33 Dr Banens in his statement of evidence states that, "water quality in streams and drinking water storages is largely the reflection of the nature of land use within their catchments". He also notes that:
The Werriberri Sub-catchment is located with the Warragamba special area close to lake Burragorang and Warragamba Dam. It is the closest sizable catchment near the off take of Sydney's water supply at the dam wall. Compared with much of the Warragamba catchment Werriberri Sub-catchment has a moderate - high population density in close proximately to the dam. Further, Sydney's increase in population is placing additional pressure on the peri-urban areas such as Werriberri sub-catchment. The Audit report also noted that large areas of agriculture, increases in intensive agriculture and increase urbanisation and rural residential will all continue to put pressure on water quality within the catchment.
34 Dr Banens considers that:
Further, the nature of activity associated with rural residential use are uncertain and cannot be determined in advance… Un-sewered rural residential development is linked with prudent runoff, however there are site factors other than land use that also influence such impact.…
This subdivision has several major drainage lines running through it, while significant parts of two blocks are relatively steep, which are likely to increase pollutant runoff and have a greater impact on water quality.
Furthermore, being located relatively close to the reservoir, this development can be considered to have proportionally greater impact than in equivilent development located away from the drainage network and in the outer part of the catchment.
The site constraint may also concentrate activities over a smaller area resulting in a greater pressure than if that activity had been spread more evenly over the block. If this proposed subdivision is a precedent for allowing similar subdivision of larger lots across the Wollondilly LEP 5(c1) water catchment zone then there is the potential for very significant increases in polluted loads to be generated, as this zone comprises around 25% of the Werriberri catchment.
35 In response Mr Morse states:
Dr Banens is being relatively simplistic in linking pollution hazards to the intensity of development if intensity is measured mainly in terms of houses and the number of bedrooms contained in them. Pollutants also come from other sources, including livestock. While a proposed development will increase the number of people living on the site, it will substantially reduce livestock numbers.
The site as it exists today is one where the land use is highly polluting because of very high horse stocking rates (48 mares and 10 foals on 30 h). …
In terms of nutrient pollution on head for head basis, horses are not as pollutant as beef or dairy cattle nevertheless they still produce significant quantities.
36 Mr Morse proposes a number of development control measures in the form of conditions and these are outlined in his statement of evidence as follows:
We propose to allow for the extra houses and waste water treatments systems by reducing the horse carrying capacity by three horses from the current 53 to 50. This means each of the current allotments will carry the equivalent of 16.66 horses.
Further we propose to reduce the captivated carrying capacity to less than half that being carried now i.e. to eight horses to each allotment. Should a future owner wish to run cattle, however this number is reduced to four. Should a future owner wish to run any other form of livestock the total number is confined to eight.
Confining livestock numbers will be achieved through a s 88 the instrument.
By following the above requirements we can confidently state that we will a neutral or beneficial effect from nutrients from storm water.
37 The applicant also proposes that a 'plan of management' be prepared before any dwelling house is constructed on the resultant lots. The purpose of the plan is to provide water quality goals and bush-land regeneration, erosion control and stocking and fencing guidelines. The plans would also address issues like the on-going maintenance and monitoring of the system.