Date sent:        Mon, 29 Apr 1996 17:51:14 +1000

            Tom O'Callaghan
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Questions:
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What conclusions can you come to regarding the issues we have considered in 
the Cooks River Valley and at Bicentennial Park?

Are these issues becoming worse or are they being improved? What is the role
of management in these changes?


 The issues that we looked at were: uses of the areas, both water and
land, and their impacts; water pollution; visual water quality; impacts of 
fooding; role of mangroves; management strategies.

The sites visited were:
1)      Alexandra Canal
2)      Occupation Road - Kyeemagh
3)      Canterbury
4)      Fifth Avenue - Campsie
5)      Bicentennial Park - Homebush

 Area uses at site one have a considerable impact on the Cooks River.
The land uses were residential, industrial, commercial, recreational, and 
also roads and the airport. Water uses were boating, fishing, waste disposal,
storm water drainage, and possibly a scenic resource. The impact of the land 
uses are that they increase runoff, because of the surface being covered by 
buildings and impermeable surfaces, water cannot be absorbed by the ground; 
a further impact of these land uses is and increase in rubbish, and then 
possibly water pollution. The impact of the water uses is water pollution, 
caused by the boats themselves, and by waste disposal and the storm water 
drains, bringing rubbish from elsewhere. 

 The uses at site two were land based. These uses were a market 
garden, and a bridge. The impacts of the market garden would be an increase 
in fertilizers, herbicides, pesticides, and some sedimentation in severe 
flooding that would effect Muddy Creek and Cooks River. The impact of the 
bridge would be "back-up flooding". This would be caused when debris such as 
branches would become stuck between the pylons of the bridge, thereby further 
reducing the flow (the presence of the pylons presently slows the flow down), 
this would then lead to back-up flooding.

 At the Canterbury section of Cooks River, there were only land uses. 
The area was predominately residential and recreational, with a small amount 
of agriculture, storm water runoff drainage, and the remains of an industrial 
building. There were facilities for boating, however, now they are not used. 
The was a very large amount of pollution in the water. However, there were 
some fish in the river, and a pelican and other water fowls.

 At the fourth site, the main land use was recreation, with some 
residential. The impact of these and the car bridge were not great, with not a 
great amount of visual pollution. At Bicentennial Park, the land uses were 
recreational, wildlife reserve, scientific research, and an educational 
resource. These uses with the water uses, boating, do not appear to have an 
impact upon this area.

 The water pollution in all sites was caused by industrial dumping, 
storm water drains, litter, and sediment. The number of industries dumping 
waste into the Cooks River has decreased from 110 in 1975 to 10 in 1991. The 
storm water drains bring rubbish, in addition to the rubbish that falls into 
the river directly. Due to the amount of bank erosion, there is a large 
amount of sediment, 25 000 tonnes. This sediment is so rich in heavy metals, 
that it could be mined. There are also approximately 150 points where raw 
sewerage can enter the river in times of heavy rain.

 The visual water quality varied from site to site. At Alexandra Canal, 
visually, the water appeared to be reasonably good. At Canterbury, the visual 
quality was at its worse, the river was covered in floating rubbish. Further 
upstream at Fifth Avenue, the visual water quality was not too bad (that is 
there was some rubbish in in the water). At Homebush Bay, the visual water 
quality appeared to constitute nothing.

 In a time of flood, the areas that would have an impact on the river 
would be sites 2,3 and 4. Site 2 could (if the flood was high enough) cause 
sediments, fertilisers, herbicides, and pesticides to be dumped in to Muddy 
Creek and Cooks River. The increase in fertiliser level could create and algal 
bloom, and the introduction of herbicides and pesticides could have adverse 
affects on the marine population. Sites 2 and 4 would have an impact because 
then the residential areas could be flooded, or the flow of rubbish would be 
disrupted.

 The role of Mangroves is to be a natural treatment of water pollution. 
The Mangroves achieve this by trapping pollutants in their net-like 
entanglement of roots. The Mangroves also supply a habitat for birds and 
aquatic life. The Mangroves provide the Paramatta River with oxygen. The 
Mangroves also provide a Scenic source, and trap sediment. The benefit of 
Mangroves is the large savings that they give, to replace the Mangroves with 
manmade sewerage treatment plants would cost US$123 500 per hectare, and to 
replace them with recreational amenities would cost US$8 105 per hectare.

 When compared with last years results, there does appear to be an 
improvement in the water quality. However, this was aided by the heavy 
rainfall. The management strategies seem to be working, however, the 
management strategies need to be extended, because they are not solving the 
problem completely.

The Management Strategies were:
- Protection of banks with rocks, concrete, or steel, to stop bank erosion,   
  and hence sedimentation
- Signs with fines for littering ($20 000 at Fifth avenue)
- Storm water drains to stop urban flooding
- Floating Booms to capture rubbish
- Trash Racks to capture rubbish on a rack, in the storm water drains
- Gross Pollutant Trap (this uses a deep well to trap sediment, and a trash   
  rack to capture floating rubbish)
- Water Quality Testing, to judge the effectiveness of these strategies
- Mangroves at Bicentennial Park, pollutant trap, wildlife refuge.

 In conclusion, the management strategies do appear to be making an 
improvement to the Cooks River. However, the improvement is at a slow rate, 
and needs to be expanded to start to show any great signs of improvement.
