewerage mains and possible leaks..
An investigation of possible leaking sewerage pipes is suggested for this sub-catchment. It may be beneficial to place an additional sampling point in the upper reaches of the sub-catchment to determine where the bulk of the problem is coming from.
Water Quality Ranking: 34 / 43
Data Reliability Ranking: 35 / 43
Constituent Council(s):Willoughby City Council, Lane Cove Council
Constituent stream(s):Swaines Creek
Rainfall Station(s)R09
Sewerage Overflows: 2
Stormwater outlets: 37
Water Quality sampling points: WQ026, WQ027, WQ034
Pollution Control Device Numbers: D018
Landuse | Area (ha) | % sub-catchment | % LCR catchment |
Open space | 72 | 52 | 3.6 |
Residential | 56 | 40 | 1.2 |
Business | 2 | 1 | 1.5 |
Industrial | 1 | 1 | 0.5 |
Special Uses | 7.5 | 5 | 0.9 |
Special Zones | 0.5 | 0 | 0.2 |
Total | 139 | 100 | 1.7 |
Period of sampling records: December 1996, March 1998 % wet days: unknown
Number of sampling occasions (N): 4
Parameter:
pH | Faecal Coliforms | % Diss. Oxygen | Diss. Solids | Total P | Total N | Ammonia | Chl. - A |
75 | 67 | 25 | 50 | 0 | 50 | no test | no test |
Water quality in this sub-catchment is poor. Swaines creek is largely urbanised, contains Chatswood golf course, bowling greens and a number of ovals and playing fields.
This area of the catchment is quite old and sewerage infrastructure is failing. Large trees penetrate and choke sewerage lines with their roots and the pipes crack and leak. There is little flow in the stream and so stagnation can occur, reducing the DO levels.
More information regarding exfiltration and other sewerage overflows is required. The effectiveness of PCDs is unknown.
Creek treatments such as that in Ferndale park need to be assessed for their effectiveness. If they are deemed to be successful, more devices need to be installed. A rapid improvement would be achieved if the sewerage system were expanded to allow for greater volumes and relined to reduce leakage.
(1992 - 1998)
Station number : NPWS1 Station name :
Locality : CHATSWOOD WEST
Lat : Long:
Map: U0952 E: 2914 N: 5930
Elevation : metres
Opened on : 02-08-92
Still open -
WQ018: Blue Gum Creek
Map U0952
Easting 2977; Northing 5928
WQ026: Swaines Creek - Chatswood Golf Club
Map U0952
Easting 2953; Northing 5842
WQ027: Lane Cove River 200m upstream Swaines Creek
Map U0952
Easting 2938; Northing 6863
WQ034: Mowbray Park Athletic Field
Map U0952
Easting 2835; Northing 5832
Swaines Creek Overflows
Site #67 Swaines Creek: Swaines Creek Sub-main; Easting 2968; Northing 5840. SWCRef: NS251MH
Site #68 Swaines Creek: suburban: Easting 2897; Northing 5798. SWCRef: NS085
Blue Gum Creek Overflow
Site #69 Blue Gum Creek: Blue Gum Creek submain; Easting 2977; Northing 5918. SWCRef: NS250MH
Site #71 Blue Gum Creek SPS 278 suburban; Easting 2942; Northing 5850; SWCRef: NS139
D018: Willoughby Council creek treatment installed `1996 Ferndale Park, Chatswood; Easting 3075; Northing5795
DNNN: Willoughby Council stormwater overflow treatment installed 1996 (?); O.H.Reid Reserve; Easting ????; Northing ????