Managing the health of our rivers: Shoalhaven River environmental flows
The NSW Office of Water developed new environmental flow rules for the lower Shoalhaven River that ensure more water is reserved for river health and better mimic the natural river flow.
The Office's work has advanced scientific knowledge of the Shoalhaven River and of the impacts of drought and water transfers on river health in general.
The new environmental flow rules were implemented in July 2009 and are being monitored under an adaptive management framework.
What are environmental flows?
The term 'environmental flows' refers to water that is protected from extraction or released from a dam or weir to maintain river health.
In the Shoalhaven, the environmental flow rules determine how much of the water flowing into Tallowa Dam must be released for the health of the lower Shoalhaven River.
What are the new rules?
The new environmental flow rules ensure more water is reserved for river health and better mimic the natural river flow. Under the new rules:
- 100 per cent of low dam inflows less than or equal to the 80th monthly inflow percentile (between 150 million litres per day and 371 million litres per day) will be released for river health. The amount of water released will vary depending on the actual inflows into Tallowa Dam, to better mimic the natural flow variability in the river
- 20 per cent of flows above the 80th monthly inflow percentile will also be released
- Special purpose environmental flow releases could be made to address specific downstream river health issues. Importantly water will continue to spill over the dam wall when Tallowa Dam is full.
What improvements are expected?
To support the new environmental flow rules, the Sydney Catchment Authority built new infrastructure at Tallowa Dam to allow native fish passage and improve the temperature and quality of water released from the dam.
The new rules and dam modifications are expected to bring about improvements in:
- The distribution of native fish species upstream and downstream of Tallowa Dam
- Water quality, particularly temperature, which will benefit native plants and animals
- Habitat and flow conditions, which could support the re-establishment of the endangered Australian grayling
- The size of river flows, which will benefit canoeists
- The length of the freshwater reach below Tallowa Dam, which will benefit swimmers and other recreational users.
How were the new rules determined?
An holistic approach was used when developing the new rules to ensure the water requirements of the entire river ecosystem were taken into account.
A broad range of scientific investigations were undertaken to better understand how ecological processes respond to changes in river flow and the likely implications for key ecological, social, economic and cultural heritage values.
Rules were selected that would best sustain those values and mimic natural river flow patterns.
Was the community consulted?
An extensive community consultation process was carried out, in partnership with the Sydney Catchment Authority (SCA). Consultation activities included:
- Regular meetings with the Shoalhaven Community Reference Group and key stakeholder groups
- Community newsletters
- An information centre in Nowra
- Roaming information booths in Nowra, Kangaroo Valley and Bowral
- Public exhibition of a discussion paper and release of technical information
- Advertisements and media releases
- Publication of fact sheets and information in hard copy and on the NSW Office of Water and SCA websites.
Comprehensive social, economic and cultural heritage assessments were also undertaken.
More information and publications
The following publications provide more detail on this work and the new environmental flows rules:
- Shoalhaven Illawarra riparian cover mapping study (PDF 2 MB)
- Report cards
- Boro Creek (PDF 1.2 KB)
- Broughton Creek (PDF 432 KB)
- Bungonia Creek (PDF 513 KB)
- Corang - Endrick (PDF 541 KB)
- Gerringong (PDF 432 KB)
- Jervis Bay (PDF 587 KB)
- Kangaroo River (PDF 447 KB)
- Lower Kangaroo (PDF 496 KB)
- Lower Shoalhaven (PDF 480 KB)
- Macquarie Rivulet (PDF 428 KB)
- Mid-Shoalhaven (PDF 594 KB)
- Milton-Ulladulla (PDF 468 KB)
- Minnamurra (PDF 477 KB)
- Mongarlowe (PDF 966 KB)
- Murramarang (PDF 419 KB)
- Nerrimunga Creek (PDF 565 KB)
- Reedy Creek (PDF 492 KB)
- Shoalhaven Estuary (PDF 468 KB)
- Shoalhaven Gorge (PDF 557 KB)
- Upper Shoalhaven (PDF 620 KB)
- Wollongong (PDF 465 KB)
- Shoalhaven River Water Transfer and Environmental Flows Discussion Paper (PDF 3.2 MB)
- Report 1 - Environmental Flows Knowledge Review (PDF 5 MB)
- Report 2 - Environmental Flows Investigations (PDF 2 MB)
- Map of the Shoalhaven River (PDF 449 KB)