Aquaculture Groundwater Resource Atlas - Perth Basin

 Overview

The Perth Basin contains Western Australia's most important groundwater resources. It has extensive aquifers and renewable resources from the relatively high rainfall. Large supplies can be pumped from most parts of the basin, although some areas have high groundwater salinity, and some areas are now fully allocated.

There are three major aquifers in the basin: the superficial formations on the Swan and Scott Coastal Plains; the Leederville Formation (together with the Parmelia Formation in the northeast); and the Yarragadee Formation. There are also groundwater resources in other Cretaceous, Jurassic, Triassic and Permian formations.

Groundwater salinity ranges from very fresh (less than 0.25 ppt) to saline, as shown in the following salinity distribution maps. These maps can also be accessed in greater detail through the Hydrogeological Atlas.

There is development potential for aquaculture throughout the basin, apart from a few areas which are fully allocated. The greatest potential may be in areas where salinity is too high for other uses, such as horticulture (exceeding 1.5 ppt).

For allocation purposes, the Perth Basin is divided into Groundwater Areas, each of which is subdivided into Groundwater Sub-areas. Information on the allocation status of a particular area may be obtained from the Water and Rivers Commission Regional Offices.

A detailed description of the hydrogeology and groundwater resources of the Metropolitan Region is given in Bulletin 142 of the Geological Survey (Davidson, 1995).

Elsewhere in the basin, groundwater information can be obtained from the reports referenced after each aquifer section.

  Superficial aquifer – Swan and Scott Coastal Plains

The superficial aquifer on the Swan Coastal Plain consists of Quaternary and Late Tertiary sediments extending from Geraldton in the north to Busselton in the south. A number of superficial formations together make up the superficial aquifer. The principal formations are the Yoganup Formation, the Ascot Limestone, the Bassendean Sand and the Tamala Limestone. These formations overlie Cretaceous, Jurassic and Triassic sediments. The coastal plain formations are bounded to the east by scarps; the Whicher Scarp (in the south), the Darling Scarp (centre) and the Gingin Scarp (in the north). The superficial formations reach a maximum thickness of some 70 metres on the Gnangara Mound. The aquifer consists mainly of quartz sands, especially in the Bassendean Sand, and calcareous sands and limestone in the Tamala Limestone. The eastern part of the coastal plain between Gingin and Boyanup comprises clayey Guildford Formation.

The groundwater level is close to the surface in the south and in the centre of the coastal plain, supporting lakes and wetlands, but may be as much as 60 metres below the surface, beneath the crests of the Tamala Limestone dunes along the coast.

Groundwater salinity is variable. It is lowest in the centre of the coastal plain in the Gnangara Mound, and in the Yanget/Mialla Mounds on the Harvey Flats, where salinity is less than 0.2 ppt. The salinity tends to be highest on the east of the coastal plain. The salinity also increases from the centre of the plain towards the coast. Down-gradient of the lakes and wetlands, groundwater is generally brackish, and groundwater is hypersaline underneath the coastal lakes between Mandurah and Bunbury.

Groundwater salinity in the superficial formations – north

Groundwater salinity in the superficial formations – south

The superficial aquifer is used most in the Perth Basin because it is near the surface. The aquifer is developed for Perth water supply from the Gnangara and Jandakot Mounds. It is used for garden bores in Perth, for horticulture between Gingin and Australind, and elsewhere for rural supply. The superficial formations are thin on the coastal plain southwest of Bunbury. In the Dongara to Geraldton area, the groundwater is generally non-potable, but some is used for irrigation.

The superficial formations on the Scott Coastal Plain thicken from west to east. They overlie Permian, Triassic, Jurassic and Cretaceous sediments, and also the Cretaceous Bunbury Basalt. They reach a maximum thickness of about 40 metres in the Jangardup area. The groundwater level is close to the surface on much of the Scott Coastal Plain but is deep beneath the coastal dunes. The groundwater salinity is low, less than 500 milligrams per litres. Current usage is for horticulture.

References (from north to south): Dongara to Leeman - Nidagal (1995); Leeman to Cervantes- Kern (2001, in print); Cervantes to Lancelin -Kern (1993); Lancelin to Guilderton- Moncrieff and Tuckson (1989); Lancelin to Mandurah- Davidson (1995); Mandurah to Bunbury -Deeney (1989) and Commander (1988); Bunbury to Busselton - Commander (1984) and Hirschberg (1988); Scott Coastal Plain - Baddock (1995).

  Rockingham Sand

The Rockingham Sand is a concealed sand channel orientated along a buried valley, running from Yunderup, southeast of Mandurah, northwards to Rockingham. It is about 60 metres deep and cut into the Leederville Formation. The Rockingham Sand is overlain by the superficial formations. Because it is in contact with the sea and the overlying superficial formations, the groundwater in mostly saline. However, groundwater in the eastern part of the Rockingham Sand is fresh, owing to discharge of groundwater from the Leederville Formation. There is currently little development of the Rockingham Sand.

Reference: Davidson (1995); Commander (1974, 1975).

  Mirrrabooka Member

The Mirrabooka aquifer comprises the Mirrabooka Member of the Osborne Formation and overlying aquifers in the Molecap and Poison Hill Greensands. It is generally overlain by, and in contact with, the superficial formations aquifer on the coastal plain, and it overlies the Kardinya Shale of the Osborne Formation. The Mirrabooka aquifer is restricted to the southern part of the Gnangara Mound in the centre of the coastal plain. It has a maximum thickness of around 160 metres. The groundwater is fresh and is used exclusively for public water supply from the Mirrabooka borefield.

Reference: Davidson (1995).

Hydrogeology of the northern Perth Basin

Diagrammatic hydrogeological section through the northern Perth Basin

Click here for an enlarged view

Leederville Formation

The Leederville Formation is a major confined aquifer in the Perth Basin. It extends in the north from Ledge Point north of Lancelin to the south coast at Augusta and is overlain by the superficial formations on the Swan and Scott Coastal Plains. The Leederville aquifer includes the Henley Sand, which is the lowermost member of the Osborne Formation. The Leederville Formation has been subdivided into three members in the Metropolitan area – the basal Mariginiup Member, the Wanneroo Member and the uppermost Pinjar Member.

The aquifer is overlain by the superficial formations, and in the Swan Syncline by the Osborne Formation, where the top of the aquifer is taken as the base of the Kardinya Shale. The aquifer overlies the South Perth Shale in the Metropolitan area, the Bunbury Basalt in the Bunbury to Augusta area, the Yarragadee Formation from lancelin to the south coast, and older formations adjacent to the Leeuwin Complex. The formation reaches a maximum thickness of about 650 metres with the thickest development in the metropolitan area, and near Lancelin. It is about 250 m thick south east of Bunbury.

The aquifer is artesian on low-lying western parts of the coastal plain. The groundwater is generally fresh except between Waroona and Harvey. The salinity is particularly low beneath the Gnangara Mound, north of Perth, and to the south of Bunbury where the salinity is less then 0.4 ppt.

Groundwater salinity in the Leederville and Parmelia Formations - north

Groundwater salinity in the Leederville Formation - south

The aquifer is the shallow artesian aquifer used for public water supply in the Perth Metropolitan area and is used for water supply to Park Ridge, Preston Beach, Myalup, Binningup, Australind, Dardanup, Busselton, Donnybrook, and Dunsborough–Quindalup. Groundwater from the Leederville Formation is used for irrigation of parks and gardens in Perth and for horticulture and vineyards in the Swan Valley, West Gingin, Donnybrook and Busselton – Capel areas.

References: Lancelin to Gingin – Moncrieff (1989); Metropolitan area – Davidson (1995); the Mandurah – Commander (1974); Harvey– Deeney (1989, 1989); Bunbury – Commander (1984); Busselton – Hirschberg (1988); Cowaramup – WRC hydrogeology Report 164 by S. Johnson (2000); Blackwood Plateau – Appleyard (1991); Scott Coastal Plain – Baddock (1995); Water Authority of Western Australia Groundwater Area Management Plans, 1993 Gingin, 1994 Bunbury, 1995 Busselton – Capel; Water and Rivers Commission (1996).

  Leederville-Parmelia aquifer

From Gingin north to Mingenew, the Leederville and Parmelia formations are connected, and it is convenient to refer to the combined aquifer as the Leederville – Parmelia aquifer. Both formations are Early Cretaceous in age, are difficult to distinguish, and consist of interbedded sand and shale. The aquifer is confined by the Osborne Formation in the southern part and unconfined in the northern area. The base of the aquifer system is marked by the Otorowiri Siltstone which crops out along the Dandaragan scarp between Cataby and Mingenew. The aquifer extends eastwards from there to the Darling and Urella Faults. Older formations between the Urella and Darling Faults, southwest of Carnamah, are also included in the aquifer. The aquifer thickens to the south, being about 400 metres thick between Eneabba and Carnamah and increasing to 1000 metres south of Moora.

Between the Agaton area northwest of Moora and the Arrowsmith River, the watertable is fairly flat with an elevation of 200 to 220 metres above sea level, falling to some 80 metres near Gingin. The water level is commonly 50 m or more below the ground surface throughout much of the area. The aquifer is in hydraulic connection with the Leederville Formation aquifer along the Gingin Scarp between Reagans Ford and Gingin. Groundwater in the formation flows southwards from Agaton to discharge into the Leederville aquifer below the coastal plain.

The groundwater is mainly of low salinity, of less than 1 ppt with some small areas of higher salinity close to the Urella Fault. A zone of saline water associated with the Coonderoo River stretches down the eastern margin of the aquifer close to the Darling Fault.

Groundwater from the aquifer is used for town supply to Mingenew, Morawa and Perenjori (from the Arrowsmith River Borefield), Carnamah–Coorow, Moora, Dandaragan and Gingin. Use by agriculture is increasing with irrigation of field crops, trees and orchards, vines and wildflowers.

References: Barnett (1969); Commander (1978); Harley (1975); Balleau and Passmore (1972); Water Authority of Western Australia (1995, Arrowsmith; 1995, Jurien: 1993, Gingin Groundwater Area Management Plans). Briese (1979), Moncrieff (1989), WRC Hydrogeology Report HR 156 by R. Diamond and T. Kay (2000).

Diagrammatic hydrogeological section through the southern Perth Basin

Yarragadee and older aquifers in the southern Perth Basin

  Yarragadee Formation – north and central

The Yarragadee Formation is the largest aquifer in the Perth Basin, reaching 3000 metres thickness and covering an area stretching from north of Dongara to the Serpentine area south of Perth. The aquifer includes the Gage Sandstone in the Metropolitan area. It is unconfined between Badgingarra in the south and Allanooka (south east of Geraldton) in the north, and confined by the Leederville Formation in the south. It is bounded to the east by the Otorowiri Siltstone, which overlies it and crops out along the Dandaragan Scarp. To the west, the Yarragadee aquifer is in faulted contact with the Cockleshell Gully Formation (Cattamarra Coal Measures) in the Hill River area. The aquifer ranges in thickness from several hundred metres in the Allanooka area to about 3000 metres in the Badgingarra area. The formation is mainly sand with minor interbedded shale and siltstone.

The water table is deep, ranging up to as much as 150 metres below the surface near Badgingarra. The water table comes to the ground surface in the Hill River valley where the aquifer is artesian around Hill River Spring.

The lowest groundwater salinity is beneath the Gnangara Mound because of recharge from the overlying Leederville and superficial aquifers. To the north of Perth, beneath the coastal plain, groundwater salinity is approximately 1 ppt. Near the coast in the Dongara area groundwater is saline. Groundwater is brackish below the Otorowiri Siltstone, the eastern part of the coastal plain, and to the south of the Swan River.

Groundwater salinity in the Yarragadee Formation and older aquifers in the northern Perth Basin

Potential bore yields are very large, ranging up to 20 000 kL/day. The major bore fields supply Perth and Geraldton (from Allanooka), and mineral sands operations at Eneabba and Cooljarloo. The aquifer is also used for Eneabba and Badgingarra town water supply, and for farm water supply. There is currently minor horticultural use, and there is significant development potential of the aquifer.

References: Allen (1980), Hydrogeology Report HR 10 by Commander (1996); Commander (1978, 1981); Harley (1975); Briese (1979). Water Authority of Western Australia (1993, Gingin; 1995, Arrowsmith; 1995, Jurien Groundwater Area Management Plans). Commander (1978); Harley (1975); Briese (1979), Moncrieff (1989) and Davidson (1995); Water Authority of Western Australia (1993 Gingin; 1995 Arrowsmith; 1995, Jurien Groundwater Area Management Plans).

  Yarragadee Formation – south

The Yarragadee Formation also occurs in the southern Perth Basin, extending from Kemerton in the north through to the south coast. It is bounded on the east by the Darling Fault and on the west by the Busselton Fault. It is overlain by the Leederville Formation or the Bunbury Basalt, or near Bunbury directly by the superficial formations. It also occurs at the surface on the Blackwood Plateau south west of Nannup. The aquifer reaches a thickness of about 1500 metres and is mainly sand. The base of the aquifer is marked by the shales of the Cockleshell Gully Formation.

The groundwater level falls from around 40 metres in the recharge area, south west of Nannup, towards sea level at Bunbury. Carbon-14 ages indicate a travel time from the recharge area to Bunbury of around 30 000 years.

Groundwater salinity ranges from less than 0.2 ppt to about 0.4 ppt. The Yarragadee aquifer is considered to include part of the Cockleshell Gully Formation at Kemerton where the groundwater is less than 1 ppt. A salt water interface exists in the aquifer along the coast at Bunbury.

Groundwater salinity in the Yarragadee Formation and older aquifers in the southern Perth Basin

The aquifer is high yielding and is used for water supply at Kemerton, Bunbury, Boyanup, Capel and Busselton, and for the mineral sands industry in the area. To the south it is also used for mineral sand processing at Jangardup on the Scott Coastal Plain.

References: Kemerton-Commander (1989), Commander (1984); Smith (1984); Wharton (1980, 1981); Hirschberg (1988), Appleyard (1991); Baddock (1994, 1995); Bunbury, Water Authority of Western Australia (1995, Busselton–Capel Groundwater Area Management Plan): Baddock (1994, 1995).

  Cockleshell Gully Formation – Hill River area

The Cockleshell Gully Formation includes both the Cattamarra Coal Measures and the Eneabba Formation, but here the Eneabba formation is described with the underlying Lesueur Sandstone.

The Cattamarra Coal Measures crop out in the Hill River area, and are overlain by the superficial formations on the coastal plain. The Cattamarra Coal Measures are predominantly shaley with relatively thin sandstones and coal seams.

The Cattamarra Coal Measures are characterised by brackish to saline groundwater. Bores are artesian in the Hill River valley and on the coastal plain.

There is minor use for on farm stock water supplies. Aquaculture could be a suitable use as the generally high salinity precludes irrigation.

References: Commander (1978, 1981); Harley (1975); Briese (1979); Kern (1993, 2001 in prep.), Water Authority of Western Australia (1993, Gingin; 1995, Arrowsmith; 1995, Jurien Groundwater Area Management Plans).

  Cockleshell Gully Formation south

The Cockleshell Gully Formation lies directly below either the Leederville Formation or the superficial formations between Rockingham and Kelmscott in the north, and Kemerton in the south. In this area the Yarragadee Formation is absent. The Cockleshell Gully Formation consists of two sub-divisions: the overlying Cattamarra Coal Measures and the underlying Eneabba Member or Eneabba Formation. Between Pinjarra and Bunbury the Cattamarra Coal Measures is the major aquifer containing sand beds and minor coal as well as shale. The Eneabba Member appears in this area to be mostly shale (commonly red).

Groundwater salinity is low between Kelmscott and Pinjarra but exceeds 2 ppt elsewhere. In the Harvey area the groundwater is saline.

Development has taken place in those areas along the east of the basin between Pinjarra (alumina refinery) and North Dandalup where the formation contains fresh water.

References: Davidson (1995); Commander (1974); Forth (1974), Deeney (1988, 1989).

  Lesueur Sandstone – Hill River area

The Lesueur Sandstone is exposed at the surface in the Mount Lesueur area east of Jurien and Green Head. The aquifer is described here together with the sandstones of the Eneabba Formation that immediately overlie the Lesueur Sandstone, and any sands within the underlying Woodada Formation that are significant aquifers. The aquifer is underlain by the Kockatea Shale, and is in faulted contact. The combined Eneabba Formation and Lesueur Sandstone are about 1000 metres thick and consist mainly of sandstone. Both the upper and lower contacts are transitional.

Groundwater recharge occurs in the outcrop area around Mount Lesueur where groundwater salinity is mainly less than 0.5 ppt. Groundwater flows both north and south and discharges into the overlying superficial formations. There is currently little use, but significant development potential exists inland of Jurien and Cervantes.

References: Harley (1975); Kern (1993, 2001 in print). Water Authority of Western Australia (1993, Gingin; 1995, Arrowsmith; 1995, Jurien Groundwater Area Management Plans).

  Lesueur Sandstone – Vasse Shelf

The Lesueur Sandstone occurs southeast of Margaret River and extends to the south coast near Augusta. It underlies the Leederville Formation and the superficial formations and is exposed in a small area on the Blackwood Plateau. It is about 500 metres thick near Beenup but may be considerable thicker to the north. The aquifer consists entirely of sand. Groundwater salinity is less than 0.5 ppt. The aquifer was used for water supply at Beenup mine before its closure, and bores were put down to supply Augusta. There is significant development potential.

References: Baddock (1994, 1995).

  Sue Coal Measures – Vasse Shelf

The Sue Coal Measures underlies the Leederville Formation on the Vasse Shelf, between the Busselton and Dunsborough Faults, and directly underlies the superficial formations in a small area east of Augusta. The Sue Coal Measures consists of several thousand metres of sandstone containing coal seams. The sandstone is lithified and groundwater bore yields are highly variable depending on permeable sections of the aquifer, or the intersection of fracture zones.

Groundwater salinity is low, less than 0.5 ppt west of Busselton, but higher on the south coast near Augusta. Bores have been drilled into the formation for the Dunsborough – Quindalup water supply and for supply to horticulture in Broadwater – Jindong Sub-area, but have had limited success with obtaining high yields.

References: Hirschberg (1988), Wharton (1981), Appleyard (1991), Baddock (1994, 1995); WRC Hydrogeology Report 164 by S. Johnson (2000); Water Authority of Western Australia (1995, Busselton–Capel Groundwater Area Management Plan).

  Northeastern Perth Basin

Between the Darling and Urella Faults north of Carnamah, and between the Urella Fault and the Northampton Complex, are Precambrian igneous rocks and Precambrian, Silurian and Permian sedimentary rocks. There are few high yielding aquifers, and groundwater salinity tends to be relatively high, too high for stock in places. Most bores are shallow and produce water from the weathering profile.

The main aquifer in the Wicherina area is Permian sandstone, which abuts the Cockleshell Gully Formation adjacent to the Greenough River. It is bounded by the Northampton Complex to the east and by the Yarragadee Formation to the south. The groundwater salinity is marginal to brackish with low-salinity water adjacent to the Northampton Complex becoming brackish towards the Greenough River. Groundwater was formerly pumped to Geraldton from the Wicherina bore field but this was replaced by supplies from the Yarragadee Formation for Geraldton because of high and increasing salinity concentrations.

High yields of saline groundwater may be available from the Permian High Cliff Sandstone and the Irwin River Coal Measures, and from the Tumblagooda Sandstone, east of the Northampton Complex.

Reference: Berliat (1965); Swarbrick (1964).