About Lake Cowal

Birds on Lake CowalLake Cowal forms part of a large ephemeral inland wetland system in the Lachlan Catchment and is located 43 km northwest of West Wyalong, and approximately 60 km south west of Forbes in Central New South Wales, Australia. Significant concentrations of water birds visit the Lake and the Australian Heritage Commission listed Lake Cowal on the Register of the National Estate in 1992.

Lake Cowal is New South Wales' largest natural inland lake at approximately 21 km long and 9.5 km wide with an average depth of around 2.5m and covering an area of over 13,000 hectares when full.

Above: Sunrise at Lake Cowal

During the summer of 2000/2001 Lake Cowal dried out completely and remained dry until March 2010 when it commenced refilling mainly via flows from Bland Creek , reaching capacity and flowing into the smaller Nerang Cowal during March 2011. A small amount of water flowed into Lake Cowal during the spring of 2005 covering approximately 1,200 hectares, but being shallow it dried out within 3 months.

Due to the warmer summer weather and hot, dry winds, Lake Cowal completely dried out during the third week of December 2014. Large numbers of dead European carp and some unfortunate waterbirds are concentrated in the lake's centre where the last sheets of water lingered. Following over 85 mm of rain during July 2015, approximately 1,800 ha of Lake Cowal was covered with water leaving some opportunity barley crops standing in water. Lake Cowal completely dried again on 13th December 2015, remaining dry until falls totaling over 200 mm for the months of June/July 2016 saw flows from the Bland and other local creeks cover approximately 8,915 ha (66%) of the lake bed. Significant flooding rains in the Lachlan River and Bland Creek Catchments will be required to further lift water levels in Lake Cowal.    


Pelicans on Lake Cowal

Climate

Lake Cowal is located on the boundaries of the south-eastern semi-arid and the south-eastern temperate regions of Australia. Historical data has been collated from weather stations from Condobolin, Forbes and Wyalong. The temperature ranges from 32.7ºC in January to 2.8ºC in July. Morning humidity ranges from 21% in October to 39% in June. Lake Cowal is strongly influenced by winds from the southwest during Autumn, Winter and Spring, and from the west and northwest during the Summer months with wind speeds usually in the vicinity of 6-10 kph and sometimes up to 20 kph in Summer.

Rainfall is said to be evenly distributed throughout the year, but rainfall events are often erratic. The highest recording of rain falling in one day at Lake Cowal is 225mm (9inches) on the 18th January 1962. Average annual rainfall is 481 mm, but the annual average pan evaporation is 2045 mm.

Geology

Lake Cowal is located on the Lachlan Fold belt which has historically been the source of many mineral discoveries of local, regional and national importance. The Cowal ore body is hosted in an Ordovician-aged volcanoclastic sequence informally referred to as the Lake Cowal volcanic complex. The volcanic sequence is overlain by alluvial sediments of the Jemalong Plains, depending on the underlying palaeo-topography. Gold mineralisation primarily occurs in dilational quartz-carbonate-sulfide and carbonate+/-quartz-sulfide veins. The highest gold grades have been recorded in a series of pods that are vertically elongated and trending north south. These pods are disrupted by west-northwest trending faults near the centre of the mineralisation zone. Sulfide mineralisation in the veins consists of pyrite, sphalerite, chalcopyrite, pyrrhotite and galena. Adularia is a common mineral.

Geomorphology

Lake Cowal is located on the fluvial landforms of the Jemalong Plains. The Jemalong Plain is bounded to the east by the Jemalong Range, to west by the Manna anticline and its associated ridge, to the north by the Lachlan River and to the south by the Bland Creek Catchment. The plain has been formed by the fluvial infilling of the Lachlan and Bland Creek palaeochannels with sediments of the Lachlan and Cowra formations. The depth of these sediments is over 100 metres above the Bland Creek palaeochannel and decreases to the east and west and as bedrock ridges are approached. Gravel and sand lenses within the Lachlan and Cowra formation, as well as gravels at the base of the Bland Creek palaeochannel are important groundwater stores and conduits, and play a major role in the regional groundwater hydrology.

Lake Cowal is underlain by sediments from 1metre to more than 50metres, which in turn overlie bedrock of the Lake Cowal volcanic complex. In contrast to other sediments of the Jemalong Plain, those beneath Lake Cowal are dominated by dark grey clays suggesting a strong lacustrine influence. These clays extend to the considerable depth of 80 metres in the area.

Soils

Soils range from silty loam on the higher undulating country to self-mulching grey clays soils on the seasonally inundated floodplains. Gilgai’s are also common on the lower floodplains around Lake Cowal. The soils are generally very low in organic carbon, are highly compacted and often lack ground cover due to overgrazing and cultivation. Soil erosion and soil structure decline are prevalent over extensive areas of the catchment.

Landuse

The general landscape of the area is flat to very gently undulating land with occasional rocky outcrops and low hills. The majority of the vegetation of the area has been heavily cleared with remnant regrowth vegetation restricted to elevated rocky areas. Lake Cowal is located within the 940 000 ha Bland Creek Catchment area which falls steadily from east to west and drains via the Bland Creek into the southern end of Lake Cowal. The region supports mainly dryland agriculture with irrigation farming in the Jemalong/Wyldes Plains irrigation districts located to the north of the lake.

Primary land uses include cropping (predominantly wheat, barley, canola and oats) and grazing of both sheep and cattle. Common cropping systems incorporate rotational, minimum tillage systems (direct drilling, stubble retention) with some landholders initiating new farming methods including the use of biological inputs and incorporation of machinery exhaust emissions.

Grazing and occasional opportunity cropping below the lake full storage water line occurs as the lake recedes in drier times. The Lake bed provides valuable pastures on recently flooded land as opposed to adjacent lands, particularly during drought conditions.

There are a number of State Forests in the local area including Euglo and Nerang to the north, Lake View and Corringle to the west, Clear Ridge, Wyrra, Boxhall and Back Creek to the south and Little Blow Clear, Blow Clear and Hiawatha State Forests to the south west.

A game reserve which provided public access and was used for camping during duck hunting season was situated on the western edge of Lake Cowal, but has been relocated to the southern end of Lake Cowal due to the development of the Cowal Gold Mine in 2003. Travelling Stock Reserves are situated along the southern, western and northern ends of the Lake.

Historically Lake Cowal was a significant inland commercial fishery in NSW, ranking in the top five producers of fish for 14 of the past 23 years prior to 1980. Several methods of commercial fishing were employed including gill, drum and loop netting and yabby trapping. Golden perch, Redfin, European Carp and the Freshwater Yabby were worth up to $120,500 per annum. Presently yabbies are the main species targeted by commercial fishers using opera house style nets with up to eight licences being issued for the lake under the management of Fisheries New South Wales. Recreational fishing for yabbies is also popular amongst the local community.

Hydrology

The Lachlan River Valley has a catchment area of 84,700 km2 and incorporates 413,520 ha of recognised wetlands of which Lake Cowal is a part. The Lachlan River has an estimated mean annual flow of 1,270,000ML at Forbes. Lake Cowal is situated on a the fluvial Jemalong Plain which is bound by Jemalong Range (east), Manna Range (west), Lachlan River (north) and tributaries of the Bland Creek system (south). Jemalong Plain is 20 - 30 km in width and elevations range from 203 – 220 m. Landform features include relict stream ridges, stream beds, levees and floodplains.

 

Surface water inflow to Lake Cowal comes primarily from the Bland Creek in the south and the Lachlan – Lake Cowal floodway in the northeast. The Bland Creek Catchment has a catchment area of 940,000 ha upstream of the Lake. Inflows also occur from the Lachlan River via breakout flows just below Jemalong Weir that occur during major flood events in the Lachlan River causing back flooding into Lake Cowal. The Lachlan – Lake Cowal floodway flows through the Corinella area and is a modified, breakout channel of the Lachlan River. In flood conditions Lake Cowal drains through Nerang Cowal, Manna Creek, Manna Swamp, Bogandillon Creek, Bogandillon Swamp and finally back into the Lachlan River.

The lake is a typical ephemeral inland system with highly variable flooding/drying cycles. It has been known to dry completely for extended periods of up to 30 years in the early part of the 20th Century and since that time for lesser periods typically from 3 to 18 months. Without inflows, Lake Cowal dries from evaporative losses, which usually takes three years from full storage.

Vegetation

Lake Cowal lies within the botanical subdivision of the Central Western Slopes of NSW. Nine major vegetation alliances have been identified from the Lake Cowal area. These include:

  1. Remnant woodland of Eucalyptus dwyeri (Dwyer’s Red Gum) – Acacia doratoxylon (Currawang) – Callitris endlicheri (Black Cypress Pine);
  2. Eucalypt woodland dominated by  Eucalyptus dwyeri (Dwyer’s Red Gum), Eucalyptus populnea (Bimble Box), Eucalyptus microcarpa (Western Grey Box),  Callitris glaucophylla (White Cypress Pine) and Casuarina cristata (Belah);
  3. Cleared agricultural land with scattered Eucalyptus populnea (Bimble Box) – Eucalyptus microcarpa (Western Grey Box) woodland;
  4. Fringing Eucalyptus camaldulensis (River Red Gum) woodland;
  5. Muehlenbeckia florulenta (Lignum);
  6. Eragrostis australasica (Swamp Canegrass) and the exotic, Medicago polymorpha (Burr Medic);
  7. Acacia pendula (Myall) – Casuarina cristata (Belah) mixed woodland;
  8. Geijera parviflora (Wilga) woodland; and
  9. Casuarina cristata (Belah) woodland.

Remnant woodland of Eucalyptus dwyeri (Dwyer’s Red Gum) – Acacia doratoxylon (Spearwood) – Callitris endlicheri (Black Cypress Pine) occurs on the high exposed ridges with shallow soils. Given the occurrence of rocky outcrops and ridges in the generally flat landscapes of the Lake Cowal region, this community occurs as scattered unconnected islands amongst other communities and cleared farmland. The shallow soils on which this vegetation community occurs are unsuitable for farming and most of it has been relatively free from clearance or disturbance although some areas have been affected by quarrying for gravel, harvesting of timber for fencing and livestock grazing.

Eucalypt woodland dominated by Eucalyptus microcarpa  (Western Grey Box), Eucalyptus dwyeri (Dwyer’s Red Gum), Eucalyptus populnea (Bimble Box), Callitris glaucophylla (White Cypress Pine) and Casuarina cristata (Belah) occurs predominantly on well-drained sloping country and low ridges and has been predominantly thinned from natural densities. The common associate is E. populnea which would have occurred naturally as disconnected islands around the base of isolated ranges and on low hills and ridges in the areas.

Cleared agricultural land with scattered Eucalyptus populnea (Bimble Box) and Eucalyptus microcarpa (Western Grey Box) woodland. These are the most dominant vegetation communities of the region that dominate the flatter more arable parts of the landscape. E. populnea and E. microcarpa frequently occur with Callitris glaucophylla (White Cypress Pine) and Brachychiton populneus (Kurrajong). On wetter sites, Casuarina cristata (Belah) is also a common associate. A variety of large shrubs - smaller trees also occur in this community including Acacia pendula (Myall), Acacia stenophylla (River Cooba), Geigera parviflora (Wilga) and Alectryon oleifolius (Rosewood). Pre-European settlement this community would have been continuously connected through the area.

Fringing Eucalyptus camaldulensis (River Red Gum) woodland occurs along the edges of Lake Cowal and other more permanent creeks in the area (although these too can dry out from time to time) such as Sandy and Bland Creeks. Its upper limit is the high watermark of the Lake and it extends for a short distance into the areas that flood. Acacia stenophylla is an occasional associate. This community has been severely thinned and in many areas only scattered trees remain.

Muehlenbeckia florulenta (Lignum) occurs in dense thickets to the north of Lake Cowal and form the basis of the breeding habitat for many water birds. Open areas without Lignum tend to be covered by Marsilea drummondii (Nardoo) and Myriophyllum verrucosum (Water Milfoil) when the Lake is inundated. Scattered E. camaldulensis may occur amongst the Lignum.

Eragrostis australasica (Swamp Canegrass) and the exotic, Medicago polymorpha (Burr Medic) dominate shallower sections of the Lakebed, particularly in the south. The area of E. australasica alters with the flooding cycle of the Lake.

Acacia pendula (Myall) – Casuarina cristata mixed woodland mainly occurs on the alluvial flats and drainage impeded gilgai areas.

Geijera parviflora (Wilga) woodland is widespread in the area reaching its optimum densities on the alluvial gilgai soils and other heavy soils on the flats or lower slopes. It is commonly associated with Casuarina cristata, E. microcarpa and Alectryon oleifolius (Rosewood).

Casuarina cristata (Belah) woodlands dominate drainage impeded gilgai areas on grey soils. It is a common associate in many other communities.

Surveys conducted in 1993 for the proposed gold development recorded 411 plants species comprising 21% weeds. Five of the weeds species were declared noxious in the Bland Shire.

Impacts on native vegetation

The native vegetation communities have been modified mostly by clearing, fire and grazing. Many areas of remnant vegetation, predominantly situated on the rocky hills, are dense regrowth forests, derived as a result of ongoing disturbances. Typically, few shrubs are present and the herbaceous understorey has been significantly modified from overgrazing. The E. microcarpa – E. populnea woodlands that naturally occupied the more arable areas of the catchment would have contained a diverse shrubby/grassy understorey. These too have been significantly altered for agricultural practices with often only scattered paddock trees remaining. Some partially intact woodland can be found on the local Travelling Stock Reserves.

There is little evidence of what the original vegetation may have been along the ephemeral creeks, drainage lines and wetlands. Some old growth trees remain on the foreshores of Lake Cowal, but are highly stressed and dieback is evident.

Lake Cowal is under threat by dryland salinity induced by poor catchment management practices. Overall, the native vegetation exists in a highly modified state and is non-sustainable under present conditions. Many species have been lost from these vegetation communities, weeds have become prevalent, little regeneration is occurring and mature trees are in poor condition. The ongoing drought conditions over the past few years, has accelerated the problem.

Threatened Plants

Piluraria novae-hollandiae (Austral Pilwort) and Lepidium monoplocoides (Winged Peppercress) are threatened plants occurring at Lake Cowal. Austral Pilwort is a semi-aquatic fern with long creeping rhizomes and grows in seasonally dry depressions, margins of marshes and gilgai country. Winged peppercress is a cryptic annual or perennial forb. It grows to 15-20cm and flowers between August – October.

Other threatened plants in the Lake Cowal area include Acacia curranii (Curly Bark Wattle), Eleocharis obicis (Barrier Range Spike-Rush), Kippistia suedifolia (Fleshy Kippistia), Monotaxis microphylla (Broad-leaf Monotaxis) and a significant population of Swainsona murrayana occurs in the native grassland along the Horror Stretch between Marsden and Quandialla.

There are many plants which are locally rare.

Fauna

Numerous fauna surveys of the Lake Cowal area and surrounds have been undertaken since the early 1960’s and have included surveys of the terrestrial and aquatic fauna with a primary focus on the water birds.

Birds

A total of 277 birds species have been recorded or are considered possible occurrences in the Lake Cowal region. The Grey Teal, Eurasian Coot and the Australian Pelican are the most abundant birds recovered. Great Egret, Royal Spoonbill, Pacific Black Duck, Australasian Shoveler, Masked Lapwing, Latham’s Snipe and Silver Gull are also common species. Fourteen birds are listed as threatened species. These species are shown in table below

Common Name Scientific Name
Magpie Goose Anseranas semipalmata
Blue-billed Duck Oxyura australis
Freckled Duck Stictonetta naevosa
Australasian Bittern Botaurus poiciloptilus
Osprey Pandion haliaetus
Square-tailed Kite Lophoictinia isura
Black-breasted Buzzard Hamirostra melanosternon
Brolga Grus rubicunda
Black-tailed Godwit Limosa limosa
Painted Snipe Rostratula benghalensis
Major Mitchell’s Cockatoo Cacatua leadbeateri
Superb Parrot Polystelis swainsonii
Turquoise Parrot Neophema pulchella
Painted honeyeater Grantiella picta

Australia is a signatory to the Bonn Convention and has international agreements which relate to the conservation, preservation and protection of important habitat areas and migratory birds species. Species protected by the JAMBA and CAMBA agreements that are known to occur at Lake Cowal include the Cattle Egret, Great Egret, Glossy Ibis, Painted Snipe, Caspian Tern and Red-necked Stint.

Terrestrial fauna

A total of 72 terrestrial fauna species have been recorded in the Lake Cowal area, including 30 mammals, 31 reptiles and 11 amphibians. Four other species of burrowing frogs are likely to have been excluded from the area due to extensive grazing and cultivation practices. The Yellow-bellied Sheath Bat, Little Pied Bat and Troughton’s Bat are endangered species.

Above: Bandy Bandy

Above: Blue Tongue Lizard

Macroinvertebrates

49 species of macroinvertebrates were collected during 1991. Lake margins were found to be the area richest in species diversity and abundance.

Fish

Fourteen fish species have been recorded in the lake. Five of these are introduced species. The European Carp occurs in high numbers and has a detrimental impact on the ecology on Lake Cowal.

Threatening Processes

Since European settlement, native vegetation has been extensively cleared in the central western slopes for agricultural production. In some areas, 95% of the native vegetation has been cleared. Clearing has been the most obvious change however several other degrading processes are also affecting native vegetation. These include:

  • Overgrazing of livestock and feral grazers;
  • Weed invasion and introduction of exotic plants;
  • Alterations of fire regimes;
  • Modification and pollution of waterways;
  • Increased use of pesticides and fertilisers; and
  • Fragmentation.

Due to landscape clearing and European agricultural practices occurring within the catchment, Lake Cowal suffers from salinisation, loss of habitat and biodiversity, declining water quality and reduced productivity on surrounding agricultural lands. Weeds and pests such as Lippia and European Carp are also major problems threatening this unique wetland ecosystem.

European Heritage

European exploration of the Bland region occurred in 1817 under the direction of Surveyor General John Oxley. Oxley described the area as unfavourable, although based on the physiology of the area Oxley did note that the area was typical of gold bearing country. Gold was discovered by the Neeld family in 1893 near West Wyalong and by 1894, 10,000 people descended on the gold fields. By 1899, the Wyalong gold fields had been developed ‘so vigorously that it was the most productive in the colony’. Between 1895 and 1915, the Wyalong fields yielded over 200,000 ounces of gold – in today’s terms A$270 million. During the First World War many diggers abandoned the goldfields to join the war and by 1920 gold mining had almost ceased in the area.

Pastoral settlement began in the area around 1842. By the early 1900s, wheat growing had become well established with around 11,900 acres of land devoted to wheat production.

Aboriginal Heritage

The Wiradjuri people cover one of the largest cultural areas in NSW from Nyngan to Albury and from Hay to Bathurst. Wiradjuri means ‘people of three rivers’, these rivers being the Macquarie, Lachlan and Murrumbidgee. For the Wiradjuri, the three rivers were their livelihood and supplied a variety and consistent availability of food. Wiradjuri people moved around the country according to seasonal conditions, and often resided at Lake Cowal where they made the most of the abundant waterfowl, grains and fish.

Lake Cowal itself is named after the Aboriginal word “Cowal” meaning “large water” and while “nerang” (as in Nerang Cowal) means “little water”. When the first European settlers arrived at Lake Cowal, there appeared to be substantial evidence that the area was inhabited by large numbers of Aborigines. The Bland Creek has previously been referred to as a meeting place of the Lachlan and Murrumbidgee Rivers.

Many aboriginal sites of significance have been identified around Lake Cowal. These have included scarred trees, flakes, cores, backed blades, burin, hearths, hand axes, hammer stones, ground artifact and mussel shell fragments.

Cowal Gold OPERATIONS

Gold MineEvolution Mining is a leading, growth-focussed Australian gold miner and owns and operates Cowal Gold Operations. Development consent for Cowal Gold Operations was issued by the NSW Government in March 1999, following submission of a comprehensive Environmental Impact Study and Development Plan.

Prior to the grant of the Development Consent two Commissions of Inquiry (COI) sought public comment and conducted rigorous examinations of the potential environmental impacts of mine construction and operation.

The major components of the Cowal Gold OPERATION include:

  • An open pit which will measure approximately 100 ha on the surface and 325 m deep;
  • A processing plant to extract the gold from the mineral ore;
  • Waste rock emplacements which contain mined rock with no commercial quantities of gold;
  • Tailings storages which contain the treated and detoxified process residues;
  • A lake isolation system to separate mining operations from Lake Cowal over the long term;
  • A bore field and pipeline that provides fresh water to the mine site; and
  • A 100 km 132 kv electricity transmission line from Temora to Lake Cowal.

The COI found that the project could be developed and operated in a manner that was compatible with the environmental values of Lake Cowal. Cowal Gold Operations was met with some opposition from Environmental groups and organisations. After considerable consultation with these groups, a Memorandum of Understanding was signed and the Lake Cowal Foundation (LCF), a not for profit Environmental Trust was established in June 2000 with the objective of protecting and enhancing the natural environment in the Lake Cowal region. The Lake Cowal Foundation is primarily sponsored through a negotiated royalty from Cowal Gold Operations, for the life of the gold project. During the operational life of the mine, payments exceeding $2 million are expected to be made to the Lake Cowal Foundation.

After a period of construction, mining commenced at the Cowal Gold Operations in April 2005. The average workforce employed at Cowal Gold Operations is currently 350 (including Evolution staff and on-site contractor personnel). Cowal Gold Operations is currently approved to operate until 31st December 2024.

Cowal Gold Operations' approval is subject to numerous conditions of operation, most notably the Development Consent Conditions issued by the Department of Infrastructure and Planning. The Development Consent Conditions can be reviewed by visiting the Department’s website: www.planning.nsw.gov.au. Further information regarding Evolution's approach to environment and community at Cowal Gold Operations can be found on the Evolution website: http://www.evolutionmining.com.au/

In accordance with its Community Relations Policy and Community Principles, Evolution maintains a commitment to working together with local communities for mutual long-term success. At Cowal, this commitment translates to a series of partnerships, like the one with the Lake Cowal Foundation, and community development initiatives. Cowal Gold Operations contributes to the local community through its Cowal Partnering Program, the Cowal Cares volunteering initiative, and through the Endeavour and Wiradjuri Scholarship Programs. Evolution contributes to local employment outcomes and economic stability through the ongoing presence of Cowal Gold Operations.