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Looking after all our water needs

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Lower Fortescue River - ecological values and issues

Lower Fortescue River -ecological values and issues

Looking after all our water needs

Department of Water

Environmental water report series

Report no. 15

September 2010

Department of Water 168 St Georges Terrace Perth Western Australia 6000 Telephone +61 8 6364 7600 Facsimile +61 8 6364 7601 www.water.wa.gov.au

© Government of Western Australia 2010

September 2010

This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to the Department of Water.

ISSN 1833-6582 (print) ISSN 1833-6590 (online)

ISBN 978-1-921736-80-3 (print) ISBN 978-1-921736-81-0 (online)

Acknowledgements This report was prepared by Robyn Loomes from the Department of Water’s Environmental Water Planning section. The author acknowledges the input and comments provided by Mike Braimbridge and Michelle Antao

This project is part funded by the Australian Government’s Water for the Future initiative

For more information about this report, contact: Robyn Loomes, Environmental Officer, Water Allocation Planning Telephone 08 6364 7600 Facsimile 08 6364 7601.

The recommended reference of this publication is:

Loomes, R 2010 Lower Fortescue River: ecological values and issues, Environmental water report series, report no. 15, Department of Water, Government of Western Australia, Perth. Disclaimer

This document has been published by the Department of Water. Any representation, statement, opinion or advice expressed or implied in this publication is made in good faith and on the basis that the Department of Water and its employees are not liable for any damage or loss whatsoever which may occur as a result of action taken or not taken, as the case may be in respect of any representation, statement, opinion or advice referred to herein. Professional advice should be obtained before applying the information contained in this document to particular circumstances.

This publication is available at our website <www.water.wa.gov.au> or for those with special needs it can be made available in alternative formats such as audio, large print, or Braille.

http://www.water.wa.gov.au/�

Environmental water series report no. 15

Department of Water iii

Contents Summary ..................................................................................................................... v

1 Introduction.............................................................................................................. 1

2 Biophysical setting ................................................................................................... 2

2.1 Climate ................................................................................................................................ 2 2.2 Physiography and geomorphology ..................................................................................... 5 2.3 Hydrogeology ...................................................................................................................... 6

Aquifers ................................................................................................................................................ 7 Current use .............................................................................................................................................. 7 Groundwater ............................................................................................................................................ 7 River flow, recharge and discharge ......................................................................................................... 8

2.4 Vegetation and flora ........................................................................................................... 9 2.5 Land use and cultural values ............................................................................................ 10

3 Identification and description of groundwater dependent ecosystems .................. 11

3.1 Defining groundwater dependent ecosystems ................................................................. 11 Groundwater attributes .......................................................................................................................... 11

3.2 River pools ........................................................................................................................ 11 Conceptual link to groundwater ............................................................................................................. 12 Ecology 15 Conservation significance and sensitivity .............................................................................................. 20

3.3 Riparian ecosystems ........................................................................................................ 21 Conceptual link to groundwater ............................................................................................................. 21 Ecology 22 Conservation significance and sensitivity .............................................................................................. 29

3.4 Aquifer ecosystems .......................................................................................................... 30 Conservation significance ...................................................................................................................... 30

3.5 Summary of ecological values .......................................................................................... 31 River pools ............................................................................................................................................. 31 Riparian vegetation ................................................................................................................................ 32 Aquifer ecosystems ............................................................................................................................... 33

4 Ecological management objectives ....................................................................... 34

4.1 Background and overall objective .................................................................................... 34 4.2 Objectives for river pools and riparian vegetation ............................................................ 35

River pools ............................................................................................................................................. 35 Riparian vegetation ................................................................................................................................ 36 Ecological management objectives and ecological water requirements ................................................ 36

Appendices ................................................................................................................ 37

Appendix A –Conceptual models of selected pools ................................................................... 37 Appendix B –2008 vegetation survey data ................................................................................ 44

Shortened forms ........................................................................................................ 46

Glossary .................................................................................................................... 47

References ................................................................................................................ 49

Lower Fortescue River – ecological values and issues

iv Department of Water

Figures

Figure 1 Lower Fortescue River study area ....................................................................... 3 Figure 2 Mean monthly temperatures at Mardie Station (1886-2009) ............................... 4 Figure 3 Long-term annual rainfall at Mardie Station (1886-2009) .................................... 4 Figure 4 Mean monthly evaporation (Dampier Salt, 1972-2009) and rainfall (Mardie

Station, 1886-2009) ......................................................................................................... 5 Figure 5 Lower Fortescue River cross-section (from Haig 2009) ....................................... 6 Figure 6 Selected lower Fortescue River monitoring bore hydrographs ............................ 8 Figure 7 Lower Fortescue River daily discharge 1968-2009 (measured at three

gauging stations) ............................................................................................................. 9 Figure 8 Location and permanence of lower Fortescue River pools ................................ 13 Figure 9 Conceptual diagram of longitudinal cross-section of the lower Fortescue

River during a flood event ............................................................................................. 14 Figure 10 Conceptual diagram of a longitudinal cross-section of the lower Fortescue

River during a period of no flow ..................................................................................... 15 Figure 11 Conceptual diagram of a longitudinal cross-section of the lower Fortescue

River pools during a drought period .............................................................................. 15 Figure 12 Conceptual diagram of a longitudinal cross-section of the lower Fortescue

River and floodplain ....................................................................................................... 22 Figure 13 Riparian vegetation of the lower Fortescue River study area .......................... 24 Figure 14 Mesquite density in the lower Fortescue River study area (2004) ................... 27

Tables

Table 1 Stratigraphic units of the lower Fortescue River (from Commander 1994). .......... 6 Table 2 Freshwater and marine fish species recorded in study area ............................... 16 Table 3 Description of freshwater fish habitat requirements or preferences (Beesley

2006; Pusey et al. 2004; Dames & Moore 1984). .......................................................... 17 Table 4 Physico-chemical parameters measured in 2008 ............................................... 20 Table 5 Vertebrate species of high sensitivity to groundwater decline (Outback

Ecology 2004) associated with river pools of the lower Fortescue River ....................... 21 Table 6 Vegetation community descriptions (from HGM, 2000) ...................................... 23 Table 7 Fauna of moderate sensitivity to groundwater decline (Outback Ecology

2004) associated with riparian vegetation ..................................................................... 28


Department of Water v

Summary This document reviews hydrological and biological data available for the lower Fortescue River. This information is used to identify and describe the ecological values of groundwater dependent ecosystems and to conceptualise their reliance on the underlying alluvial aquifer.

The Fortescue River, like most Pilbara rivers is ephemeral, flowing after rainfall from summer cyclones and autumn thunderstorms. The alluvial aquifer is recharged from direct infiltration through the riverbed during these periods of flow.

Three types of ecosystem are regarded as dependent on the lower Fortescue River alluvial aquifer; river pools, riparian vegetation and stygofauna.

River pools of varying size, depth and permanency are hydraulically connected to the aquifer are maintained by groundwater flow between flood events. Pools support aquatic and emergent plants, fish (including two previously undescribed species), phytoplankton, macroinvertebrates and terrestrial fauna as well as providing a range of ecosystems services. Of note is that the fish fauna of the Fortescue River is the most diverse of all rivers in the Pilbara region.

The shallow alluvium also provides areas where deep rooted, riparian vegetation can access groundwater in the absence of rainfall and/ or surface flow. Riparian, woodland and forests ecosystems provide habitat and food for birds, macroinvertebrates, reptiles and mammals (including bats). Large areas of lower Fortescue River riparian vegetation however, are degraded and at further risk from mesquite (Prosopis pallida) invasion. This weed species currently covers about 200, 000 ha of the Pilbara region and the single largest population in Australia is found across the lower Fortescue delta. It is thought that at these densities, evapotranspiration from the mesquite is having an impact on the local groundwater table.

Aquifers in the Pilbara region have been associated with diverse subterranean fauna. Sampling of the lower Fortescue alluvia indicates that species richness is comparable to other alluvial aquifers across the region.

Through the conceptualisation of groundwater dependence, the key linkages between the ecosystems and hydrogeology of the lower Fortescue River are identified. In this report these are framed as ecological management objectives, which will inform the estimation of ecological water requirements.

The ecological water requirements will be a key input into the determination of an allocation limit for the system which will also consider the social and cultural water requirements and consumptive demand for water.

Allocation planning for the Pilbara coastal ports and towns is underway and scheduled to be completed in 2012.


Department of Water 1

1 Introduction The hydrogeology of the lower Fortescue River was first investigated in 1965 (Bradberry and Associates 1965). Additional assessments of the resource were conducted in the 1980’s and more recently, the 2000’s. There is currently significant interest in groundwater for mining operations (Haig 2009). The Department of Water will consider the sustainability of any development of the water resource and is also currently investigating and assessing the lower Fortescue River’s hydrogeology and associated cultural values.

In this report we identify and describe groundwater-dependent ecosystems in the lower Fortescue River area using available information and additional (limited) field studies. We then use existing hydrological and biological data and updated vegetation mapping to conceptualise the groundwater dependence of key ecosystems, enabling us to formulate management objectives.

The outcomes of this work will set the framework for development of ecological water requirements (EWR) and ultimately for a water allocation plan.


2 Department of Water

2 Biophysical setting The lower Fortescue River alluvial aquifer lies along the lower reaches of the Fortescue River on the Ashburton Plain, approximately 100 km south-west of Karratha. The EWR study area extends approximately 30 km along the Fortescue River, downstream of the North West Coastal Highway crossing (Figure 1).

The biophysical environment of the lower Fortescue River has been described previously in Dames and Moore (1979), Commander (1994), Maunsell (2006) and Haig (2009). The following sections provide a summary of these reports and incorporates updated climatic and hydrological data.

2.1 Climate

The climate of the Pilbara region is classified as semi-arid to arid with low variable annual rainfall and hot dry conditions most of the year. Average monthly temperatures recorded at Mardie Station exceed 35 oC from October to April and fall to 28 oC in July (Figure 2). Monthly minimums range from 12 oC in July to 25 oC in February.

Average annual rainfall (1886-2009) in the region is generally low (272 mm at Mardie) (Figure 3). Rainfall is also highly variable as it is mostly from summer cyclones and autumn thunderstorms, with 90% of rain falling between January and June. In addition, the heat and clear skies result in average evaporation greatly exceeding rainfall (Figure 4). High evaporation and low rainfall cause an extreme moisture deficit across the region.



Figure 1 Lower Fortescue River study area



Figure 2 Mean monthly temperatures at Mardie Station (1886-2009)

Figure 3 Long-term annual rainfall at Mardie Station (1886-2009)

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Figure 4 Mean monthly evaporation (Dampier Salt, 1972-2009) and rainfall (Mardie

Station, 1886-2009)

2.2 Physiography and geomorphology

The lower Fortescue River area lies in the northern part of the Carnarvon Basin (Hocking et al. 1987). Quaternary alluvial deposits up to 30 m thick form part of the alluvial fan associated with the discharge of the river onto the Ashburton Plain. The present surface is dominated by clayey overbank deposits with gravel beds in drainage channels and subsurface paleochannels (Figure 5).

The Quaternary alluvium unconformably overlies Tertiary Trealla Limestone, consisting of interbedded clay, marl and fine grained limestone (Table 1). This typically forms the beds of the alluvial sequence.

The tertiary sediments unconformably overlie a series of gently northwest-dipping Early Cretaceous strata (Muderong Shale and Yarraloola Conglomerate) up to 90 m thick. The Muderong Shale is composed of grey-green siltstone and basal greensand, and the Yarraloola Conglomerate, of angular to rounded pebble gravel, with minor beds of sand and clay.

The Yarraloola Conglomerate unconformably overlies and infills incised valleys in the Precambrian basement rocks of the Mount Bruce Supergroup. Basement rocks outcrop on hills either side of the river near the North West Coastal Highway crossing and in patches between the Mardie and Balmoral homesteads. The Yarraloola Conglomerate crops out adjacent to the Precambrian bedrock north of the Balmoral homestead.

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rainfall evaporation



Figure 5 Lower Fortescue River cross-section (from Haig 2009)

Table 1 Stratigraphic units of the lower Fortescue River (from Commander 1994).

Age Formation Thickness* (m) Lithology Quaternary Alluvium 30 Clay, gravel, calcrete

close to the watertable Unconformity Tertiary (Miocene)

Trealla Limestone 17 Limestone, clay, marl

Unconformity Cretaceous Muderong Shale 0 Shale Yarraloola conglomerate 23 Conglomerate Unconformity

Precambrian Mt Bruce Supergroup Basalt, chert

* maximum thickness intersected during drilling

2.3 Hydrogeology

The alluvial sediments of the lower Fortescue River have been explored as a potential source of water. Previous investigations (Bradberry and Associates 1965; Commander 1989; Commander 1994) indicate that the alluvium is potentially a major source of freshwater at a scale suitable for town supply.

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West Fortescue River East

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Gravel Clay Calcrete Sandstone Limestone, marl Chert, banded iron

A Alluvium T Trealla limestone Y Yarraloola conglomerate B Basement 3 Bore No



An assessment of ground and surface water issues was undertaken in 2000 in response to a proposal to develop the George Palmer mine deposit (Skidmore 2008). The assessment characterised the aquifers and determined groundwater flow direction and quality.

These investigations have lead to the development of a conceptual understanding of the lower Fortescue River’s hydrogeology. This conceptual understanding will be tested by the numerical model currently under construction for the study area.

Aquifers

The alluvial, Yarraloola Conglomerate and fractured basement rock aquifers are present within the lower Fortescue River area. The alluvial aquifer extends over approximately 200 km2 of the alluvial fan deposit to the west of the present day river channel. Where present, the alluvium clay has an average thickness of 6.0 m while the gravel is approximately 13.6 m thick. The gravel deposits coincide with a freshwater lobe (< 1000 mg/L), which grades into saline groundwater near the saltwater interface and alluvial fan margins.

The Yarraloola Conglomerate is less extensive than the alluvial aquifer. It is limited to the current position of the river where it fills narrow channels in the underlying Precambrian basement rocks (Aquaterra 2006a). The Yarraloola Conglomerate Aquifer is confined by the overlying and less permeable Trealla Limestone (MWH 2010).

Groundwater also occurs in fractures and faults within the basement rock. Storage however, is generally low due to the low portion of rocks containing voids and the impermeability of the rock itself (Skidmore 2008).

Current use

Although current groundwater use is largely restricted to pastoral wells, mining companies have been licensed to take water from the alluvial aquifer in a staged development, with a current allocation limit of 6 GL/yr. Mine pit dewatering from the adjacent bedrock is likely to commence within the next 12 months. Recent groundwater modelling shows there is little interaction between the bedrock and the alluvium (MWH 2010). It is therefore unlikely that dewatering will impact groundwater levels in the alluvial aquifer.

Groundwater

Groundwater levels have been monitored discontinuously at up to 32 bores across the study area since 1983 (Figure 1). Data indicate the watertable in the alluvial aquifer currently occurs between 5 and 12 m below the ground surface (Figure 6).



Figure 6 Selected lower Fortescue River monitoring bore hydrographs

River flow, recharge and discharge

Through the majority of the study area the lower Fortescue River has a well defined main channel, which is four to six metres deep and up to 100 m wide. Closer to the river mouth the channel becomes less defined allowing floods to extend over the adjacent floodplains (Aquaterra 2006b).

The lower Fortescue River gauging station has been relocated twice following flood damage. The current station, monitored since 1987, is located at Bilanoo Pool immediately upstream of the North West Coastal Highway crossing. The full flow record incorporating data from three stations (Bilanoo Pool: 1987–2009, Jimbegnyinoo Pool: 1969–1998, Koolumba Pool: 1968–1974), extends back to 1968 (Figure 7). All three locations are in close proximity to one another and are located upstream of the groundwater study area boundary.

Recharge to the alluvial aquifer results mainly from direct infiltration through the riverbed during periods of flow. The volume of recharge is controlled by the duration, depth and frequency of flow and the storage available in the aquifer. Recharge to the Yaraloola Conglomerate is from downward leakage from the overlying alluvium where sections of the Trealla Limestone have eroded away.

Over the 23 years of record the mean annual flow at Bilanoo Pool was 335 GL. The largest flow (1372 GL) occurred in 2004. There were three years with no flow recorded and another five years with total flows less than 10% of the mean annual flow. This indicates that in one out of three years recharge to the lower Fortescue River alluvial aquifer is very low. The longest period of no flow was 32 months, recorded between June 2001 and February 2004.

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Flow corresponds closely with rainfall, with high flows occurring between January and April and peaking in February. Low or no flow is typically experienced from July through to December.

Figure 7 Lower Fortescue River daily discharge 1968-2009 (measured at three

gauging stations)

Flow from the river’s two main tributaries within the study area, Edwards and Du Boulay creeks, enters the Fortescue within 10 km of the river mouth and are unlikely to contribute significantly to recharge. However, a number of minor tributaries and creeks join the river further upstream and are likely to contribute during major flow events.

Discharge from the alluvial aquifer occurs as evapotranspiration from phreatophytic (groundwater-dependent) vegetation fringing the Fortescue River and evaporation from river pools and the tidal flats. Evapotranspiration from dense stands of the exotic tree species, Mesquite (Prosopis pallida), is thought to be considerable and to influence local groundwater levels.

2.4 Vegetation and flora

The study area is located within the northern extremity of the Onslow Coastal Plain Botanical District (Beard 1975). Vegetation formations over the alluvium vary according to changes in surface soils (Dames and Moore 1979). The area is characterised by complex patterns of grassland formations which are usually associated with open shrubland or open woodland.

Generally, the lower Fortescue and major tributaries are fringed by Eucalyptus camaldulensis, E. victrix and Melaleuca argentea over open shrublands, herblands and/or grasslands. Dense patches of the exotic Mesquite (Prosopis pallida), covering

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up 200 000 ha, occur along across the alluvial delta near the mouth of the river (van Vreeswyk et al. 2004).

Shrub savannah dominates the plains, with scattered Acacia xiphophylla over Eragrostis, Eriachne and Aristida grasses, with introduced Cenchrus ciliaris and C. setigerus.

2.5 Land use and cultural values

The lower Fortescue River study area lies within the Mardie Station pastoral lease. Established as a sheep station in 1865, the station now runs approximately 8000 head of cattle.

Several exploration and mining leases occur within and adjacent to the study area. These include Citic Pacific’s site close to the Balmoral homestead and Mineralogy’s sites, all along the eastern boundary of the study area.

The Kuruma Marthudunera people are the traditional owners of the land around the lower Fortescue River. A desktop survey for mythological Aboriginal sites and on-country visit by Department of Water staff and Kuruma Marthudunera people were conducted. Although mythological sites were only found beyond the study area, river pools of the lower Fortescue and the fauna they support remain culturally important to the Kuruma Marthudunera people (Pilbara Native Title Service 2009).



3 Identification and description of groundwater dependent ecosystems

3.1 Defining groundwater dependent ecosystems

To manage potential impacts of groundwater abstraction, the department must identify those ecosystems that have some degree of groundwater dependence and determine the type and level of that dependence.

Three types of ecosystems have been identified as possibly being dependent on the shallow alluvial aquifer of the lower Fortescue River. These are;

• river pools – aquatic and emergent macrophytes, phytoplankton, fish, macroinvertebrates and terrestrial vertebrate fauna

• riparian vegetation – phreatophytic vegetation and dependent terrestrial fauna

• aquifer ecosystems – stygofauna.

Groundwater attributes

An ecosystem’s groundwater dependence is based on one or more of four basic groundwater attributes (Sinclair Knight Merz 2001):

• flow or flux – the rate and volume of supply of groundwater

• level – for unconfined aquifers, the depth below surface of the water table

• pressure – for confined aquifers, the potentiometric head of the aquifer and its expression in groundwater discharge areas

• quality – the chemical quality of groundwater expressed in terms of pH, salinity and/or other potential constituents, including nutrients and contaminants.

3.2 River pools

Permanent or near permanent (freshwater) pools occur within the Fortescue River project area where the river channel intersects the water table (Dames and Moore 1979).

Pool permanency was characterised by analyses of satellite imagery (Department of Water 2009). Permanency was assessed based on pool occurrence across seven sets of Landsat imagery spanning 1999 to 2007. Pools were defined as permanent if they were present across all image sets; semi permanent if present in 60 – 99% of image sets and intermittent if present in <60% of image sets.

Two permanent pools (Mungajee and Tom Bull), five semi-permanent pools (Bilanoo, Stewart, Chuerdoo, Jilan Jilan and one unnamed) and two unnamed intermittent pools were identified in the project area (Figure 8). As the imagery pixel size was 25



m it is possible that the number and permanency of pools have been underestimated. Numerous pools were also identified in a system of gorges immediately upstream of the study area.

Conceptual link to groundwater

Based on a literature review, GIS techniques and the long-term groundwater monitoring program, we have developed conceptual models of groundwater dependence for the different types of groundwater-dependent ecosystems identified within the study area.

The Fortescue River and its pools are connected to and interact with the underlying alluvial aquifer. The direction of interaction changes seasonally in response to flooding, evaporation from pools or transpiration of groundwater by riparian vegetation. The permanence of the interaction is determined by the level of the groundwater in relation to the base height of the pool.

When the river is in flood there is connectivity between pools, the floodplains and the riparian zone (Figure 9). This hydrological connectivity allows biota, nutrients and carbon to disperse or migrate through the system. During river flow events groundwater is recharged from the surface water and the watertable rises.

During periods of no flow (Figure 10) the hydraulic gradient between the groundwater and the pools reverses and groundwater discharges into the pools. Intermittent pools begin to dry out as the watertable drops below the base height of the pool and the groundwater becomes disconnected.

Drought conditions and declining groundwater levels result in shallower pool depths and semi-permanent pools disconnecting from the groundwater (Figure 11). This greatly reduces the area of available aquatic habitat. Permanent pools have demonstrated long-term connectivity to the groundwater and are expected to be maintained by groundwater discharge during these drought periods. Because of this, these pools provide critical habitat and are an important refuge for native flora and fauna.



Figure 8 Location and permanence of lower Fortescue River pools



Figure 9 Conceptual diagram of longitudinal cross-section of the lower Fortescue River during a flood event

Permanent pool

Semi-permanent pool

Intermittent pool

RIVER FLOWING

Direction of groundwater flow

Direction of river flow

Permanent pool

Semi-permanent

pool

Intermittent pool

• Connectivity between pools, flood plain and riparian habitats • Period of dispersal and nutrient/carbon cycling • Groundwater recharged from surface water



Figure 10 Conceptual diagram of a longitudinal cross-section of the lower Fortescue River during a period of no flow

Figure 11 Conceptual diagram of a longitudinal cross-section of the lower Fortescue

River pools during a drought period

Ecology

The Fortescue River pools support freshwater and marine fish species, terrestrial vertebrate fauna, birds, frogs and macroinvertebrates. Numerous studies have been conducted of river pools within the study area (Dames and Moore 1979; Massini 1988; Morgan et al. 2003; Beesley 2006; Pinder and Leung 2009). As large flow

DROUGHT


• Isolated pools acting as refuge for native flora and fauna • Pool water levels driving changes in habitat availability • Groundwater discharge maintaining permanent pools

Permanent pool

Semi-permanent

pool

Intermittent pool

• Isolated pools acting as refuge for native flora and fauna • Pool water levels driving changes in habitat availability • Groundwater discharge maintaining permanent pools


NO RIVER FLOW



events are known to ‘re-set’ both the physical and ecological nature of river pools (Dobbs & Davies 2009), the most recent available data were used here to describe river pool ecology. Conceptual models of groundwater-ecology linkages of selected river pools of the lower Fortescue are presented in Appendix A.

Fish

Combined results of previous fish sampling in Bilanoo and Mungajee pools (Beesley 2006; Massini 1988; Morgan et al. 2009; Morgan et al. 2003) recorded 15 species of fish including ten freshwater taxa and two possibly undescribed species (Table 2). Of note, is that all known fish taxa of the entire Fortescue River catchment were found in the two pools sampled by Morgan et al. (2009).

Table 2 Freshwater and marine fish species recorded in study area

Common name Species Bilanoo Pool Mungajee Pool

Masini (1988)

Beesley (2006)

Morgan (2009)

Morgan (2009)

Freshwater Salmon catfish Arius graeffei x x Barred grunter Amniataba percoides x x x x Flathead goby Glossogobius giurus x x Empire gudgeon Hypseleotris compressa x x Spangled grunter Leiopotherapon aheneus x x x Spangled perch Leiopotherapon unicolor x x x x Western rainbowfish Melanotaenia australis x x x x Bony bream Nematalosa erebi x x x Catfish Neosilurus hyrtlii x Neosilurus sp. x Northern eel Anguilla bicolor unnamed x x

Marine Oxeye herring Megalops cyprinoides x x Milkfish Chanos chanos x x Sea mullet Mugil cephalus x Total no. species/ pool 3 9 10 11

The structure of fish communities in Pilbara rivers is influenced by pool stability (Beesley 2006), depth and size (van Dam et al. 2005). Large-bodied species and adult fish are generally restricted to more permanent, deeper pools as they have greater habitat diversity, carrying capacity and refuge values (Morgan et al. 2009). This suggests the level of permanence of Bilanoo and Mungajee pools is a major factor in determining fish species richness on the lower Fortescue. More permanent deeper pools are the preferred habitat of a number of freshwater species, including the northern eel (Anguilla bicolour), bony bream (Nematalosa



erebi), catfish (Neosilurus hyrtlii) and salmon catfish (Arius graeffei) (Table 3). Although the rainbow fish (Melanotaenia australis) also inhabits permanent pools, it is capable of rapidly colonising temporary pools and shallow areas. Spangled perch (Leiopotherapon unicolour) and banded grunter (Amniataba percoides) can also rapidly colonising temporary pools with anecdotal evidence that it is also capable of surviving in mud during drought (HGM 1998).

Table 3 Description of freshwater fish habitat requirements or preferences (Beesley 2006; Pusey et al. 2004; Dames & Moore 1984).

Species General description and habitat preferences Nematalosa erebi

A widespread and common species of northern Australia and inland rivers of south-eastern Australia. A detritivore commonly found in deep water in permanent and temporary pools. Susceptible to low dissolved oxygen.

Anguilla bicolour A long-lived species that is estimated to reach maturity at 10 to 25 years. Once mature it migrates to the tropical deep sea to spawn. Only breeds once. Strongly restricted to permanent pools due to life-history requirement for long-term stability.

Arius graeffei A relatively long-lived species with relatively late maturity. Requires deep pools for incubation of eggs and larvae. Mainly deeper parts of permanent pools.

Neosilurus hyrtlii Very widespread species found across northern Australia in a wide range of habitats. In the Fortescue it is mainly found in permanent pools.

Melanotaenia australis

Found throughout the Pilbara and Kimberley and into the Northern Territory in a wide range of habitats including shallow pools, streams and the margins of deep pools. Relatively tolerant of a range of environmental conditions.

Leiopotherapon unicolor

Very widespread and abundant across northern Australia in a wide range of habitats. Species is considered hardy and tolerant of a wide range of environmental conditions. It is often found in tributaries and upstream reaches.

Glossogobius giuris

Widespread throughout northern Australia. Appears to have a preference for more permanent pools.

Amniataba percoides

Widespread across northern Australia. Found in a wide range of habitats but may be susceptible to low dissolved oxygen concentrations.

Leiopotherapon aheneus

A schooling species restricted to the Fortescue, Ashburton and Robe rivers. Found in shallow pools, streams and margins of deep pools.

Hypseleotris compressa

Found in flowing streams; congregates around fallen logs and other vegetative debris.

Invertebrates

Pinder and Leung (2009) assessed the relationship between aquatic invertebrates and habitat variables. Species richness at the lower Fortescue pools was comparatively low (56 taxa at Mungajee and 75 at Bilanoo Pool compared to an average of 93, and a high of 105 at Deep Reach Pool at Millstream).

It was found that community structure and composition were mostly influenced by macrophyte cover and biomass, sediment type and nutrient loads yet not to the extent that would allow thresholds to be recognised (Pinder and Leung 2009). The importance of sediment type was evident at Mungajee Pool, which was mildly turbid due to naturally high clay content in the sediments and supported the lowest number



of taxa in the study. The study indicated that pool depth, size and permanency were also important.

Pinder and Leung (2009) concluded it was important to maintain habitat diversity and adequate conditions (including water quality) in a variety of pools within a catchment to ensure the present assemblage of species persisted.

Other vertebrate fauna

Although the Fortescue River pools provide distinct, isolated habitat for fish and invertebrates, they are also used opportunistically by other vertebrate species. Waterbirds, waders and frogs are most strongly correlated with this habitat type, with reptiles and both native and introduced mammals using pools for foraging, shelter and drinking.

HGM et al. (2001) identified 96 birds, 17 native mammals, five introduced mammals, 58 reptiles and three amphibians in the lower Fortescue area. Of these, it is likely that 10 bird, three reptile and the three amphibians (frogs) are associated with river pools (Outback Ecology 2004).

Permanent pools may also be important to the productivity of surrounding landscapes. During the dry season, the abundance of flying adult insects in the riparian zone is likely to be much higher than the nearby savannah, providing important food sources for terrestrial consumers such as bats, reptiles, birds and spiders (Douglas et al. 2005).

Flora

Aquatic flora of the lower Fortescue River have been surveyed as part of numerous broader studies. Dames and Moore (1979) found a relatively diverse but undescribed algal flora in permanent pools. Massini (1988) identified one emergent macrophyte, Cyperus sp. and two submerged aquatic species, Myriophyllum sp. and Vallisnera sp. Beesley (2006) reported considerable stands of submerged macrophytes (Myriophyllum sp., Vallisneria nana., Najas marina, Potamogeton crispus, Ruppia megacarpa) in Bilanoo Pool with some emergent macrophytes (Eleocharis sp., Scirpus littoralis, Typha domingensis). Department of Water staff identified a further two submerged macrophytes, Potamogeton tricarinatus and Triglochin dubia, during a vegetation survey in August 2008 (Appendix A).

Most recently Pinder and Leung (2009) sampled submerged and emergent macrophytes as part of their pool habitat assessments. No macrophytes were found at Mungajee Pool, possibly due to the turbidity but, Bilanoo and Stewart pools both supported aquatic flora.

The most dominant species - Myriophyllum sp., Vallisneria nana and Potamogeton crispus are submerged root angiosperms typically found only in permanent pools. V. nana occurs at a water depth range of 0.0-1.3 m, with maximum densities found at 0.6 m (George et al. 2002).

Although not common to all pools, macrophytic vegetation is an important ecological component of the river, providing food and habitat for fauna. This is indicated by



Pinder and Leung’s (2009) findings that aquatic invertebrate richness increased with increased biomass and cover of submerged macrophytes.

Water quality

The most recent and comprehensive assessments of pool water quality were carried out in October and November 2008 by Pinder and Leung (2009) and Morgan et al (2009) respectively (Table 4). The pools of the lower Fortescue (Bilanoo, Stewart and Mungajee) were fresh, with salinities ranging from 631 to 880 mg/L, and alkaline with pH ranging from 7.01 to 8.0. Bilanoo and Stewart pools were relatively clear, (NTU = 0.0 to 3.4) but, Mungajee was quite turbid (NTU = 17.6 to 22). This was thought to be natural and caused by suspension of the clay sediment. Mungajee Pool also had the lowest oxygen levels (Morgan et al 2009) falling below that recommended in the ARMCANZ & ANZECC (2000) water quality guidelines (85%). Low dissolved oxygen levels can place aquatic fauna and flora under stress resulting in deaths if falling too low.

Fresh groundwater is distributed in a lobe coinciding with the main gravel aquifer (Haig, 2009). It extends north-west onto the tidal flats from the main river channel. The low pool salinities measured at the end of the dry/ beginning of the wet season suggests that once flow ceases, the pools are maintained by this fresh groundwater. In contrast, following large flow events and during exceptionally wet years, it is likely that pool salinities rise following more saline surface water inputs. This situation has been noted on the De Grey River (Loomes & Braimbridge 2010) and other Pilbara Rivers (Commander et al. 2004).

Water chemistry parameters, including total nitrogen and total phosphorus (linked to water quality problems including toxic algal blooms, hypoxia and declines in habitat values) suggested water quality within the lower Fortescue pools was good (Pinder and Leung 2009).

Declines in groundwater would likely result in falling pool levels. Where pools become shallow, nutrients (from stock usage) will concentrate and may cause algal blooms, increased plant growth and night time anoxia. Maintenance of water levels and pool water quality is important to ensure oxygen levels remain sufficient for aquatic biota and to facilitate nutrient cycling associated with primary productivity and decomposition of organic carbon for food webs.



Table 4 Physico-chemical parameters measured in 2008

Pinder and Leung (2009) Morgan et al (2009)

Parameter Mungajee Stewart Bilanoo Mungajee Bilanoo

Temperature 28.25 32 31 25.37 22.10

Total dissolved salts (mg/L) 690 710 880 631 715

pH 7.4 7.9 8.0 7.01 6.75

Turbidity (NTU) 22 0 0.4 17.59 3.24

Dissolved oxygen (mg/L) - - - 56.83 96.17

Total nitrogen (mg/L) 0.37 0.79 0.28 - -

Total filterable nitrogen (mg/L) 0.19 0.71 0.26 - -

Total phosphorus (mg/L) 0.01 0.01 <0.01 - -

Total filterable phosphorus (mg/L) <0.01 <0.01 <0.01 - -

Total chlorophyll (mg/L) 0.012 0.005 0.003 - -

Conservation significance and sensitivity

The pools of the lower Fortescue River are representative of aquatic ecosystems of coastal Pilbara rivers. They provide habitat and food for aquatic and terrestrial fauna with permanent pools acting as drought refuges.

Consistent with the conclusions of Kendrick and Stanley (2002) permanent pools in the lower Fortescue River are considered sub regionally significant as they support vertebrate and invertebrate fauna.

Bilanoo and Mungajee pools provide habitat for all fish taxa known from the Fortescue River catchment, including previously unidentified species and taxa with restricted distribution (Morgan et al. 2009). As the Fortescue River has the highest diversity of freshwater fish taxa of all Pilbara rivers including those requiring deep, permanent pools (Morgan et al. 2009), it is likely that these two pools have high habitat value and are highly sensitive to groundwater decline.

Outback Ecology (2004) conducted a desk-based sensitivity assessment of fauna species of the lower De Grey River, taking into account potential impacts of groundwater decline on river pools and riparian vegetation. Each species was assigned to one of three categories as described in Bamford (2003).

Ten species of bird, considered to be highly sensitive to groundwater decline on the De Grey River were also identified on the lower Fortescue (HGM et al. 2001) (Table 5). An additional 52 species of the lower Fortescue were considered moderately sensitive.

Included in the ten highly sensitive species is the Great-white Egret. This species is listed as a protected marine species under Environment Protection and Biodiversity Conservation Act 1999, and a migratory species under the China-Australia Migratory Birds Agreement (CAMBA) and the Japan-Australia Migratory Birds Agreement (JAMBA). It is a wader that mainly inhabits shallow freshwaters, including river pools.



Although only considered at moderate risk, the Rainbow bee-eater (Merops ornatus) and White-bellied sea eagle (Haliaeetus leucogaster), are listed migratory species under the CAMBA and JAMBA agreements respectively (Outback Ecology 2004).

Birds are more likely to occupy the area during the wet as, being highly mobile, they would be able to move to nearby water bodies and habitat if the lower Fortescue pools dried (Outback Ecology 2004).

Three frog species were recorded within the study area (HGM et al. 2001). Although not of high conservation significance all three species were considered highly sensitive to groundwater decline (Outback Ecology 2004). Although three reptiles were recorded along creek or drainage lines (HGM et al. 2001), none were of high conservation significance or highly sensitive to groundwater decline.

Table 5 Vertebrate species of high sensitivity to groundwater decline (Outback Ecology 2004) associated with river pools of the lower Fortescue River

Common name species Massini (1988)

Dames and Moore (1979)

HGM et al (2001)

Birds

Pacific Black duck Anas superciliosa x x

White-faced Heron Ardea novaehollandiae x x

Great (white) Egret Ardea alba x

White-necked heron Ardea pacifica x

Grey Teal Anas gracilis x

Black-fronted Dotterel Charadrius melanops x x

Greenshank Tringa nebularia x

Pied Stilt Himantopus himantopus x

Whiskered tern Chlidonias hybridus x

Australian grebe Tachybaptus novaehollandiae

x

Amphibians

Desert tree frog Litoria rubella x

Main’s frog Cyclorana mainii x

Russell’s toadlet Uperoleia russell x

3.3 Riparian ecosystems

Conceptual link to groundwater

A conceptual model of groundwater dependency of riparian vegetation along the lower Fortescue study area was developed using vegetation mapping and available groundwater data (Figure 12).



The distribution of riparian plant communities generally reflects the depth to groundwater and the area inundated during flooding. The shallow depth to groundwater in the recent alluvium and especially along the river provides areas where deep rooted vegetation can reach groundwater. Groundwater sustains these communities in the absence of rainfall and/ or surface flow.

The riparian tree species Melaleuca argentea is likely to be restricted to areas where the watertable is very shallow or at the surface. Eucalyptus camaldulensis, also a riparian species can reach deeper watertables, but its distribution is restricted by groundwater depth and reliance on flood waters for recruitment.

Where average depth to groundwater along the course of the river is less than 4.0 m. and inter-annual fluctuations are in the order of 2.0 m, M. argentea and E. camaldulensis are likely to be highly dependent on groundwater. The ability of these trees to adapt to groundwater decline beyond these levels depends upon their physiology (e.g. how quickly roots grow and to what maximum depths).

Figure 12 Conceptual diagram of a longitudinal cross-section of the lower Fortescue River and floodplain

Ecology

Groundwater-dependent vegetation

HGM (2000) described 64 vegetation communities in the project area. Ten of these are considered likely to be or at least contain species that are groundwater dependent (Table 6). This classification is based on;

FLOODPLAIN WOODLAND WOODLAND OPEN SCRUB

Clay

Gravel No river flow groundwater level

Drought groundwater level

Flood stage height

E. camaldulensis Cyperus sp.

M. argentea E. camaldulensis Cyperus sp.

E. camaldulensis and E. victrix

Herbs Shrubs and Triodia sp.

River channel



• presence of species known or demonstrated to use groundwater or to be groundwater dependent. These include M. argentea, E. camaldulensis and E. victrix.

• estimates of local depth to groundwater (ie. where depth to groundwater is <10-15m the possibility of use by deep rooted vegetation increases).

Table 6 Vegetation community descriptions (from HGM, 2000)

Code Community description

Pc1 Major creeklines with woodlands of Eucalyptus victrix and E. camaldulensis above a high shrubland dominated by Acacia coriacea, with significant invasion by Mesquite (*Prosopis pallida hybrid) over a sparse to open herbland dominated by Alternanthera nana, with lesser amounts of Vigna lanceolata var. lanceolata.

Pc2 Minor creeklines with a scattered to open woodland of E. victrix above a high shrubland dominated by A. coriacea over a moderately dense to dense grassland of *Cenchrus cilliaris and C. setiger.

Pc3 Minor creeklines with and open woodland of E. victrix above a high open shrubland dominated by A. coriacea, over an open cover of Triodia epactica and an open tussock grassland dominated by *C. ciliarus, with lesser amounts of Cymbopogon ?ambiguus and Themeda triandra.

Pc4 Minor creeklines with scattered low trees of E. victrix above a high open shrubland dominated by Acacia ancistrocarpa, over an open grassland dominated by annual Sorghum ?plumosum with lesser amounts of *C. ciliaris, Eulalia aurea, T. triandra and Triodia wiseana.

Rc1 Occasional trees (E. camaldulensis) and tall shrubs (Melaleuca glomerata) in scoured beds of major creelines.

Rc2 Open forest of Melaleuca argentea and E. camaldulensis over patches of tall shrubs dominated by A. coriacea, over a moderately dense cover of grass dominated by *C. ciliaris and C. setiger.

Rc3 Woodland of E. camaldulensis over patches of tall shrubs dominated by M. glomerata over patches of sedges dominated by Cyperus vaginatus in major creeklines and tributaries.

Rc4 Woodland of E. victrix with lesser amounts of E. camaldulensis over patches of tall shrubs dominated by M. glomerata, frequently with small amounts of Acacia ampliceps, over a moderately dense cover of grasses dominated by *C. ciliaris and C. setiger in tributaries.

Rf1 Scattered tall trees of E. victrix with occasional low trees of Erythrina vespertilio over a moderately dense grassland dominated by *C. ciliaris and C. setiger on floodplains.

Rf2 Moderately dense, tall shrublands of Mesquite (*Prosopis pallida) on dense clayey plains.

*exotic species

These vegetation communities are dominated by deep rooted perennial species associated with creeklines, the Fortescue River and its floodplains within the River and Paraburdoo land systems (Figure 13).



Figure 13 Riparian vegetation of the lower Fortescue River study area



These results are consistent with the communities identified in the Pit dewatering and vegetation monitoring report (Maunsell 2006) prepared for the Austeel Iron Ore development and observations made by Department of Water staff during a field assessment in 2008 (Appendices A & B).

The tree species E. camaldulensis and M. argentea are widespread across riparian zones in the Pilbara and the lower Fortescue study area, and E. victrix is common on floodplains. The dependence of these species on groundwater is the most studied and understood for Pilbara riparian species. A database of water level ranges of key Pilbara riparian species was recently created (Loomes 2010). Ranges were calculated using measured distributions and elevational ranges (either measured or obtained from LiDAR) of species across the riparian fringe and depth to groundwater or pool levels measured at the nearest bore or pool. E. camaldulensis, M. argentea and E. victrix were amongst the species considered.

Previous studies indicated that M. argentea has a shallow planform root system and is adapted to areas of shallow groundwater, from 2.0 to 3.0 m below ground level (mbgl) (Strategen 2006). Loomes (2010) described a similar mean water level range of between 1.15 and 3.87 mbgl. With the watertable at these depths this species is likely to have difficulty adjusting to short periods of dry conditions (Graham 2001; Strategen 2006).

Eucalyptus camaldulensis is also commonly associated with shallow depths to groundwater of 2.0 to 5.0 mbgl (Strategen 2006) and 1.82 to 4.92 mbgl (Loomes 2010), although it has been recorded where groundwater is up to 21 mbgl (Landman 2001). The bimorphic root system (surface lateral roots and a tap root) of this species enables it to use both groundwater and water held in the unsaturated, vadose zone above the watertable.

Although E. camaldulensis is reported to be capable of sinking new tap roots in response to groundwater decline, drawdown of >10.0 m over a prolonged period may cause irreversible stress (Woodward-Clyde 1997). Both E. camaldulensis and M. argentea are phreatophytic (Muir Environmental 1995), but it is thought they will access surface or flood water where available (O’Grady et al. 2002). Surface or flood waters also play an important role in reproductive morphology, with the period of greatest seedfall for both species timed to coincide with receding floodwaters (Pettit and Froend 2001). This ensures moist sediments are available to support seed germination and survival. Flood frequency is important because the small seeds of E. camaldulensis dry out quickly and do not become incorporated into the seedbank (Pettit and Froend 2001). Flood frequency and intensity also determines size and age class structure: immature, small individuals can be removed in relatively low intensity flows and mature trees in large events.

Eucalyptus victrix tends to be found in drier areas than E. camaldulensis and M. argentea (Muir Environmental 1995). Loomes (2010) described a mean water level range of 2.18 to 4.03 mbgl. This is similar to that described for E. camaldulensis however, the plots used in the assessment were restricted to the river edge and did not capture the deeper, up-gradient range of E. victrix. Although tolerant of long



periods of drought and less susceptible to drawdown, this species appears sensitive to prolonged inundation (Strategen 2006).

Mesquite (Prosopis pallida) is one of 20 ‘weeds of national significance’ in Australia, due to invasiveness and environmental and socioeconomic impacts (van Klinken et al. 2007). Introductions in Western Australia occurred in the late 1920’s, predominately around homesteads and water points in the arid rangelands regions. Mesquite infestations now extend over 200,000 ha across five pastoral stations in the Pilbara region, with sparse to dense infestations (van Klinken et al. 2007). The single largest population of mesquite in Australia occurs at Mardie Station, with greatest densities found across the lower Fortescue delta within 15 kms of the coast (Figure 14). It is thought that at these densities, evapotranspiration from the mesquite is having an impact on the local groundwater table (Haig 2009).

The tree species, Sesbania formosa, also occurs in the riparian zone. It is restricted to alluvium and creek lines or rivers (Paczkowska and Chapman 2000). Its’ cork-like, aerenchymous, root and stem tissue allow seedlings to establish along high water zones and mature plants to survive waterlogging (Massini 1988). Large plants, 7.0 to 8.0 m tall, are only found near permanent water. Loomes (2010) described a mean water level range of 1.46 to 3.46 mbgl. Although less well studied than other riparian species, its habitat preference suggests it is poorly adapted to low moisture availability and is likely to be using groundwater.

Melaleuca glomerata, a small tree or large shrub species, also occurs along the lower Fortescue River. It is found along rocky river beds and shallow depressions (Paczkowska and Chapman 2000). A mean water level range of 0.74 to 1.85 mbgl along with its habitat preference suggests M. glomerata is also poorly adapted to low water availability.

Although these species are generally adapted to the water regimes described above, local groundwater conditions must also be considered, at it is under these that individuals and/or populations germinate, establish and persist.



Figure 14 Mesquite density in the lower Fortescue River study area (2004)



Vertebrate fauna

Woodlands and forests of E. camaldulensis and M. argentea fringing the Fortescue River provide habitat for terrestrial fauna, including reptiles, mammals and birds. Massini (1988) and Dames and Moore (1979) previously identified ten bird species associated with riparian vegetation in the study area (Table 6). HGM et al (2001) identified 52 birds, 7 mammals and 22 reptiles within creekline habitats.

Table 7 Fauna of moderate sensitivity to groundwater decline (Outback Ecology 2004) associated with riparian vegetation

Common name Species Massini (1988)

Dames and Moore (1979)

HGM et al (2001)

Birds

Whistling Kite Haliastur sphenurus x x

Blue-winged Kookaburra Dacelo leachii x x

Red-plumed Pigeon Geophaps plumifera x

Little Corella Cacatua sanguinea x x x

Port Lincoln Parrot Platycercus zonarius x x x

Red-backed Kingfisher Todiramphus pyrrhopygia

x x

Black-faced Cuckoo-Shrike

Coracina novaellandiae x x

White-plumed Honeyeater Meliphaga penicillata x x

Magpie Lark Grallina cyanoleuca x x

Australian Raven Corvus coronoides x

Spotted Harrier Circus assimilis x

Brown Falcon Falco berigora x

Nankeen Kestrel Falco cenchroides x

Australian Hobby Falco longipennis x

Sacred Kingfisher Todiramphus sanctus x

Rainbow Bee-eater1 Merops ornatus x

Mammals

Pilbara Ningaui Ningaui timealeyi x

Inland cave Bat Vespadelus finlaysoni x

Northern Long-eared Bat Nyctophilus arnhemensis

x

Northern free-tail Bat Chaerephon jobensis x

Reptiles

Bynoe’s Gecko Heteronotia binoei x

Gehyra variegata x 1Listed migratory species under the JAMBA agreement



Bats were also recently surveyed as part of the Pilbara Biological Survey. The greatest diversity was found in well-developed riparian zones with complex vegetation structure (McKenzie & Bullen 2009). In a survey of fauna on the Robe River, the richest sites were found close to the river or its tributaries. This suggests that the availability of water and associated higher productivity and greater structural diversity associated with riparian environments is important for faunal diversity and richness (Biota Environmental Services 2006).

Conservation significance and sensitivity

Riparian vegetation is important to the ecological functioning of river ecosystems. Intact, healthy vegetation provides the following ecosystem services;

• provides complex habitat for native fauna

• provides carbon for food webs

• stabilizes sediment

• filters pollutants from surface run-off

• shades the littoral zone and mediates microclimate. Searches of Department of Environment and Conservation’s Threatened (Declared Rare) Flora and of the Western Australian Herbarium Specimen databases identified the following ‘priority flora’ species within or adjacent to the lower Fortescue River study area;

• Gunniopsis sp Fortescue (Priority 1)

• Goodenia pascua (Priority 3)

• Goodenia nuda (Priority 4)

• Owenia acidula (Priority 3)

• Acacia glaucocaesia (Priority 3).

Based on habitat preferences, two of these species may show some sensitivity to groundwater decline; Goodenia nuda, an annual herb found in the mesquite scrub of the lower Fortescue and Acacia glaucocaesia, a shrub associated with floodplains.

Vegetation types associated with the riparian zone of the Fortescue River (particularly Rc1/2/3/4 and Pc1/2/3/4) and tributaries, and identified as likely to be groundwater dependent, were considered to be of conservation value by HGM (2000). This was based on its relatively restricted distribution within the study area, comparatively high floral species richness, presence of priority flora species and role as an important faunal habitat.

This was considered to particularly be the case where the condition of vegetation, as indicated by the effects of grazing and invasion by weeds, was relatively good. Overall the condition of vegetation in the study area is considered to be fair to degraded (Kendrick and Stanley 2002). Major threatening processes are weed invasion and grazing by stock and feral animals.



The sensitivity of phreatophytic vegetation to changes in groundwater availability is a function of species’ tolerances to altered hydrology, of the potential for surface or soil water to meet water requirements and of the groundwater conditions under which it established. Of the dominant riparian species identified on the Lower Fortescue River, M. argentea is considered the most sensitive and E. victrix the least (HGM 2003). Communities containing M. argentea, such as Rc2 are therefore considered the most sensitive to altered hydrology and from the effects of groundwater abstraction.

Fauna

Four occurrences of ‘declared threatened’ mammals, one Priority 4 mammal and one Priority 4 bird species were identified in land adjacent to the study area. The northern quoll, Dasycercus hallucatus, listed as vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and as a Schedule 1 species under the Western Australian Wildlife Conservation Act 1950, can occur along watercourses in the Pilbara and may also be present in the area (Astron Environmental Services 2008). Although these and other terrestrial fauna are unlikely to be directly affected by groundwater decline, any loss of habitat may have an indirect impact.

Bird fauna relying on the riparian vegetation for feeding, breeding and habitat are thought to be sensitive to changes in the groundwater regime (Outback Ecology 2004). Although they are mobile and can relocate to other suitable areas, there is the potential for over population of habitats and overall reduction on carrying capacity.

Sixteen bird species, four mammals (including three bats) and two reptiles identified in riparian zones of the lower Fortescue were described by Outback Ecology (2004) as moderately sensitive to groundwater decline (Table 6).

3.4 Aquifer ecosystems

The Pilbara region is recognised as a ‘global hotspot’ for stygofauna, with estimates suggesting that between 500 and 550 species occur in the region (Halse 2008). Although the coastal plain alluvia support a rich fauna, many of these taxa appear to have wider geographical ranges than non-coastal species.

Stygofauna in the lower Fortescue alluvium have been sampled by the Western Australian Museum (Humphreys 2000) and as part of numerous environmental surveys for proposed mining projects (Halse 2000; Halse 2008; HGM et al. 2001).

A review of these studies indicates that 55 taxa of stygofauna have been recorded in the alluvium (Halse 2008). This is comparable to the species richness typically reported in intensive stygofauna monitoring across the Pilbara.

Conservation significance

Given the cryptic nature of stygofauna and lack of information regarding their habitat requirements or preferences it is difficult to comment on their sensitivity to altered hydrological regime.



Similarly relatively little is known regarding the significance of stygofauna assemblages recorded for the lower Fortescue River alluvium.

Because of this paucity of information it is proposed that a precautionary approach be taken in regard to potential impacts on stygofauna.

3.5 Summary of ecological values

In this study, groundwater-dependent ecosystems of three different types have been identified and described in the lower Fortescue River study area:

• river pools

• riparian vegetation

• aquifer ecosystems.

This section provides a summary of the ecological values of each type of groundwater-dependent ecosystem. Values are divided into the following categories following Horwitz and Rogan (2003):

• biotic – important species and/or communities (including rare or threatened biota)

• functional – ecosystem services that maintain habitat for dependent populations or species

• landscape and waterscape – contributions to landscape connectivity, habitat provision, representativeness and ecosystem resilience to disturbance.

Cultural values will be discussed in a separate report.

River pools

Pools of varying size, depth and permanency occur along the lower Fortescue River. They are hydraulically connected to the aquifers and maintained by groundwater flow between flood events. Recent pool mapping (Department of Water 2009) suggests there are two permanent pools (Mungajee and Tom Bull), five semi-permanent pools (Stewart, Bilanoo, Cherdoo, Jilan Jilan and one unnamed) and two unnamed intermittent pools within the study area.

Biotic values

The lower Fortescue River pools are known or thought to support the following flora and fauna:

• phytoplankton

• submerged and emergent macrophytes

• approximately 50 macroinvertebrate taxa

• 12 freshwater and 3 marine fish species

• 10 waterbird species



• mammals

• reptiles

• frogs.

Functional values

The pools maintain ecological processes important to habitat provision including:

• water quality

• nutrient recycling associated with primary productivity

• decomposition of organic carbon required for food webs.

Landscape and waterscape values

The lower Fortescue River pools and the river itself have a number of broader scale and regional values. These include:

• connectivity – hydrological linkage of pools plays an important role in the natural functioning of the lower Fortescue River

• habitat provision – pools act as a drought refuge for native flora and fauna

• representativeness – the river is a good example of wetlands of the surrounding region

• resilience – the health and condition of the pools and river allow them to absorb seasonal changes (including drought and floods).

Riparian vegetation

The pools and shallow groundwater adjacent to the lower Fortescue River support numerous riparian vegetation community types.

Biotic values

Riparian vegetation supports the following fauna:

• birds

• reptiles

• mammals

• macroinvertebrates.

Functional values

Riparian vegetation maintains ecological processes important to habitat provision including:

• maintenance of water quality through biofiltration

• soil and bank stabilisation

• mediation of microclimate



• supporting complex food webs.

Landscape values

Riparian vegetation of the lower Fortescue River supports the following landscape values:

• connectivity – vegetation provides corridors allowing fauns to move between habitats (e.g. pools)

• habitat provision – vegetation provides both direct habitat and refuge habitat during drought

• representativeness – vegetation communities are good examples of riparian ecosystems of the region

• resilience – the health and condition of vegetation allows it to absorb seasonal changes (including drought and floods).

Aquifer ecosystems

Biotic values

Aquifers in the Pilbara region have been associated with diverse subterranean fauna. Although studies within the lower Fortescue River alluvial aquifer have been relatively limited, stygofauna have been identified throughout the area.



4 Ecological management objectives

4.1 Background and overall objective

Formulating management objectives for a water resource system is an integral component of the allocation planning process. Objectives presented in this report are based on our conceptual understanding of the links between ecosystems and groundwater – hydroecological linkages – and the ecological values and issues identified during the review of ecological information. The objectives set here will frame the development of ecological water requirements. In developing an allocation plan, management objectives will also consider social, cultural and economic values.

Ecological management objectives influence all aspects of ecosystem management including:

• determining the study area

• identifying management triggers

• designing and implementing a monitoring program

• reporting of outcomes

• subsequent response of management within an adaptive management framework.

This review has identified groundwater-dependent ecosystems of three different types associated with the lower Fortescue River – river pools, riparian vegetation and aquifers – as well as their associated values. Management objectives are now required to ensure these values are maintained and considered in future water resource planning.

Although floods are an important component of the water regime, they cannot be managed through abstraction. Objectives to maintain the ecological functions performed by high flow events have not been developed as part of this process, even though they are important to Pilbara river systems such as the Fortescue River in a number of ways;

• recharging groundwater

• triggering recruitment of riparian vegetation and movement of aquatic fauna

• redistributing carbon and nutrients within and around river and floodplain systems

• geomorphological processes in river channels.

The overall objective to guide the determination of ecological water requirements for the lower Fortescue River has been developed with the variable climate and the role of the river and groundwater system as a refuge in mind.

The overarching objective is:



• to maintain the ecological characteristics of the lower Fortescue in the context of a naturally variable climate.

The management objectives have been based on the components of groundwater regime that we consider the most important to the ecology – or the hydro-ecological linkages. The assessment parameters have focussed on the parts of the hydrological regime that can be managed through water resource management and in particular through the management of groundwater abstraction.

4.2 Objectives for river pools and riparian vegetation

River pools

The river pool ecosystems support a diverse aquatic biota with specific habitat requirements. River pools are also considered important in terms of supporting birds and other terrestrial fauna that is associated with this habitat. The role of permanent pools as a refuge for aquatic and terrestrial biota during drought periods is particularly important for maintaining ecosystem processes and systems. Groundwater contributions to the river pools are critical during drought periods when surface water inputs are negligible.

To maintain the extent and diversity of river pool habitats the following objectives need to be met within the context of a dynamic climate.

1 Maintain areas of permanent pools consistent with regional seasonality to maintain pool stability and pool refuges for fish and other fauna.

Parameters:

a. minimum aquifer level in the vicinity of river pools to maintain discharge/surface expression of groundwater

2 Sufficient areas of inundated shallow macrophyte habitat available for macroinvertebrates, small-bodied fish and juveniles of large-bodied fish

Parameters:

a. minimum pool depth and area to provide macrophyte habitat

b. minimum aquifer level to ensure sufficient contribution to pools

3 Sufficient deeper habitat permanently inundated and available for mature and large-bodied fish.

Parameters

a. minimum pool depth and area to provide deep pool habitat

b. minimum aquifer level to ensure sufficient contribution to pools

4 Sufficient depth in deeper pools to ensure dissolved oxygen levels do not reduce to anoxia.

Parameters



a. minimum aquifer level to ensure sufficient contribution to pools

b. suitable water quality in the aquifer

c. suitable pool water quality

Riparian vegetation

Riparian vegetation provides habitat and habitat corridors for birds and other terrestrial fauna. It is also important in maintaining waterway condition and functionality. Riparian vegetation also contains species and represents a habitat type that is typically restricted in distribution across the region.

The water requirements of the riparian vegetation are met by access to groundwater through maintenance of local watertables or soil moisture. During drought periods groundwater contributions to maintenance of vegetation is critical as it is likely to be the only source of water available.

The magnitude and rate of water level (or water availability) change, and the duration and frequency of periods of low water levels are important considerations for phreatophytic vegetation. All of these factors will affect:

• the vigour of established vegetation

• the resilience of vegetation to recover from drought periods

• the recruitment and establishment of new individuals.

To maintain the extent and diversity of riparian habitats the following objective needs to be met within the context of a dynamic climate/consistent with regional seasonality.

5 Sufficient water provided for phreatophytic vegetation by maintenance of accessible watertable levels during periods of no surface water inputs

Parameters

a. minimum depth to water table in areas of phreatophytic riparian vegetation

b. rate of change in groundwater levels

c. frequency and duration of periods of ‘low’ groundwater levels

Ecological management objectives and ecological water requirements

The ecological management objectives will inform the development of ecological water requirements for the lower Fortescue River. The ecological water requirements will be a key input into determining an allocation limit for the system along with social and cultural water requirements and the consumptive demand for water.

The ecological water requirements will also define rules to ensure sustainable management of the resource. It will have clearly set out links between monitoring, management and the underlying understanding of the ecology-hydrology linkages and will be related to easily measured parameters such as bore water levels.



Appendices

Appendix A –Conceptual models of selected pools

Bore stratigraphy, groundwater levels and stage heights, combined with vegetation mapping and occurrences of pool biota (fish, macroinvertebrates and flora), were used to provide a conceptual understanding of groundwater dependence of six of the most significant lower Fortescue River pools. In addition, cross sectional diagrams by Dames and Moore (1979) and Massini (1988), provided topographical representation of Bilanoo and Mungajee pools and associated riparian zones.

Biota and water quality have been assessed at three pools, Mungajee, Stewart and Bilanoo. However, as surface water levels are only available from the gauging station at Bilanoo Pool, groundwater data from bores close to Mungajee and Stewart pools have been used to infer pool water levels. Conceptual models for each site depict groundwater-dependent ecosystems reliant either directly on groundwater or on surface expressions of groundwater.

Bilanoo Pool

Bilanoo Pool is a medium-sized (>500 m long, 80 m wide), semi-permanent to permanent pool located in the main channel of the Fortescue River at the North-West Coastal Highway Crossing, approximately 40 km upstream from the river mouth (Beesley 2006).

Bilanoo Pool, May 2008

Bilanoo Pool provides habitat for fish, macroinvertebrates and probably waterbirds as it has areas of varying depth and coarse sediments, and it supports stands of submerged macrophytes and less dense emergent macrophytes (Beesley 2006). The riparian zone overstorey is dominated by M. argentea and E. camaldulensis with



S. formosa. Cenchrus ciliaris (exotic buffel grass) and Triodia sp. (spinifex) are dominant in the understorey.

The conceptual model (Figure 12) was based on measurements of pool size and depth (Beesley 2006; Pinder and Leung 2009), a cross-sectional diagram (Massini 1988), bore logs, stage heights recorded at the gauging station and biotic data.

The riparian tree species, E. camaldulensis, M. argentea and S. formosa, are phreatophytic. At the shallow depths to groundwater illustrated in the conceptual model, these species are likely to be highly dependent on groundwater.

Bilanoo Pool is isolated between river flow events with pool levels maintained through groundwater discharge. It is therefore important that minimum groundwater levels are maintained (during periods of no flow) to sustain pool depth, water quality, habitat diversity and in-stream and riparian vegetation.

Conceptual groundwater dependence at Bilanoo Pool

Stewart Pool

Stewart Pool is a semi-permanent pool located approximately 12 km downstream of Bilanoo Pool. Little is known about the biota of the pool as it has not been sampled for macroinvertebrates or fish. However, like Bilanoo Pool, coarse sediments and the presence of submerged and emergent macrophytes would provide aquatic habitat.

The conceptual model was based on bore logs, aerial photographs and observations made by departmental staff during a field assessment in August 2008 (Appendix B).

The riparian vegetation fringing Stewart Pool is open E. camaldulensis woodland over an understorey of scattered Acacia coriacea, Melaleuca glomerata and C. ciliaris. At the shallow depths to groundwater illustrated in the conceptual model E.

E. camaldulensis M. argentea Senna sp.

Cenchrus cilaris

Triodia sp.

Cyperus bifax Triglochin sp.

GRASSLAND BILANOO POOL WOODLAND SCRUB GRASSLAND

0m 2m 4m 6m 0m 15m 30m 45m

Clay

Gravel

Pool levels at gauging station (05-09) max mean min

Horizontal

Vertical scale



camaldulensis is likely to be highly dependent on groundwater. As a submerged aquatic, Triglochin sp. is dependent on permanent or near-permanent surface water.

Stewart Pool, August 2009 (left) August 2010 (right)

Conceptual groundwater dependence at Stewart Pool

Stewart Pool is isolated between river flow events with pool levels maintained through groundwater discharge. It is therefore important that minimum groundwater levels are maintained (during periods of no flow) to sustain pool depth, water quality, habitat diversity and in-stream and riparian vegetation.

Mungajee Pool

Mungajee Pool is a narrow, possibly permanent pool lying on the western anabranch of the Fortescue River (Pinder and Leung 2009) approximately 10 kms downstream of Bilanoo Pool and 12 kms from the river mouth.

Cenchrus ciliaris

Submerged macrophytes

Melaleuca glomerata E. camaldulensis Acacia coriacea

FLOODPLAIN STEWART POOL OPEN WOOLAND GRASSLAND

Gravel

Horizontal scale Vertical scale Clay Pool water level August 2009

0m 15m 30m 45m 0m 1m 2m 3m



The fine, clay sediments of Mungajee Pool results in naturally, turbid water, which severely restricts the growth of submerged and emergent macrophytes. However, the pool still supports fish and macroinvertebrates. The Department of Water described the riparian vegetation as ‘woodland of Eucalyptus camaldulensis over closed shrubland of Acacia coriacea and Prosopis sp.’

The conceptual model was based on a cross sectional diagram by Dames and Moore (1979), bore logs and field data recorded by Department of Water staff in 2008 (Appendix B). As pool water levels are unknown, groundwater levels measured at bore 22A were used to infer both the depth to groundwater across the site and the depth of the pool itself. The estimated pool depth (e.g. mean annual minimum of ~1 m) supports the finding that Mungajee Pool is permanent.

Mungajee Pool, May 2008

E. camaldulensis is likely to be highly dependent on groundwater at the shallow depths to groundwater illustrated in the conceptual model. As M. linophylla is known to occur only on creeklines (Paczkowska and Chapman, 2000), it is also likely to be at least partially, groundwater dependent. Emergent macrophytes (e.g. Typha domingensis) will also depend on permanent or near-permanent surface water.

Mungajee Pool is isolated between river flow events, with pool levels maintained by groundwater discharge. It is therefore important that minimum groundwater levels are maintained (during periods of no flow) to sustain pool depth, water quality, habitat diversity and in-stream and riparian vegetation.



Conceptual groundwater dependence at Mungajee Pool

Tom Bull, Jilan Jilan and Chuerdoo Pools

In addition to the three pools discussed above, several other pools are found along the lower Fortescue River. Of these, only Tom Bull Pool, located on the western channel north of Mungajee Pool and 6 km from the river mouth, is considered permanent. Jilan Jilan and Chuerdoo pools are considered to be semi-permanent.

Tom Bull Pool is fringed by isolated E. camaldulensis over M. glomerata with a large area of E. camaldulensis and E. victrix over Mesquite (Prosopis sp) shrubland to the east (Astron Environmental Services 2008). Due to its proximity to the river mouth and possible inundation by spring tides, Tom Bull Pool is likely to be brackish. This is supported by the observation of shell scatters near the pool during an ethnographic survey (Pilbara Native Title Service 2009). However, due to its permanent nature it is likely to support diverse fauna.

0m 10m 20m 30m

Horizontal scale Clay Gravel

Groundwater levels at 22A (86-07) max mean min

WOODLAND OPEN SCRUB MUNGAJEE POOL OPEN SCRUB GRASSLAND

E. victrix E. camaldulensis Sesbania formosa

Prosopis pallida Acacia coriacea

Cenchrus ciliaris Typha domingensis

Vertical scale

0m 5m 10m 15m



Mesquite at Tom Bull Pool, August 2009

The semi-permanent Jilan Jilan Pool is located on the main river channel approximately half way between Stewart and Mungajee pools. The pool is fringed by isolated E. camaldulensis over M. glomerata (Astron Environmental Services 2008). Chuerdoo Pool, located approximately 5 km downstream of the North West Coastal Highway is also semi-permanent. Vegetation mapping shows that very open E. camaldulensis woodland fringes the pool, with denser vegetation occurring to the east.

Jilan Jilan Pool, August 2010 (left), August 2009 (right)

There is no record of sampling of aquatic fauna at Jilan Jilan and Chuerdoo pools however, up to six fish species and two aquatic macrophyte species were observed at Jilan Jilan Pool during a field visit by DoW staff in August 2010. The pools are



also they are likely to support other species similar to those recorded in semi-permanent pools of the lower Fortescue River.

These pools are isolated between river flow events with pool levels maintained by groundwater discharge. It is therefore important that minimum groundwater levels are maintained (during periods of no flow) to sustain pool depth, water quality, habitat diversity and in-stream and riparian vegetation.



Appendix B –2008 vegetation survey data

Transect/ E N

Coll. No.

Species % cover

Community Description

Fort01 Eucalyptus

camaldulensis 25.0 Open woodland of Eucalyptus camaldulensis and Eucalyptus

victrix over shrubland of Acacia coriacea, Cleome viscosa and Adriana utricoides var. utricoides. Cleome viscosa 20.0

Acacia coriacea 8.0 Adriana utricoides var.

utricoides 20.0

Eucalyptus camaldulensis (saplings)

15.0

Triodia wiseana 5.0 Acacia inaequilatera 5.0 Sesbania formosa 1.0 Fort02 Melaleuca argentea 5.0 Woodland of Melaleuca argentea with Eucalyptus camaldulensis

over cobbles in broad river channel. Eucalyptus camaldulensis

5.0

MB5 Triglochin dubia 0.0 Submerged MB6 Potamogeton

tricarinatus 0.0 submerged

MB7 Ipomoea ?muelleri 1.0 MB1 Cleome viscosa 1.0 Fort03 Mardie Station Stewart Pool. 6.4 km east of Mardie access road E 405741 Eucalyptus

camaldulensis 8.0 Open woodland of Eucalyptus camaldulensis over scattered

Acacia coriacea and Melaleuca glomerata over Cenchrus ciliaris N 7656053 MB8 Acacia coriacea 2.0 Melaleuca glomerata 2.0 MB7 Ipomoea ?muelleri 1.0 MB1 Cleome viscosa 1.0 Aerva javanica 1.0 Cenchrus ciliaris 30.0 Prosopis sp. 2.0 Fort04 Mardie Station 200m west of the Fortescue River Stewart Pool. MB10 Eucalyptus ?victrix 1.0 Very open woodland of Eucalyptus ?victrix with occasional Acacia

coriacea over grassland of Cenchrus ciliaris. Acacia coriacea 0.1

Cenchrus ciliaris 70.0 Ipomoea ?muelleri 1.0 MB11 Boerhavia repleta 1.0 MB12 Dactyloctenium radulans 3.0 Fort05 Jilan Jilan Pool on Fortescue River. 8.2 km east of Mardie access road on old North West Coastal

Highway. E 406181 Eucalyptus

camaldulensis 8.0 Very open woodland of Eucalyptus camaldulensis over Acacia

coriacea and Melaleuca glomerata on in channel shingle bar/bed. N 7660272 Acacia coriacea 2.0

Melaleuca glomerata 6.0 Cenchrus ciliaris 12.0 Ipomoea ?muelleri 1.0 Cleome viscosa 1.0 Prosopis sp. 4.0 Boerhavia repleta 1.0 Aerva javanica 1.0 Cucumis melo 1.0 Fort06 Old North west Coastal Highway east of Mardie Access Road. E 404915 Prosopis sp. 35.0 Shrubland of Mesquite (Prosopis sp.)over Cenchrus ciliaris. N 7659964 Hakea lorea subsp.

lorea 2.0

MB13 Acacia sclerosperma 1.0



Eucalyptus victrix 1.0 Acacia inaequilatera 1.0 Cenchrus ciliaris 65.0 Cleome viscosa 1.0 Boerhavia repleta 1.0 Fort07 Old North West Coastal Highway 5.5km east of Mardie Access Road E 402277 MB14 Eucalyptus ?victrix 15.0 Woodland of Eucalyptus ?victrix over Prosopis sp. Shrubland in

minor drainage line. N 7658944 Prosopis sp. 35.0 Cenchrus ciliaris 60.0 Dactyloctenium radulans 1.0 Fort08 Mungajee Pool NE of Mardi Homestead on side branch of Fortescue River Eucalyptus

camaldulensis 20.0 Open forest of Eucalyptus camaldulensis with occasional

Melaleuca argentea over grassland of Cenchrus ciliaris. Melaleuca argentea 1.0

Cenchrus ciliaris 20.0 Passiflora foetida 20.0 Prosopis sp. 10.0 MB15 Cyperus vaginatus 5.0 Sesbania formosa

(seedlings) 1.0

MB16 Amaranthus ?clementii 5.0 Fort09 E 404512 Prosopis sp. 30.0 Open shrubland of Prosopis sp. With occasional Eucalyptus

?victrix over Cenchrus ciliaris N 7666303 Eucalyptus ?victrix 10.0 Hakea lorea subsp.

lorea 1.0

Cenchrus ciliaris 70.0 Boerhavia repleta 0.5 MB17 Portulacca oleracea 0.5 Fort10 Fortescue River approximately 250m east of Tom Bull Pool E 408157 Eucalyptus

camaldulensis Woodland of Eucalyptus camaldulensis over closed shrubland of

Acacia coriacea and Prosopis sp. N 7670940 MB26 Acacia coriacea subsp.

Pendens

Prosopis sp. Cenchrus ciliaris Passiflora foetida MB18 Unknown 2 (MB18

Kennedia twiner)

MB19 Cenchrus setiger MB20 Cyperis bifax MB21 Mentha sp. MB22 Ipomoea plebeia MB23 Unknown 1 (MB23 Ugly

weed)

MB24 Melaleuca linophylla MB25 Indigofera sp. Fort11 Bilanoo Pool on North West Coastal Highway E 411261 Eucalyptus

camaldulensis 4.0 Open woodland of Eucalyptus camaldulensis.

N 7644827 Melaleuca argentea 2.0 Cyperus bifax 1.0 Cenchrus ciliaris 5.0 MB27 Senna sp. 0.5 Triglochin dubia 0.5



Shortened forms CAMBA China–Australia Migratory Birds Agreement

GIS Geographic information system

JAMBA Japan–Australia Migratory Birds Agreement

LiDAR Light detection and ranging

m AHD metres Australian height datum

mbgl metres below ground level



Glossary Abstraction The permanent or temporary withdrawal of water from any source of

supply, so that it is no longer part of the resources of the locality.

Allocation limit The amount of water set aside for annual licensed use. Each water resource (aquifer) within a subarea has an allocation limit that will be amended over time to reflect significant measurement outcomes and sustainability determinations.

Alluvium Fragmented rock transported by a stream or river and deposited as the river floodplain.

Aquifer A geological formation or group of formations capable of receiving, storing and transmitting significant quantities of water. Usually described by whether they consist of sedimentary deposits (sand and gravel) or fractured rock.

Bore A narrow, normally vertical hole drilled in soil or rock to measure or withdraw groundwater from an aquifer.

Discharge The water that moves from the groundwater to the ground surface or above, such as a spring. This includes water that seeps onto the ground surface, evaporation from unsaturated soils, and water extracted from groundwater by plants (evapotranspiration) or engineering works (groundwater pumping).

Ecological water requirements

The water regime needed to maintain ecological values of water dependent ecosystems at a low level of risk.

Ecosystem A community or assemblage of communities of organisms, interacting with one another, and the specific environment in which they live and with which they also interact, e.g. a lake. Includes all the biological, chemical and physical resources and the interrelationships and dependencies that occur between those resources.

Ecosystem services

Benefits provided to humankind from a multitude of resources and processes supplied by natural ecosystems. Services include clean drinking water and processes such as the decomposition of wastes.

Environment Living things, their physical, biological and social surroundings, and the interactions between them.

Groundwater Water that occupies the pores and crevices of rock or soil beneath the land surface.

http://en.wikipedia.org/wiki/Ecosystems�

http://en.wikipedia.org/wiki/Decomposition�



Habitat The area or natural environment in which an organism or population normally lives. A habitat is made up of physical factors such as soil, moisture, range of temperature, and availability of light as well as biotic factors such as the availability of food and the presence of predators.

Hydrology The study of water, its properties, movement, distribution and utilisation above, on and below the Earth’s surface.

LiDAR Light detecting and ranging

Life forms A way of classifying plants alternatively to the ordinary species-genus-family scientific classification. Plants may be classified as trees, shrubs, herbs.

Macrophyte A plant, especially an aquatic or marine plant, large enough to be visible to the naked eye.

Rhizome Characteristically a horizontal stem of a plant that is usually found underground, often sending out roots and shoots.

Riparian vegetation

Plant communities along the river margins and banks or at the interface between land and a river or stream.

Surface water Water flowing or held in streams, rivers and other wetlands on the surface of the landscape.

Water regime A description of the variation of flow rate or water level over time. It may also include a description of water quality.

http://en.wikipedia.org/wiki/Scientific_classification�

http://en.wikipedia.org/wiki/Tree�

http://en.wikipedia.org/wiki/Shrub�

http://en.wikipedia.org/wiki/Herb�

http://en.wikipedia.org/wiki/Plant_stem�

http://en.wikipedia.org/wiki/Plant�

http://en.wikipedia.org/wiki/Root�

http://en.wikipedia.org/wiki/Shoot�

http://en.wikipedia.org/wiki/River�

http://en.wikipedia.org/wiki/Bank_(geography)�

http://en.wikipedia.org/wiki/River�

http://en.wikipedia.org/wiki/Stream�



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Department of Water168 St Georges Terrace, Perth, Western Australia

PO Box K822 Perth Western Australia 6842Phone: 08 6364 7600

Fax: 08 6364 7601www.water.wa.gov.au

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