The total number of ecological assets identified in the preliminary assessment extent (PAE) of the Namoi subregion is 1964 as outlined in the final column of Table 7. All 1142 surface water features (including assets classed as ‘River or stream reach, tributary, anabranch or bend’, ‘Lake, reservoir, lagoon or estuary’, ‘Waterhole, pool, rock pool or billabong’, ‘Wetland, wetland complex or swamp’, ‘Marsh, sedgeland, bog, spring or soak’ or ‘Floodplain’) were assumed to be water dependent and were included in the water‑dependent asset register. Most of the 41 groundwater features (subsurface) were assumed to be water dependent, with the exception of the eight geological formations that were not assumed to be water‑dependent ecological assets. Most (682 of 781) ecological assets in the vegetation subgroup were sourced from the National atlas of groundwater dependent ecosystems (Bureau of Meteorology, 2012). Two thirds (531) of the 688 groundwater dependent ecosystems included in the asset list were assumed to be water dependent based on previous studies or their moderate or high potential for groundwater interaction. Most (67) of the remaining 93 ecological assets in the vegetation subgroup, were assumed to be water dependent habitat, contain water dependent features, be associated with water dependent features or have water-dependent lifecycle requirements.
The total number of water-dependent ecological assets identified in the Namoi subregion PAE is 1684, including 1142 in the surface water feature subgroup, 33 in the groundwater feature subgroup and 509 in the vegetation subgroup, as outlined in the fourth column of Table 7.
Table 7 Summary of ecological assets within the preliminary assessment extent of the Namoi subregion
Data: Bioregional Assessment Programme (Dataset 1)
A range of groundwater‑dependent ecosystems are present in the PAE of the Namoi subregion including groundwater‑dependent vegetation, baseflow systems and associated riverine vegetation and wetlands and springs and aquifers (Welsh et al., 2014). Forty one ecological assets within the ‘Groundwater feature (subsurface)’ subgroup were included in the Namoi asset list. The 22 groundwater management zones in the asset list were considered water dependent, including the 13 Upper and Lower Namoi alluvium groundwater management zones shown in Figure 5 and the nine groundwater management zones shown in Figure 6. Nine groundwater flow systems (including the Pilliga Sandstone, Tertiary Volcanics and Riverine Plain Alluvium, the Cadna-owie Hooray Equivalent GAB recharge and Narrabri Water Table Aquifer) were also assumed to be water dependent. However, eight groundwater formations (e.g. the Allaru formation) were not assumed to be water dependent as they are geological formations.
The PAE of the Namoi subregion contains 21 springs fed by groundwater that are classed as ‘Marsh, sedgeland, bog, spring or soak’ in the surface water feature subgroup of the asset list. These are predominantly in the upper Namoi river basin associated with the Pilliga, Liverpool Range, Peel and Kaputar IBRA subregions (Figure 7).
The asset list contains 1142 ecological assets classed in the ‘Surface water features’ subgroup that occur in the PAE of the Namoi subregion and are listed in Table 7. These assets include: rivers, creeks and tributaries, riparian vegetation, wetland complexes, springs and lakes. The Namoi River itself forms part of the endangered ‘aquatic ecological community in the natural drainage system of the lowland catchment of the Darling River’ (Green et al., 2011). All 1142 ecological assets within this subgroup are assumed to be water dependent.
The PAE of the Namoi subregion contains one wetland listed in DIWA (Environment Australia, 2001): Lake Goran within the Liverpool Plains subregion of the Interim Biogeographic Regionalisation of Australia (IBRA; SEWPaC, 2012). Two IBRA bioregions occur within the PAE: (i) the Bundarra-Barraba bioregion and (ii) the Pilliga bioregion. The Pilliga IBRA bioregion is predominantly associated with the Liverpool Plains, Pilliga and Pilliga Outwash IBRA subregions. Less than 0.25% of the Bundarra-Barraba IBRA bioregion that is associated with the Peel IBRA subregion occurs within the PAE. Forty-three Collaborative Australian Protected Area Database (CAPAD) areas occur in the PAE. CAPAD areas include: national parks (e.g. Mount Kaputar National Park), conservation reserves (e.g. Bullawa Creek state conservation area) and Indigenous Protected Areas. These areas largely represent terrestrial nature reserves and were all assumed to contain water dependent features.
Seven threatened ecological communities listed under the EPBC Act are represented within the PAE of the Namoi subregion (Table 8). Four of these threatened ecological communities are included in the water‑dependent asset register where the community was known to occur within the maximum flood extent of the Namoi subregion or was a dominant floodplain vegetation community.
Table 8 Threatened ecological communities listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 within the preliminary assessment extent of the Namoi subregion
Typology and punctuation are given as they are used in the legislation.
The PAE for the Namoi subregion includes the potential spatial habitat distribution of 41 species listed under the EPBC Act. This includes 19 plant, one frog, three reptile, 12 bird and six mammal species (Table 9). Note that the asset under consideration is the habitat of these species rather than the species per se, hence these assets are listed under the subgroup, vegetation. The habitat of 18 of the 41 species was considered water dependent for the following reasons: associated with drainage or soakage areas, wetland or permanent open water dependent or associated with floodplain or riparian vegetation communities. Most of (23 of 41) the remaining species were not considered to be water dependent because they were associated with grassland, woodland, dry scrub, open forest, heathlands or rainforest vegetation communities, rocky outcrops, upstream of potential development activities, insufficient habitat information or it was a wide-spread migratory species.
Table 9 Species listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 within the preliminary assessment extent of the Namoi subregion
Water dependency represents a preliminary assessment based on a literature review of habitat requirements.
aAlthough examples of individual species are listed, bioregional assessments consider the potential impact to the habitat of species not individual species per se. Punctuation and typography appear as used in the asset database. Data: Australian Government Department of the Environment (Dataset 3)
The asset list contains 682 assets derived from the National atlas of groundwater dependent ecosystems (Bureau of Meteorology, 2012) that are classed as ‘Groundwater-dependent ecosystems’ in the vegetation subgroup of the asset database. These comprise mostly vegetation areas or surface water areas identified as being potentially groundwater dependent. Water dependency of these assets was assumed if the asset had been classified in the National atlas of groundwater dependent ecosystems (Bureau of Meteorology, 2012) as: identified in a previous study (27 assets), high (35 assets), moderate to high (66 assets), moderate (242 assets) or low to moderate (155 assets) probability of groundwater interaction. This included groundwater dependent vegetation, and rivers, streams, springs and wetlands identified as connected and gaining systems – where gaining systems receive water from the groundwater system and losing systems lose water to the groundwater system. A connected system has a continuous saturated zone, whereas surface water – groundwater interactions are disconnected by an unsaturated zone in disconnected systems. Assets classed in the National atlas of groundwater dependent ecosystems (Bureau of Meteorology, 2012) with a low potential for groundwater interaction or connected, losing systems (246) are not considered to be water dependent. A further six assets were identified by the community as groundwater dependent ecosystems and are considered water dependent.
Product Finalisation date
- 1.3.1 Methods
- 1.3.2 Ecological assets
- 1.3.3 Economic assets
- 1.3.4 Sociocultural assets
- Contributors to the Technical Programme
- About this technical product