14 Blue Gum Creek
Water Quality Ranking: 32 / 43
Data Reliability Ranking:
31 / 43Constituent 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
Overview:
Landuse:
|
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
Compliance of key indicators to guidelines - % of time guidelines met under all conditions.
|
Parameter |
|||||||
|
pH |
Faecal Coliforms |
% Diss. Oxygen |
Diss. Solids |
Total P |
Total N |
Ammonia |
Chl. - A |
|
87 |
10 |
23 |
0 |
10 |
3 |
10 |
0 |
Summary: 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.
Issues: 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.
Knowledge Gaps: 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..
Recommendations: 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.