Unregulated Diversions Water Outlook for Melbourne Water Licence Holders
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Unregulated Diversions
Water Outlook for
Melbourne Water Licence
Holders
November 2017
Melbourne Water is owned by the Victorian Government. We manage Melbourne’s water
supply catchments, remove and treat most of Melbourne’s sewage, and manage rivers and
creeks and major drainage systems throughout the Port Phillip and Westernport region.
Table of contents
1. Executive Summary ........................................................................................ 3
2. Introduction ................................................................................................... 3
3. Season to date & current streamflow ............................................................. 4
4. Climate Outlook .............................................................................................. 6
4.1 Average rainfall and warmer season ahead........................................................... 6
4.2 Seasonal Streamflow Forecasts October – December 2017 ..................................... 8
5. Forward outlook for 2017/18 summer season................................................ 9
6. Other factors affecting entitlement holders and the environment ................ 10
7. Further information ...................................................................................... 10
2
Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
1. Executive Summary
Prevailing dry to average conditions through winter and spring this year has led to the early
introduction of bans and restrictions within major catchments in the Yarra basin. The seasonal
rainfall and temperature outlooks suggest Melbourne Water’s unregulated stream customers
should anticipate high levels of bans and restriction commencing in early December and likely
to extend to the end of the peak irrigation period in March / April 2018. Recovery of
streamflows is likely to be slow without an influx of above average rainfall over several
months. The outlook does favour chance of wetter than average rainfall but this is coupled
with higher chances of warmer than average temperatures which will increase water demand.
2. Introduction
The Minister for Water has delegated Melbourne Water with the responsibility for managing
surface water licensing within the waterways and major drainage systems of the Yarra River,
the lower Maribyrnong River, Stony, Kororoit, Laverton and Skeleton Creek catchments.
Within these catchments we currently manage approximately 1300 licenses from waterways
and administer approximately 500 farm dam registrations and licences relating to catchment
dams. The total allocation issued under these licences is approximately 44,000 Megalitres
(ML). The majority of allocation (41,700ML) is issued on catchments in the Yarra River basin,
while the Maribyrnong and western catchments account for approximately 1,600ML and south-
east catchments approximately 800ML. Water use is primarily for agricultural, industrial,
commercial, sporting grounds and domestic and stock purposes.
All licences managed by Melbourne Water are on unregulated systems except for a small
number of licences in the lower Maribyrnong which are semi-regulated.
The Water Act 1989 requires Melbourne Water to protect the environment and consider the
needs of water users. Management of the water resource is achieved through a number of
different mechanisms that include a Drought Response Plan (DRP), Stream Flow Management
Plans (SFMPs) and Local Management Rule (LMRs).
During drought or low flow conditions, licenced diverters’ access to water may be restricted or
banned to protect the environment. Our Drought Response Plan is active at all times, and
specifies how water is shared when there is not enough to meet all users’ needs.
It states river flow levels which trigger restrictions or bans, and how these are applied to
different licence types. These trigger points have been developed together with stakeholders in
formulating stream flow management plans or local management rules.
The status of restrictions and bans for individual catchments is posted on Melbourne Water’s
website at www.melbournewater.com.au/diverters and is also available by calling Melbourne
Water on 131 722 at any time. Individual catchment status is also available via an automated
SMS services to subscribed customers. In addition the website will provide catchment specific
stream-flow data including daily and 7-day average stream flow conditions.
For additional licensing information and data please visit the website
www.melbournewater.com.au/diverters.
3Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
3. Season to date & current streamflow
2017 rainfall across the Yarra Valley, where the majority of licensed users are located, has
been well below average in most months. Annual rainfall total to the end of November has
been 615.0mm at Coldstream against a mean total of 674.2mm.
The May-July period through winter proved particularly dry and translated to lower winter
streamflows than expected. In ephemeral systems such as the Steels Creek and Dixons Creek
catchments around Yarra Glen, this resulted in bans being in place across the entire winter-fill
period for all but 5 days. Winter-fill licences in other catchments fared slightly better,
particularly with a return to average rainfall conditions in the August to November period.
Current flow conditions (as at 29 November) across all major catchments are tabled in the
information below. On the back of the dry winter and average spring rainfall conditions, a
number of the usually more reliable systems such as the Hoddles Creek, Stringybark Creek
and Wandin Yallock Creek have already gone onto early bans and the Woori Yallock, Yarra
River Upper and Yarra River Lower catchments are restricted.
No. Bans / No. Bans /
7 Day
Restriction Restriction
Access to Flow Rolling
Catchment days days -
water (ML/d) Average
1/7/16 – 1/7/17 -
(ML/d)
20/11/16 20/11/17
Arundel Creek Available 12.2 17.5 0 9
Cockatoo and
Restricted 26.4 30.9 4 17
Shepherd Creek
Darebin Creek Available 8.5 15.3 4 9
Diamond Creek Available 2.1 6.1 0 84
Dixons Creek Banned 0.2 8.4 80 139
4Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
Don River Banned 6.9 7.4 0 5
Gardiners Creek Available 5.1 37.9 6 1
Hoddles Creek Banned 3.9 4.3 5 56
Kororoit Creek Available 11.2 19.8 0 0
Little Yarra River Restricted 42.2 44.3 0 20
Maribyrnong River
Available 31.7 57.6 0 0
(all year)
Maribyrnong River
Licence Ban 31.7 57.6 28 90
(winter-fill)
McCrae Creek Restricted 8.4 9.8 4 87
Merri Creek Available 12.8 29.5 0 0
Moonee Ponds Creek Available 12.2 17.5 0 9
Mullum Mullum Creek Available 3.3 12.6 3 27
Olinda Creek (Lower) Available 17.6 23.4 0 11
Olinda Creek (Upper) Available 8.8 8.2 18 73
Pauls Creek Banned 0.2 0.6 111 143
Plenty River Available 3.9 8.1 0 4
Steels Creek Banned 0 0.5 106 141
Stringybark Creek
Banned 2.2 3.0 0 65
(Lower)
Stringybark Creek
Available 2.3 3.0 51 84
(Upper)
Wandin Yallock Creek Available 2.8 5.2 0 63
Watsons Creek Available 2.4 8.7 0 0
Watts River Available 15.3 22.6 0 0
Woori Yallock Creek Restricted 66.2 70.6 0 38
5Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
Yarra River Lower Restricted 581.1 665.5 8 39
Yarra River Upper Restricted 433.2 413.8 0 11
Restrictions and bans - www.melbournewater.com.au/diverters
4. Climate Outlook
4.1 Above average rainfall combine with warmer season ahead
The Bureau of Meteorology seasonal climate outlook for the next three months shows no
strong swing towards wetter or drier conditions for most of Australia. However, coastal regions
of southeast Australia including Victoria are likely to have a wetter than average summer.
There is a slightly wetter and warmer climate outlook across Melbourne & the water supply
catchments for December 2017 - February 2018.
The Bureau's ENSO Outlook is at La Niña alert, as the tropical Pacific approaches La Niña
thresholds. Most international models maintain a weak La Niña until early autumn. Typically
when the tropical Pacific cools towards La Niña levels, the western Pacific and seas around
northern Australia warm significantly, but models suggest this is not likely to occur this
summer.
Likewise, La Niña periods typically see warmer than average waters develop in the eastern
Indian Ocean. This season, near average to cooler waters are forecast to remain in this area,
while warmer waters remain off Africa. The combination of ocean patterns, and the likely weak
La Niña itself, is why Australia does not have significant and widespread increased chances of a
wetter and cooler summer.
Temperature and rainfall influence water use, especially during summer periods. At the same
time, rainfall and temperature also influence catchment soil moisture levels and inflows to
Melbourne’s unregulated waterways. Melbourne Water continually monitors flow conditions
and the Bureau’s seasonal climate outlooks which are updated monthly.
Rainfall outlook – The Australian Bureau of Meteorology outlook for rainfall (issued on 30
November 2017) for the period from December 2017 to February 2018 indicates December is
likely to be wetter than average for Victoria with weakening chances moving into January. The
map below provides Chance of above median rainfall for the December to February period:
6Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
Temperature outlook – The Australian Bureau of Meteorology outlook for rainfall (issued on
30 November 2017) for the period from December 2017 to February 2018 indicates that both
the daytime and overnight temperatures are likely to be warmer than average across Victoria.
The map below provides Chance of above median maximum temperature for the December to
February period:
Source: Australian Bureau of Meteorology - www.bom.gov.au/climate/outlooks
7Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
4.2 Seasonal Streamflow Forecasts November 2017 – January 2018
Predicting Melbourne’s future streamflow levels is complex and uncertain. This is primarily
because it is not possible to accurately forecast the timing and extent of rainfall events and
consequently the catchments’ runoff response to them up to one year ahead. Nevertheless the
Bureau of Meteorology produces seasonal streamflow forecasts based on its climate data and
flow conditions at 180 monitoring sites across Australia. This information is available at:
http://www.bom.gov.au/water/ssf/index.shtml
Their broad forecast summary for the October to December period is:
Low and near-median streamflows likely to dominate for November to January
Low and near-median flows observed at 76% of locations in October
El Niño–Southern Oscillation and Indian Ocean Dipole remain neutral
8Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
5. Forward outlook for 2017/18 summer season
Based on the already below average rain conditions to date, low streamflows and forecast
warmer temperatures in the coming summer months, licence holders can expect to face
extended periods of bans and restriction in the coming summer irrigation period until the
autumn break arrives.
As highlighted under Section 3 above, a number of significant catchments such as the Hoddles
Creek, Stringybark Creek, Wandin Yallock Creek and Yarra River are already on bans or
restrictions. If predicted average rainfall conditions occur over the next three months this may
delay the onset of bans in additional systems but if higher than average temperatures also
occur, this will increase both water demand by users and system transpiration losses leading
to reduced streamflows.
Under average conditions unregulated licence holders around Melbourne are still likely to see
an early introduction of bans / restrictions starting in December and likely to extend until at
least March. This may be delayed somewhat if above average rainfall conditions occur as
predicted.
Under dry conditions, restrictions may start in November and continue through until May.
Under worst on record conditions customers could see restriction starting immediately and not
lifting until winter rainfalls occur in June.
Access to water in unregulated systems in 2017/18 will remain highly dependant on weather
conditions. The Melbourne Water region can be broken up into western and eastern areas
when considering the impact of weather on streamflows, with the western region having a
higher level of restrictions / bans in comparison to the eastern region (Table 5). This is due to
significant differences in average rainfall totals across Melbourne as well as the eastern region
catchments often benefitting from strong groundwater contribution.
Region Worst on record Dry weather Average weather
weather conditions conditions conditions
th
(5th percentile) (25 percentile) (50th percentile)
Western All streams on bans for All streams on bans Minor tributaries will be
(Maribyrnong extended period. on bans.
Basin)
Eastern All minor tributaries All minor tributaries on All minor tributaries on
(Yarra Basin) on bans for extended bans for extended bans. Limited access in
periods. Yarra River periods. Limited short response to rain
mainstem will be on term access in response events.
restrictions and/or to rain events. Yarra River mainstem
bans. Yarra River mainstem will be on restrictions
will be on restrictions.
Licence holders should continue to monitor restriction and ban status of their relevant
catchment in accordance with their licence conditions by visiting the Melbourne Water website:
Restrictions and bans - www.melbournewater.com.au/diverters
9Unregulated Diversions Water Outlook for Melbourne Water Licence Holders |
6. Other factors affecting entitlement holders and
the environment
Melbourne Water, in partnership with the Victorian Environmental Water Holder (VEWH), may
commence an environmental water release to the Yarra River during the coming summer
period.
Releases are normally considered in response to low flow conditions in the Yarra River which
can result in available habitat for aquatic species being reduced. Releases over the summer
have been successful in improving water quality in the lower part of the river.
Potential water releases will benefit the river’s many aquatic inhabitants, including the
regionally significant River Blackfish, and Macquarie Perch. While not available for harvesting
by water users, environmental water releases can help sustain flow levels in the river and
make it more likely to come off bans or restrictions following subsequent rain events.
7. Further information
While these water outlooks are produced only annually by Melbourne Water, information
around rainfall and river levels is available on our website for over 200 monitoring sites across
Melbourne. https://www.melbournewater.com.au/water/rainfall-and-river-levels#/
In addition our catchment ban and restriction status is updated daily on the website at 5am.
https://www.melbournewater.com.au/water/waterway-diversions/restriction-and-ban-status
Monitoring of both of these sources of information can provide useful insights to likely changes
in catchment conditions.
Other useful information around what the application of bans and restrictions means to your
licence can be found in Melbourne Water’s Drought Response Plan for Licensed Water Users:
https://www.melbournewater.com.au/water/waterway-diversions/stream-flow-management
Climate and weather data including outlooks can be found on the Bureau of Meteorology
website: http://www.bom.gov.au/climate/
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