1.    General Description

Blacktown Creek flows from Prospect Reservoir in the south to join Toongabbie Creek at International Park north of the railway line. Several large parks, William Lawson and Orana Park, form part of the creek corridor. This creek corridor is one of the most altered in the Upper Parramatta River Catchment with large sections of the creek in concrete channels and the adjacent open space containing only scattered vegetation remnants in exotic mown grass.

2.Map Title

See Map 6 - Blacktown Creek Sub-catchment Map.

3.Geology

Blacktown Creek along with Greystanes Creek, Pendle Hill Creek, Finlaysons Creek, and Coopers Creek, drain from the south west of the catchment to join with Toongabbie Creek north of the railway line. These creeks flow across the Cumberland Plain, which is a low, undulating plain underlain by horizontally bedded sediments of the Wianamatta Group, mainly Bringelly Shales. These shales are generally composed of claystones, siltstones and carbonaceous shales with sparse sandstone lenses. The sediments were laid down in a coastal alluvial plain during the middle Triassic, (200Mybp). The creek bed has been engineered along much of its length so rock exposure is rare.

4.Geomorphology

Blacktown Creek has been severely altered by engineering so little of it is in its natural state. At its upper reaches, the creek is contained in a concrete drainage swale. In the lower reaches, through Orana Park, Wall Street Reserve and International Peace Park the creek bed remains in a natural state. Commercial, retail and school properties impinge on the easement of the creek at St Martins Crescent and Mitchell High School. Water velocity increases as it passes along the engineered sections of the creek, resulting in erosion of the banks in the more natural, lower reaches of the creek. The topography of the sub-catchment is flat to undulating, the highest point less than 100 metres above sea level near Prospect Reservoir.

5. Soil Types

The Blacktown Creek sub-catchment soils are generally fine-grained silts and clays. The predominant soil landscape in the sub-catchment is Blacktown, which has been formed by residual geomorphic processes. These soils are generally of low fertility and less than 100 cms in depth.

Much of the creek has been altered by engineering with concrete drains and grassed swales so little natural vegetation and soil exposure remains.

6. Vegetation communities

The most significant vegetation remnant in the corridor is a stand of Grey Box Woodland, (including species such as Spotted Gums, Forest Red Gums (E tereticornis), Grey Box (Eucalyptus moluccana)) on private land at Norman Street, Prospect. Grey Box also occurs on the eastern edge of William Lawson Park. Grey Box, or Cumberland Plain Woodland, is listed as a Schedule 1 endangered ecological community. Scattered indigenous trees, either Grey Box or Forest Red Gums, with little or no understorey occur in other parks and easements along the remainder of the creek.

Along the western edge of the creek, adjacent to St Martins Crescent exotic poplars have been planted.

In Orana Park, patches of riparian vegetation including Swamp Oaks, ( line'>Casuarina glauca) survive along the steep banks of the creek. Exotics such as Willows and Silky Oak have self-seeded.

7. Biodiversity

Blacktown Creek is in varying states of ecological health along the corridor. There are negligable aquatic fauna or flora along the engineered sections of the creek.

The remnant vegetation supports only limited fauna as the communities are isolated.

In Orana Park, where the creek is in a semi-natural state, native and introduced birds feed and nest in the Swamp She Oaks and the weedy understorey provides protection and shelter for small birds and possibly lizards and ring-tailed possums.

8.Hydrology

Flow regime is the long term pattern of high flows and low flows in creeks and rivers.

Generally there is very little flow in catchment creeks for the majority of the time. 98% of total flow volume leaves the catchment 2% of the time, (Master Thesis, Downes, 1998).

Dry weather, (base) flows are generally greater in Darling Mills Creek, Hunts Creek and their tributaries which rise in the Hawkesbury Sandstone areas in the north east of the catchment. Creeks such as Blacktown Creek that originate in the Wianamatta Shale country, that is, in the Cumberland Plain to the west and south, have very little dry weather flow.

As the creek is enclosed in concrete swales for the majority of the upper reaches, water velocity during storm events can become exceedingly high, this causes severe erosion of the natural banks in the lower reaches of the creek.

9. Rainfall

Rainfall measurements between 1969 and 1996 show that there is a significant variation in the rainfall intensity and average in the catchment.  The highest average rainfall occurs in the north-east section of the catchment, (headwaters of Darling Mills Creek, 1200mm per year) and the lowest in the south-west, (headwaters of Toongabbie and Greystanes Creeks, 800mm per year).

10.Landuse

Blacktown Creek begins at Prospect Reservoir and joins Toongabbie Creek at International Peace Park. It flows through several large parks, William Lawson, Wall Street Reserve, Mitchell Reserve and Orana Park, beside three schools and through a commercial district. Much of the corridor is in public ownership, either crown land or owned by Commonwealth agencies. Suburban development backs onto the creek throughout most of its length with existing pedestrian footpaths connecting east to west across small sections of public parks. Informal paths and cycle ways indicate the easement is used as a corridor connecting Seven Hills railway station with the southern suburbs. There are a number of recreational facilities in the park – playing fields, tennis courts and picnic areas.

Litter and silt from surrounding cleared land and housing development ends up in the creek and accumulates excess nutrients and heavy metals from vehicular emissions and other industrial materials.

11. Social History and impacts on landuse and the environment (incl. Aboriginal history)

The following information concerning the History of Blacktown is taken from Blacktown Library website.

Today Parramatta and Blacktown are thriving urban areas and make up a major regional centre. The catchment area of 108 km², is 70% urbanised and contains approximately 80,000 properties and a population of 220,500 (Australian Bureau of Statistics, 1999). The cities of Parramatta and Blacktown are located at the perimeter of the catchment; Parramatta Central Business District being at the outlet, and Blacktown at the western extremity.

The long history of intensive use of the catchment has resulted in significant environmental management problems. Today factories, residences and commercial businesses cover the area, impervious surfaces such as roads, roofs and car parks result in more frequent flooding and all forms of land use, (residential, commercial, recreational and industrial), have caused severe deterioration in water quality.

12.Community Groups

Local communities should be encouraged to participate in the revegetation of Blacktown Creek. The following opportunities have been suggested in the Green Corridor Management Strategy:

·           Encourage greater awareness of the importance of maintaining a healthy creek ecology through letter drops, signage along the creek corridor, formation of creek restoration groups and creek visit days

·           Encourage community groups to apply for funding via such means as the Natural Heritage Trust

·           Encourage local community groups to enlist the support and backing of local business and retail outlets

·           Encourage active involvement of Mitchell High School to rehabilitate that section of the creek alongside their school

·           Initiate Bushland Watch schemes incorporating local volunteers at Norman Street to prevent fires and dumping in the significant Grey Box Woodland remnant.

13.Management Measures in Place

The following management measures have been taken to alleviate flooding and improve water quality in Blacktown Creek. These are maintained by Blacktown City Council.

14.Management Issues

Revegetation and restoration works could substantially improve biodiversity along the creek corridor. This is readily achievable as much of the land is zoned public open space. The following ideas have been put forward for the rehabilitation of Blacktown Creek

·          Between Keyworth Drive and Blacktown Road, where the creek flows through open space behind Mitchell High School and adjacent to St Martins Crescent, the opportunity presents itself for rehabilitation of the creek to a more natural state by introducing riffles, meanders and a constructed wetland.

·          Rehabilitate banks in Orana Park by planting indigenous riparian and aquatic vegetation and install litter traps

·          Replant understorey species and create “no-mow” zones around existing Grey Box Woodland trees in William Lawson Park, Orana Park and Wall Park Reserve to encourage regeneration.

·          Revegetate large grassed easements between Lancelot Street and Blacktown Road with riparian and Grey Box Woodland communities especially reintroducing understorey species, grasses, sedges and aquatic flora

15. Other Resources and Links

·           Blacktown Creek Sub-Catchment Map

·           Upper Parramatta River Catchment Trust www.uprct.nsw.gov.au

·           Nature Conservation Council www.nccnsw.org.au

·           Department of Land & Water Conservation www.dlwc.nsw.gov.au

·           National Parks & Wildlife Service www.npws.nsw.gov.au

·           Blacktown City Council www.blacktown.nsw.gov.au