Southern Rural Water Water Outlook for 2018-2019

30 November 2018

Tarwin River

Introduction The Minister for Water has delegated Southern Rural Water (SRW) with the responsibility for managing surface water licensing, groundwater extraction, storage dams and irrigation districts across the southern third of .

Within this wide geographic area, SRW manages take and use licenses from waterways, farm dam registrations, licences relating to catchment dams and seven major dams, and operates irrigation districts. Water use is primarily for agricultural, urban and industrial purposes. SRW manages the Macalister Irrigation District (MID) in central and the Werribee (WID) and Bacchus Marsh (BMID) irrigation districts west of Melbourne. The majority of the water used in the irrigation districts is for primary agricultural production, along with stock and domestic and minor industrial use. Water shares are held by individual customers within the districts and transactions are recorded in the Victorian Water Register. Blue Rock Lake (part of the system) plays a major role in providing cooling water for Victoria’s brown coal power generation. These are bulk entitlements held by the various companies which own and run the power stations. Blue Rock Lake and Lake Glenmaggie have environmental water entitlements (bulk entitlements and water shares respectively) that are managed by the Catchment Management Authority on behalf of the Victorian Environmental Water Holder. Visit SRW website for further information: www.srw.com.au

Page 2

Executive Summary A drier than average winter has produced a high demand for irrigation across the state and this is predicted to continue. There is a low chance of above average rain. In addition, the dry winter has impacted on input prices (feed etc), and some crops which required water at that time, so that, overall, users could have numerous impacts on their ability to produce efficiently. MACALISTER IRRIGATION DISTRICT The seasonal allocation opened at 40% of High Reliability Water Shares (HRWS), increasing to 100% following rainfall. Inflows in the catchment were steady during July and August but the rainfall was not consistent across the district, resulting in steady demand and increased usage well above the five year average. MID customers typically use 120% water over the season with high demand during the summer period. A predicted increase in LRWS, along with allocation trades, is expected to cover any shortfall for customers. WERRIBEE AND BACHUS MARSH IRRIGATION DISTRICTS The 2017-18 season started with an unprecedented volume of carryover (equivalent to 70% of high reliability water share) due to above average rainfall received during the 2016-17 irrigation season. The 2017-18 season allocation only reached 45% in December 2017. As a result of the lower allocation in 2017-18 there was 8.4GL of water carried over into the 2018-19 season compared with 11GL the previous year. Despite the dry conditions there is enough allocation (including carryover) to meet irrigation demand. However the situation varies for each individual irrigator and a number in the Werribee Irrigation District will need to buy more river water allocation and/or use more recycled water in order to meet their needs based on last years water use. LATROBE SYSTEM Central Gippsland is also expected to receive warmer than average temperatures across the region with a neutral rainfall outlook. Given these factors and the dry winter, median to low streamflow is likely for summer. MARIBYRNONG The Maribyrnong catchment has had another very poor winter and spring with Rosslynne Reservoir around 10% lower all year. GROUNDWATER AND RIVERS The western and central Groundwater and Rivers areas are coming off essentially average rainfall conditions and so catchments and flows remain more positive in these areas. In the area, rainfall deficiencies have occurred over an extended period now and this does not bode well for the coming irrigation period. Many users have had to start watering earlier than normal and this may lead to pressures, not just on streamflows but on allocation limits also. Without a lot more rain to make up the deficit this season, it is likely that the river systems across the East Gippsland area will face extended periods of restrictions or bans across the coming summer season. Where water does remain available there is potential for an increased demand in trading due to the drier seasonal conditions.

Page 3

Regulated surface water Recent winter/spring filling season and current water resource position Victoria’s climate has shown a warming and drying trend over recent decades, and this trend is expected to continue. In comparison with historical conditions we are already experiencing: • higher temperatures • reductions in rainfall in autumn and winter, and in some locations, increases in rainfall during the warmer months • in many catchments, a shift in the streamflow response to rainfall, with less streamflow generated for the same amount of rain. The decline in rainfall during autumn and winter is associated with a southerly shift in rain bearing weather systems. Global warming is a contributor to this southerly shift, which means that the downward trend in winter rainfall is likely to continue. The cause of the downward shift in the 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 remain, or become drier still • possible increases in summer rainfall • possible increases in potential evapotranspiration due to higher temperature • reductions in streamflow across all catchments because of less rainfall and possible higher potential evapotranspiration • the streamflow response to rainfall to no longer remain stationary, 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 runoff in Victoria occurs during the cooler months of the year. Although there will still be a lot of variability in Victoria’s climate, the chances of experiencing warmer conditions and less streamflow is now higher than in past decades. The BOM seasonal climate outlooks build in the influence of changes in climate that have already occurred. 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

Table 1: Rainfall received from July 1 2018 to (30 November); the same time last year and 10 year average. Region Rainfall received 2018 Rainfall received 2017 Rainfall received (mm) (mm) (mm) 10-year average Lake Glenmaggie * 141.8 152 237.3 Blue Rock 257.7 482 518 Merrimu 196.6 332 377 Werribee 145 316 485.7 *Glenmaggie Creek site The SRW website, www.srw,com.au provides up-to-date information on allocations, streamflow restrictions and rainfall data for SRW’s region. Further rainfall data is available at the Bureau of Meteorology website www.bom.gov.au.

Page 4

MACALISTER IRRIGATION DISTRICT The Macalister Irrigation District’s (MID) primary source of water is from Lake Glenmaggie, and Thomson Reservoir. Lake Glenmaggie is an annual fill and spill reservoir, which means SRW is largely reliant on winter and spring rains to fill it in order to provide a 100% seasonal determination for the Thomson/Macalister Irrigation District. Thomson Reservoir holds the drought reserve which is designed to provide additional allocation in years with very little rainfall. Although Lake Glenmaggie is currently close to full, the dry start to the winter meant that opening allocations were low. The seasonal allocation opened at 40% of High Reliability Water Shares (HRWS). Inflows in the catchment were steady during July and August allowing SRW to increase the allocation to 100% HRWS for customers on 28 August (Table 2). Rainfall in the catchment totalling 70.8mm helped inflows but this was not consistent across the district, resulting in steady demand and increased usage well above the five year average. In the MID there will be no further allocation reviews until 15 December which is the end of the spill period. At this time SRW will assess storage levels, inflows, customer usage and Thomson reserve payback volume and will provide an outlook on when allocation against Low Reliability Water Shares will be issued. This will be published on the website on 19 December 2018. As at 30 November Lake Glenmaggie is holding 136,404 ML compared with 151,452 ML at the same time last year, and SRW’s share of Thomson Reservoir is holding 38,770 ML compared with 38,215 ML at the same time last year (Table 3). Irrigation deliveries to date are estimated at 59,778 ML which is 17,945 ML above the five-year average. Rainfall across the district remains below the 10-year average which continues to impact on inflows overall. Table 2: Summary of current allocation compared to last year and the 10 year average for irrigation districts District Current Last year 10-year average Macalister 100%HRWS 100%HRWS 100% HRWS 20%LRWS 34%LRWS

WERRIBEE AND BACCHUS MARSH IRRIGATION DISTRICTS The 2017-18 season started with an unprecedented volume of carryover (equivalent to 70% of high reliability water share) due to above average rainfall received during the 2016-17 irrigation season. However, the 2017 winter and spring saw lower than average rainfall which resulted in low inflows into the storages on the Werribee system. Subsequently the 2017-18 season allocation only reached 45% in December 2017. As a result of the lower allocation in 2017-18 there was 8.4GL of water carried over into the 2018-19 season compared with 11GL the previous year. Rainfall in the catchments was close to average over the 2018 winter and early spring but a very dry September has seen the catchments dry off and stream flows drop off significantly.

Page 5

1600 MOUNT HOPE RAINFALL Upper 1400

1200 2010 Rainfall (mm)

2011 Rainfall (mm) 1000 2012 Rainfall (mm)

800 2013 Rainfall (mm)

2014 Rainfall (mm) 600 2015 Rainfall (mm)

400 Mount HopeAverage for period 2016 Rainfall (mm) 200 2017 Rainfall (mm)

0 2018 Rainfall (mm) Week 1 Week 3 Week 5 Week 7 Week 9 Week 11 Week 13 Week 15 Week 17 Week 19 Week 21 Week 23 Week 25 Week 27 Week 29 Week 31 Week 33 Week 35 Week 37 Week 39 Week 41 Week 43 Week 45 Week 47 Week 49 Week 51 As a result of the dry end to spring, inflows into the reservoirs have been low, even lower than 2017. We only received approximately 1,500ML into both Melton and Pykes Creek reservoirs. Consequently the storages are significantly lower than the same time last year.

Same time Last Reservoir Volume/ML Level/ %FSL Year Pykes Creek 16,790 76% 93% Melton 4,544 32% 70% Lake Merrimu 11,152 34% 50% Werribee System storage levels as at 30 November 2018 Due to the low inflows and storage levels the 2018-19 seasonal allocation is currently only 30% of high reliability water share (HRWS). LATROBE SYSTEM: Blue Rock reservoir is the primary storage for the Latrobe System. Water from Blue Rock reservoir is primarily used for electricity generation in the Latrobe Valley coal fire power plants. It also supplies Gippsland Water with water to supply to towns in the Latrobe Valley, and river diverters along the Latrobe River. Last year Blue Rock reservoir declined to 82.5% of capacity on 8 May, but has since recovered to 93% on 30 November.

Page 6

MARIBYRNONG SYSTEM: Rosslynne Reservoir supplies Western Water with water for the townships of Sunbury and Gisborne. It also supplies river diverters along the . The Maribyrnong catchment has had another very poor winter and spring with Rosslynne Reservoir even lower all year. Rosslynne reservoir held 26.5% on 30 November 2018, compared with 35.4% at the same time last year.

Table 3: Storage levels as at 30 November compared with the same time last year and the 10-year average. Storage Current Level Same time last year 10-year average Lake Glenmaggie 77% 85% 91% Blue Rock 93% 99% 95% Melton Reservoir 32.9% 70% 55% Pykes Creek 75.8% 93% 67% Merrimu 34.2% 62% 51% Rosslynne 26.5% 35% 49% Thomson (SRW share) 86% 85% 82%

Page 7

Twelve month Seasonal Outlook The Bureau of Meteorology’s (BOM) seasonal rainfall outlook for the December to February period continues to predict average conditions for the state with a neutral chance of above median rainfall and warmer days and nights for the period. The BOM has also increased the El Nino Southern Oscillation outlook from watch to alert, reflecting a 70% chance of an El Nino developing this summer. This is three times the normal likelihood although it has less rainfall influence in southeast . There is also a high chance of a positive Indian Ocean Dipole developing which also weakens in summer. However, the climatic indicators are still pointing to the continuation and possible worsening of dry conditions. WERRIBEE SYSTEM Applying this outlook to the already dry conditions resulting from no rainfall in September, it is unlikely that the seasonal allocation for Werribee/Bacchus Marsh will increase significantly in the near term. While there is enough allocation to meet irrigation demand the situation varies for each individual irrigator and there are a significant number in the Werribee Irrigation District who will need to buy more river water allocation and/or use more recycled water in order to meet their. MACALISTER IRRIGATION DISTRICT The BOM outlook suggests central Gippsland will receive warmer than average temperatures across the region and a neutral rainfall outlook. Given these factors and the dry winter, median to low streamflow would be likely for the period December to February. MID customers typically use 120% water over the season with high demand during the summer period. By the end of summer period we will have expected to use 70% of this to maintain production on farm. Under current conditions, with no spill entitlement available, predictive modelling suggests that a minimum of 25% LRWS will be available to MID customers on 15 December. This increase in LRWS, along with allocation trades, would be expected to cover any shortfall for customers. With no spill entitlement for customers available at this stage, the MID would be tending more towards a normal year with the availability of allocation against LRWS expected to reach 40-50% by the end of the water year based on the median end of stream flows occurring. Because Lake Glenmaggie is a fill and spill system, opening allocations for are highly dependent on rainfall over autumn and winter within the Macalister catchment area. Additionally the Thomson drought reserve volume is used to supplement opening allocations. Seasonal conditions are determined by total inflows into Lake Glenmaggie for the previous two months, as outlined in Table 3.1. In a typical dry season, opening allocation is 45% HRWS (i.e. 2017), in a normal season the typical opening allocation is 65% HRWS, and in a wet season the typical opening seasonal allocation is 85% HRWS. Table 3.1: Determining seasonal conditions by means of inflows over previous two months. Decision Date Wet Normal Dry 1 June >13,000 ML 1,200-13,000 ML 0-1,200 ML 1 July >47,000 ML 2,900-47,000 ML 0-2,900 ML 1 August >100,000 ML 25,000-100,000 ML 0-25,000 ML 1 September >150,000 ML 50,000-150,000 ML 0-50,000 ML

Dry, normal and wet scenarios have been considered in the table below based on the seasonal conditions presented. High trade volumes and low stream flows will result in lower storage volumes at the end of the season and this may impact on the opening allocation for the 2019-20 season.

Page 8

The average storage volume on the 30 June over the last 30 years is 58,000ML, which can support allocations of 32% HRWS for customers, and August average storage volume over the last 30 years is 129,000ML which can support allocations of 72.6% of HRWS for customers, an increase of 40% allocation in a very short space of time. Table 4: Irrigation outlook: likely allocations by 30 June 2019 under different rainfall scenarios District Current Wet Normal Dry allocation Macalister 100% (N) 160%+ 140% 100% Werribee * 30% HRWS 60-70% 60-70% 55-60% Bacchus Marsh * 30% HRWS 60-70% 60-70% 55-60% * Dependent on carryover usage which is difficult to predict. LATROBE SYSTEM: As for the Macalister district, the BOM outlook suggests central Gippsland will receive warmer than average temperatures across the region and a neutral rainfall outlook. Given these factors and the dry winter, median to low streamflow would be likely for the period December to February. Under a medium to low streamflow scenario, Blue Rock Reservoir is likely to decline over summer and will rely on winter/spring rains to fill again. Blue Rock Reservoir is highly reliable and has filled in seven out of the last 10 years. MARIBYRNONG SYSTEM The BOM outlook for the Maribyrnong system indicates there is an equal chance of receiving above or below average rainfall. Rosslyn reservoir is already below last year’s low levels and the inflow is unlikely to be high enough to change the current level of restriction.

Page 9

Unregulated surface water Unregulated systems are monitored in accordance with relevant Local Management Rules. These rules set out a framework for trading and how local water issues are managed. SRW releases annual reports in October each year which report, at a catchments scale, how the rivers fared last season; groundwater level trends; number of irrigation licences in each system; how much water irrigators used last season, compared with previous years; and emerging local water issues. To find a copy of all 12 reports visit our website. For up to date information about unregulated rivers and streams on restrictions visit: srw.com.au

Table 5: Comparison of stream flows across major systems on 30 November 2017 and 30 November 2018

River or Stream Nov Nov River or Stream Nov Nov 2017 2018 2017 2018 (ML/d) (ML/d) (ML/d) (ML/d) South West Region Gippsland Region (Zone A) 39 10 Mitchell River 565 463 Barwon River (Zone B) 24 14 Avon River 13 17 Barwon River (Zone c) 60 80 Valencia Creek 2 3 30 80 Upper Latrobe River 210 254 15 2 20 42 Mt Emu Creek 24 8 20 76 110 50 Narracan Creek 61 49 45 33 Creek 71 23 380 170 78 271 450 35 54 359 Darlots Creek 110 82 & Westernport Region Eumarella River 40 13 River 111 95 80 43 74 26 230 85 145 37 Grange Burn River 30 20 96 55 Crawford River 16 5 Jacksons Creek 9 11 Brucknell (Cudgee) Creek 40 20 Deep Creek 23 4 30 12 Turitable Creek 124 1 Surry River 16 3 Upper Werribee River 25 3 16 5

Current conditions and outlook for unregulated river systems Rainfall deficiencies have occurred across most regions over the last six months compared to mean conditions. In the western areas the deficit is relatively minor at between 10-20% of mean, whereas the variation is far more significant in the East Gippsland areas, particularly along coastal areas which are as high as 40-60% below mean. The rainfall deficits were not helped by a very dry September which was among the lowest recorded in most areas.

Page 10

Gippsland Region The Gippsland region has faced mixed conditions over the past period with deficiencies in rainfall increasing the further you head towards the East. East Gippsland itself has been extremely dry for the past two years and the lack of spring rains has translated to an early start to the irrigation season for many. While there are only a few systems that have already reached restriction or ban levels, such as the , conditions are generally similar or worse than at the corresponding period last year. The outlook is indicating a very low chance of exceeding median rainfall over the next three months, particularly along coastal areas and the Latrobe Valley, and so it is likely that we will trigger roster / restrictions in systems earlier than normal. There may be bans on and Swifts Creek by November or early December and other systems, which normally may not face restrictions until February-March may be activated by December. The Mitchell River is the most significant of the systems in the East due to volume of licences and production. Last season restrictions were imposed from February through to May with one month of high level restrictions but no bans applied. This season current flow at Glenaladale is the second lowest flow since 2006-07 when restrictions started in October. If current dry conditions persist then restrictions are likely to come in as early as November and unlikely to be lifted before April 2019. In the Latrobe system, while the Moe River and Upper Latrobe River managed to remain just above restriction levels, several smaller systems such as the Traralgon Creek and Middle Creek ceased to flow earlier in the year and were placed on bans throughout the late summer and autumn period. Similarly the Morwell River was placed on restricted rosters during this period. In the Thorpdale area, the Narracan Creek is flowing 40-50% less than last season and Ten Mile Creek is around 20% less. While restrictions or bans were limited on these systems last year, without significant rains over the coming months these systems are likely to face more significant bans commencing in late November or December. Similarly the Avon River system has already faced 80 days of restrictions and only 43 days of unrestricted access since 1 July this year. West Close to average winter rainfall in the far South-West of Victoria has seen the major streams, Glenelg River, Wannon River and Merri River sustain reasonable flow levels for lengthy periods and they are still slightly higher than for the same time last year. Wannon and Glenelg Rivers had no restrictions in place for the 2016-17 season for the first time in several years. The 2018 spring has been below average for rains and this has led to a rapid decline in flows leading to average timing for restrictions on the smaller streams and tributaries. The major streams are looking like restrictions will be in place by late January to early February under current conditions. The Otway system has experienced average rainfall and flows are similar to that of last season. Restrictions on the Gellibrand River will be in place as per last season. The Barwon system has experienced below average rainfall for the winter and a well below rainfall pattern for spring. Flows are generally lower than for the same time last year with some higher flows with interspersed rainfall events recently maintaining average flows. The Barwon and Leigh Rivers will have a similar restriction pattern to that of last season. The Moorabool is trending to that of last season with lengthy period of total bans to be in place prior to Christmas without any additional rainfall occurring in the meantime.

Page 11

Central There has been less than average rainfall within the Central Region and as a result stream flows are significantly lower than previous years. Forward predictions are for higher than average temperatures and below average rainfall for the November – January period which is likely to result in water restrictions in many areas. Annual rainfall across the Dandenong Creek catchment is currently less than half compared to last year. Average stream flows in the Dandenong Creek are significantly lower than last year and this is reflected in the Mile, Monbulk and Eumemmering Creek tributaries. While usage is currently only around 20% of active licences, further reduction in rainfall across the catchment may lead to restrictions for some areas. The Werribee and Maribyrnong Catchments have had slightly below average rainfall for the first six months of 2018. Restrictions will likely be implemented in the Maribyrnong Catchment as early as December. The Turitable and Willimigongong Creeks are usually subject to a total ban and Qualification of Rights in the summer months. Without rainfall this will likely occur earlier than previously this season. Rainfall across the Tarago/Bunyip catchment was generally between 100 to 200mm less than the mean between October 2017 and September 2018. Tarago/Bunyip system flows were maintained last season via SRW releases from the Tarago Reservoir. Active irrigators on the Lang Lang River were intermittently restricted as trigger flows were reached. Flows in the Tarago/ this year appear to be well under what they were this time last year and, if the trend continues, rosters will likely be needed by late November into December as demand for irrigation water increases into the peak summer period.

Page 12

Groundwater

Current conditions and outlook: In the Southern Rural Water area it is unlikely that there will be rosters/restrictions across the majority of the Water Supply Protection Areas (WSPA) or Groundwater Management Areas (GMA). The exception to this is the Deutgam GMA which is again restricted to 50% of entitlement, similar to last year’s allocation. Groundwater levels in the Lancefield GMU remain stable. Levels within the Deutgam WSPA are slightly declining. The allocation for the Deutgam WSPA is unlikely to be increased this season. Generally groundwater levels across the Koo Wee Rup WSPA have been relatively steady with some gradual overall decline across the region. No restrictions are anticipated at this stage. Groundwater levels within Wandin Yallock are stable and are fluctuating within normal ranges. Changes range between 0.5m to 20m, with all having stable trends with data taken since the late 1970s. Usage in Wandin Yallock last year was 23% and for unincorporated / Non GMA GW was 20%, both similar to previous years. There have been no bans, rosters or restrictions in Wandin Yallock GMA In the Moorabbin GMA trends are plus/minus around 6m, which is well in line with seasonal trends over the last decade. Usage is generally around 50% of active licences. There is unlikely to be rosters/restrictions in this area, even under dry conditions

Table 4: Trends in groundwater management units Groundwater Management Unit Restrictions Groundwater Level Trend Gippsland Region Wa De Lock GMA No Declining Denison GMA No Not available Rosedale GMA No Declining Sale WSPA No Stable Stratford GMA No Declining Corinella GMA No Declining Giffard GMA No Declining Leongatha GMA No Stable Tarwin GMA No Stable Yarram GMA No Declining Wy Yung GMA No Stable Moe GMA No Declining South West Region Jan Juc GMA No Declining Newlingrook GMA No Stable Paaratte GMA No Stable South West Limestone GMA No Declining Glenormiston GMA No Not available Condah GMA No Declining Glenelg WSPA No Stable

Page 13

Portland GMA No Declining Colongulac GMA No Stable Warrion WSPA No Stable Bungaree GMA No Declining Cardigan GMA No Stable Gerangamete GMA No Stable Port Phillip & Westernport Region Koo Wee Rup WSPA No Stable Frankston GMA No Declining Moorabbin GMA No Stable Nepean GMA No Stable Deutgam WSPA Currently 50% Declining Lancefield GMA No Stable Merrimu GMA No Stable Cut Paw Paw GMA No No SOBN bores in this area currently

Page 14

Climate outlook 2018-19

Rainfall and temperature ahead Temperature and rainfall influence water use, especially during summer periods. At the same time, they also influence catchment soil moisture levels and inflows to Southern Rural Water’s unregulated waterways and storages. Southern Rural Water continually monitors flow conditions and the Bureau’s seasonal climate outlooks. Waterway flow and rainfall information is made publically available on the Southern Rural Water website. For the most up to date weather, temperature and rainfall data and predictions, see the BOM website www.bom.gov.au Rainfall outlook – The Bureau of Meteorology’s (BOM) seasonal rainfall outlook for the December to February period continues to predict drier than average conditions. It is showing only a 50% chance of above median rainfall across the state for the period. The BOM forecast shows a 50% chance of exceeding rainfall across much of the south of the state with areas in the west expecting even less.

BUREAU OF METEOROLOGY Chance of exceeding the median rainfall December 2018 – February 2019

Page 15

ENSO outlook The BOM has also increased the El Nino Southern Oscillation outlook from watch to alert reflecting a 70% chance of an El Nino developing this summer. This is three times the normal likelihood. There is also a high chance of a positive Indian Ocean Dipole developing which may exacerbate the effects of an El Nino. Therefore, the climatic indicators are pointing to the continuation and possible worsening of dry conditions.

BUREAU OF METEOROLOGY Chance of exceeding the median maximum temperature December 2018 – February 2019

Temperatures are predicted to exceed normal maximums particularly in the far south and east Gippsland which will only increase demand for water and put greater pressure on storages and river systems.

Further information SRW provides a variety of information on allocations, streamflows, rosters and restrictions and delivery/availability issues on our website www.srw.com.au Water trading information is also available through SRW and on our WaterMatch site www.watermatch.com.au For all climate and weather predictions and observations, customers should go to the Bureau of Meteorology site at www.bom.gov.au

Page 16