Victoria's Water Supply
- Melbourne has the good fortune to have one of the cleanest water supplies
in the world with most of it coming from uninhabited rainforests in the
Yarra Ranges to the east of Melbourne, where more than 140,000 hectares has
been reserved for the primary purpose of harvesting water. There are only
4 other cities in the world that has such protected catchments.
- Melbourne's water storage capacity is 1,773,000ML, and consumption is some
500,000ML/yr = 400L per person day (having steadily risen from 250L per
person day in 1930, prior to which it was reasonably steady).
- the 2 major household measures to save water is AAA shower roses
(20,000ML/yr) and AAAA front-loading washing machines (27,000ML/yr)
- Major reservoirs:
- Thomson Reservoir:
- capacity 1,068,000ML contributing 60% of Melbourne's storage
capacity - currently is 40% full.
- it has a catchment area of 48,700 hectares and a surface area when
full of 2,230 hectares.
- inflows into the reservoir range from 93,000-310,000ML/yr with an
avg. of ~200,000ML/yr, peaking in 1996 but since then the drought
has resulted in avg. of only ~140,000ML/yr inflow.
- downstream releases are 46,500-239,000ML/yr avg. 50,000ML/yr
- created by the damming of the Thomson River in the 1970's,
diverting up to 93% of its river flow away from the Gippsland Lakes
to Melbourne's water supply which was said to drought-proof
- it was completed in 1983.
- unfortunately, the drop in some 57 billion litres/yr of water flow
into the Thomson River has had substantial impacts on the health of
the Gippsland Lakes ecosystem.
- to restore this, 40 billion litres/yr from the Thomson
Reservoir would have to flow back to Gippsland - 10% of
Melbourne's annual water usage - and a further flow from
reduction of down-stream irrigators.
- it may be possible to supplement this with redirection of
Melbourne's treated sewage from the existing outlet into
Bass Strait at Gunnamatta Beach, to the Gippsland region &
the Gippsland Lakes although locals are concerned about the
impact of sewage and in particular, the effect of residual
oestrogen & antibiotics on the ecosystem. Such a pipeline
would cost some $1b.
- Upper Yarra Reservoir:
- capacity 200,000ML, completed in 1957
- catchment 33,670 hectares with additional water is supplied from
- supplies Silvan
- O'Shannassy Reservoir:
- capacity 3,000ML, completed in 1928
- supplies Silvan
- Maroondah Reservoir:
- capacity 22,000ML, completed in 1927
- supplies Sugarloaf
- Sugarloaf Reservoir:
- capacity 96,000ML, completed 1981, receives water from Maroondah
- supplies north-eastern, western & central suburbs
- Yan Yean Reservoir:
- capacity 30,000ML, completed 1857
- supplies northern suburbs & central Melbourne
- Greenvale Reservoir:
- capacity 27,000ML, completed 1971
- supplies north-western & western surbs
- Silvan Reservoir:
- capacity 40,000ML, completed in 1932
- the heart of the water transfer system, receiving water from Upper
Yarra & O'Shannassy, and transferring it to the Cardinia and
smaller reservoirs for suburban distribution.
- Cardinia Reservoir:
- capacity 287,000ML, completed in 1973, water supplied from Silvan
- supplies south-eastern suburbs & Mornington Peninsula
- Watersmart City strategy:
- Melbourne's blue print for next 50yrs, released in 2002
- no new dams to be built for 50yrs & city not to take water from
north of the Great Dividing Range
- 15% cut on water use by 2010, although environmentalists believe the
target should be 25% reduction
- climate change & an extra million population by 2030 means a new
water source needs to be found.
- Melbourne's households predicted to increase by 50% by 2050