A water sensitive future

Improving Water Quality in the Botany Bay 'Hot Spot'

To achieve long-term protection of the surface waters of Botany Bay and its catchment a water quality improvement plan has been finalised and is being implemented through three key elements: monitoring of water quality, developing a decision support tool to find the best methods for improving water quality, and devolved grants to undertake work on the ground.

If Botany Bay’s development was to continue unheeded, then by 2030 there would be an 11 to 22 per cent increase in pollutants entering its waterways. If councils incorporate water sensitive urban design (WSUD), the impact of urban development will reduce dramatically.

Future scenarios for Botany Bay and its catchment are being modelled by the Sydney Metropolitan Catchment Authority as part of a water quality improvement project, funded with $1.5 million from Caring for our Country. The aim – in line with the national priorities of improving coastal hotspots and improving coastal community engagement – is for long-term protection of the surface waters of Botany Bay and its catchment.

This is vital to Botany Bay and its estuaries, which boast numerous endangered species and communities, a Ramsar-listed wetland and migratory bird species, and listed Aboriginal and European heritage sites.

Funding has helped to implement a Water Quality Improvement Plan that is deploying a real-time monitoring network, as well as a decision support tool to help land managers prioritise best practice methods to improve water quality.
Project manager John Dahlenburg says if WSUD is included in new developments and retro-fitted to existing developments, by 2070 water quality levels will be better than levels in 2006.

“WSUD is a new way of planning, designing and constructing urban environments that is sensitive to the issues of water sustainability and environmental protection,” John explains. “It requires a shift in thinking so that stormwater is viewed as a valuable resource rather than a nuisance.”

An example is a commercial building in the suburb of Loftus, which has permeable pavements on the car park and a bio-retention system to treat its stormwater. Developed and owned by the Sutherland Shire Council, the building captures the rainwater that falls on its roof and stores it in below-ground rainwater tanks to be used to flush the toilets throughout the building.

The project has also helped to develop a decision support tool for councils to test scenarios and then undertake the most effective water quality improvement activities.

“Training sessions have been held throughout the program and take-up by councils and stakeholders has been exceptional with great results throughout the catchment,” John says.

A Water Quality Monitoring Network of five stations has also been set up using real-time monitoring stations in the catchment, with data accessible online. The monitoring stations measure the water quality automatically every 10 minutes and send data back every half hour, which then appears on the project’s website:

• www.sydney.cma.nsw.gov.au/bbcci/monitoring-network.html 

Caring for our Country has also invested $770 000 into two rounds of water quality improvement grants, with a total project value of $3.2 million for 11 projects. One of these, in the suburb of Greenacre, involves a “rain garden” (a planted depression that allows rainwater runoff from impervious urban areas like driveways and walkways), built into a traffic median strip, which treats stormwater from the Drew Street residential area before it enters Coxs Creek and the Cooks River. Locals had significant input into design and construction. Computer modelling predicted that one 50 square metre rain garden could reduce 850kg of sediment from entering the waterway each year.