'Near to final' draft for independent review - 2 May 2016 Table E2: Site-specific flow indicators for ecological function of lateral connectivity with the floodplain in the Barwon- Darling UEA. In this table, frequency is the number of years between watering events Ecological target Example related to lateral connectivity ecological function Flow indicator gauge Magnitude: flow (ML/d) Duration (days) Timing Frequency Low High uncertainty uncertainty Provide a flow regime which: supports recruitment opportunities for a range of native Connectivity with riparian zone including forests Bourke 30,000 24 Minimum of 1 event at any time of year 2 years 3 years aquatic species (e.g. fish, frogs, turtles, invertebrates) supports the habitat requirements of waterbirds Connectivity with inner floodplain including wetlands Bourke 45,000 22 As above 3.5 years 4 years ensures the current extent of native vegetation of the riparian, floodplain and wetland communities is Connectivity with mid floodplain including woodlands Bourke 65,000 24 As above 6 years 8 years sustained in a healthy, dynamic and resilient condition supports key ecosystem functions, particularly those related to connectivity between the river and the floodplain Connectivity with outer floodplain including grasslands Wilcannia 2,350 GL (volume) > 60 As above 10 years 12 years Page 6
'Near to final' draft for independent review - 2 May 2016 selecting flow indicator gauges (section 2.2.6) using site-specific flow indicators in hydrological modelling (section 2.2.7). These steps of the approach are discussed below. Selecting Umbrella Environmental Assets within a valley Within each valley chosen for assessment, the following five principles were used to guide the selection of UEAs: High ecological value. The Basin Plan lists five criteria for identifying environmental assets, and four criteria for identifying ecosystem functions, which indicate a site has high ecological value. These criteria are listed in Box 4. Representative of water requirements. The water requirements of a UEA are assumed to represent the water needs of a broader reach of river or an entire river valley. This principle tends to focus the selection of UEAs on large, water-dependent ecosystems, typically at the downstream end of a river reach or valley. Flows at these downstream sites are associated with a broad extent of floodplain inundation upstream. Spatially representative. The hydrology and geomorphic character of UEAs is to be representative of river valleys or large reaches, rather than sites of unusual hydrology and geomorphic character. Significant flow alteration. UEAs experience significant departures from without development flows (i.e. simulated conditions without water resource development) in parts of the flow regime. Availability of data. The quality and quantity of hydrological and ecological information associated with a UEA needs to be sufficient to allow a detailed assessment of environmental water requirements. Applying these selection principles to the Barwon-Darling system has resulted in one UEA being selected. This is the Barwon-Darling River upstream of Menindee Lakes to Mungindi on the NSW/Queensland border, as shown in Figure 2. This is the same UEA that was used in the original analysis of the Barwon-Darling river system (MDBA 2012a). A description of this UEA is provided in chapter 3. Page 14
'Near to final' draft for independent review - 2 May 2016 Geomorphic setting Channel Riparian zone (and near channel) Inner floodplain Mid floodplain Outer floodplain Features / communities Snags and benches River red gums forests Coolibah or black box woodlands Floodplain grasslands In-channel freshes provided longitudinal connectivity down the channel. This is important for and maintaining, and providing access to, No flows and base flows Freshes replenish soil water/bank storage for Bankfull flows reshape the channel creating or maintaining Bankfull and overbank flows fill the river channel and inundate the riparian zone, anabranches, flood- runners, wetlands and the floodplain. These flows Overbank flows are the larger flow events that provide lateral connectivity with the floodplain. They provide water and nutrients to floodplain in-stream habitats. It maintain aquatic habitat Base flows are riparian vegetation habitats such as provide opportunities for vegetation is also important for cycling sediment and nutrients between different parts of the river. for fish, plants and invertebrates, providing drought refuge during dry periods and diluting nutrients and other material following flood events. generally maintained by seepage from groundwater or bank storage; and also by low surface flows. and inundate benches, anabranches and snags which are important for fish migration and spawning. pools, bars and benches. some birds to breed and allow fish, frogs, turtles and invertebrates to move from the river to the wider floodplain next to the river, and back again. communities. Flows that reach these areas are also very important for the dispersal of seeds and aquatic animals. Figure 3. Key components of the flow regime of rivers like the Barwon-Darling river system, and their connection with ecological functions and processes Flood plain
'Near to final' draft for independent review - 2 May 2016 Table 2. Site-specific flow indicators for small in-channel freshes for the Barwon- Darling UEA. In this table, frequency is the percentage of years in which there is the flow event. Frequency range is shown as low uncertainty to high uncertainty Magnitude: flow (ML/d) Basis of magnitude Duration (days) Basis of duration Timing Basis of timing Freq. range Basis of frequency 6,000 (Bourke gauge) Small scale fish movement between Walgett and Tilpa, and access to over half the snags and three quarters of the in-channel benches 14 The typical duration of this size event in the Darling River at Bourke and the hatch time of most native fish species, including short-lived species Minimum of 1 event any time of the year Provides regular short scale movement opportunities and access to ideal habitat 90% – 80% To provide regular freshes (close to annual) for maintenance and condition of short- lived fish populations and other aquatic biota 6,000 (Louth gauge) In addition to the above, some spawning opportunities for in stream specialists such as Murray cod 20 The minimum duration for some Murray cod to breed (from nest development to dispersal of larvae); considered sufficient for other groups of fish Minimum of 1 event between Aug - May Fish response expected when the water temperature exceeds the critical temperature threshold (15 degrees) 70% Frequency to provide improved breeding opportunities for species such as for Murray cod 6,000 (Wilcannia gauge) Promote in-stream primary productivity: provide inundation of 90% of mapped in-channel benches between Tilpa and Wilcannia 7 Shorter duration as carbon and nutrients are rapidly absorbed - would also provide an opportunity for some movement and access to habitats, some spawning Minimum of 2 events any time of the year Two events in a year for increases in food supply into the river; common for this type of flow to occur more than once per year 60% – 45% Based on estimated frequency for increased productivity benefits of river ecosystem Page 45
'Near to final' draft for independent review - 2 May 2016 Table 3: Site-specific flow indicators for large in-channel freshes for the Barwon- Darling UEA. In this table, frequency is the percentage of years in which there is the flow event. Frequency range is shown as low uncertainty to high uncertainty Magnitude (ML/d) Basis of magnitude Dur. days Basis of duration Timing Basis of timing Freq. range Basis of frequency 10,000 (Bourke gauge) Trigger opportunity for large- scale fish movement (Walgett to Wilcannia) through drown out of barriers; improved access to ideal habitat (two thirds of snags, most benches and a few wetlands) 14 The typical duration of this size flow event at Bourke and the hatch time of most native fish species Minimum of 1 flow event between Aug - May Provide at least one opportunity outside the two coldest months 80% - 60% To improve mixing of populations (genetic diversity) and improved conditions for breeding, especially for flow dependent specialist fish 10,000 (Bourke gauge) In addition to above, provides peak of 15,000 ML/d for five days, considered sufficient to cue flow dependent specialist fish breeding 20 The minimum duration for Murray cod to breed (from nest development to dispersal of larvae); sufficient for other groups of native fish Minimum of 2 flow events between Aug - May Consistent with spawning season of flow dependent fish, with second flow event enhancing recruitment 35% – 25% Ideal spawning and recruitment opportunities in about 3 out of 10 years. Linked to biological requirements of flow dependent specialist fish 21,000 (Louth gauge) In addition to above, provides access to all snags in the Bourke to Louth reach to support in-channel specialist breeding, and access to an increased number of anabranches and wetlands. 20 As above Minimum of 1 flow event between Aug - May As above 40% To provide breeding opportunities for extensive breeding of in- channel specialists fish - linked to biological requirements including those of medium to long lived fish 20,000 (Wilcannia gauge) Extensive inundation of in- channel benches to support in- stream primary productivity, food supply and habitat access 7 Based on evidence showing carbon and nutrients are rapidly absorbed Minimum of 1 flow event any time of the year Considered to provide productivity benefits for fish any time of year 60% - 45% Based on a percentage of the frequency under without development conditions Page 46
'Near to final' draft for independent review - 2 May 2016 Table 7. Site-specific flow indicators for lateral connectivity for the Barwon- Darling UEA. In this table, frequency is the number of years between watering events. Frequency range is shown as low uncertainty to high uncertainty Magnitude: flow (ML/d) Basis of magnitude Duration (days) Basis of duration Timing Basis of timing Freq. Basis of frequency 30,000 (Bourke gauge) Inundation of riparian forests, and near-channel and fringing wetlands. The flow is around bankfull, which is important for in- channel geomorphic processes and maintaining habitats. 24 Median duration above this flow under the without development scenario Any time of year These flows will be largely unregulated events and can occur at any time of year 2 - 3 Reflects flow requirements for vigorous river red gum forest, and lignum communities in riparian forests. Frequency based on historical flows. 45,000 (Bourke gauge) Connectivity with inner floodplain including approximately 90% of wetlands. 22 As above As above As above 3.5 - 4 Frequency based on historical flows, and the requirements of vegetation in river red gum woodlands and wetlands, including some habitat within the Talyawalka-Teryaweynya system 65,000 (Bourke gauge) Broad floodplain inundation flows starting to inundate large areas of black box and coolibah woodlands and some grasslands. 24 As above As above As above 6 - 8 Frequency based on historical flows, and the requirements of vegetation including black box, coolibah 2,350 GL above 30,000 ML/d (Wilcannia gauge) Minimum volume to fill the more frequently inundated lakes in the Talyawalka - Teryaweynya system based on 5 events. Foraging of waterbirds. Rejuvenation of grasslands. Substantial exchange of material between river and floodplain. > 60 The duration is tied to a volume of inflow to fill Talyawalka - Teryaweyna system As above As above 10 - 12 Frequency requirements of native grasslands, as well as critical frequencies for black box, coolibah and lignum Page 60
'Near to final' draft for independent review - 2 May 2016 Appendix D - Listed species, Barwon-Darling river system Selection of species for the Barwon-Darling river system relevant to the Basin Plan, schedule 8, criteria 1 and 4 Species Recognised in international agreement(s) (1) Environment Protection & Biodiversity Conservation Act 1999 (Cwlth) Fisheries Management Act 2004 (NSW) Threatened Species Conservation Act 1995 (NSW) Birds Australasian bittern (Botaurus poiciloptilus) E Blue-billed duck (Oxyura australia) V Brolga (Grus rubicundus) V Caspian tern (Hydroprogne caspia) Yes Common sandpiper (Actitis hypoleucos) Yes Eastern great egret (Ardea modesta) Yes Freckled duck (Stictonetta naevosa) V Glossy ibis (Plegadis falcinellus) Yes Fish Freshwater catfish (Tandanus tandanus) E (MDB population) Murray cod (Maccullochella peelii peelii) V Olive perchlet (Ambassis agassizii) E (MDB population) Purple spotted Gudgeon (Mogurnda adspersa) E Silver perch (Bidyanus bidyanus) CE V Communities Lowland Darling River aquatic ecological community E E = endangered V = vulnerable CE = critically endangered 1 Japan–Australia Migratory Bird Agreement, China–Australia Migratory Bird Agreement, or Republic of Korea – Australia Migratory Bird Agreement. Page 76
'Near to final' draft for independent review - 2 May 2016 Appendix E - Frequency statistics Site-specific flow indicator Without development^ Low uncertainty^ High uncertainty^ Baseline frequency^ Maximum spell under without development Maximum spell under baseline 6,000 ML/d for 14 days any time of the year (Bourke) 96% 90% 80% 66% 2 years 3 years 6,000 ML/d for 20 days between August and May (Louth) 91% 70% 70% 58% 2 years 4 years Two 6,000 ML/d events for 7 days any time of the year (Wilcannia) 77% 60% 45% 42% 5 years 8 years 10,000 ML/d for 14 days between August and May (Bourke) 89% 80% 60% 54% 3 years 6 years Two 10,000 ML/d events for 20 days between August and May (Bourke) 42% 35% 25% 20% 7 years 12 years 21,000 ML/d for 20 days between August and May (Louth) 54% 40% 40% 32% 4 years 12 years 20,000 ML/d for 7 days any time of the year (Wilcannia) 70% 60% 45% 39% 3 years 8 years 30,000 ML/d for 24 days any time of the year (Bourke) 1.8 years 2 years 3 years 3.9 years 9 years 19 years 45,000 ML/d for 22 days any time of the year (Bourke) 3.3 years 3.5 years 4 years 4.9 years 15 years 29 years 65,000 ML/d for 24 days any time of the year (Bourke) 5.4 years 6 years 8 years 8.7 years 19 years 29 years 2,350 GL once flow is above 30,000 ML/d any time in the year (Wilcannia) 8 years 10 years 12 years 14 years 29 years 29 years ^ - In these four columns, the '%' is percentage of years in which there is a watering event, and the 'years' is the average number of years between watering events. Page 77