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Stormwater Pollution in the Botany Bay Catchment

As part of this program the extent of stormwater pollution entering into Botany Bay and its estuaries was modelled using E2 (now called Source Catchments). This information has been used to provide input data for the Ecological Response Model that was developed for the Bay and its estuaries. It covers a broad range of stormwater pollutants.
The report was completed in October 2007 and can be downloaded below.

Click here to download the Botany Bay E2 Pollutant Load Modelling Report, October 2007 (3.3 Meg!)

Some additional modelling has been done, again using E2, to breakdown the mean annual loads from the October 2007 report, based on council areas within the Botany Bay Catchment. This report contains a detailed breakdown of the pollutant loads being produced by each council as well as estimated annual council generation rates of stormwater pollutants. This report was completed in January 2008 and it can be downloaded below.

Click here to download the Council Pollutant Loads Modelling Report, February 2008 (1.4 Meg!)

We have also used the E2 model to look at the likely changes in pollutant loads due to landuse changes in 2030 and 2070. Some of the pollutants will increase by significant amounts if water quality improvement measures are not put in place. This modelling also looked at the reductions in certain pollutants (TSS, TN and TP) that could be achieved by implementing water sensitive urban design (WSUD). The report was completed in May 2008 and it can be downloaded below.

Click here to download the Modelling Report on Predicted Future Landuse Changes 2030 & 2070, May 2008 (2.7 Meg!)

The model results from the earlier work were then used to examine what might happen in the Botany Bay Catchment as result of climate change in 2030 and 2070 as well as changes in future landuse. This report was completed in July 2009 and can be downloaded below

Click here to download the Modelling Report on Predicted Climate Change & Future Landuse Changes 2030 & 2070, July 2009 (2.3 Meg!)

In addition to modelling the catchment pollutant loads UNSW were engaged to complete an Environmental Assessment of the sediments of Botany Bay and the Georges River. These studies are based on samples taken from more than 200 sites around Botany Bay and the Georges River over the last few years ago. These have been analysed for sediment type and geochemistry. The report displays the results on a series of maps of the Bay and the Georges River. The Botany Bay Report was completed in May 2008 with the Georges River report competed in May 2010. They y can be downloaded via the links below.

Click here to download the Environmental Assessment of Botany Bay's Sediments, May 2008 (4.8 Meg!)

Click here to download the Environmental Assessment of the Georges River Sediments, May 2010 (13 Meg!)

 

The following table and graph are extracts from the October 2007 final report, which can be downloaded above.
The table below shows the pre-urbanisation and current load differences for common stormwater pollutants in the Botany Bay catchment.

Constituent*

Mean Annual Load
(tonnes/yr)

Pre-European

Mean Annual Load
(tonnes/yr)

Current

Flow GL/yr

260 (GL/yr)

290 (GL/yr)

TSS

7,600

21,000

TOC

1,900

3,700

TN

180

360

TP

16

39

BOD

1,100

2,600

FC (*10 12 counts/yr)

1.1 (*10 12 counts/yr)

20 (*10 12 counts/yr)

* TSS= Total Suspended Solids, TOC= Total Organic Carbon, TN= Total Nitrogen,
TP
= Total Phosphorous, BOD= Biochemical Oxygen Demand, FC= Faecal Coliforms

 

The graph below shows the mean annual contributions of suspended solids from the major sources in the Botany Bay catchment (note the Prospect Creek figures are already included in the Georges River total).

Total Suspended Solids Graph showing breakdown of major sources

 
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Botany Bay Coastal Catchments Initiative Website