urban & rural water outlook... · 2020. 11. 27. · table 4 rural customers and licence volume...

A N N U A L W A T E R O U T L O O K 2 0 2 0 - 2 1

Annual Water Outlook

Urban & Rural

November 2020


Table of Contents

Executive Summary .............................................................................................................................................. 3

1 Introduction .................................................................................................................................................. 5

1.1 Purpose ................................................................................................................................................. 5

1.2 Coliban Water ........................................................................................................................................ 5

2 Water Resource Position ............................................................................................................................. 8

2.1. Rainfall ................................................................................................................................................... 8

2.2. Storage inflows and volume ................................................................................................................... 9

2.3. Water supply system entitlements and allocations .............................................................................. 11

3 Climate outlook .......................................................................................................................................... 13

3.1 Climate outlook .................................................................................................................................... 13

3.2 Current climate and streamflow in the longer-term context .................................................................. 15

4 Water Resource outlook ............................................................................................................................ 16

4.1 Inflows into Coliban Headworks Storages ........................................................................................... 16

4.2 Allocations ........................................................................................................................................... 16

4.3 Carryover and trade ............................................................................................................................. 16

4.4 Risk of spill .......................................................................................................................................... 17

4.5 Supply & Demand ................................................................................................................................ 17

4.6 System constraints .............................................................................................................................. 18

5 Short-term action plan ............................................................................................................................... 19


Executive Summary

Water is our greatest asset and an essential resource for the communities that we service. Our region is critically

impacted by our changing climate and we must continually adapt to ensure water is available for all customers.

Current projects show that the region will have less water, while facing growing populations and changing

consumer demand.

Strategy 2030 is our plan to meet future challenges and opportunities and achieve our vision of Water to Live,

Grow and Enjoy. Our Urban Water Strategy 2017 identifies actions that we are taking to ensure that we have

water that is secure and reliable for our growing population. Last year this included connecting to the South West

Loddon Pipeline; purchasing an additional 200 megalitres of low reliability water shares; and acquiring an

additional 55 megalitres per year of groundwater for Trentham.

As well as outlining the current water resource position, this Annual Water Outlook looks forward to the coming

year, how that impacts agreed levels of service, and what actions are needed, or planned, in the short and

medium term to continue to meet those agreed levels.

We need to develop climate resilient water supplies that can maintain the community’s liveability and economic

growth, even during drought. These water supplies are centred around eight water supply systems, each defined

by their water source. In some systems there are multiple water sources that can provide supply as part of the

Victorian water grid, which connects water sources via pipelines or rivers. We have a varied portfolio of water

holdings including bulk entitlements, water allowances, high and low reliability water shares and licenses to take

and use groundwater, which provide us with flexibility to manage entitlements to meet demand.

Overall, we experienced slightly below average rainfall and low inflows in 2019/20, but it was a year clearly

defined by two halves. Conditions were drier than average at the start of the water year; but the latter half was

wetter with very high rainfall totals received in April. This resulted in good inflows to the Coliban Headwork

Storages toward the end of 2019/20.

The Coliban Headwork Storages contained 61,739 mega litres (ML) (88.71% of capacity) on 1 October 2020, and

our share of Lake Eppalock was at 80.1% with 43,926 ML. Opening allocations were low in systems managed by

Goulburn-Murray Water and Grampians Wimmera Mallee Water, but had increased to 82% in the Campaspe,

58% in the Goulburn System, 40% in the Murray System and 9% in the Wimmera-Mallee Pipeline by 1 October

2020.

We carried over unused water allocation from 2019/20 to secure in excess of 24 months’ supply in the Coliban

Northern and Southern Systems and 12 months’ supply in the other water supply systems to satisfy our reserve

rules (Table 1). The total available supply was 139,599 ML on 1 October 2020.

The climate outlook suggests above average rainfall and warmer than average temperatures for the remainder of

2020 and early 2021. Under this scenario it is likely that the Coliban Headwork Storages will fill and we will

receive 100% allocations in the Campaspe, Loddon, Goulburn and Murray Systems. It is likely that we will

receive less than 100% allocation in the Wimmera Mallee System. We will carryover allocation to secure supplies

in 2021/22.

Restrictions may be considered where our reserve rules are not satisfied, but based on the current resource

position and forecast wetter than average conditions the likelihood of restrictions in 2020/21 is very low.

Permanent Water Saving Rules (PWSR) continue apply in all water supply systems. In the rural systems, we

have announced a 100% allocation for 2020/21. Each month, we provide an update of our water resource

position on our website http://www.coliban.com.au

Some of the projects that we will be undertaking in 2020/21 to further improve water security, as identified in our

Corporate Plan 2020-2025, include publishing water restriction and reserve rules for our rural customers; further

investigating options for groundwater augmentation; and updating our Drought Response Plans.


Table 1 Water Supply Systems supply and demand

Water Supply System

Towns supplied

Available Supply (ML)

1 Oct 2020

Annual demand (ML)

Reserve

Status (months) Average Dry

1. Campaspe Goornong 319 81 97 >12

2. Coliban Northern

Bendigo, Axedale, Huntly, Marong, Raywood, Sebastian

Heathcote, Tooborac

66,687 26,849 31,720 >24

3. Coliban Southern

Castlemaine, Harcourt, Taradale, Elphinstone, Fryerstown, Chewton, Campbells Creek, Guildford, Newstead, Maldon, Kyneton, Malmsbury, Tylden

61,739 17,320 19,624 >24

4. Elmore Elmore 284 137 165 >12

5. Goulburn Rochester, Lockington, Serpentine, Pyramid Hill, Boort, (Dingee, Mitiamo, Jarklin, Mysia, Macorna)

2,717 1,211 1,453 >12

6. Loddon - Wimmera

Bridgewater, Inglewood

Laanecoorie, Tarnagulla, Bealiba, Dunolly, Korong Vale, Wedderburn

(Borung, Wychitella)

843 652 783 >12

7. Murray Echuca

Cohuna, Gunbower, Leitchville 6,787 4,515 5,418 >12

8. Trentham Trentham 223 143 172 >12


1 Introduction

1.1 Purpose

This Annual Water Outlook has been prepared, as required under the Statement of Obligations (2015) and in

accordance with guidelines issued by the Department of Environment, Land, Water and Planning, to inform our

customers, stakeholders and the community on:

a) the current water resource position

b) a forward outlook for water resources over the coming year under a range of plausible climatic scenarios

c) ability to meet agreed levels of service; and

d) actions to improve system performance, if required, to meet agreed levels of service.

1.2 Coliban Water

Coliban Water provide water and wastewater services to urban and rural customers across an area of 16,500

square kilometres in North-Central Victoria, from Kyneton and Trentham in the south to Cohuna and Echuca in

the north (Figure 1).

Water is supplied from 8 Water Supply Systems, each defined by their water source, to 49 towns (Table 2). In

some case cases there are multiple water sources that supply a system as part of the Victorian water grid, which

connects water sources via pipelines or rivers. This includes:

• the Coliban Northern System connection to the Coliban Southern System via the Coliban Main Channel;

and to the Goulburn System via the Goldfields Superpipe from the Waranga Western Channel;

• the Goulburn System towns that take water from the Waranga Western Channel can also receive water

from the Campaspe or Loddon River; and

• the Loddon Wimmera System is supplied from Wimmera Mallee Pipeline; the South West Loddon

Pipeline (which can source water from the Waranga Western Channel or Wimmera Mallee Pipeline);

and the Loddon River for Bridgewater and Laanecoorie.

Table 2 Water Supply Systems and towns supplied

System Towns Supplied1 Primary water source Alternative water source

1. Campaspe Goornong Campaspe River None

2. Coliban Northern

Bendigo, Axedale, Huntly, Marong, Raywood, Sebastian

Heathcote, Tooborac

Coliban Headworks Storages

Lake Eppalock, Waranga Western Channel

3. Coliban Southern

Castlemaine, Harcourt, Taradale, Elphinstone, Fryerstown, Chewton, Campbells Creek, Guildford, Newstead, Maldon, Kyneton, Malmsbury, Tylden

Coliban Headworks Storages

None

4. Elmore Elmore Groundwater None

5. Goulburn Rochester, Lockington, Serpentine, Pyramid Hill, Boort, (Dingee, Mitiamo, Jarklin, Mysia, Macorna)

Waranga Western Channel

Campaspe River,

Loddon River

6. Loddon Wimmera

Bridgewater, Inglewood

Laanecoorie, Tarnagulla, Bealiba, Dunolly, Korong Vale, Wedderburn

(Borung, Wychitella)

Wimmera Mallee Pipeline / South West Loddon Pipeline

Loddon River

7. Murray Echuca

Cohuna, Gunbower, Leitchville

Murray River

Gunbower Creek

None

8. Trentham Trentham Spring Groundwater bore

Note 1: Towns shown in bold indicate the location of the Water Treatment Plant (WTP) with all following towns

supplied from that WTP. Towns within (brackets) are supplied with raw water


Figure 1 Coliban Water region services

We maintain and operate 34 reservoirs and water storage basins. Raw water is treated in one of our 19 water

treatment plants, and distributed through 2,375 km of water mains to customers. At 30 June 2020 there were

over 77,000 water connections (Table 3).


Table 3 Water connections per system at 30 June 2020

System

Water Connections at 30 June 2020

Major Customers Residential

Non

Residential

1. Campaspe 168 24

2. Coliban Northern 46,906 3,708 Hazeldenes Chicken Farm Pty Ltd

Lactalis Australia Pty Ltd

3. Coliban Southern 10,523 1,152 KR Castlemaine

Hardwicks Meatworks Pty Ltd

4. Elmore 394 59

5. Goulburn 2,374 386

6. Loddon Wimmera 1,815 239

7. Murray 7,856 1,397 Kagome Food Pty Ltd

Simplot Australia Pty Ltd

Lactalis Australia Pty Ltd

8. Trentham 641 66

TOTAL 70,677 7,031 7

The Coliban Water Rural System supplied 1,382 licensed customers as at 30 June 2020 (Table 4).

Table 4 Rural customers and licence volume and use at 30 June 2020

Rural System Licensed customers Licence volume (ML) Use

(ML)

Northern 721 5,697.8 2,611.9

Southern 661 10,119.8 1,862.7

Total 1,382 15,817.6 4,474.6


2 Water Resource Position

2.1. Rainfall Rainfall received at Malmsbury Reservoir for 2019-20 was 686 mm, slightly below the current climate baseline period (1975-2017) median of 721 mm (Figure 2). Rainfall was below average for the first half of the water year, but the latter half was wetter with very high rainfall totals received in April (Figure 3).

Figure 2 Annual Rainfall received at Malmsbury Reservoir compared to rainfall received over the current climate

baseline

Figure 3 2019-20 monthly rainfall at Malmsbury Reservoir compared to rainfall received over the current climate

baseline


2.2. Storage inflows and volume

Inflows to the Coliban Headwork Storages (comprising the Upper Coliban, Lauriston and Malmsbury Reservoirs)

during 2019-20 was 35,779 ML. This is 73% of the median inflow (49,200 ML) for the current climate baseline

period (1975-2017) (Figure 4).

Figure 4 Annual inflows to the Coliban Headwork Storages

Most inflows are typically received between July and October each year. Greater than average inflows were

received in July 2019 and between April and June 2020 (Figure 5).

Figure 5 Monthly inflows to the Coliban Headwork Storages

We pumped 4,611 ML from Lake Eppalock between 1 July 2019 and 30 June 2020 (compared to 8,282 ML in

2018-19) when the volume in the Coliban Headwork Storages was below the Volumetric Trigger (Figure 6).


Figure 6 Combined storage volume in the Coliban Headwork Storages

The Coliban Headwork Storages contained 61,739 ML (88.7% of capacity) on 1 October 2020 compared to

66,753 ML (95.9% of capacity) at the same time last year. Coliban’s share of Lake Eppalock was 43,926 ML

(80.1%) compared to 36,694 ML (67%) at the same time last year (Table 5).

Table 5 Coliban Water volume in storage on 1 July 2020 and 1 October 2020

Storage Capacity 1 July 2020 % Capacity 1 October 2020 % Capacity

Upper Coliban 37,770 ML 31,624 ML 83.7% 36,469 ML 96.6%

Lauriston 19,790 ML 16,520 ML 83.5% 17,880 ML 90.3%

Malmsbury 12,034 ML 2,327 ML 19.3% 7,390 ML 61.4%

Sub-total 69,594 ML 50,471 ML 72.5% 61,739 ML 88.7%

Lake Eppalock 54,837 ML 39,145 ML 71.4% 43,926 ML 80.1%

Sub-total 54,837 ML 39,145 ML 71.4% 43,926 ML 80.1%

Barkers Creek 1,690 ML 1,090 ML 64.5% 1,650 ML 97.6%

McCay 1,360 ML 1,121 ML 82.4% 1,281 ML 94.2%

Caledonia 214 ML 181 ML 84.6% 129 ML 60.4%

Sandhurst 2,590 ML 2,180 ML 84.2% 2,289 ML 88.4%

Spring Gully 1,680 ML 1,017 ML 60.5% 1,184 ML 70.5%

Trentham 1 & 2 90 ML 86 ML 95.6% 89 ML 99.1%

Sub-total 7,624 ML 5,675 ML 74.4% 6,623 ML 86.9%

Total 132,055 ML 95,291 ML 72.2% 112,288 ML 85.0%


2.3. Water supply system entitlements and allocations

Our water holdings include Bulk Entitlements (BE), High Reliability Water Shares (HRWS), Low Reliability Water

Shares (LRWS), Water Allowances (WA), and licenses to take and use groundwater. On 1 October 2020 the total

amount of raw water available for all our water supply systems was 139,599 ML (Table 6).

Campaspe System

Our Campaspe System is supplied under the BE from the regulated Campaspe River. We receive a minimum of

50% allocation under our BE, which is sufficient to meet demand in 2020/21.

Coliban Northern and Southern Systems

The BE for the Coliban Southern and Northern Systems entitles us to all the storage capacity of the Coliban

Headwork Storages (Upper Coliban, Lauriston and Malmsbury Reservoirs) and an 18% share of Lake Eppalock.

We can take an average volume of 50,260 ML over any period of 3 consecutive years under the BE. This

includes up to 17,440 ML per year averaged over 3 years from Lake Eppalock for the Coliban Northern System.

We deliver water to the Coliban Southern and Northern Systems via the Coliban Main Channel. As the Coliban

Headwork Storages are the only supply source for the Coliban Southern System, a Volumetric Trigger (ranging

from 45 to 55 GL based on the resource position and climate outlook) has been established to change the source

of supply for the Coliban Northern System to Lake Eppalock to secure reserves for the Coliban Southern System.

The Coliban Northern System can also be supplied from high and low reliability water shares in Goulburn-Murray

Water’s regulated Campaspe System (Lake Eppalock) and Goulburn System (Waranga Western Channel) via

the Goldfields Superpipe. This provides flexibility to meet demand in the Coliban Northern System, particularly

with the ability to trade and carryover. Opening allocations were 32% in the Campaspe System and 35% in the

Goulburn System, and on 1 October had increased to 82% and 58% respectively.

Elmore System

The Elmore System is supplied from groundwater in the Lower Campaspe Valley Water Supply Protection Area,

which is managed by Goulburn-Murray Water. It is noted that there has been a declining trend in groundwater

levels in the area in recent years which has resulted in reduced allocation of 75% of the licence volume. We have

sufficient supply to meet demand in 2020/21.

Goulburn System

Our Goulburn System is supplied from the Waranga Western Channel, which is part of Goulburn-Murray Water’s

regulated Goulburn System. We have a high reliability under the BE with an allocation of 100% which is sufficient

to meet demand in 2020/21. We also have water allowance from the East Loddon Pipeline to supply Jarklin and

Serpentine which is subject to allocations.

Loddon Wimmera System

Coliban Water’s Loddon and Wimmera Systems have been combined from a resource management perspective

now that they can both be serviced from the South West Loddon Pipeline. Borung and Wychitella continue to be

supplied from the Wimmera Mallee Pipeline. Korong Vale, Bridgewater and Laanecoorie systems can be

supplied from the South West Loddon Pipeline, which can source water from either the Wimmera Mallee Pipeline

or the Waranga Western Channel. Bridgewater can still access water from the Loddon River, with the Loddon

River remaining the main source of supply for the Laanecoorie system at present. Under the Loddon BE, we

have a minimum allocation of 50%. Opening allocations in the Wimmera Mallee Pipeline were 0% and increased

to 9% on 1 October. We have carried over to ensure that reserves are sufficient to meet demand for 2020/21.

Murray System

Our Murray System takes water from the Murray River. Opening allocations in the Murray Systems are low (8%),

with allocations increasing to 40% on 1 October. We have carried over allocation from our Murray water shares to

ensure there were sufficient reserves to meet demand in 2020/21.

Trentham System

The BE for Trentham is the average of 120 ML over any 3 consecutive years from spring discharge into the

reservoirs. Groundwater is pumped from licensed bores in the Central Victorian Mineral Springs Groundwater

Management Area to augment the system. There have not been any restrictions on this source in the past.


Table 6 Water supply system entitlements and allocations

Water entitlements 1 July 2020 1 October 2020

Supply Entitlement Trade Allocation Carryover Spillable Available Allocation Spillable6 Trade Available

System Source Type ML Yes/No % ML ML ML ML % ML ML ML ML

Campaspe GMW Campaspe BE 349 Yes 50% 175 33 0 0 82% 286 0 0 319

sub-total 349 Yes 175 33 0 208 286 0 0 319

Coliban Northern

GMW Goulburn HRWS 22,774 Yes 35% 7,971 15,752 0 23,723 58% 13,209 0 -10,409 18,552

GMW Goulburn LRWS 2,857 Yes 0% 0 1,920 0 1,920 0% - 0 0 1,920

Lake Eppalock BE 17,440 N/A N/A N/A N/A N/A 39,145 N/A N/A N/A N/A 43,926

GMW Campaspe HRWS 2,591 Yes 32% 829 3 0 832 82% 2,125 0 0 2,128

GMW Campaspe LRWS 646 Yes 0% 0 161 0 161 0% - 0 0 161

sub-total 46,308 8,800 17,836 0 65,781 15,334 0 0 66,687

Coliban Southern

CW Storages BE 32,820 N/A N/A N/A N/A N/A 50,471 N/A N/A N/A N/A 61,739

sub-total 32,820 N/A N/A N/A 50,471 N/A N/A 61,739

Elmore Groundwater Licence 284 No 100% 213 71 N/A 284 75% 213 N/A N/A 284

sub-total 284 213 71 N/A 284 213 N/A N/A 284

Goulburn

GMW Goulburn BE 2,420 Yes 100% 2,420 262 0 2,682 100% 2,420 0 0 2,682

GMW Goulburn WA 60 No 35% 21 0 N/A 21 58% 35 N/A N/A 35

sub-total 2,420 2,441 262 0 2,703 2,455 0 0 2,717

Loddon Wimmera

GMW Loddon BE 820 Yes 50% 410 58 N/A 468 58% 476 N/A -268 266

GWM Water BE 300 Yes 0% 0 172 0 172 9% 27 0 0 199

GWM Water WA 110 No 100% 110 0 N/A 110 100% 110 N/A 268 378

sub-total 1,230 520 230 N/A 750 613 N/A N/A 843

Murray

GMW Murray BE 6,285 Yes 8% 503 3,553 0 4,056 40% 2,514 0 0 6,067

GMW Murray HRWS 55 Yes 8% 4 698 0 702 40% 22 0 0 720

GMW Murray LRWS 722 Yes 0% 0 0 0 - 0% - 0 0 -

sub-total 6,794 507 4,251 0 4,758 2,536 0 0 6,787

Trentham

Groundwater BE 120 N/A N/A 120 N/A N/A 120 N/A 120 N/A N/A 120

Groundwater Licence 103 N/A N/A 103 N/A N/A 103 N/A 103 N/A N/A 103

sub-total 223 223 N/A N/A 223 223 N/A N/A 223

TOTAL 90,756 12,879 22,683 0 125,178 21,659 0 0 139,599


3 Climate outlook

3.1 Climate outlook

The Bureau of Meteorology (BoM) suggest that it is going to be warmer and wetter over the next few months with

an increased likelihood of exceeding median maximum temperatures and rainfall (Figure 7 and Figure 8).

Figure 7 Chance of exceeding median maximum temperature for November 2020 to January 2021

Figure 8 Chance of exceeding median rainfall for November 2020 to January 2021


Sea surface temperature patterns in the Pacific and Indian oceans and can indicate the presence, or potential

development, of ENSO (El Niño/La Niña) and Indian Ocean Dipole (IOD) events that influence the Australian

climate. The El Niño/Southern Oscillation (ENSO) is currently persisting with La Niña values, suggesting wetter

conditions over the coming months (Figure 9).

Figure 9 Pacific sea surface temperatures

The Indian Ocean Dipole (IOD) is likely to remain neutral for the remainder of spring, supporting the outlook for

wet conditions, before returning to near-average values by early 2021 where it has little impact on Australian

climate through monsoon season (Figure 10).

Figure 10 Indian Ocean Dipole


3.2 Current climate and streamflow in the longer-term context

Victoria’s climate has shown a warming and drying trend over recent decades, and this trend is expected to

continue over the longer-term future. In comparison to historical conditions we are already experiencing:

• Higher temperatures;

• Reductions in rainfall in late autumn and winter and, in some locations, some increases in rainfall during

the warmer months; and,

• In many catchments, a shift in the streamflow response to rainfall, with less streamflow generated for

the same amount of rain.

Some of the rainfall decline in late autumn and winter can be attributed to global warming and changes in the

weather systems that deliver rainfall to Victoria. The cause of the reduction in streamflow response to rainfall is

not yet fully known and is the subject of continuing research.

Over the longer term, we can expect:

• the rainfall reductions in winter to persist;

• possible increases in summer rainfall;

• increases in potential evapotranspiration due to higher temperature and lower relative humidity;

• reductions in streamflow because of less rainfall and higher potential evapotranspiration; and

• the streamflow response to rainfall to no longer remain the same, and generally decline.

Even if there is an increase in summer rainfall, it is unlikely to offset the streamflow impact of rainfall reductions in

winter because most of the runoff in Victorian catchments occurs over winter and spring. In the warmer months,

catchments are drier and more rainfall soaks into the ground, is used by vegetation or evaporates.

Although there will still be a lot of variability in Victoria’s climate and streamflow, the chances of experiencing

warmer conditions and less streamflow is now higher than in past decades.

More information on the observed changes and longer-term future climate and water projections can be found at

https://www.water.vic.gov.au/climate-change

The Victorian Government is investing in further research to better understand how Victoria’s climate is changing

and the water resource implications, as part of implementing Water for Victoria.

We have used the current climate baseline for the period July 1975 to June 2017 for long-term planning in the

Urban Water Strategy 2017. Analysis suggests a step change shift in inflows to our storages post-1997 (Table 7);

however, until there is greater certainty around the catchment behaviour of the upper Coliban River the current

climate baseline will continue to be used.

Table 7 Median rainfall and inflow for climate periods

Parameter Current climate baseline

July 1976 to June 2017

Step change climate July 1997 to June 2017

Median rainfall at Malmsbury 721 mm/year 638 mm/year

Median inflows to Coliban Headwork Storages 49.2 ML/year 23.5 ML/year


4 Water Resource outlook

4.1 Inflows into Coliban Headworks Storages

Inflows to the Coliban Headwork Storages can be highly variable (Table 8).

Table 8 Inflow for various climatic scenarios for the current climate baseline (1975-2017) and worst year on record

Climate scenario Inflow (GL/year)

Dry (10th percentile inflow) 9.1

Median (50th percentile inflow) 49.2

Wet (90th percentile inflow) 97.5

Worst year on record 2006/07 3.1

Greater than average rainfall received in recent months has wet the catchment. Given that BoM modelling

suggests that conditions are likely to be wetter than average, goods inflows are anticipated and the Coliban

Headworks Storages are expected to fill in 2020/21.

4.2 Allocations

Allocations vary between all water sources and between bulk entitlements and water shares. Allocations increase

progressively throughout the year as the resource position improves. Initial allocations in 2020/21 were low but

have improved with inflows over winter and spring (Table 9).

Forecast allocations are based on projected inflows using historical flow records that have been adjusted to

match climate conditions observed since 1975 for the Campaspe, Goulburn and Murray source systems.

For the Wimmera Mallee Pipeline the full historic inflow record has been used but it has not been adjusted for

climate change. In this case a more conservative approach should be taken when considering allocation

forecasts in this system.

Average inflow conditions deliver the volume that will be exceeded 50 years out of 100 and dry inflow will be

exceeded 90 years out of 100. Given the climate outlook for wetter than average conditions it is likely that all

sources will receive 100% allocation except the Wimmera-Mallee Pipeline (Table 9).

Table 9 Allocations and Forecast Allocations as at 1 July 2020

Source Allocation

1 Jul 2020

Allocation

1 Oct 2020

Average

Forecast

Allocation

Dry

Forecast

Allocation

Campaspe1 32% 82% 100% 100%

Murray1 8% 40% 100% 72%

Goulburn and Loddon1 35% 58% 100% 86%

Wimmera-Mallee Pipeline2 0% 9% 66% 48%

1 Forecast allocations in February 2021 2 Forecast allocations in January 2021

Monthly updates are provided by the Northern Victoria Resource Manager (https://nvrm.net.au/) for the

Campaspe, Goulburn, Loddon, and Murray systems; and the Grampians Wimmera Mallee Water Storage

Manager (https://www.gwmwater.org.au/current-announcements/latest-seasonal-allocations) for the Wimmera

Mallee Pipeline.

The first outlook for the 2021/22 water year will be available in February 2021.

4.3 Carryover and trade

We can carryover in all of our water supply systems except the Coliban Southern and Trentham Systems. We

carried over 22,683 ML into 2020/21 to ensure that our reserve rules were satisfied (refer Table 6).

We plan to carryover sufficient volume that, when combined with allocations and storage volumes, shall satisfy

the reserve rules in the following year (i.e. 24 months of demand for Coliban Northern and Coliban Southern

systems, and 12 months in all other systems).


We can participate in the Southern-connected Basin water market. Where the allocation volumes are in excess

of water required to meet our level of service obligations, or there is a water shortage, there is an opportunity to

trade.

4.4 Risk of spill

Where we hold greater than 100% of surface water entitlement (i.e. carryover) the volume is quarantined in a

spillable water account until the Resource Manager declares a low risk of spill, or the storage spills. The

Resource Manager will declare a low risk of spill where the chance of the reservoir spilling is less than 10%. The

risk of spill depends on the current storage capacity, predicted inflows and consumptive demands.

Risk of spill is updated progressively through the season, and the current risk of spill is outlined in Table 10.

Table 10 Risk of spill

Source Risk of spill Date

Murray 20% 12 October 2020

Goulburn Low 10 August 2020

Loddon Low 10 August 2020

Campaspe Low 12 October 2020

Wimmera –Mallee Pipeline Low 3 July 2020

4.5 Supply & Demand

Demand varies from year to year depending on weather patterns (e.g. rainfall, temperature and humidity),

population change, consumer behaviour, and prevailing economic conditions (commercial and industrial

demands).

Total demand is defined here as the total raw water required to meet all the consumptive and operational

requirements including urban and rural use, system operations (backwash, mains flushing, and leakage),

evaporative losses, and any passing flow requirements. Total demand in all water supply systems in recent years

has varied between 34.4 GL and 53.9 GL (Figure 11).

Figure 11 Total Raw water demand including urban and rural use

The demand forecast considers both average and dry weather scenarios. Average demand is based on a three-

year rolling average of the total demand under Permanent Water Saving Rules (PWSR). Dry demand, which

represents use in warmer and drier conditions, is the average demand plus an additional 20% for urban and 50%

for rural use.

The climate outlook suggests average rainfall and warmer than average temperatures for the remainder of 2020

and early 2021. In this case total demand may be expected to be closer to the average demand.


An assessment of the available supply against the average demand forecast indicates that we have greater than

24 months of reserves for the Coliban Northern and Coliban Southern Systems, and 12 months reserve for all

others systems (Table 11). This satisfies the Drought Policy as described in our Urban Water Strategy 2017.

Table 11 Available supply and demand forecast

Supply System Available supply (ML) Annual demand (ML) Reserve

status 1 July 2020 1 October 2020 Average Dry

1. Campaspe 208 319 81 97 >12

2. Coliban Northern 65,781 66,687 26,849 31,720 >24

3. Coliban Southern 50,471 61,739 17,320 19,624 >24

4. Elmore 284 284 137 165 >12

5. Goulburn 2,703 2,717 1,211 1,453 >12

6. Loddon Wimmera 750 843 652 783 >12

7. Murray 4,758 6,787 4,515 5,418 >12

8. Trentham 223 223 143 172 >12

Total 125,178 139,599 50,910 59,432 -

Restrictions may be considered where our reserve rules are not satisfied, but based on the current resource

position and the forecast wetter than average conditions the likelihood of restrictions in 2020/21 is very low.

Permanent Water Restriction Rules continue to apply in all water supply systems. In the rural systems, we have

announced a 100% allocation for 2020/21.

Each month, we provide an update of our water resource position on our website http://www.coliban.com.au

4.6 System constraints

There are no known constraints to meeting system demands in 2020/21.

We have the capacity to manage water quality risks and ensure ongoing supply at the water treatment plants, or

by carting water in some cases if required.

Minor maintenance works are proposed on the Coliban Main Channel in 2020/21 that are unlikely to disrupt flow.

Works are also being undertaken at the Lake Eppalock pump station to ensure bushfire safety compliance for the

electrical system.


5 Short-term action plan

Our Urban Water Strategy 2017 identifies a mix of measures to provide water security now and into the future

and is available from our website https://www.coliban.com.au/urban-water-strategy.

In 2019/20 Coliban Water undertook the following works to improve water security:

• Connect Korong Vale, Bridgewater and Laanecoorie to the South West Loddon Pipeline. This now

provides greater security of supply as there are now multiple sources of water, as well as providing

improved water quality outcomes. Laanecoorie will to continue to be supplied from the Loddon River

until a raw water basin is constructed.

• Purchased of 200 megalitres of low reliability water shares in zone 7 of the Murry System.

• Secured an additional 55 megalitres per year of groundwater licence volume for the Trentham System

Projects to be undertaken in 2020/21 are listed in Table 12.

Table 12 Actions to further improve water security

Supply system Action Timing Status Comments

Coliban Northern and Southern

Publish Water Restriction Rules for Rural customers

2020/21 Commenced Consultation to be undertaken

Coliban Southern Investigate option for groundwater augmentation

2020/21 Desktop study commenced

Field investigations to be undertaken

Coliban Northern Case study for Managed Aquifer Recharge in the Campaspe Deep Lead

2020/21 Integrated Water Management Forum project led by Goulburn-Murray Water

Consider potential opportunity for Coliban Water

Murray Secure additional water shares

Ongoing Purchased low reliability water shares in the Murray System

Further opportunities being considered

Loddon Wimmera Raw water basin design at Laanecoorie

2020/21 Detailed design underway

Storage required

Trentham Groundwater investigations

2020/21 New urban supply bore installed

Undertake pumping test and apply to increase licence volume

We are updating our Drought Response Plans to incorporate changes to water supplies. This provides an

opportunity to undertake a review of each system to inform our future Urban Water Strategy.

We are also undertaking actions to manage demand including the Target Your Water Use initiative, which is a

Victorian government water efficiency program for regional Victorian householders. It offers advice and activities

to encourage the efficient use of our precious water.

urban & rural water outlook... · 2020. 11. 27. · table 4 rural customers and licence volume...

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