Eyre Peninsula Groundwater Dependent Ecosystem Scoping Study 6. Prioritisation of GDEs 6.1. Overview A two tiered approach has been taken to prioritising GDEs. The first tier addresses ecosystems that have been identified for their high conservation value, which of these are most vulnerable to changed groundwater regimes and which are threatened by current or proposed groundwater affecting activities. The second tier addresses those ecosystems whose value has not been recognised, but are vulnerable to changes in groundwater regime and are threatened by current or proposed groundwater affecting activities. 6.2. Tier 1 prioritisation of recognised high value GDEs There are six wetlands that occur within and/or close to the study areas that are declared as nationally important through their inclusion in the Directory of Important Wetlands in Australia. These include: Big Swamp, Coffin Bay Coastal Wetland System, Lake Hamilton, Lake Newland, Pillie Lake and Sleaford Mere (Figure 6.1 and Figure 6.2). Of these Sleaford Mere, Pillie Lake and the Coffin Bay Coastal Wetland System are closest to groundwater extraction and considered the most vulnerable to changes in groundwater conditions in the current environment. There are four vegetation communities considered to be threatened in South Australia that occur within the study areas that are potentially components of GDEs. These are mapped in Figure 6.1, Figure 6.2 and Figure 6.3 and include Gahnia trifida Sedgeland which are classified as Endangered, and G. filum Sedgeland and Allocasuarina verticillata Grassy low woodland, which are classified as vulnerable (Matthews et al., 2001). Of these G. trifida sedgeland is considered the highest priority vegetation community since it is endangered and only occurs near groundwater extraction areas (Uley South lens and Lincoln-A lens fringing Sleaford Mere). The next highest priority vegetation community is A. verticillata grassy low woodland which occurs near groundwater extraction in Robinson Basin, Musgrave PWA (Bramfield lens) and Southern Basins PWA (Coffin Bay-A, Wanilla, Lincoln-A and Lincoln- C lenses). It is interpreted to occur over shallow water tables in most of the groundwater extraction areas, except near Lincoln-C where it is not considered to be dependent on groundwater. A. verticillata grassy low woodland is not limited to areas of groundwater extraction and is likely to be more resilient than G. trifida to changes in groundwater condition. G. filum sedgeland does not occur near groundwater extraction in the study areas and therefore is not currently considered at risk from groundwater extraction. SINCLAIR KNIGHT MERZ I:\VESA\Projects\VE23226\Deliverables\Reporting\VE23226_final.docx PAGE 75 DDDD DDDDDDDDDD D D DDDDDDDDD DDD DDDDD D D 540000 560000 D D 580000 ! COFFIND BAY COASTAL AA! D D WETLAND SYSTEMD A!D WANILLAA!D COFFIN BAY A!D D COFFIN BAY-C A! D D COFFIN BAY-B ! D D A D COFFIND D!D BAY-A A!A!D ! BIG SWAMP D A ! ULEYA!D WANILLADA D D D D D A!D D A! D DDD Production Wells D D D D D Monitoring Well D D Nationally important wetlands D D Threatened communities D D D D Allocasuarina verticillata 6160000 LINCOLN-D woodland D D LINCOLN-D-WEST D PORT LINCOLN D ULEYD EAST Gahnia trifida (mixed) D DD sedgeland D D LINCOLN-D A!D Quaternary Aquifer DD D A!D D Low salinity groundwater lens D D ! !D 0 - 1000 mg/L D A! A!DDA D AD A!DA!D ULEY SOUTH!D D !D D D AA! A Water table in limestone D A!D D D D ! D D D A TULKA Southern Basins D A!D LINCOLN-A D D PANTANIA Prescribed Wells Area D D A! A! !D ! D A!DD A!AD D D A! DA! A D MIKKIRA A!D A! DA!D LINCOLN-C A!! A!A PILLIE LAKE D LINCOLN-B D ° D D !D AD! AD!A 0 10 SLEAFORD MERE A! D A! A4 1:270,164 Kilometres LINCOLN-C 6140000 SLEAFORD D ADELAIDE Southern Basins PWA GDA 1994 MGA Zone 53 September 2009 Figure 6.1: Threatened communities and nationally important wetlands I:\VESA\Projects\VE23226\Technical\GIS\Spatial_Data\ArcGIS\VE23226_Grasslands and Sedgelands - Musgrave.mxd 480000 500000 520000 540000 560000 D D D D D D D D D D D D D D D D D D D Talia D D TaliaD D D D D D DD D D Lake Newland D D D D D D DD D D D D D D D D D D D ! D D D A Bramfield PB 6300000 D D D DD D D D D D D D D D D D D DD D D D D A! Polda Bore 7 D D D DD D D D DD D D D D Polda D D D DDD D D D A! Polda Trench D D DDDD D DDD D D D D D D D D D DD D D D D D D D D D D D D!DDD D D D D D D D D D D D DDAD DDD D Monitoring Well D D D DD D D D D D D D D DDD D D D D D D D D D D D D D SQR 28 D D DD D D DD D D D D D DD D D!DDDD D D Nationally important wetlands D D D D A DD D D D D D D D D D D D D DDD D D D D D D D DD Allocasuarina verticillata D D D D D D D D D D woodland D D D D D D TinlineD D D DD D D D D D D D D D D DD D D DDDD D D DDD D D DD D D D D Gahnia filum sedgeland D D D BramfieldD D D D D D D D D D D D D D D D D D D D D DD D D Quaternary Aquifer D D D D D D D D DD D D D Low salinity groundwater lens D D D D D D D D D D D D D 6280000 D D D D D D D DD 0 - 1000 mg/L D D D D D D D D D D !A! D D D A D D D D D DD D D D D D D D D DD D D D D Water table in limestone Elliston D D D D D D DDDD D D D D D D D D D DD KappawantaD D D DDDDDDD D D D County Musgrave D D D D D D D D D D D D D D D D D Prescribed Wells Area D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D Sheringa-A D D D D D D D DD D D D D ° D D DDD DDDDDSheringaD D D 0 10 D D D D D D D D D D Sheringa D D A4 1:440,000 Kilometres D D D D D D D D D D D D D D D D D D D D D 6260000 D D D Sheringa D D D D D D D D D D D D D D D D D D D D D D D D D D D D D DD D D D D D D D D Sheringa D D D DDD D D D D Sheringa-B D D DDD D D D D D D ADELAIDE Lake Hamilton Musgrave PWA GDA 1994 MGA Zone 53 September 2009 Figure 6.2: Threatened communities and nationally important wetlands I:\VESA\Projects\VE23226\Technical\GIS\Spatial_Data\ArcGIS\VE23226_Grasslands and Sedgelands - Musgrave.mxd 440000 STREAKY BAY D D D D A! Robinson Well Points D D A! Robinson PB 2 D A! Robinson PB D Monitoring Well D D D Nationally important wetlands D D Allocasuarina verticillata D A! D D D D woodland D D A!D A!D D D A! DA! D Quaternary Aquifer A! D D A!D D D Low salinity groundwater lens A! D!D ROBINSONDA D 0 - 1000 mg/L !D D D A D D Water table in limestone A!DD D D !!!D!! D D AAAAA D D ° D 0 3 D D D A4 1:81,198 Kilometres D D D D D MARYVALE 6360000 D ADELAIDE Robinson Basin GDA 1994 MGA Zone 53 September 2009 Figure 6.3: Threatened communities I:\VESA\Projects\VE23226\Technical\GIS\Spatial_Data\ArcGIS\VE23226_Grasslands and Sedgelands - Musgrave.mxd Eyre Peninsula Groundwater Dependent Ecosystem Scoping Study 6.3. Tier 2 prioritisation of GDEs whose value has not been recognised There are a number of potentially groundwater dependent ecosystems that are likely to have high conservation value, but are not currently formally recognised and protected. Table 6.1 provides a prioritisation of GDE types found in the study areas, based on (in order of significance): threat of change in groundwater condition induced by groundwater extraction; the inferred levels of resistance and resilience (form of dependence, Table 1.1) of the GDE to changes in groundwater condition; and whether or not the GDE is restricted to areas where it can access groundwater (obligate or facultative). For example, those potential GDEs that are likely to occur in areas where there is a high risk of change to the groundwater regime are ranked highest.