Loddon River system (including Tullaroop, Serpentine and Pyramid creeks)

The Loddon River flows from the Great Dividing Range in the south to the Murray River in the north. Tullaroop Creek is the main tributary in the upper Loddon River system (Figure 5.7.1). The middle section of the Loddon River is characterised by many distributary streams and anabranches that carry water away from the river onto the floodplain. The lower Loddon River is joined by Pyramid Creek at Kerang, at which point the Loddon becomes part of the Murray River floodplain.

The two main storages on the Loddon River are Cairn Curran Reservoir and Tullaroop Reservoir. Laanecoorie Reservoir is a smaller storage that is used to regulate water released from the larger upstream storages. Flow in the Loddon River downstream of Laanecoorie Reservoir is regulated by the operation of the Bridgewater, Serpentine, Loddon and Kerang weirs.

Water for the environment can be delivered to the Loddon River from Cairn Curran or Tullaroop reservoirs or from the Goulburn system via the Waranga Western Channel, which intersects with the Loddon River at Loddon Weir. Water is provided to Pyramid Creek through releases from Kow (Ghow) Swamp, which receives water diverted from the Murray River at Torrumbarry Weir. Water is diverted from the Loddon River to the Loddon Valley Irrigation Area to supply agriculture and to Serpentine Creek to support environmental values and supply agriculture.

The highly regulated nature of the Loddon system provides both challenges and opportunities for effective management of water for the environment. The ability to manipulate the timing of releases at multiple locations can help achieve environmental outcomes at discrete locations. However, coordinating environmental flows and consumptive flows is difficult through the irrigation season, especially when irrigation demand is high or flow in the river is highly variable. These issues can constrain the timing and delivery of water for the environment or lead to greater-than-recommended flows above Loddon Weir. The structures used for managing irrigation water form barriers in the waterway, restrict flow reliability and create barriers to aquatic animal movement throughout the river, which make it harder to achieve good outcomes for native fish and possibly platypus.

Proportion of water entitlements in the Loddon system held by private users, water corporations and environmental water holders on 30 June 2020

System map

Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches can receive environmental water.

Environmental watering objectives in the Loddon River

Increase populations of small and large-bodied native fish

Provide habitat for fish to feed and breed and opportunities for movement between habitats

Enhance the channel form and features, including deep pools and benches

Maintain the condition of suitable substrate to maintain ecosystem processes

Engage floodrunners, distributary channels, anabranches and backwaters

Increase the population and recruitment of resident platypus

Maintain a stable rakali (water rat) population in the long term

Maintain productive and dynamic food webs

Maintain/increase the diversity and abundance of biofilms

Maintain the condition of streamside and floodplain vegetation

Maintain and increase the extent of in-stream vegetation

Maintain/increase the diversity and abundance of waterbugs and waterbug functional feeding groups

Maintain water quality to support aquatic animals and minimise the occurrence of blackwater events

Environmental values

The Loddon River system supports platypus, rakali (water rats) and several species of native fish (such as Murray cod, golden perch, silver perch, river blackfish and Murray-Darling rainbowfish). Streamside vegetation varies in condition depending on the recent water regime, the extent of clearing and historic and current land management practices. The areas that remain relatively intact support a variety of woodland birds and other native animals. Important plant species across the system include cane grass, tangled lignum, black box and river red gum.

Although fish populations in the Loddon system are affected by the many barriers caused by weirs and reservoirs, a large range of species are still found through the catchment. Native fish are most abundant and diverse in the upper catchment. River blackfish are found in Serpentine Creek, and rare Murray-Darling rainbow fish are found in the middle and lower sections of the Loddon River.

The highest-priority reach for water for the environment is from Loddon Weir to Kerang Weir. The reach does not carry irrigation water, and it relies heavily on environmental flows to maintain its environmental condition. Environmental flows to this reach aim to improve the condition of streamside vegetation, maintain water quality and increase the abundance and diversity of native fish. Environmental flows are delivered to the upper Loddon River, Tullaroop Creek and Serpentine Creek to maintain or increase populations of river blackfish and platypus.

Pyramid Creek and the lower Loddon River support large-bodied fish (such as golden perch, Murray cod and silver perch) and are important corridors for fish migration between the Loddon and Murray systems. Engineering works to provide fish passage at the Chute, Box Creek regulator, Kerang Weir, Fish Point Weir and Little Murray Weir on the Little Murray River in recent years have been important in reopening these migration routes. The Arthur Rylah Institute has monitored fish movement and populations in Pyramid Creek and the lower Loddon River since 2017, and results have indicated that the combined Loddon and Pyramid flows are stimulating native fish movement through the fishways.

Traditional Owner cultural values and uses

The Barapa Barapa and Wamba Wemba are the Traditional Owners in the northern part of the Loddon catchment, and the Djaara (Dja Dja Wurrung People) are the Traditional Owners in the southern part of the catchment. Artefacts of cultural practices are present throughout the Loddon and Pyramid system and its floodplain.

In planning for environmental flows in the Loddon River system, Djaara, Barapa Barapa and Wamba Wemba and North Central CMA have considered how environmental flows in the Loddon system can be managed to support their respective values, priorities and uses.

In the southern part of the catchment, Dja Dja Wurrung Clans Aboriginal Corporation (trading as DJAARA) Kapa Gatjin (water advisory) Group and North Central CMA have been working together to identify opportunities and sites where water for the environment can support Djaara aspirations for the Loddon River. A key aspiration is for Djaara to play a greater role in the management and administering of environmental water, with an aim of future ownership and management of environmental water.

Recently DJAARA conducted a Cultural Values Assessment (CVA) – similar to an Aboriginal Waterways Assessment (AWA) – at two sites along the Loddon River. The assessments included detailed visual inspections, questionnaires and data analysis. On Country DJAARA participated in two-way learning with North Central CMA staff. Discussion points included cultural heritage, effects of river regulation, and alignment of watering and cultural objectives. This is the beginning of a longer journey to collaborate on realising joint aspirations for the Loddon River.

In early 2022, Barapa Barapa and Wamba Wemba Traditional Owners joined North Central CMA staff on Country to reflect upon environmental watering in the Loddon River system in 2021-22 and to discuss aspirations for 2022-23. Barapa

Barapa and Wamba Wemba Traditional Owners emphasised the importance of water for the environment in supporting fish populations (such as Murray cod and golden perch) in the Loddon River system, particularly over summer.

Barapa Barapa and Wamba Wemba Traditional Owners discussed a long-term vision to create a golden perch nursery at Kow (Ghow) Swamp and supported the North Central CMA re-snagging of Pyramid Creek. Traditional Owners also expressed the need for improved access to Pyramid Creek, and the fact that private land tenure often creates impediments to floodplain watering and Traditional Owner restoration efforts on Country.

Barapa Barapa Traditional Owners have communicated their cultural objectives for the Loddon River and other waterways in the Barapa Barapa Healthy Country Plan. Objectives that relate to the Loddon River system include:

all wetlands surrounding the Murray River, Gunbower Forest, Loddon River and associated lakes have good plant life and healthy native fish (cod and yellow belly), mussels and turtle populations by 2033
by 2033, the Murray, Gunbower, Loddon and associated lakes will have enough water. Water quality is improving and water is clear for most of the year in good years
Barapa people are actively involved in water management
reduce the number of major fish and plant deaths from toxic blackwater events to improve water quality.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 5.7.1, North Central CMA considered how environmental flows could support values and uses, including:

water-based recreation (such as fishing, powered and non-powered boating, water skiing and water sports)
riverside recreation and amenity (such as birdwatching, bushwalking, camping and cycling)
community events and tourism (such as water skiing competitions at Bridgewater and associated visitation)
socio-economic benefits (such as diverters for domestic and stock uses, local and regional economic benefits from increased visitation and ecosystem services, including carbon storage, groundwater recharge and nutrient recycling).

If the timing or management of planned environmental flows may be modified to align with a community benefit, this is acknowledged in Table 5.7.1 with the following icon.

Watering planned to support water sports activities (e.g. water skiing)

If possible, North Central CMA will work with Goulburn-Murray Water to manage the delivery of low flow rates and the timing of freshes over summer/autumn to support optimum conditions for annual water skiing competitions at Bridgewater weir pool, where possible.

Recent conditions

Rainfall across the Loddon system during 2021-22 was close to the long-term average, while temperatures were warmer than average. Two unregulated high-flow events occurred in the Loddon River in August and November; the largest event peaked at 961 ML per day at Loddon Weir on 5 November. High-reliability water share allocations in the Loddon system opened at 33 percent at the start of July and reached 100 percent by early October. No low-reliability water share allocation was issued in 2021-22. The VEWH also traded 5 GL into the Loddon system from its Goulburn entitlements to support planned watering actions in 2021-22.

Deliveries of water for the environment for the Loddon system were managed in line with an average climate scenario during 2021-22. Most planned watering actions for the Loddon River, Serpentine Creek and Pyramid Creek were achieved through the use of environmental flow, passing flow, releases for consumptive use and some unregulated flow.

The winter/spring high flow in reach 4 of the Loddon River and Pyramid Creek was coordinated in October 2021 to deliver a high flow at Kerang Weir that aimed to cue native fish to move into the system from the Murray River. The flow was delivered at a slightly lower magnitude than in previous years — peak flow at Kerang Weir was 638 ML per day on 17 October — to avoid flooding private land. The effectiveness of the lower flow rate is yet to be confirmed by monitoring.

Heavy rainfall in January 2022 delivered a natural fresh in the lower Loddon River that washed a lot of organic matter into the river and caused low oxygen levels during a subsequent hot spell. North Central CMA delivered one of three planned summer/ autumn freshes to increase oxygen levels, but it was not effective, and a larger fresh — 200 ML per day — was delivered under the emergency watering provision to prevent fish deaths. Water for the environment was also used to deliver a summer fresh in Serpentine Creek in late January to alleviate water quality issues.

Flow in Pyramid Creek was reduced in May and June 2022 to allow water levels to draw down in Kow (Ghow) Swamp. The low flow remained within the minimum recommended range, and it was not considered harmful to native fish or other environmental values in the creek.

Two planned watering actions were not delivered in 2021-22. The first was a combined autumn high flow in the Loddon River and Pyramid Creek, which aimed to trigger the upstream movement of native fish from the Murray River and facilitate the dispersal of juvenile platypus. This is the second consecutive year that capacity constraints in Pyramid Creek have prevented delivery of an autumn high flow, and delivering it in 2022-23 will be a high priority to help achieve environmental objectives for native fish and platypus. The second planned watering action not achieved in 2021-22 was a winter/spring fresh in Serpentine Creek. It was not delivered to avoid potential flooding of private land at the end of the system. The flood risk applies to any increased flow in Serpentine Creek that cannot be redirected back into the irrigation channel system. The North Central CMA, storage manager and the VEWH have partly resolved the issue to allow summer/autumn freshes to be delivered in Serpentine Creek, and we will continue to explore options that will allow larger environmental flows to be safely delivered in future.

Scope of environmental watering

Table 5.7.1 describes the potential environmental watering actions in 2022-23, their expected watering effects (that is, the intended physical or biological effects of the watering action) and the longer-term environmental objective(s) they support. Each environmental objective relies on one or more potential environmental watering actions and their associated physical or biological effects.

Table 5.7.1 Potential environmental watering actions, expected watering effects and associated environmental objectives for the Loddon River system

Potential environmental watering action	Expected watering effects	Environmental objective
Loddon River (targeting reach 4)
Winter/spring low flow (25-100 ML/day during June to November	At 25-50 ML/day, low flows will provide a minimum level of continuous flow through the reach and maintain water quality¹ At 100 ML/day: increase the water depth for fish, platypus and rakali (water rat) dispersal (especially for male juvenile platypus) to colonise new breeding territory in winter and provide foraging habitat prevent silt and fine sediment from settling on submerged wood and other hard surfaces inundate a variety of habitats to increase the growth of biofilms and support waterbug productivity water the native fringing bank vegetation to support seed germination and growth and prevent the encroachment of exotic terrestrial plants in the river channel
Winter/spring low flow trial (100-200 ML/day for one to 10 days during June to November, if triggered by an unregulated flow event)	Increased longitudinal connectivity by drowning out fish barriers to allow fish to access new habitats Inform future works to modify or remove fish barriers
Winter/spring high flow (one high flow of 400- 450 ML/day for six to 10 days during August to November)	Provide sufficient velocity to scour accumulated sediment from pools and scour biofilms, promoting the growth of new biofilms and increasing waterbug productivity Flush accumulated organic matter from the bank and benches to increase productivity and reduce the risk of a hypoxic blackwater event in summer Wet the banks to promote the recruitment and growth of streamside and emergent vegetation Stimulate native fish movement and breeding
Summer/autumn low flow (25-50 ML/day during December to May)²	At 25 ML/day, low flows will provide a minimum level of continuous flow through the reach At 50 ML/day: maintain an adequate depth in pools for aquatic plants and to provide habitat for waterbugs, fish and rakali (water rats) provide continuous flow through the reach to maintain water quality wet the banks and shallow riffles to support the growth of in-stream and fringing non-woody vegetation
Summer/autumn low flow trial (50-100 ML/day for one to two months during January to February, if triggered by hot conditions)	Provide continuous flow through the reach to maintain water quality and potentially mitigate against a hypoxic blackwater event Prevent emigration of native fish species due to low water quality
Summer/autumn freshes (three freshes of 100 ML/ day for three days during December to May)	Increase the water level to promote seed germination and the growth of fringing emergent macrophytes Increase connectivity between deep pools to promote the local movement of fish and prompt the dispersal of juvenile platypus in autumn Generate sufficient force to flush fine sediment and old biofilms from submerged wood and other hard surfaces, promoting the growth of new biofilms and increasing waterbug productivity Freshen water quality and reoxygenate pools
Autumn high flow (one high flow of 400 ML/ day for six days³ during March to May)	Trigger and facilitate the upstream movement of golden perch, silver perch and Murray cod older than one year Facilitate the dispersal of juvenile platypus Generate sufficient force to flush fine sediment and old biofilms from submerged wood and other hard surfaces, promoting the growth of new biofilms and increasing waterbug productivity
Year-round fresh (trigger- based, 50-200 ML/day as required) Triggers: the oxygen level is below 5 mg/L the air temperature is above 28° there are low or cease-to-flow river conditions there are high water temperatures and/or low river flow	Destratify pools and improve water quality (increase oxygen levels) along the river in reach 4, ensuring there is adequate oxygen to support aquatic animals (such as native fish and platypus)
Pyramid Creek and Loddon River (targeting reach 5)
Year-round low flow (90-300 ML/day at Box Creek regulator)	At 90 ML/day, low flow will maintain connectivity between pools and provide habitat for aquatic animals At 200 ML/day: increase longitudinal connectivity to allow native fish and platypus to access new habitats improve water quality by reducing salinity levels increase the wetted area to maintain and promote the growth of fringing emergent (non-woody) vegetation along the lower banks of the channel At 300 ML/day: facilitate greater movement for large-bodied native fish wet a larger perimeter of the riverbank to enhance the growth of fringing emergent (non-woody) vegetation along the lower banks of the channel increase hydrodynamic diversity and improve the quality of flowing habitats
Winter/spring high flow (one high flow of 650 ML/ day at Kerang Weir for 10 days)⁴	Trigger the migration, spawning and recruitment of native fish species, including Murray cod Maintain connectivity between habitats and improve water quality Provide sufficient energy to flush accumulated sediment from pools and substrates
Autumn high flow (one high flow of 650 ML/day at Kerang Weir for six days³ during March to April)⁴	Trigger and facilitate the upstream movement of golden perch, silver perch and Murray cod older than one year Maintain connectivity between habitats and improve water quality Facilitate platypus dispersal Provide sufficient energy to flush accumulated sediment from pools and substrates
Serpentine Creek (targeting reach 1)⁵
Winter/spring low flow (10-30 ML/day⁶ during June to November)	At 10 ML/day, low flow will maintain connectivity between habitats At 20-30 ML/day: maintain habitat for native fish and facilitate movement for aquatic animals wet exposed roots, woody debris, emergent vegetation and leaf packs to provide habitat for aquatic animals maintain water quality by preventing stagnation provide flow variability to maintain the diversity of fringing vegetation provide a sufficient depth of water and variability of flow to maintain microbial biofilms
Winter/spring fresh (one fresh of 40-120 ML/ day6 for two days during August to November)	Provide connectivity for fish and waterbugs to access different habitat areas, supporting a diversity of functional feeding groups Transport organic matter that has accumulated in the channel, to increase the breakdown of organic matter in winter/spring Wet the banks to promote the recruitment and growth of streamside and emergent vegetation At 120 ML/day: maintain the channel form and scour pools encourage female platypus to select nesting burrows higher up the bank to reduce the risk of greater flow later in the year flooding burrows when juveniles are present flush accumulated leaf litter from the banks and low benches to reduce the risk of blackwater events during summer
Summer/autumn low flow (10-20 ML/day⁶ during December to May)	Provide connectivity between pools to allow the dispersal of small- to medium-bodied native fish Wet exposed roots, leaf packs and woody debris to provide habitat for aquatic animals Provide sufficient flow to maintain water quality by oxygenating pools Maintain foraging habitat for platypus Maintain the wetted area to support in-stream aquatic vegetation (such as water ribbons, eel weed and milfoil)
Summer/autumn freshes (three freshes of 40 ML/ day⁶ for two days during December to May)	Maintain the channel form by inundating benches Generate sufficient force to flush fine sediment and old biofilms from submerged wood and other hard surfaces, promoting the growth of new biofilms, increasing waterbug productivity and replenishing the food supply for aquatic animals Increase connectivity between pools to promote the local movement of fish and prompt the dispersal of juvenile platypus in autumn Transport organic matter that has accumulated in the channel to provide carbon and nutrients downstream Provide flow variability to maintain the diversity of fringing vegetation (such as emergent macrophytes) Freshen water quality by diluting salt and reoxygenate pools

¹ Winter/spring low flow of 50 ML per day is below the passing flow magnitude and will result in the VEWH banking passing flows savings for use in other potential watering actions.
² Under all scenarios, a 100 ML/day summer low flow rate may be trialled in January and February to mitigate hypoxic blackwater and prevent the emigration of native fish species.
³ The peak magnitude of this event is planned to be delivered for six days, but there is an extended, 14-day ramp-down period.
⁴ Winter/spring and autumn freshes are planned to occur at the same time in the Loddon River and Pyramid Creek, with the peak timed to meet at Kerang Weir. 650 ML/day is the total combined target at Kerang Weir.
⁵ Flow in Serpentine Creek may be allowed to either return to the Loddon River or continue down Pennyroyal and Bannacher creeks or Nine Mile Creek with the agreement of landholders.
⁶ Flow delivered from Serpentine Weir may be restricted to manage end-of-system outfalls to avoid third-party impacts until an alternate solution is determined.

Scenario planning

Table 5.7.2 outlines potential environmental watering and expected water use under a range of planning scenarios.

Loddon River

In the Loddon River, delivery of three summer/autumn freshes and continuous, year-round low flow are high priorities under all climate scenarios to maintain habitat for native fish, platypus and native vegetation and prevent poor water quality. Flow will likely be delivered at the lower end of the recommended range under drought conditions to conserve supply. Lower magnitude flow will aim to prevent critical harm to aquatic plants and animals rather than improve their condition. Low-oxygen incidents in recent years have highlighted the need for a fresh that can be delivered at any time to respond to poor water quality. This new watering action may be delivered up to a magnitude of 200 ML per day, based on the flow rate needed to improve water quality in 2017 and 2022, and it is considered a high priority under all climate scenarios.

The prescribed passing flow in the Loddon River between May and October is 77 ML per day. Under the drought climate scenario, the passing flow may be reduced to 25 ML per day (in consultation with Goulburn-Murray Water) to accrue additional water savings that can be used to supplement flow in summer and autumn, when there are higher risks of poor water quality, and to prevent cease-to-flow events in reaches that do not carry consumptive water. The forecast high water availability will potentially allow summer/autumn freshes to be delivered at 100 ML per day under all climate scenarios in 2022-23. Under a dry climate scenario, the winter/spring low flow will likely be delivered at the standard passing flow rate of 77 ML per day, and the summer/autumn low flow will be delivered at 40 ML per day. If additional water becomes available or an average or wet scenario eventuates, water for the environment may be used to increase winter/spring low flow to 100 ML per day and summer/autumn low flow to 50 ML per day to improve the condition of vegetation higher up the bank, improve water quality and increase the abundance and improve the condition of fish and platypus populations.

Fish ecologists have recommended trialling different flow rates to improve fish outcomes in the Loddon River if sufficient water is available. The first trial is to increase summer/autumn low flow to 100 ML per day during January and February if hot conditions are forecast to reduce the risk of fish emigration and mitigate water quality issues. The second trial involves increasing the winter/spring low flow to 200 ML per day after an unregulated event to increase fish passage past low-level barriers. The first trial may occur under any scenario if there is an available supply, but the second trial will only be considered if there are large natural events; it is, therefore, more likely under a wet climate scenario. There will need to be appropriate monitoring as part of either trial.

Pyramid Creek

Pyramid Creek is regionally significant for native fish. Fish populations within Pyramid Creek have increased since the Millennium Drought, and the removal of fish barriers means it is now an important dispersal corridor for fish moving between the Murray River, Kow (Ghow) Swamp and Gunbower Creek. Maintaining adequate low flow to allow fish to remain in Pyramid Creek all year (including during the non-irrigation season) and delivering high flow to cue and facilitate fish movement at key times of the year are high priorities under all climate scenarios.

Modelling conducted by the Arthur Rylah Institute indicates that maintaining a low flow of at least 200 ML per day throughout the year in Pyramid Creek is optimal for resident fish populations. Maintenance and fishway construction works planned for the 2023 irrigation shut-down period may affect water deliveries to Pyramid Creek and make it difficult to maintain a flow of at least 200 ML per day. North Central CMA and the storage manager will aim to maintain flow within a range of 90-300 ML per day in Pyramid Creek during this period if construction works proceed.

The winter/spring high flow in Pyramid Creek has a target flow rate of 650 ML per day at Kerang Weir, which requires coordinated releases in Pyramid Creek and reach 4 of the Loddon River. The ideal duration of this event is 10 days, but it may be reduced to six days under a drought or dry climate scenario to conserve water. The reduced duration should still be sufficient to allow many fish to move through the system. A similar-sized event in autumn is recommended for average and wet climate scenarios, when large numbers of juvenile fish are likely to be trying to migrate from the Murray River into the Loddon system. It may also be delivered under drought and dry climate scenarios, if it can be delivered with the available supply or, more likely, by using operational transfers.

Serpentine Creek

In Serpentine Creek, the main priority will be to maintain low flow throughout the year to provide habitat for native fish, waterbugs, rakali (water rats) and platypus and to deliver freshes to improve water quality, allow fish and platypus movement and improve the condition of streamside vegetation. Flow will likely be delivered at the lower end of the recommended range under drought and dry climate scenarios to conserve available water.

Carryover of 4,338 ML is prioritised into 2023-24 under all scenarios. This water will help meet early-season, low-flow and winter/spring fresh demands in all waterways.

Planning scenario table

Table 5.7.2 Potential environmental watering for the Loddon River system under a range of planning scenarios

Planning scenario	Drought	Dry	Average	Wet
Expected river conditions	Negligible contributions from unregulated reaches and tributaries of the Loddon River,consumptive water deliveries in the irrigation season (and none in reach 4) Reduced passing flows in autumn/ winter are possible	Small inflows from unregulated reaches and tributaries of the Loddon River contributing to low flow, consumptive water deliveries in the irrigation season (but not in reach 4)	Natural flow will provide low flow and multiple freshes, most likely in winter/spring Consumptive water deliveries in the irrigation season (but not in reach 4) No spill is likely	Spills from Loddon system storages will provide extended-duration high flow, and overbank flow is most likely in late winter/spring
Expected availability of water for the environment¹	18,002-23,745 ML²	21,568 ML	21,568 ML	21,568 ML
Loddon River (targeting reach 4)
Potential environmental watering – tier 1 (high priorities)	Tier 1a (can be achieved with predicted supply)
	Winter/spring low flow (delivered at 25-50 ML/day³) Winter/spring high flow (one high flow, delivered at a lower duration)⁴ Summer/autumn low flow (delivered at 25-40 ML/day)⁵ Summer/autumn freshes (three freshes) Year-round fresh (trigger-based) Winter/spring low flow (delivered at 50-77 ML/day)	Winter/spring high flow (one high flow, delivered at a lower duration) Summer/autumn low flow (delivered at 40 ML/day) Summer/autumn freshes (three freshes) Year-round fresh (trigger-based) Winter/spring low flow (delivered at 77-100 ML/day)	Winter/spring high flow (one high flow) Summer/autumn low flow (delivered at 50 ML/day) Summer/autumn freshes (three freshes) Year-round fresh (trigger-based) Winter/spring low flow (delivered at 77-100 ML/day)	Winter/spring high flow (one high flow) Summer/autumn low flow (delivered at 50 ML/day) Summer/autumn freshes (three freshes) Autumn high flow (one high flow) Year-round fresh (trigger-based)
	Tier 1b (supply deficit)
	Summer/autumn low flow (delivered at 40-50 ML/day)	Winter/spring low flow (delivered at 77-100 ML/day) Summer/autumn low flow (delivered at 40-50 ML/day)	Autumn high flow (one high flow)	N/A
Potential environmental watering – tier 2 (additional priorities)	Winter/spring low flow delivered at 50-100 ML/day magnitude Summer/autumn low flow trial (50- 100 ML/day) Autumn high flow (one high flow)	Summer/autumn low flow trial (50- 100 ML/day) Autumn high flow (one high flow)	Summer/autumn low flow trial (50- 100 ML/day)	Winter/spring low flow trial (100- 200 ML/day) Summer/autumn low flow trial (50- 100 ML/day)
Possible volume of water for the environment required to achieve objectives	5,000-9,300 ML(tier 1a) 600 ML (tier 1b) 12,200 ML (tier 2)	9,300 ML (tier 1a) 4,000 ML (tier 1b) 8,800 ML (tier 2)	8,200 ML (tier 1a) 3,500 ML (tier 1b) 4,300 ML (tier 2)	8,400 ML (tier 1a) 3,000 ML (tier 2)
Pyramid Creek and Loddon River (targeting reach 5)
Potential environmental watering – tier 1 (high priorities)	Tier 1a (can be achieved with predicted supply)
	Year-round low flow Winter/spring high flow (one high flow)		Year-round low flow Winter/spring high flow (one high flow) Autumn high flow (one high flow)
	Tier 1b (supply deficit)
	N/A
Potential environmental watering – tier 2 (additional priorities)	Autumn high flow (one high flow)		N/A
Possible volume of water for the environment required to achieve objectives⁶	4, 000 ML (tier 1a) 2,000 ML (tier 2)		6,000 ML (tier 1a)
Serpentine Creek (targeting reach 1)⁷
Potential environmental watering – tier 1 (high priorities)	Tier 1a (can be achieved with predicted supply)
	Winter/spring low flow (delivered at 10 ML/day) Winter/spring fresh (one fresh,delivered at 40 ML/ day) Summer/autumn low flow (delivered at 10 ML/day) Summer/autumn freshes (three freshes)	Winter/spring low flow (delivered at 10 ML/day) Winter/spring fresh (one fresh) Summer/autumn low flow (delivered at 10 ML/day) Summer/autumn freshes (three freshes)	Winter/spring low flow (delivered at 10 ML/day) Winter/spring fresh (one fresh) Summer/autumn low flow (delivered at 10 ML/day) Summer/autumn freshes (three freshes)	Winter/spring low flow (delivered at 10 ML/day) Winter/spring fresh (one fresh) Summer/autumn low flow Summer/autumn freshes (three freshes)
	Tier 1b (supply deficit)
	Winter/spring fresh (tier 1a fresh delivered at 120 ML/day) Summer/autumn low flow (delivered at 10-20 ML/day) Winter/spring low flow (delivered at 10-20 ML/day)	Winter/spring low flow (delivered at 10-20 ML/day) Summer/autumn low flow (delivered at 10-20 ML/day)	Winter/spring low flow (delivered at 10-30 ML/day) Summer/autumn low flow (delivered at 10-20 ML/day)	Winter/spring low flow (delivered at 10-30 ML/day)
Potential environmental watering – tier 2 (additional priorities)	N/A	N/A	N/A	N/A
Possible volume of water for the environment required to achieve objectives	1,430 ML (tier 1a) 3,700 ML (tier 1b)	1,430 ML (tier 1a) 2,500 ML (tier 1b)	1,300 ML (tier 1a) 3,200 ML (tier 1b)	1,160 ML (tier 1a) 2,000 ML (tier 1b)
Priority carryover requirements for 2023-24	4,400 ML for early- season low flow and winter/spring high flow	4,000 ML for early-season low flow and winter/spring high flow

¹ Loddon system entitlements are shared between the Loddon River system and the Boort wetlands. Expected availability is used to meet demands in both systems.
² Under a drought scenario, the VEWH may request a reduction in passing-flow volume at Loddon Weir and accumulate the savings for use at other times of the year. The combined volume in Cairn Curran and Tullaroop reservoirs must exceed 60,000 ML to enable passing-flow savings.
³ When passing flow can be accumulated or water availability allows, the winter/spring low flow magnitude may be increased to 50 ML/day to maintain seasonal variability, support vegetation and aquatic animals and prevent a decline in oxygen levels.
⁴ In 2022-23, it is expected that passing flow will be accumulated in winter/spring (when the combined volume in Cairn Curran and Tullaroop reservoirs exceeds 60,000 ML), providing sufficient water to deliver the winter/spring high flow. If the combined volume in storage is less than 60,000 ML, the winter/spring high flow will become a Tier 1b watering action.
⁵ If passing flow has been accumulated in winter/spring (when the combined volume in Cairn Curran and Tullaroop reservoirs exceeds 60,000 ML) or water availability allows, the summer/autumn low-flow magnitude may be increased to 40 ML/day.
⁶ Each environmental watering event in Pyramid Creek has an estimated demand of 2,000 ML for underwriting losses associated with delivering consumptive water en route to downstream locations via Pyramid Creek. The actual demand for each event is expected to be a much lower volume.
⁷ Delivery of low flow in Serpentine Creek is constrained below recommended flow rates until an approach to deal with end-of-system flow is agreed on.

Engagement

Table 2 shows the partners and stakeholder organisations with which North Central CMA engaged when preparing their seasonal watering proposals.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the North Central Regional Catchment Strategy and North Central Waterway Strategy.

Table 2 Partners and stakeholders engaged in developing the Loddon system seasonal watering proposal

Partner and stakeholder engagement
Commonwealth Environmental Water Office Goulburn-Murray Water Department of Environment, Land, Water and Planning Individual landholders and community members Barapa Barapa Traditional Owners Dja Dja Wurrung Clans Aboriginal Corporation Wemba Wamba Traditional Owners

Page last updated: 01/12/22