Coal pit lake closure by river flow through: risks and opportunities

Mark Lund, Melanie Blanchette, Colm Harkin & Paul Irving

Project background

This project (C23025) builds upon the previous ACARP project (C21038) undertaken by the Mine Water and Environment Research (MiWER) Centre in Collie (Western Australia). In project C21038 we identified that nutrients were limiting algal productivity, water quality improvements, and the development of ecosystem values in coal pit lakes. Small catchments commonly associated with pit lakes appeared to limit natural inputs of nutrients – particularly carbon. Terrestrial leaf litter and other coarse organic material stimulated macroinvertebrate biodiversity. There were increases in taxa abundance and richness and algal productivity, in the pit lakes, despite no improvement in overall water quality. The Collie pit lakes are acidic (pH down to 2), with high concentrations of some metals (such as aluminium) and range from fresh to brackish, yet contain little sulphate. The outcomes of the previous ACARP project (C21038) suggest that developing environmental values (e.g., increasing aquatic biodiversity) could be a valid alternative to meeting (often difficult) water quality guidelines for pit lake closure criteria and subsequent relinquishment.

Connecting a pit lake to natural drainage lines could increase the effective catchment size of the lake. The South Branch of the Collie River was diverted around the pit that would eventually form Lake Kepwari. In 2011, the diversion around the lake failed during storm flows, allowing river water to pass through the lake before returning to the river downstream. Downstream water quality parameters were within ANZECC/ARMCANZ (2000) guidelines for the protection of 80% of ecosystem values. Additionally, the flow-through event appeared to have improved the water quality (increased pH) and environmental values (macroinvertebrate biodiversity) of Lake Kepwari. Following the 2011 breech, a three-year trial allowing the lake to be deliberately connected to the seasonal Collie River was approved by Department of Water (WA).

Project objectives

ACARP project C23025 will use this unique trial to assess the impacts of connecting a river to a pit lake, particularly on downstream aquatic ecosystems. This project is also a trial of the concept that increasing effective catchment size has a positive effect on lake ecology.

The seasonal Collie River is degraded by secondary salinization, resulting in occasional highly saline flows. In ACARP project C23025, we will also assess the effects of saline river water on Lake Kepwari.

The main objective of this project is to determine the risks and opportunities associated with diverting a river through a mine pit lake. Specifically, we will:

  1. Determine the downstream effects of pit-lake decant, with a particular focus on environmental and amenity values.
  2. Determine the effects river of inflow on environmental values and water quality within the pit lake. (Essentially a field-scale demonstration of a key finding from C21038 that larger catchments should enhance pit lake water and environmental quality).
    1. Understand the impact of variably saline river water on mixing within a moderately saline pit lake.
  3. Develop a national standard protocol for seasonal river monitoring that could be applied by the coal industry to manage river flow-throughs (either accidental or planned), as a part of mine closure strategy.

Current activities

To commence this project, we have focused on site selection for monitoring the Collie River South. Sites have to be readily accessible, representative of the aquatic habitats of interest, and reflective of the overall nature of the catchment. We have also identified another local flow- through system for inclusion in the monitoring program. This new system is a small stream – topped up by dewatering flows from Griffin Coal operations–that flows through Stockton pit lake. Increasing replication (i.e., 21 sites across two flow-through systems) will enhance our ability to detect the impacts of river flow-through on river and pit-lake systems. In the process we have identified an additional 30 riverine potential sites in the Collie basin that could be useful for future research.

Regular monitoring of Lake Kepwari (as part of the trial conditions) occurs quarterly and we have added a similar monitoring program for Stockton Lake. Currently we have sampled Lake Kepwari five times and Stockton three. Preliminary data from Lake Kepwari indicates that the lake is stratified continually by salinity, enhanced by temperature stratification. Conductivity of the bottom waters is highest in March and June, possibly due to saline groundwater inflows. River inflow between August and October appears to slightly dilute the bottom waters (although the exact mechanism is not currently understood). Importantly, bottom pH is >6 during October, but then appears to return to 4.5 by June probably due to incoming acidity from groundwater. The installation of continuous monitoring gear in both lakes should help clarify the processes responsible for these water quality changes. We have used off-the-shelf monitoring gear that provides detailed insight into physical (stratification) and chemical (light, temperature, conductivity and dissolved oxygen) changes in a very economical package that could be used in any pit lake.


We have also value-added to the ACARP project with Edith Cowan University- funded support for an assessment of the impacts of catchment activities (mining, agriculture) on aquatic microbes in the Collie catchment. In November 2014, we hosted colleagues from Montana State University (USA) with whom we are collaborating on the microbial work. The microbial work is likely to prove highly beneficial to the mining industry by providing an economic way of understanding microbially-mediated environmental processes as well as developing microbes as tools for environmental assessment. In April 2015, we visited our colleagues at Montana State University to discuss and test how methodological differences might influence the microbial analysis.

Knowledge transfer

A paper on approaches to pit lake closure, based on ACARP projects C21038 and C23025 was presented at the International Mine Water Association (IMWA) Conference in Xuzhou, China in 2014. A copy of the paper can be obtained for free from Abstracts based on work conducted in C21038 and a poster on our microbial work have been presented at ICARD/IMWA 2015 in Chile. Presentations on previous and current ACARP projects were made to the Hunter Coal Environment Group (NSW) in February 2015.

Figure 1. Section of Melaleuca- dominated river typical of SW Western Australia (Collie River South flowing into Lake Kepwari). Figure 2. Creek flowing into Lake Stockton.

History of water use in the Perth—Bunbury region

This is a slight modified extract from the report – Lund, M.A. and Martin, H.C. (1996) Historical association of wetlands and rivers in the Perth-Bunbury region. Water Resource Technical Series. Water and Rivers Commission Report WRT3. Perth, Western Australia. The full report also includes information on each Shire and Suburb in the Perth-Bunbury region.

Early Exploration

The Dutch were the first Europeans to discover Western Australia (WA) in 1616 and over subsequent years mapped the coast and lost many ships to reefs. The Dutch found that the land contained little in terms of accessible supplies and the Aboriginal people were seen as `fierce savages’ (Appleyard & Manford 1979). As a result they made no attempt to claim the land. Between the 1700’s and early 1800’s both French and British explorers mapped the WA coastline, although it was a British explorer (George Vancouver) who found the best natural harbour on the coast which he named King George Sound (in present day Albany). This provided a valuable base for more detailed explorations of the coast. Rivalry between British and French interests allowed Captain James Stirling to persuade Governor Darling of the New South Wales Colony to allow him to explore the Swan River with the intention of determining its suitability as a site for a new colony. His reports led to the eventual establishment of a British colony on the Swan River in 1829.

General History of Early Settlement

The early settlement of Perth and other cities/towns within the region has been well documented by historians (eg. Appleyard & Manford 1979; Stannage 1981; Ewers 1971; Barker & Laurie 1992; Richards 1978). Typically in these accounts the settlers use and needs in relation to water has been secondary to the political and social intrigues of the times. The publication of `Water: The abiding challenge’ by Morony (1980) has remedied this situation for Perth. The book provides a comprehensive history of water supply, drainage and sewage in Perth. No similar histories have been written for the other cities/towns within the study area.

Captain Stirling visited the Swan River in March, 1827 and spent 9 days exploring (Markey 1977). He concluded that the area was supplied with a wealth of fresh water sources, including wetlands, streams, springs and accessible groundwater. He also concluded that the climate was moderate. At the beginning of autumn he was fortunate to find the area with ample water supplies. On his return in 1829, he located the Swan River Colony (later renamed Perth) on the northern banks of the Swan River, just east of Mount Eliza. Why he choose this particular site has been cause for much speculation (see Markey 1977 and Seddon & Ravine 1986). The colony was surrounded to the north by ten wetlands which at times of high rainfall joined and flowed through Claise Brook to the Swan River (Figure 2). In the colony’s first summer, it became apparent that the wetlands were an unreliable source of water and many settlers resorted to using groundwater extracted from shallow wells. The same situation occurred in Fremantle where the two inland wetlands also proved unreliable as a water resource and were quickly filled in and built over. Once the wetlands lost their importance for a water supply they turned from assets to liabilities restricting further growth of the city and posing drainage problems.

A Timeline of Water Related Events in the History of the Region

The following is a summary of major historic events that are related to water in Region, although most of the information concerns Perth (based on information from Ewers 1971; Jarvis 1979; Markey 1977; Morony 1980; Parker 1983; Seddon & Ravine 1986; Tauman 1978; WAWA 1994; WAWRC 1992).

The early years – 1829 to 1839

1829 Swan River Colony founded.
1829-1864 Water for ships docking at Fremantle is obtained at a price, from the well of Mr Bateman. Water is transferred in barrels by boat
1829 – 1885 Swan River used as the principal means of transport for both goods and passengers between Perth and Fremantle.

Fremantle Trust encourages the draining and infilling of all wetlands around Fremantle.

1829-1890 Most drinking water is supplied by shallow wells, wealthier people may also have a water storage tank, otherwise water from the drains and lakes is used.
1831 The construction of Burswood Canal allows boat passage from Fremantle, past Heirisson Island to Guildford.
1832 Henry Reverley constructs the first of the colony’s reservoirs by excavating an area of land between Mill St and William Street in Perth. The reservoir is to be used to power a mill.
1833 Agricultural output is so poor, that the colony nearly starves before supplies arrive by ship.

A rival mill, built by Samuel Kingsford (on Mill St) is given perpetual rights to four of the lakes as water sources, which marked the end for Reverley’s Mill. It is also hoped that this venture would reduce the chances of flooding, but it didn’t.

1834 Wool is first exported, and is an agricultural success.
1836 Jarrah is first exported to England.
1837 Whaling operations commence in Cockburn Sound.
1839 A dam is constructed across the Swan River ie. first Causeway.

The colony struggles 1840 -1879

1842 Perth’s first jetties are built at William and Mill St into the Swan River.
1843 Canning Bridge and a bridge over the Causeway are built. 
1845 Sandalwood is exported.
1848-1854 Lake Kingsford is deepened by removing sediment in summer when it is dry. The sediment is used to raise the height of the surrounding land, of which a condition of sale is that it is raised by 0.6 m above the winter level of the lake. This aims to reduce flooding of the area. 
1848 A drain is constructed from Lake Kingsford to Claise Brook to control peak water levels in the lake. Lakes Irwin and Sutherland are drained into Lake Kingsford. One aim is to improve the quantity of water available to wells. 
1850 Bridges had been built over the Serpentine River, Collie River (at Australind) and Vasse River.
1850’s Mounts Bay is partially infilled with rubble through quarrying of the limestone cliffs of Mount Eliza. 
1854 The lake drains of 1848 are upgraded, but numerous difficulties are encountered. 
1855 Small scale dredging of Perth water. 
1862 Disastrous floods affect Perth and settlements along the Avon River.

Main Perth drain collapses.

1862-1882 Mason and Bird Timber Company use barges on the Swan River to transport timber from Swan to Nicholson Bridge.
1864 Lake Kingsford is drained. 
1864-1866 Water powered timber mill is built on Canning River.
1867 A small jetty from Mr Bateman’s well is built to allow ships to collect their own water.

Fremantle Bridge is built.

1868 Appointment of `Inspector of Nuisances’ by both Fremantle and Perth Councils.
1868-1869 More serious flooding occurs in Perth.
1869 The colonies first dredge is acquired.

Perth drains are upgraded.

1870-1872 First artesian bores are dug around Gosnells and upper Canning Bridge.

Private railways are established from Darling Scarp to Canning River, Rockingham and Busselton by timber companies. 

1871 A channel is dredged from the Narrows to William St Jetty. 
1872 & 1873 Severe flooding occurs in many parts of the region.
1875 Wells dug by prisoners under Fremantle Goal provide a large supply of freshwater, this was pumped by prisoners into a reservoir. A main pipe was laid down High Street from the Goal reservoir to the new jetty in the harbour and pipes directed to the Railway Station, Public Officers headquarters, the Land and Water Police stations and Round House goal.
1876 Fremantle Council fails to introduce regulations for the adoption of a dry-earth sewage system, despite demands from the public. 
1877 The Perth drains are upgraded again.

Attorney-General produces suggested by-laws for the disposal of nightsoil, these are not taken up in full by either Council, although Fremantle Council does ban dumping of nightsoil into rivers or the sea within it’s municipality. 

1878 Normal practice is for nightsoil to be used on market gardens.

Perth City Council backs out of introducing a dry-earth system but resolves to encourage citizens to use it.

1879 Landfill of Perth Water to form the Esplanade.
1879-1880 Private contractors employed by the Councils to remove nightsoil.

A Government rail line is built between Northampton and Geraldton.

The goldrush years 1880-1889

1880-1881 An artesian bore is sunk in the Perth railways yards, this is used to supplement Perth’s water supplies in 1891.
1881 Fremantle to Guildford railway is completed. This effectively put an end to use of the Swan River as a means of transport. The line and Perth station, which is built on a drained wetland proved to be an effective barrier to development further north for many years. Ferries link Perth to South Perth until they are replaced with the New Causeway and Narrows Bridge. A rail bridge is built at Fremantle.
1881-1889 The Guildford rail line is extended to Clackline with branches to Toodyay, Northam and to Beverley.
1883 Construction of Barrack Square by reclamation, first of a series of infill projects in Mounts Bay.

Flooding occurs again in Perth.

1884 Government sets up Sanitation Commission which reports that sewers were unsuitable for both Perth and Fremantle, cesspits should be abolished and the dry-earth system should be introduced.

Governor Broome approves construction of three public taps down High St in Fremantle.

1885-1893 Gold discovered in the interior, this is followed by a gold rush. The population of Perth increases at record rates, there is a lot of building as wealth pours into the city. 
1887 About 20 wealthy members of the community, paid for connections to the Fremantle Harbour main.

Fremantle introduces sewage by-laws.

Government rail line from Bunbury to Boyanup completed, but was so poorly laid as to be unusable.

1888 Members of the west ward of Fremantle are allowed to be connected to the Harbour Main, but not north and south wards.

A dam was constructed at Clackline to allow trains to fill up with water at a reasonable cost. This illustrates the need for regular water supplies for the rail network, especially as the line was extended towards Kalgoorlie.

1889 The wells, the main and reservoir in the Fremantle goal are upgraded.

A rail line linking Beverley and Albany is completed and run by a private company in a land-grant deal.

Water supply and sewage systems 1890- 1909

1890 Work starts on Victoria Reservoir, materials for which are transported up the river and by rail to the site.
1890s Legislation is introduced covering regulations for sanitary arrangements, detection and abatement of `public nuisances’.

A serious outbreak of typhoid is the trigger for the construction of a sewage system.

Fremantle’s Board of Health, starts to `clean’ up the town by closing cesspits and contaminated wells.

Few of the State’s roads are sealed with bitumen, most are just gravel or sand.

Another land-grant scheme results in the construction of a rail line from Perth to Geraldton (joining the existing line at Walkaway).

The scarcity of water in the goldfields became a major concern for the government and plans are devised by C.Y. O’Connor to pipe water to Coolgardie from a dam in Perth. 

1891 Victoria Reservoir completed, providing Perth with it’s first water from the Darling Scarp.

Establishment of a piped water system, run by the privately owned City of Perth Water Works Co. There are numerous complaints about pricing and the service offered by the company. The company builds a storage reservoir on Mt Eliza. 

1892 `Municipal Water Supply Preservation Bill 1892′ was passed to protect the catchment of the reservoirs.

All wards in Fremantle are reticulated for drinking water. 

1893 A double pan system is introduced into Perth.

Government railway from Perth to Bunbury completed and later extended to Collie.

1894 Perth City Council introduces its own night soil collection service. 
1896 Fremantle Council introduces a covered pan system for sewage disposal.

The Government passed the `Perth Waterworks Purchase Bill’ and bought the Water Works Co and let control pass back to the Council. The Council had been trying to get control of the company soon after its formation, as the Victoria reservoir had been allowed to become polluted. The Company becomes the Waterworks Board.

Fremantle strengthens it’s sewage by-laws.

Fremantle Council contracts out nightsoil collection and leases its sewerage farm to Laudehr and Gillespie.

1896-1898 Perth Council introduces a series of by-laws aimed at improving sanitation and drainage.
1897 Under C.Y. O’Connor’s direction, the bar across the mouth of the Swan River was removed by explosives, thus changing the nature of the estuary forever. This allowed the construction of Fremantle’s Inner Harbour, which saw it replace Albany as the principal port in the state. The bar was made of Calcarenite and not sand as Stirling had originally predicted. Previous attempts to remove the bar occurred in 1849 and 1869 without success.

A channel is dredged between Barrack St jetty and both Mends and Coode St jetties.

`Bathwater’ carts were used to supply Fremantle’s Canvas Town (a shanty town established during the gold rush).

Peak of typhoid epidemic in Perth.

Perth experiences the `Great Water Famine’ and the Board responds by laying larger mains from Victoria reservoir, sinking another artesian bore at the Railway yards and by carting water to badly affected areas.

1897-1904 The drains of the city were upgraded resulting in raw refuse being discharged into the Swan River.
1898 Fremantle Council demolishes Canvas Town.

The Board is forced to resign and its members are replaced in response to allegations of corruption and mismanagement. The new Board extends the mains into Subiaco, Leederville, Victoria Park, North Perth and Mt Lawley. They introduce an aeration process to purify the water, and increase the storage capacity of Victoria reservoir.

A temporary bridge was built next to the old Fremantle traffic bridge which had become to unstable for traffic use

The Perth City Council had many problems with a sewage disposal site in Bayswater. As a result waste was pumped to a site further away, where the pans were steam cleaned and the waste was filtered and settled before being used to grow crops for council horses.

1899 The Fremantle Water Supply Bill passed control of Fremantle’s water supply from the Government to an independent Board. The Board sank more bores near the Goal, built a new reservoir at Swanbourne St and started treating the water with lime to remove iron salts.

A private member’s bill was introduced into parliament which allowed Peppermint Grove, Cottesloe and Cottesloe Beach to be supplied by the private Osborne Water Supply Company.

The `Metropolitan Waterworks Bill’ gave the Waterworks Board more power to collect revenue.

Laudehr and Gillespie introduce the two-pan system to Fremantle and extend the sewage farm. 

1900 ‘Land Drainage Act’ was passed in which the Government assumed responsibility for the drainage of rural land.
1900s Comprehensive drainage scheme started around Harvey.

Harvey River de-snagged and straightened.

Waroona and Harvey main drains were built. 

1900-1930 Large areas of land brought into agricultural production, this lead to salinization of many streams, rivers and wetlands on the Darling Plateau.
1902 Coolgardie pipeline is finished, pumping tests take place, and amid constant criticism C.Y. O’Connor commits suicide. Eight months later water arrives in Coolgardie. 
1903 The Osborne Water Supply Company is bought by the Government. Bores are sunk at Butler’s Swamp (Lake Claremont) and more domestic reticulation is installed

The `Metropolitan Water and Sewerage Bill’ combined for the first time water supply and sewerage under the same authority.

Hugh Oldham is asked to devise a bacterial system to deal with sewage.

Mundaring Dam is completed. 

1904 The responsibilities of the Waterworks Board are invested in the Public Works Department by the `Metropolitan Waterworks Act Amendment Bill’.

After a successful demonstration of septic tanks and bacterial filters at the Midland Junction Railway Workshop, the system is installed by some private citizens.

Area fringing Geographe Bay west of Capel is drained by a network of channels. 

1907 Construction of Perth’s sewerage main begins.

Drainage schemes built at Vasse and Wonnerup. 

1908 Old Fremantle Traffic bridge is upgraded and supports a new tramway to the northern parts of the city.
1909 The Government proclaims the `1904 Water and Sewerage Act’ and appoints a Metropolitan Board of Water Supply and Sewerage, after political manoeuvring the Board was disbanded and absorbed into the Minister for Works Department. This was an important step as for the first time there was a state controlled integrated approach to drainage, sewerage and water supply in the metropolitan area.

The war and postwar years 1910- 1929

1910-1911 Another storage reservoir is constructed at Mt Eliza.
1911 The availability of galvanised iron water tanks allows many householders to collect water off roof tops. This is needed as many areas still have limited access to reticulated water, water is also variable in quality and high in price.

A pipehead dam is constructed across Bickley Brook.

Below ground cesspits are abolished by the Health Act. 

1912-1967 The use of septic tanks for residential housing becomes increasingly common as subdivisions are opened up at a faster rate than sewers can be provided. 
1912 A new Department of Water Supply, Sewerage and Drainage is established by the incoming Labour Government.

Claise Brook and Burswood Island sewerage treatment plants are completed, which utilised bacteria, percolating filters and large septic tanks.

Fremantle’s sewerage system is commissioned, with a main sewer draining into 3 septic tanks near Robb’s jetty, the effluent is pumped out into the sea.

For the first time, shipping and the railways in Fremantle are supplied with water from Victoria Reservoir.

An experiment to increase runoff into Mundaring Weir by thinning trees in the catchment results in increased salinity in streams entering the dam.

1912-1913 Large infill sewer program and construction of stormwater drains.
1913 Sewerage pump houses built on the Perth foreshore.
1913-14 The metropolitan area is regazetted and now includes Armadale (supplied by a pipehead dam on Narrogin Brook), Guildford and Midland.
1914 Perth, Fremantle and Claremont are consolidated together with common account systems, ratings and pricings for water.

More filter beds are built at Claise Brook.

Mt Hawthorn reservoir is completed.

Fremantle’s domestic water is augmented by Hill’s water.

Claremont also starts to use Hill’s water.

1914-1916 Water is taken from Mundaring Dam to supply Perth.
1918 – 1920 Another 3 filter beds are completed at Claise Brook and a new settling pond is built at Burswood Island.
1920 Fewer than 30% of Perth houses are connected to the sewers.

Water restrictions are introduced for the summer.

1920s Service reservoirs are constructed at Melville Park, Swanbourne Terrace, Fremantle, Richmond Hill, Mt Eliza and Mt Hawthorn.

Algal blooms become a problem during summer in the Swan River, the sewerage plants at Claise Brook and Burswood Island are blamed although various experts are produced to find other causes. To combat the problem, the algae is harvested during 1922-23. 

1921 A reservoir is constructed on Bickley Brook.
1921-1932 Loss of Point Fraser and some of Mounts Bay by reclamation to allow construction of Langley Park.
1923 Pipehead dam constructed on the upper Canning at Araluen.

Legislation is enacted which provides for the Public Health Department to administer the design and installation of septic systems.

1925 Wungong Brook Pipehead dam is completed, this is eventually removed following the construction of a major storage reservoir on the site in 1979.
1926 Fremantle is connected to the Hill’s water main.

Severe flooding occurs along the Avon River. River training takes place to reduce flooding risk.

Collie floods up to 2.5 m deep in places.

1926-1927 A wastewater treatment plant (WWTP) is built at Subiaco.
1928 The Government commits to ocean rather than river disposal of sewage effluent.
1929 Churchman’s Brook Reservoir is completed.
1929-1931 Smiths Lake drain is upgraded to reduce flooding at Lake Claremont.

The Great Depression 1930 -1939

1930s During the Depression, expenditure on water and sewerage works were the largest items in the State’s capital expenditure account.

Dams are constructed at Harvey, Waroona and Collie (Wellington).

Sewering continues into Mt Lawley, Claremont, Peppermint Grove and Mosman Park.

Harvey River diversion drain is built entirely by hand to change the outlet of the river from Harvey estuary to the ocean near Myalup.

1933 Construction of Canning Dam begins to provide employment during the Depression and to provide a valuable water resource for the city.

The mosquitofish (Gambusia
holbrooki (sic affinis) is introduced into Western Australia by an amateur fish breeder, it has since spread throughout the region. It is believed responsible for the elimination of native fish in certain areas.

1935-1939 Subiaco WWTP is expanded and a sludge digestion system is introduced.
1936 Burswood Island and Claise Brook Sewerage plants are closed, and wastewater is diverted to Subiaco WWTP.

Swanbourne WWTP is built to service Claremont and Cottesloe with an ocean outfall (same as used by Subiaco WWTP).

1937 Riverside drive is extended to the Causeway by reclamation.
1938 Filling of Millers Pool (Mill Point).
1939 Completion of Smiths Lake and Bayswater drains.

New Fremantle Traffic Bridge (Stirling Highway) is built on the site of the temporary bridge.

The second war and postwar years 1940 -1959

1940 Canning Dam is finished

A pipe is laid between Canning and Mundaring weir to allow Mundaring to be augmented by Canning water

1941 A tank on Mt Flora is used to connect North Beach to the water supply system.

A tank is built at Doubleview to improve supply water to the area.

1945 The suburbs, Inglewood, Bassendean and Graylands are sewered.
1947 Work on the New Causeway is started.

Old Fremantle Traffic Bridge is demolished.

1950 South Perth, Claremont, Bassendean, Inglewood, Subiaco, Victoria Park and North Perth are finally completely sewered.

Severe water restrictions are introduced following the collapse of the Canning contour channel near Araluen.

Kent St weir is built.

1950s A diversion weir is constructed on Kangaroo Gully to divert water into Canning Dam.

More bores are dug to augment Hill’s water supply.

Upgrade of the Mundaring reservoir to Greenmount service reservoir pipeline to improve water supply to Midland.

Construction of high-level tanks, pumping stations and feeder mains at Scarborough, Roleystone, Yokine, North Beach and Melville.

A main is constructed from Fremantle to Kwinana, with a storage tank at Mt Brown to supply the industry starting at Kwinana.

Another traffic bridge is planned for Fremantle.

Mechanisation allows rapid clearing of native vegetation, this continues strongly into the 1960’s, the result is salinization of rivers, streams and wetlands.

1955 Publication of `Plan for the Metropolitan Region – Perth and Fremantle’. The plan is quickly adopted and Perth develops along four corridors which leave semi-rural to rural areas over the Groundwater Mounds. This plan fundamentally alters the design for the city making it ideal for cars but poor for public transport users.

Thomson’s Lake reservoir is completed to improve supply to industry and Medina.

Severe flooding occurs along the Avon River.

1955-1960 Drainage work is undertaken in Bayswater, Bentley, Victoria Park and Belmont.
1957 A pipehead dam is constructed at Serpentine River, which also includes an automatic chlorinator
1958-1970 Extensive river training of the Avon River takes place between Brookton and west of Toodyay.
1959 Narrows Bridge is opened.
1960 A longer ocean outfall is built for Subiaco WWTP.

The boom years 1960 to 1979

1960s Mass immigration and a booming economy result in rapid re-development of much of Perth, with the loss of many historic buildings.

Some Perth wetlands are used as sites for sanitary landfill (eg. Lake Monger and Bibra Lake).

1961 The Serpentine Dam is completed.
1961-1962 Completion of the upgrade of Subiaco WWTP to secondary treatment using an activated sludge process, and a new longer ocean outfall is constructed.
1963 A scheme to provide sewerage to properties south of the river is announced and a primary treatment plant is built at Woodman Point.

Catchment clearing is believed responsible for the Collie River flooding Collie.

First stage of the Bunbury sewerage scheme is commissioned, with secondary treatment and ocean discharge at Bunbury (north).

1964 Collie is flooded again.
1964-1965 Fremantle septic tanks (Robb’s Jetty) are abandoned as their role is taken over by Woodman Point WWTP. Treated wastewater is discharged by outfall to Cockburn Sound.
1965-1968 Collie River is widened and cleared to reduce the risk of flooding.
1966-1967 Testing of the Gnangara Mound leads to the development of new borefields to extract groundwater.
1967 Mounts Bay is filled for the Mitchell Freeway interchange.

Government Policy dictates that all new subdivisions must be sewered.

1968 Fremantle’s inner harbour is extended upstream.
1969 Opening of Point Peron WWTP and ocean outfall.
1970s Up to 1970, only untreated artesian water was used to augment the Hill’s supply of domestic water. By 1979, only 6% of the domestic water used came from artesian sources, 34% came from shallow groundwater

The mid-seventies saw a rise in public education with regards to water conservation techniques, overall individual consumption decreases as one in five customers sink private bores.

Severe eutrophication occurs of the Peel-Harvey estuary.

1971 Water restrictions are introduced for the summer.

North Dandalup pipehead dam is completed

1972 Bunbury (north) WWTP is upgraded.

Gordon Road (Mandurah) WWTP is commissioned using land infiltration to dispose of the effluent.

1973 Metropolitan Water Board disconnects services for failure to pay rates.

An amendment to the Water Supply, Sewerage and Drainage Act gives the Metropolitan Water Board the power to protect and regulate areas in the interests of conservation and protection of the aquifers.

First stage of Beenyup WWTP is completed to serve the northern suburbs, it includes secondary treatment. Land infiltration is used to deal with treated wastewater.

1976 Water restrictions are introduced during summer.
1977 Treated wastewater from Beenyup WWTP is discharged into the ocean at Ocean Reef.
1978 Introduction of a pay-for-use system for domestic water.

Halls Head (Mandurah) WWTP is commissioned, using land infiltration for effluent disposal.

1979 Wungong storage dam is completed.

Second WWTP is commissioned at Bunbury (south), with land infiltration.

Eaton WWTP is commissioned, with land infiltration.

Gordon Road WWTP is upgraded.


Unprecedented growth 1980-1995

1980s The Water Authority of WA sponsors research into wetland and stream ecology.
1981 Government Sewage Policy aims to eliminate the backlog of sewerage work.
1983 Australind WWTP is commissioned, with land infiltration.

New primary WWTP is opened at Woodman Point.

1984 Woodman Point WWTP effluent is now directed down to Point Peron for discharge to reduce pollution of Cockburn Sound.

Severe algal blooms are observed on the south branch of the Collie River.

1985 The Metropolitan Water Board becomes the Water Authority of Western Australia.

Subiaco WWTP is upgraded and Swanbourne WWTP is abandoned with waste being diverted to Subiaco WWTP.

Government Sewage Policy commences to eliminate the backlog of sewerage work.

1986 Gordon Road WWTP is upgraded.
1987 Bunbury (south) WWTP is upgraded.
1989 Severe algal blooms observed on the south branch of the Collie River.
1990s Construction of residential canal developments in the Peel Harvey estuary (Mandurah).
1992 The Water Authority commissions the `Perth Coastal Waters Study’, to assess the likely effects of any increase in the discharge of treated wastewater effluent to the sea.

Gordon Road WWTP is upgraded.

1993 The free water allowance is reduced and then removed.

Government announces a large infill sewerage program, designed to reduce reliance on domestic septic systems which are believed to be contaminating the groundwater.

Severe encroachment onto the Jandakot Mound by housing. Construction of a series of drains to control flooding in the new estates links a series of wetlands together and increases water depth and reduces water quality in the majority of them.

1994 Water restrictions are introduced for the summer.

An extensive power cut results in a small amount of sewage overflowing into the Swan River from pump stations (as per design), resulting in public outcry.

Publication of `Wetlands of the Swan Coastal Plain, Volume 1, Their nature and management’ by Dr Shirley Balla, brings together a series of research projects sponsored by the Water Authority of WA and the Environmental Protection Agency.

`Wastewater 2040 Discussion Paper’ is produced by the Water Authority to examine options for dealing with sewage in the future.

The following WWTP’s are in operation; with ocean outfalls – Woodman Point (primary treatment, discharged through Point Peron), Beenyup and Subiaco, and using land infiltration – Wundowie, Northam, Kalamunda Hospital (Private), Health Department Septage and Industrial Wastes Plant, Kwinana, Port Kennedy, Gordon Road, Yunderup, Pinjarra, Halls Head, Eaton, Australind, and Bunbury (north and south). The following temporary WWTP’s are also being used – Two Rocks, Yanchep, Bullsbrook and The Vines Resort. New plants are proposed at Alkimos, East Rockingham and Caddadup.

1995 The Water Authority of WA is undergoing a process of division into the Water and Rivers Commission and The Water Authority. Corporatization of the supply division promises substantial changes to the future of water supply in the state.

Relining of Coolgardie pipeline takes place to extend life by 50 years.

Demands for Water

Despite Captain Stirling’s rosy descriptions of the availability of water, the early settlers quickly found that the provision of water was an impediment to growth and expansion inland. Initially settlers and explorers may have gained insight into the location of sites of good water from Aboriginal people. The rapid decline in relations between Aboriginal people and settlers, especially through the attitudes of the first generation of locally born settlers, is likely to have limited this cooperation (Reece & Stannage 1984). Settlers obtained drinking water mainly from groundwater wells, as the lakes and springs proved to be often dry during summer. Accompanying the problems of finding water was disposal of sewage, which initially ended up in cesspits contaminating many of the wells. The provision of drinking water and sewage didn’t become widely available until the early 1910’s. Corruption, intransigent local councils and a faltering economy until the 1880’s goldrush are probably responsible for this (see Morony, 1980). The gold was located in an area where water was difficult to find and this became an impediment to the development of this resource. This lead to one of the world’s great civil engineering projects, the goldfields water pipeline which piped water from Perth (Mundaring Dam) to Coolgardie (eventually to Kalgoorlie).

Contamination of the shallow groundwater supplies, resulted in a shift to using water from reservoirs on the Darling Scarp. Apart from problems at Victoria Reservoir, the State has been fortunate that dam construction preceded urban expansion and early legislation has led to the protection of the catchments of these reservoirs. The limited opportunities for construction of further dams, the corridor plan (which indirectly protected groundwater mounds) and improvements in sewerage disposal have led to a return to using groundwater for domestic supply. Rapid urban expansion in the late 1980’s onto the Jandakot groundwater mound has again threaten this resource. The construction of reservoirs has had a profound impact on the environment, with areas permanently flooded and the natural flow of streams and river altered downstream of the dams.

Progress in dealing with wastewater was also slow with a gradual move from cesspits, to collection of nightsoil, to septic tanks and finally to sewers transporting the waste to a treatment plant. The construction of sewers has often lagged behind urban expansion and many suburbs are not sewered and use septic tanks. Potential problems identified with the use of septic tanks has encouraged a shift towards underground sewers.

Transport initially very difficult with the cost of moving supplies from Fremantle to York being more than nine times more expensive than shipping them from England (Markey 1977). This was because overland transport was so difficult, the use of the river and sea transport was used where possible as this was much more economical. As the Swan River was very shallow and blocked by a bar at its mouth this limited shipping considerably. Dredging allowed boats to move up the river and near the turn of the century the bar was removed. By this time, however the construction of railway lines and reasonable roads had led to the demise of river transport.

The steam trains used on the rail lines required regular water points. The expansion of the rail network into the goldfields meant that numerous storage reservoirs had to be created to supply the trains. The same situation can be found on all the other major train routes (including private timber company lines). Along with the tracks a variety of bridges had to be built, where standing, these are now of historical interest. Roads also required supply stops where water could be obtained. Roads had a profound effect on the landscape; increasing the amount of surface runoff, resulting in wetland loss (many road reserves follow wetland chains), and the construction of bridges.

The timber industry used the Canning River for transporting logs downstream towards Perth. The industry is also responsible for the early pollution experienced in Victoria Reservoir, as workers were living on private land within the catchment and were contaminating streams entering the reservoir. Clearing in catchments as timber is removed increases runoff into rivers and streams. This and the extensive clearing that occurred for agriculture purposes has resulted in increased salinity within many rivers, streams, and dams (eg. Wellington Dam which was in danger of becoming too saline for even agricultural uses).


Appleyard, R.T. and Manford, T. (1979) The Beginning: European Discovery And Settlement Of Swan River Western Australia. University of Western Australia Press, Crawley, Western Australia.

Barker, A.J. and Laurie, M. (1992) Excellent Conditions: A History Of Bunbury 1836-1990. City of Bunbury, Western Australia.

Ewers, J.K. (1971) The Western Gateway: A History Of Fremantle. (2nd Ed.) University of Western Australia, Crawley, Western Australia.

Jarvis, N.T. (1979) Western Australia: An Atlas Of Human Endeavour 1829 1979. Government Printing Office of Western Australia, Perth, Western Australia.

Markey, D. (1977) More A Symbol Than A Success: Foundation Years Of The Swan River Colony. Westbooks, Bayswater, Western Australia.

Morony, F.B. (1980) Water: The Abiding Challenge. Metropolitan Water Board, Perth, Western Australia.

Parker, W.F. (1983) Microbial Aspects Of Septic Tank Effluent Disposal Into Coarse Sands In The Perth Metropolitan Area. Department of Conservation and Environment, Perth, Western Australia, Bulletin 130.

Reece, B. and Stannage, T. (eds) (1984) European-Aboriginal Relations In Western Australia. UWA Press, Western Australia.

Seddon, G. and Ravine, D. (1986) A City And Its Setting: Images Of Perth. Western Australia. Fremantle Arts Centre Press, Fremantle, Western Australia.

Stannage, C.T. (1981) A New History Of Western Australia. University of Western Australia, Crawley, Western Australia.

Tauman, M. (1978) The Chief, C.Y. O’Connor. University of Western Australia Press, Crawley, Western Australia.

Thomas, A.T. (1946) The History Of Beverley 1946. Van Heurk & Thomas, Western Australia.

WAWA (1994) Wastewater 2040 Discussion Paper. Water Authority of Western Australia, Perth, Western Australia.

WAWRC (1991) Safeguarding Our Water Resources Perth – Bunbury, Draft Regional Allocation Plan. Western Australian Water Resources Council, Perth, Publication No. WRC 5/91.

Urban lakes of Perth (Western Australia): A history of degradation and loss

The original article was published by Mark Lund in the June 1995 Issue of Lakeline Magazine Vol 15(2) pg 24 (ISSN 0743-7978) and has been modified slightly for inclusion here.

“At home [the U.K. presumably], a lake is known only as a sheet of water which seldom or ever dried up, and it is naturally associated in one’s mind with pleasant and picturesque scenery, but here it is quite different … there is an air of desolation about these lakes which strikes the spectator at once … It is complete still life without one point of interest in it, as far as striking scenery goes, and totally different from anything I ever saw outside Australia.”

These sentiments were expressed in a 1847 Perth newspaper. Similar attitudes have largely been responsible for the loss and degradation of the urban wetlands of Perth from its foundation until recently.


Aborigines have occupied the region around Perth for about 38, 000 years. They made extensive use of the wetlands as sources of water and food (fish, waterfowl, turtles, frogs and edible aquatic plants). Aboriginal people are believed to have managed and possibly modified the wetlands by selective burning of fringing vegetation to increase productivity.

The British founded the Swan River Colony (later to be renamed Perth) in 1829 on a site surrounded by wetlands, adjacent to the Swan River. As Perth expanded, wetlands were drained for housing and market gardens, as it was quickly realised that the lakes were too shallow to provide useful sources of drinking water. Therefore, some were subdivided into lots, some were drained for market gardens, some used for recreation, and others used for road reserve. Interestingly, on many occasions settlers misjudged their ability to drain the wetlands and initially flooding was a serious problem. Within 16 years of settlement, six wetlands, representing approximately 50-70 ha of open water, were drained and built over. The low perceived value of wetlands has meant that reclamation of wetlands for urban development continues to the present day.

Perth is the capital city of the State of Western Australia and currently boasts a population of over one million. Perth has a ‘Mediterranean’ climate with hot, dry summers and cool, wet winters. The city lies on the Swan Coastal Plain (SCP), a series of parallel sand dunes which are bordered by the Indian Ocean to the west, the Darling Scarp to the east and extend approximately 100 km north and south of Perth. In the depressions between the dunes, the water table becomes exposed, forming chains of wetlands. As the wetlands are largely surface expressions of the groundwater, they generally have no surface inflows or outflows, although, in extremely wet years, there is evidence to suggest that groups of wetlands became linked. The seasonal changes that are experienced within the major groundwater aquifers have an important influence on the water levels of many of the wetlands.

This article will restrict itself to the Perth metropolitan area and the following types of wetland: lakes (permanent water), swamps (seasonal lakes, dry in summer) and floodplains (areas of flat land, seasonally inundated).

In few Australian cities has the ‘Australian Dream’ of a house on a quarter-acre block been so achievable as in Perth. Hence, the rate of urban expansion has been considerable with the city now covering around 2030 km2. Estimates of the area of wetlands lost from the SCP range from 60 to 80 percent. Unfortunately, the loss of wetlands per se represents only a portion of the problem, the other is the degradation of the remaining wetlands.


Health risks associated with high fecal coliforms and attempts to reduce disturbance to waterbirds stopped active recreation on the wetlands. Prior to this they had been used for swimming, boating, water skiing, diving, fishing and catching edible crayfish. Current use is restricted to passive recreation, BBQ’s, walking, bird watching, picnicking, bird feeding and so on. Lake Monger, a popular lake close to central Perth, was estimated to receive over 12,000 visitors per week.


The sentiments expressed at the start of this article are prevalent even today. There is a strong perception that our natural wetlands are not as attractive as Northern Hemisphere lakes. This has fostered a mentality that the wetlands should be altered to ‘improve’ their appearance. These improvements include lawns to the lake edge, infilling of swampy areas, dredging (to increase depth) and removal of fringing vegetation. This is particularly so in newly developing suburbs, which are frequently populated by immigrants from the Northern Hemisphere who are often uncomfortable with the uniqueness of the Australian bush. Aside from ‘improvements’, the wetlands are also seen as convenient receiving environments for pollutant discharge, including stormwater.

Artificial maintenance of water level

The majority of wetlands are shallow (1 – 4 m deep) and seasonal. As dry wetlands are deemed unattractive, many now have water levels artificially controlled (with outlets to control winter flooding and the addition of bore (groundwater) water in summer). One of the arguments for this practice other than pure aesthetics, is that it provides a permanent water source for fauna. Countering this argument are that permanent flooding can lead to the death of fringing vegetation (in particular Melaleuca trees) and the majority of fauna has evolved to cope with seasonal drying.

Nutrient enrichment

Many of the wetlands are used for water compensation (directing stormwater drains into the wetland). Surface runoff on Perth’s sandy soils is normally very low, but the increase in hard surfaces (roads, roofs, etc.) through urbanization increases runoff significantly. Many wetlands are now experiencing unusually high water levels, as a result of urbanisation of their catchment. The stormwater that enters the lakes carries nutrients (from lawns and gardens) and pollutants (oil, pesticides etc) from the surrounding urban area. The groundwater also carries fertilisers from surrounding lawns into the lake. This input can be quite significant. When the lawns around Lake Monger ceased to be fertilized, the levels of total P dropped from around 800 ug/l to 150-250 ug/l. High nutrient loads and high summer temperatures (air temperatures vary between 30 and over 40 oC) can result in blue-green algal blooms (up to 700 ug/ l of chlorophyll a) of Anabaena and Microcystis. Associated with algal blooms are localised problems of avian botulism, fish kills, noxious smells, and nuisance levels of non-biting midges (Chironomidae). The latter has resulted in the regular spraying of some wetlands for the past 27 years with Temephos (Abate). Copper sulphate has been used occasionally to control algal blooms, with varying success.

Physical modifications

Physical modifications to the wetlands include some that are probably beneficial for urban lakes, such as the construction of islands (for waterbird habitat safe from predation by cats, rats and dogs), and the construction of walkways to provide access for bird watching and educational purposes. Other modifications are more detrimental and include the use of walls to replace the shoreline, dredging, mining (sand, peat or diatomaceous earth), use as a sanitary landfill, and infilling. Walls which form the shore of the lake result in a loss of habitat, especially for invertebrates, and are rarely necessary for other than aesthetic purposes. Mining can have three major influences; 1) the physical disruption to habitat, 2) reduction in pH through oxidation of iron sulphides, and 3) deepening of the lake, which can result in long periods where the lake is thermally stratified (the wetlands are normally too shallow for this). The use of wetlands as sanitary landfill sites was an occasional practice in the 1950-60s, and was usually described as a lake beautification project. Although the areas of the wetland which had been used for landfill were eventually capped with a layer of clay, they continue to be a source of nutrients and other pollutants to the remaining area of water.

Replacement of native plants with exotics

Other modifications that are also usually the result of ‘beautification’ schemes are the removal of fringing vegetation to provide householders with an uninterrupted vista of open water. Characteristically the fringing vegetation of the wetlands on the SCP was dominated by Paperbarks trees (Melaleuca sp), with occasionally bands of reeds (Typha, Schoenoplectus and Baumea). These plants are also believed to be at least partially responsible for highly colored (brown color or gilvin) waters in many wetlands. The color has been shown to limit algal growth, even at high nutrient levels, by either limiting light penetration or through binding micronutrients. In many areas, the native vegetation has been removed and replaced with lawns. The poor nutrient status and water holding capacity of the sandy soils means the lawns require high quantities of fertilizer and watering. Along with exotic grasses, many other plants have been introduced, including water hyacinth (Eichhornia crassipes), Salvinia (Salvinia molesta), several species of Cyperus (e.g. Papyrus), Willows and Para grass (Urochloa mutica). Both Salvinia and water hyacinth are controlled, as they have been declared noxious weeds. In the 1950s, water hyacinth covered Lake Monger and was eradicated with Hormex. In lakes with submerged macrophytes they are sometimes considered a problem where they break the surface and are considered unsightly.


The feeding of waterbirds is a popular local tradition; in fact many people believe that the birds require this supplementary feeding for survival. It is extremely unlikely that this is, in fact, the case, and addition of large quantities of bread probably increases the risk of avian botulism. Council rangers tell stories of small truckloads of stale bread being dumped into wetlands, sometimes without the plastic wrap being removed. Some councils are now trying to discourage feeding with varied success. Councils have generally placed signs saying ‘Please do not feed the birds’ without providing any form of explanation as to why not, which I believe contributes to people ignoring the signs. Many degraded wetlands support large numbers of waterbirds; this doesn’t reflect the health of the wetland, but rather the fact that large numbers of birds commute from healthier lakes nearby to feed. The loss of wetland area is also likely to have concentrated birds around in those which remain.

Exotic waterbirds have been introduced to many wetlands, including domestic geese, muscovy and mallard ducks. Mallards, in particular, pose a major threat as they are capable of interbreeding with native ducks, producing fertile offspring.


The seasonal nature of the majority of wetlands has resulted in a very limited native fish fauna (only seven species). A variety of fish have been introduced into the wetlands for aesthetics (goldfish), fishing (prior to the 1980s) and mosquito control. Fish introduced for angling include common carp, redfin (English) perch, bream (probably Silver Perch; now extinct) and tench (now extinct). In 1934, the mosquitofish (Gambusia holbrooki) was introduced into Western Australia by an amateur fish breeder; they were later spread by Heath Authorities to control mosquitos. There is little evidence to suggest that mosquitoes were ever a serious problem prior to the introduction. Regardless of whether they control mosquitos (many researchers consider them relatively ineffective) or not, the fish prove a problem by consuming a wide range of invertebrate taxa. It has also been suggested that their aggressive behaviour may lead to the driving out of native species. At present, comparatively little is known about the effects of these introductions on wetland ecosystems. The introduction of these fish raises questions as to whether biomanipulation may be a useful restoration technique; in the studies I have undertaken this appears not to be the case.


Wetlands are either owned freehold by private landowners, local councils and government departments, or are on Crown Land which is often vested in a Government Department (e.g. Department of Conservation and Land Management). Legislative protection works through the three tiers of government (Commonwealth, State and Local) using a variety of Acts. The two most important are Ramsar wetlands (International treaty for the protection of migratory birds) and a State Environmental Protection Policy (EPP) (1992) which prohibits unauthorised filling, mining, drainage into or out of, and effluent discharge into lakes on the SCP that contained over 1000 m2 of water on 1st of December 1988. This date marks the start of summer when normally wetland levels would be at their highest. However, 1988 had a dry winter and, as a result of this and the fact that many wetlands fall under the minimum size, only 5.3 percent of the total wetland (using a very broad definition of wetland) area of the entire SCP was protected. The EPP was particularly important, as for the first time it allowed Government to regulate wetland damage on freehold land. Although many wetlands were overlooked, these policies are reviewed periodically and this problem may be addressed in the future.


Aside from legislation, management of the wetlands is usually left to the agency responsible for the wetland. Management Plans have been written for many of the wetlands; however, few have really been acted on. Management as a whole, certainly at the local government level, is largely reactive. As a result, there have been few attempts at lake restoration. The approaches that have been tried are dosing with aluminium sulphate, dredging, and nutrient diversion. In only one case was a coordinated approach used to tackle the problem. This involved a study of North Lake, where a nutrient and water budget identified two drains as the main sources of nutrients. The most polluting drain was redirected, and the other drain was passed through an artificial wetland to reduce nutrient loads. After a shaky start, a monitoring program was established to determine the effectiveness of the restoration. Unfortunately, this type of restoration involving a detailed evaluation of the problem, followed by treatment and then monitoring to measure success, is atypical. The scenario normally followed one where the local residents complain, the agency responds by deciding to clean up the wetland, the agency determines the best method (how is often a mystery), and then it is implemented. If there are no further complaints it is deemed a success. Perhaps this is a cynical view of the process but, certainly from my perspective, this approach leads to a treatment of symptoms, not cause, wasted money (e.g. dredging where no attempt is made to control nutrient rich surface inflows), and a failure to build up detailed knowledge on restoration processes (i.e. everyone’s working in the dark).

An example of this is a study I was involved in at Jackadder Lake. This small lake was eutrophic, and had problems with algal blooms and nuisance midges during summer. In response to public concern, the agency responsible decided, rather than spraying the lake again, to try and fix the problem. Addition of aluminium sulphate was the chosen option. I became involved when I learned through the grapevine what was planned. The agency was contacted and agreed to conduct it as an experiment. Unfortunately, there was little opportunity to collect data from before the treatment, despite the fact that the addition was delayed from late spring to mid-summer (mainly for bureaucratic reasons). I monitored the lake for the next year. The exercise was to all intents and purposes a failure (despite some overly optimistic reports which were produced at the time). This I ascribe to one main cause, the major sources of nutrients were not determined prior to the addition. As a result, it is doubtful whether the addition of aluminium sulphate was the best strategy.

Another example involves water withdrawal; Perth on an annual basis obtains approximately 30 percent of its drinking water from groundwater. The groundwater comes from two aquifers located on either side of the Swan River. To protect these aquifers, overlying development has been minimized. As wetlands are reflections of the groundwater, any lowering of the groundwater will potentially impact wetlands. The Water Authority has developed complex models of groundwater movement to use as a basis for planning the best sites for withdrawal. Despite this, or because of it, a series of wells were placed near a chain of valuable wetlands to abstract about four million cubic meters per year (a very small amount). The models were used to plan where the wells could be sunk so as to minimize potential environmental impact. Yet it is obvious that for such a low yield of water, the potential environmental harm was not justifiable and the groundwater wells should have been relocated in a less sensitive area. Unconnected with this was a government decision to place a housing estate on the same aquifer (Jandakot Mound). To ensure the site would not flood, the water table was lowered through a system of drains. The drains linked into a chain of wetlands. This has led to excessive water levels in many of these wetlands.

Until such time as a structured approach to wetland restoration and management is taken by agencies, protection of Perth’s unique wetland systems will continue to be a hit and miss affair. A positive note is the publication of a series of detailed scientific reports on a variety of wetland issues by the Water Authority and Department of Environmental Protection. The first volume (listed below) of the series is written for managers. At the media launch of the first volume the State Minister for the Environment stated that the degradation of Perth’s wetlands was the result of ignorance and that the publishing of this book should rectified that problem. Let’s hope he was right.

Aquatic macroinvertebrate communities of the seasonal Kemerton Wetlands, south-western Australia

Clint McCullough (MiWER), Mark Lund (MiWER), Mark Gell (KSS)

What are the aquatic macroinvertebrate communities of the Kemerton Wetlands, and what environmental variables are their primary determinants?

Silica sand mining by Kemerton Silica Sand Pty. Ltd. in the Kemerton wetlands, south-western Australia, is followed by rehabilitation of mined lands into conservation areas after ore extraction is complete. Assessment of successful rehabilitation to a natural wetland ecological community involves comparing biotic communities of rehabilitated wetlands with local natural reference wetland communities. Aquatic macroinvertebrates are a industry-standard for such ecological assessment. Studies are examining what aquatic macroinvertebrate communities are present in seasonal Kemerton wetlands, and what environmental parameters are the major determinants of these communities. This understanding will also lead to guidelines as to what entails a rehabilitated wetland, and how it may best be achieved.


Photo: Dr. Clint McCullough collecting water quality data from a seasonal Kemerton Wetland in late winter.

Photo: Assoc. Prof. Mark Lund collecting a macroinvertebrate sample along a stratified-habitat transect line.


Figure: Abundance and biodiversity of aquatic macroinvertebrates in Kemerton Wetlands.

Funding: Kemerton Silica Sands Ltd


McCullough, C. D. & Lund, M. A. (2008). Aquatic macroinvertebrates in seasonal and rehabilitated wetlands of the Kemerton Silica Sand Pty Ltd project area (2007). Mine Water and Environment/Centre for Ecosystem Management Report 2008-16. Edith Cowan University, Perth, Australia. 75pp. Unpublished  commercial-in-confidence report to Kemerton Silica Sand Pty Ltd.

Lund, M. A. & McCullough, C. D. (2011). How representative are pit lakes of regional natural water bodies? A case study from silica sand mining. Proceedings of the International Mine Water Association (IMWA) Congress. Aachen, Germany. 529-533.PDF