Lake Albert Scoping Study
Literature Review
Published by the Department of Environment, Water and Natural Resources
Government of South Australia 1 September 2014
Head Office Chesser House 91-97 Grenfell Street ADELAIDE SA 5000
Telephone +61 (8) 8204 9000 Facsimile +61 (8) 8204 9334
Internet: www.environment.sa.gov.au ABN 36702093234
ISBN 978-1-921800-59-7
Report prepared by:
Major Projects
Partnerships and Stewardships
Department of Environment, Water and Natural Resources Copies of the report can be obtained from:
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www.environment.sa.gov.au
Contents
1 Introduction ... 7
1.1 Purpose ... 7
1.2 Scope ... 7
2 The Coorong, Lower Lakes and Murray Mouth Region ... 8
3 Description of the CLLMM region ... 10
3.1 Climate ... 10
3.2 Topography ... 10
3.3 Bathymetry ... 11
3.4 Geology ... 12
3.5 Hydrogeology ... 12
3.6 Soil ... 13
3.7 Population ... 14
3.8 Economic Values ... 15
3.8.1 Expansion of Economic Activity ... 15
3.8.2 Present Economic Values ... 15
3.9 Resource Use ... 15
3.9.1 Land Use ... 16
4 Environmental Conditions ... 18
4.1 Water level and water regime ... 18
4.1.1 Historic Conditions ... 18
4.1.2 Current Conditions ... 18
4.2 Water quality ... 20
4.2.1 Historic Conditions ... 20
4.2.2 Current Conditions ... 20
4.3 Salinity ... 21
4.3.1 Historic Conditions ... 21
4.3.2 Current conditions ... 22
4.4 Habitat ... 24
4.4.1 Historic Conditions ... 24
4.4.2 Current Conditions ... 29
4.5 Birds ... 30
4.5.1 Historic Conditions ... 30
4.5.2 Current Conditions ... 30
4.6 Fish ... 31
4.6.1 Historic Conditions ... 31
4.6.2 Current Conditions ... 33
5 Issues Affecting Lake Albert ... 34
5.1 Pre-drought ... 34
5.2 Drought – Acidification Threat ... 36
5.2.1 Construction of the Narrung Bund and Pumping... 37
5.2.2 Removal of the Narrung Bund ... 38
5.3 Post-drought - Salinity ... 38
6 Management options considered ... 39
6.1 Acid Sulfate Soil Management Options ... 39
6.2 Water Quality Management Options ... 46
6.2.1 Removal of the Narrung Causeway ... 52
6.2.2 Dredging the Narrung Narrows ... 52
6.2.3 Construction of a channel and/or pipeline at the southern end of Lake Albert to the Coorong ... 54
6.2.4 Permanent regulating structure across Narrung Narrows ... 60
6.2.5 Groyne through the centre of Lake Albert ... 61
6.2.6 Variation of water levels in Lakes Albert and Alexandrina ... 63
6.2.7 Central Bund in Lake Albert... 66
7 Conclusion ... 67
8 References ... 68
Index of Tables
Table 1: Description of Lake Albert soil classes adapted from Taylor 1931. ... 13 Table 2: Summary of information relating to Lake Albert fringing wetlands as detailed in
Jensen et. al., 1996. ... 26 Table 3: Summary of selected species identified as occurring in the Lower Lakes (adapted
from Bice, 2010b) ... 31 Table 4: Summary of events and historical observations relating to Lake Albert (adapted from Sim and Muller 2004, additional information from DPTI, 2013) ... 35 Table 5: Salinity tolerances of livestock and poultry (PIRSA, 2008) ... 39 Table 6: Summary of reports/studies considering management of acid sulfate soils in Lake
Albert. ... 41 Table 7: Summary of Lake Albert water quality management options considered in various
reports/studies. ... 47 Table 8: Summary of findings relating to options to dredge the Narrung Narrows from Ebsary
(1983) ... 53 Table 9: Summary of channel capacity calculations from Ebsary (1983) ... 55
Table of Figures
Figure 1: The Coorong, Lower Lakes and Murray Mouth site ... 9
Figure 2: Lake Albert bathymetry ... 11
Figure 3: Predictive scenario maps depicting changes in ASS materials at different water levels in Lake Albert (+0.5 m AHD, -0.5 m AHD and -1.5 m AHD). ... 14
Figure 4: A comparison of March 2005 (left image) and March 2008 (right image) Normalised Difference Vegetation Index (Phillips and Miles, 2009) ... 17
Figure 5: Yearly Lake Albert water level in metres (calculated mean lake level) from 1 July 2012 to 1 July 2013. ... 19
Figure 6: Proposed ideal annual operating envelope for Lakes Alexandrina and Albert showing upper and lower water level limits (Lower Lakes, Coorong and Murray Mouth Icon Site Environmental Water Management Plan (draft), 2013)... 19
Figure 7: River Murray Salt Export to Sea (through Barrages) ... 23
Figure 8: Lake Albert and Lake Alexandrina salinity September 2009 to August 2013 ... 24
Figure 9: Lake Albert’s Fringing Wetlands ... 25
Figure 10: Habitat condition in the CLLMM region ... 28
Figure 11: URS (2006) pre-feasibility concept design drawing ... 57
Figure 12: Diagram of barrier positions examined by McInerney (2005). The left diagram is Barrier Position 1, the right Barrier Position 2. ... 63
1 Introduction
1.1 Purpose
The Lake Albert Scoping Study is one of 20 management actions under the Coorong, Lower Lakes and Murray Mouth (CLLMM) Recovery Project. The $137 million CLLMM Recovery Project is part of the South Australian Government’s $610 million Murray Futures program, funded by the Australian Government’s Water for the Future initiative.
The Lake Albert Scoping Study (The Study) is investigating potential options for the long-term management of Lake Albert water quality and the Narrung Narrows. The Study aims to identify flow and water level targets under different climatic scenarios to sustain water quality and ecological health in Lake Albert, including summarising environmental condition targets.
The Study is being informed by a community-based reference group, and will culminate in the development of a future directions paper (Options Paper), and the preparation of a Business Case as required. The objectives of the Study are consistent with the outcomes of the CLLMM Recovery Project, including;
The lake remains predominantly freshwater and operates at variable water levels;
Its biological and ecological features are protected;
There is a return of amenity for local residents and their communities;
There are adequate flows of suitable quality water to maintain Ngarrindjeri cultural life;
Tourism and recreation businesses can utilise the lake; and
Productive and profitable primary industries continue
The outcomes of the CLLMM Recovery Project are consistent with the ecological objectives of the long-term plan for the CLLMM region (Securing the Future: A long-term plan for the Coorong, Lower Lakes and Murray Mouth).
The Lake Albert Scoping Study Literature Review forms part of Phase One of the Lake Albert Scoping Study, and is a deliverable under the Deed of Variation to the Project Schedule for the South Australian Priority Project SA-07: Coorong, Lower Lakes and Murray Mouth Recovery Project.
The purpose of the Literature Review is to review existing information and reports related to Lake Albert and the Narrung Narrows, including considering historic environmental conditions and present environmental conditions. Undertaking this review will help inform development of an Options Paper, and assist in determining what, if any, management action(s) should be implemented to assist with managing Lake Albert water quality.
1.2 Scope
This Literature Review will provide an overview of the CLLMM region, and a focused overview of Lake Albert and the Narrung Narrows. The overview of Lake Albert will include discussion of climate, geology, bathymetry, groundwater and resource and environmental values of Lake Albert and the Narrung Narrows.
The review will also include a summary of existing information regarding environmental conditions in Lake Albert, comparing historical conditions with current conditions.
Environmental conditions considered in this review will include: water level and regime; water quality; salinity levels; habitat, including vegetation and wetlands; birds; and fish.
The review will provide a summary of the key issues affecting Lake Albert, particularly issues pertaining to managing water quality. The review will also identify and summarise reports and investigations which have previously considered management options to address water quality issues in Lake Albert. Management options previously investigated and raised be community that will be discussed in this review include: removal of the Narrung causeway;
dredging of the Narrung Narrows; construction of a channel or pipeline from the southern end of Lake Albert to the Coorong; installation of a permanent regulating structure across the Narrung Narrows; the construction of a groyne through the centre of Lake Albert; the construction of a central bund in Lake Albert; and variation of water levels in Lakes Albert and Alexandrina.
2 The Coorong, Lower Lakes and Murray Mouth Region
The River Murray exits in South Australia at the terminus of Australia’s largest river system, the Murray-Darling; passing though Lake Alexandrina, past Lake Albert, and into the Coorong, the Murray Estuary, and, finally, through the Murray Mouth into the Southern Ocean. The CLLMM region is comprised of Lakes Alexandrina and Albert, and the Coorong Lagoon (Figure 1). The Coorong itself can be separated into three sub-regions: the Murray Mouth/Estuary, and the North and South Lagoons. The River Murray flows into the northern end of Lake Alexandrina. Unlike Lake Alexandrina, Lake Albert, which lies to the south east of Lake Alexandrina, is a terminal lake as it is not physically connected to the Coorong, and experiences no through flow of river water (Ebsary, 1983). Water passes between Lake Albert and Lake Alexandrina through a restriction called Albert Passage, but more commonly known as the Narrung Narrows.
The CLLMM region covers a total area of 140,500 Ha and encompassing 23 different wetland types (Phillips & Muller, 2006). The region is a complex ecosystem that encompasses riverine, lentic, wetland, terrestrial, littoral, estuarine, marine, and hypersaline habitats (DENR 2011). The CLLMM region also supports numerous threatened and migratory species protected under state and international agreements, and state and federal legislation.
The Lower Lakes cover approximately 650 square kilometres which make them the largest freshwater body in South Australia (DEH 2000). Lake Albert is the smaller of the two lakes (at +0.75 m AHD, volume 282.2 GL, surface area 177.1 km2, mean depth 1.7 m) compared to Lake Alexandrina (at +0.75 m AHD, 1,629.4 GL, 662.3 km2,and 2.8 m) (BMT WBM, 2013).
The lakes receive freshwater inflows from the River Murray, the Eastern Mount Lofty Ranges tributaries, groundwater discharge, local run-off, and rainfall on the lakes surface.
Lakes Alexandrina and Albert (the Lower Lakes) are isolated from the Murray Mouth and Coorong by a system of barrages, with 593 independently operated gates across five structures (MDBC, 2006). The network of barrages were constructed between 1935 and 1940 to provide fresh water for irrigation, stock, and domestic purposes.
Figure 1: The Coorong, Lower Lakes and Murray Mouth site
In 1985, the CLLMM region was designated as a ‘Wetland of International Importance’ under the Ramsar Convention on Wetlands (the Coorong, and Lakes Alexandrina and Albert Wetland of International Importance). The region was listed for its physical and biological diversity and spectacular populations of migratory shorebirds, and satisfied at least eight of the nine criteria for listing when the site’s Ecological Character Description (ECD) was completed in 2006. The ecological character of the site is protected under the national Environment Protection and Biodiversity Conservation Act 1999 (Cth) (EPBC Act). The South Australian Government is responsible for providing primary legislation and policy for management of the wetland, and to report to the Australian Government on the status of the site, including any changes in ecological character.
3 Description of the CLLMM region
The following section provides a brief description of the CLLMM region, focussing on Lake Albert and the Narrung Narrows area. The description includes climate, topography, bathymetry, geology, hydrogeology, population, and resource use.
3.1 Climate
Ebsary (1983) identified the climate of the CLLMM region as typically Mediterranean, with mild, wet winters and hot, dry summers. Mean annual rainfall has been estimated as 463 mm for Lake Albert. Of this rainfall, 300 mm falls during the six months from May to October.
Mean annual Class A pan evaporation has been estimated as 1660 mm. Using a pan factor of 0.69 to convert pan evaporation to lake evaporation shows that on average, rainfall exceeds lake evaporation only during the three months of winter.
The mean daily maximum temperature at Meningie for the winter months is around 15o Celsius, and rises to around 26o Celsius during the summer months. Daily summer temperatures can be as low as 10o Celsius, and as high as 40o Celsius. The range of temperatures encountered during winter months is 2o to 18o Celsius and frosts can be expected during cold nights.
3.2 Topography
Ebsary (1983) describes Lake Albert as a body of water formed in the depression between two sand ridges lying parallel to the coast. To the south, the lake is separated from the Coorong by a ridge of elevation between 10 and 20 metres. Recent topographic surveys indicate rises up to 30 m AHD between the Coorong and Lake Albert (DENR 2011). A larger sand dune forms the northern boundary of the lake. Elevations of 50 metres AHD within 1 kilometre of the lake are common.
The countryside surrounding Lake Albert is primarily low, flat grassland or swamp. The Narrung Peninsula is particularly low lying, with most of the area below 10 metres AHD elevation. Many areas are subject to inundation, and this has led to the formation of numerous salt pans. South and east of Meningie, the land is also low lying, but less flat than the Narrung Peninsula. Adjacent to the north east corner of Lake Albert is the large Waltowa Swamp.
Phillips and Muller (2006) note that the slow-moving Lake Albert waters allow for the deposition of silts and sediments, particularly at the southern end of the lake where extensive siltation reduces water depth and topographical diversity.
3.3 Bathymetry
Lake Albert is a broad and shallow waterbody. The lowest and deepest point in Lake Albert is at -1.75 m AHD (Phillips and Muller 2006). Below is a map illustrating the bathymetry of Lake Albert.
Figure 2: Lake Albert bathymetry
3.4 Geology
Lake Albert is underlain by tertiary sandy limestone marine sediments. Overlaying these sediments are stranded coastal dunes of the Pleistocene Bridgewater Formation, exposed to the east of Meningie and north of the lake. Rippon calcrete separates the upper member from the lower member of the Bridgewater Formation and is exposed on the Narrung Peninsula and to the south west of Meningie. Low lying swamp areas around the lake are recent alluvial flat deposits. Granites are exposed near the north east corner of Lake Albert and probably extend beneath the northern half of the lake as a basement high (Ebsary, 1983).
3.5 Hydrogeology
Ebsary (1983) notes that available groundwater data indicates a very gentle regional gradient toward the sea, resulting in a movement of groundwater toward Lake Albert from the north east. Regional groundwater flow is very slow and irrigation carried out near the lake produces a localised flow of groundwater toward the lake from all directions.
A considerable variation in groundwater salinity exists throughout the area, although generally the range is 10,000-20,000 EC units. Low salinities of a few thousand EC units may be found near the lake edge, while salinities in excess of 40,000 EC units are common near numerous salt pans on the Narrung Peninsula, probably caused by evaporation from the water table (Ebsary 1983).
SKM (2009) notes that groundwater flows through two major aquifer systems: a regionally confined aquifer, and an underlying confined aquifer with sand and bryozaol limestone (coral) layers. In the east of the investigation area the two aquifers are separated by a low permeability aquitard usually made up of dark-brown carbonaceous clay.
Rural Solutions (n.d.) prepared a brief summary of groundwater resources in the Lake Albert and Narrung Peninsula area. The report acknowledges that data relating to the quaternary limestone aquifer in the Lake Albert area is limited. Depth to groundwater varies across the existing bores from less than two metres to greater than 20 metres. Water level data indicates that water levels in the majority of monitored wells on the Narrung Peninsula had been dropping rapidly over recent years due to low rainfall conditions in the area limiting aquifer recharge.
Groundwater salinity typically ranges from 2,000 mg/L [3,000 EC] to over 100,000 mg/L [65,000 EC] and is alkaline. Water in the lower end of this salinity range can be suitable for stock watering, the primary use of this resource on the Narrung Peninsula. Significant groundwater extraction would likely lead to a rise in groundwater salinity.
Phillips & Muller (2006) explain that the groundwater table is shallow and saline under much of Lake Albert’s floodplain and thus groundwater discharge creates seasonal and permanent salt-water marshes in depressions or swales around the lake edge.
In a report on element and nutrient balances in the Lower Lakes, Cook et al. (2008) conclude that the Lower Lakes are a substantial source of salts and that this is primarily due to saline groundwater entering the lakes – either directly or via the River Murray. They do, however, recommend further studies on the hydrology and geochemistry of the groundwater in the region are carried out in order that this hypothesis can be further explored.
The hydrogeology of the Coorong and Lower Lakes region is also discussed by Haese et al.
(2008). The Coorong and Lower Lakes are located in the south-western edge of the Murray Geological Basin. The significant aquifers (geological formations which hold water) in this region are the Quaternary and Murray Group Limestone sequences, and the deeper Renmark
Group sands. The limestone sequences are in good hydraulic connection and form the shallow watertable aquifer. The Renmark and Murray Groups are separated by a series of confining clay aquitards.
Major processes such as groundwater discharge, dryland salinisation, irrigation, and groundwater/surface water interaction were identified within this region. Dryland salinity in the region is a major land degradation problem on the low-lying coastal plain, where clearing of native vegetation has led to a rising watertable. The risk of salinisation is most prevalent where depth to the watertable is less than two metres.
Groundwater flows radially from the zone of recharge at Dundas Plateau in the east, northward to the Murray River or westward, discharging to the Coorong, the Lower Lakes or low-lying salinised areas.
On the western side of Lake Alexandrina, the watertable is within a Quaternary clay which overlies and semi-confines the limestone aquifer. Elsewhere in low-lying areas around the Lower Lakes, the watertable occurs in organic-rich clays which were deposited when the Lower Lakes expanded in response to higher sea level about 6,000 years ago. These areas contain highly saline groundwater (>70,000 EC) due to strong evaporative discharge which has lowered the watertable below sea level. These areas are the focus for regional groundwater discharge in preference to the Lower Lakes which are at a higher level of ~0.75 m AHD.
3.6 Soil
The soils surrounding Lake Albert have formed from Quaternary Bridgewater and St Kilda Formations deposition. The soils within Lake Albert have also formed mostly as part of the St Kilda Formation under subaqueous conditions, but are distinguished from other soil material by having properties that can be affected by the oxidation of reduced inorganic sulfides (acid sulfate soil materials).
In 1931, Taylor published a report on the soils of the bed of Lake Albert. A survey of the bed of Lake Albert was undertaken to analyse its suitability for dry farming, or for production under irrigation. The report demonstrates that the bed of Lake Albert is not suitable for agricultural purposes.
The soils of the bed of Lake Albert were grouped into seven classes by Taylor (1931). Table 1 below has been adapted from Taylor 1931.
Table 1: Description of Lake Albert soil classes adapted from Taylor 1931.
Soil Type Description Area
(acres)
Proportion of total area surveyed
A Deep uniform clay, more than 13 feet deep 10,000 29.5 B 10-13 feet of uniform clay over hard sandy
bottom
2,250 6.6
C 6-10 feet of uniform clay over hard sandy bottom 3,050 9.0 D 2-6 feet of uniform clay over hard sandy bottom 2,850 8.4 E Less than 2 feet of clay over sandy bottom 10,200 30.0 F Less than 2 feet of clay over limestone rock 3,250 9.5
G 2-6 feet of uniform clay over limestone rock 2,400 7.0 Total area surveyed 34,000
In 2008, Fitzpatrick et. al. undertook a study which analysed soil profiles from Lake Albert, Lake Alexandrina and the River Murray system below Blanchetown (Lock 1) in South Australia in order to asses potential impacts of acid sulfate soils during the drought (2006- 2010). The results of this study showed that acid sulfate soil materials were present in Lake Albert. “Sulfidic subaqueous soil and sulfuric soil marginally co-dominate in equal measures with sulfuric organic clayey soil, sulfidic subaqueous clayey soil, sulfidic soils and sulfidic cracking clay soil” (Fitzpatrick et. al. 2008, p 34).
Fitzpatrick et. al. used bathymetry, soil cores and vegetation mapping to predict the distribution of acid sulfate soil sub-types according to the following water-level scenarios:
pre-drought water level (+0.5 m AHD); current water level as at February 2008 (-0.5 m AHD);
and a further 1m drop in water levels (-1.5 m AHD). The report notes that as water levels drop, “aqueous soils become de-watered (dry, aerated) and thus potentially sulfuric (pH < 4) if sufficient sulfidic material is present in the drying layers” (Fitzpatrick et. al. 2008, p 59).
Figure 3 below depicts the predictive changes in acid sulfate soil material as water levels decline.
Figure 3: Predictive scenario maps depicting changes in ASS materials at different water levels in Lake Albert (+0.5 m AHD, -0.5 m AHD and -1.5 m AHD) as at 2008.
3.7 Population
The CLLMM region supports local communities which are dependant on an economy based on utilising the region through tourism, recreation, and primary industries. Surrounding towns include Goolwa, Clayton, Milang, Meningie, Wellington, Hindmarsh Island, Narrung, Langhorne Creek, Raukkan, and Salt Creek. The total population is approximately 30,000, of which more than 4,000 are Ngarrindjeri people who live and work on their traditional lands, primarily around Meningie, Raukkan, and Narrung (ABS, 2011).
The CLLMM region is a culturally and spiritually significant site for the Traditional Owners, the Ngarrindjeri. The CLLMM region is of central significance to the life and culture of the
Ngarrindjeri people – the land and waters of the CLLMM region must be healthy for the Ngarrindjeri to be healthy. The CLLMM region includes the “Meeting of the Waters” site, an area recognised as the place where the fresh and salt waters meet and mix and an important place for the reproduction of life.
3.8 Economic Values
3.8.1 Expansion of Economic Activity
Ebsary (1983) discussed the development of the Lake Albert region from the late 1800s to 1983. From the late 1800s until the construction of the barrages in 1940, the area consisted of large sheep and beef grazing estates. Small dryland dairy farms emerged in the years between the World Wars.
The large body of freshwater created by the construction of the barrages led to the introduction of flood irrigation in the late 1940s. By the early 1950s, there were sufficient dairies in the area to require the building of a small milk receiver factory at Meningie.
In 1954, Campbell Park Estate was purchased by the Government as a War Service Land Settlement Scheme and 14 dairy farmers were established in the area. Owners were discouraged from irrigating, but because farm sizes were inadequate to provide profitable enterprise without irrigation, sprinkler irrigation was established in 1958-59. In 1960, the area was restructured, and although only 11 farmers remained, irrigation had been introduced and the district began to grow.
Irrigation was limited to properties that bordered the lake initially, and therefore evolved in a fragmentary manner. A soil survey that was conducted identified the west and south east areas of Lake Albert as having the greatest potential for irrigation-based activities. However, the high costs of pumping water large distances precluded development in these areas.
During the 1960s, improved irrigation equipment became readily available, and this led to an expansion of irrigated areas. The issue of irrigation licences was frozen in 1968, but the amount of irrigation increased for a number of years after this due to the use of dormant licences. The area of irrigated land peaked in the early 1970s and remained relatively constant through to the mid-1980s because of the restrictions imposed by the irrigation licensing system.
In 1983, Ebsary noted that approximately 2,200 hectares were irrigated by Lake Albert water.
This consisted mainly of Lucerne. The predominant form of agriculture in the area was self- contained dairying, with stud sheep, beef, and race horses. Several properties, at the time the report was prepared, provided feed to the sheep export trade, while some contributed to the dairy industry.
3.8.2 Present Economic Values
In 2006-2007 the Gross Regional Product (GRP) of the CLLMM region was $686 million, including $124 million from primary industries of which $43 million was for irrigated agriculture. The GRP of the CLLMM region accounted for approximately 1 % of Gross State Product in 2006-07 (Econsearch, 2009). It is expected that the primary contributor to the primary industries GRP is the Lake Alexandrina region.
The CLLMM region contributes to tourism for the Fleurieu region, which generates approximately $326 million and attracts around 652,000 overnight visitors per year (note that exact figures of the CLLMM region are not known). The services sector of the Fleurieu, supporting tourism and primary production, accounts for 8 % of GRP, and 15 % of all
employment (DEWNR, 2013b). Further information on the economic value of Lake Albert could not be easily identified at the time of writing.
3.9 Resource Use
The River Murray is a critical source of water and, combined with the Lower Lakes area, provides water for agriculture and town drinking supplies for approximately 27,000 people, although the recent [January 2009] installation of potable and irrigation pipelines has reduced the reliance of communities on water from the Lower Lakes (DEH 2010b).
Importantly, the region supplies 80 per cent of the total Mulloway catch for South Australia (Pierce, 1995), as well as significant quantities of Callop, European Carp, Bony Bream, Black Bream, Coorong Mullet and Goolwa Cockles. The fishery works within its own management plan which includes the deliberate over-harvesting of European Carp in order to enhance aquatic environmental benefits. There is also a significant recreational fishery; however, its value has not been estimated.
“Commercial fishing families work hard to produce high quality product for their regional, state and interstate customers, the most popular being the iconic Coorong Mullet. Since 2008 four key species, Mullet, Mulloway, Pipis and Golden Perch have been certified as sustainable by the Marine Stewardship Council, the world’s highest environmental standard for fisheries.
The rotational harvest strategy of the fishery also allows us to target Black Bream, Flounder and Redfin as well as Bony Bream and Carp. The bait harvest supports the state’s valuable Rock Lobster industry.
Coorong fishermen are saying that they have never seen conditions as good as this, since natural flows have returned to the estuary.
Gross Value of Production figures for all Lakes and Coorong Commercial Fishery species are published annually by Econsearch (Economic Indicators for the Lakes & Coorong Fishery)”.
(Glen Hill, 2013, pers com)
3.9.1 Land Use
The CLLMM region has a mix of primary industries that is predominantly irrigated and dryland agriculture, manufacturing industries related to wine, machinery and equipment, boat building and maintenance, and recreation and tourism activity and historically irrigated agriculture (DEH 2010a). Sheep, beef and dairy cattle farming; grain, vegetable, fruit and nut growing;
viticulture and fishing are the main primary industries in the area. There is also a significant urban population with associated housing and service sectors.
There has been a notable shift away from irrigated crops during the recent drought. Phillips and Miles (2009) undertook an analysis of the Coorong, and Lakes Alexandrina and Albert Ramsar site and its surrounds to determine the extent of wetland ecosystems and change, to monitor revegetation efforts, and to potentially assess the socio-economic impact on the region.
“A Normalised Difference Vegetation Index (NDVI) analysis was used at two dates to investigate Photosynthetic Activity (PA) activity in seven land use classes, including economic cultural and ecological land use areas as Lake Albert water levels receded between March 2005 and March 2008”.
Referring to Figure 4,
“The March 2005 NDVI shows medium PA evenly spread throughout the scene, with higher activity along channel borders and waters edge (water levels at approximately +0.65 m AHD). Very high PA signals were noted in the irrigated pivot circles throughout the area of interest. The March 2008 NDVI shows generally lower levels of PA throughout (water levels at -0.48 m AHD). The medium and high PA signal is most noticeably absent throughout the scene. In the Narrung channel, wetlands have a smaller area of high PA, while the extent of wetlands is decreasing. The intensity of the signal around the lake edge wetlands has diminished markedly, and irrigated crop pivot circles are greatly reduced in number”.
Figure 4: A comparison of March 2005 (left image) and March 2008 (right image) Normalised Difference Vegetation Index (Phillips and Miles, 2009)
Sobels (2011) notes in a study of impacts to the communities of the Lower Lakes from loss of access to irrigation water since 2006, that:
“…on the Narrung Peninsula there are 76 centre pivots most of which had been idle for three to four years. Conservatively they would each cost $250,000 to replace and around
$40,000 each to refurbish. Most of them will not be used again for a variety of reasons to do with the individual farmer’s situation including a lack of certainty about access and supply. The number of irrigated dairy farms had reduced from 17 to three in the same period.
A crucial, key outcome of this situation is changed land use on the Narrung Peninsula. By January 2011 an estimated 3,500 acres (1,400 hectares) of irrigated dairy and beef farms had been converted to cropping, much of which had been purchased by a single farmer from the Mid-North of SA.”
These changes had effects on employment, on the land, and also indirect employment ramifications for local communities (Sobels, 2011).
In response to the severe region-wide drought, the $35 million Tailem Bend to Narrung pipeline project was brought forward to meet the needs of farmers who would have had to begin culling stock on or about the middle of December 2008 because they had almost no water and salinity was increasing rapidly. At the time Sobels prepared the study in mid-2011, irrigators with a licence around Lake Albert were still unable to use the lake water due to salinity of around 7,000 EC units. The pipeline to the Narrung Peninsula delivers stock and domestic water as distinct from the Creeks Pipeline which is primarily for irrigation purposes.
The rapid change of land use from irrigation-reliant industries to dry land agriculture use over a very short period of time, combined with the uncertainty caused by the lack of water/irrigation access within Meningie and the Narrung Peninsula resulted in General Valuation changes (Sobels, 2011). A letter documenting the changes in General Valuation from 2005/6 to 2010/11 from the Deputy Valuer-General to the President, Lower Lakes and Coorong Infrastructure Committee dated 16 March 2012 is provided as Attachment A.
4 Environmental Conditions
The following section provides a summary of existing information regarding environmental conditions in Lake Albert, comparing historical conditions with current conditions. The terms
‘historical’ and ‘current’ are used loosely in their definitions but generally ‘historic’ is pre the 2006 -2010 drought and ‘current’ refers to during and post drought. Environmental conditions considered in this section include: water level and water regime; water quality; salinity;
habitat, including vegetation and wetlands; birds; and fish. For the purposes of this section current conditions is proposed to include conditions post-drought. Where information is available, historic conditions includes pre and post-European settlement.
4.1 Water level and water regime
4.1.1 Historic Conditions
Phillips and Muller (2006) note of water levels prior to European settlement:
“lake levels started to rise from groundwater inputs entering the lakes prior to the first rains in late autumn (presumably driven by decreasing atmospheric pressure). Lake levels would steadily rise through winter, driven by EMLR (Eastern Mount Lofty Ranges) tributary inflows, rainfall on the lakes and groundwater inputs, with levels peaking in late spring-early summer when River Murray flows came from the headwaters. Over summer, water levels would slowly drop when evaporation exceeded trickling inputs from draining groundwater and the tributaries of Lake Alexandrina.” (Phillips and Muller 2006, p 190)
4.1.2 Current Conditions
Lake Alexandrina receives freshwater from rainfall, runoff from the local floodplain, and from inflows from the River Murray, the tributaries and from discharging groundwater. The land- locked Lake Albert receives some of these waters through the Narrung Narrows, and is supplemented by inputs from rainfall, local runoff and groundwater flows. Wind patterns (speed and direction) greatly influence flow patterns and water levels by ‘tilting’ the lake surface, or by creating waves that generate head differences between the lakes themselves, and between connected water bodies. (Phillips and Muller 2006, p 201)
Since the construction of the barrages in the 1930s/40s, the water levels of Lake Alexandrina and Lake Albert have been regulated by inflows from the River Murray and outflows through
the opening of the barrage gates. Initially built to provide fresh water for the local community and for river transportation, the barrages, and therefore lake levels, in recent times have been managed primarily to ensure irrigation supply through summer when River Murray and tributary inflows, and rainfall are lowest, and evapo-transpiration is greatest. (Phillips and Muller 2006, p 190)
At the height of the recent drought (2006-2010), Lake Albert water levels dropped to -0.5 m AHD. Following improved River Murray inflows to the region in 2010/11 and the breaching and subsequent removal of Narrung Bund, Lake Albert water levels returned to pre-drought levels. As at 25 August 2013, Lake Albert water levels were recorded at approximately 0.85 metres AHD. Figure 5 below shows the Lake Albert mean lake levels from July 2012 to July 2013.
Figure 5: Yearly Lake Albert water level in metres (calculated mean lake level) from 1 July 2012 to 1 July 2013.
http://riverdata.mdba.gov.au/sitereports/lkalbert/mdba_lkalbert_site_report.html. Accessed 1 July 2013
The Lower Lakes, Coorong and Murray Mouth Icon Site Environmental Water Management Plan (in draft) proposes a lake operating regime which fluctuates lake levels for ecological outcomes. The proposed regime and lake levels are shown in Figure 6 below.
Figure 6: Proposed ideal annual operating envelope for Lakes Alexandrina and Albert showing upper and lower water level limits (Lower Lakes, Coorong and Murray Mouth Icon Site Environmental Water Management Plan (draft), 2013)
4.2 Water quality
4.2.1 Historic Conditions
In 1998, the South Australian Environment Protection Authority (EPA) released a water quality monitoring report discussing the results of its ambient water quality monitoring program (October 1995 - December 1997). According to the findings, water quality of Lakes Alexandrina and Albert was poor.
Monthly samples from five sites on Lake Alexandrina and three sites on Lakes Albert were analysed for nutrients, heavy metals, and major ions, and for water clarity and salinity. The results of the analyses were then compared against Australian and New Zealand guidelines for fresh and marine water quality guidelines for each variable measured to designate if the water quality was good, moderate or poor. The water quality of the Lower Lakes was described as poor because of:
- high turbidity in Lake Alexandrina
- moderate nitrogen and phosphorus concentrations
- concentrations of heavy metals exceeding national guidelines for the protection of aquatic ecosystems at some sites
- salinity exceeding the guidelines for good quality drinking water at some sites.
Lake Albert was more saline but less turbid than Lake Alexandrina, and had higher concentrations of some dissolved salts. Lake Alexandrina had higher concentrations of some heavy metals and of total phosphorus.
4.2.2 Current Conditions
A report from the South Australian Environment Protection Authority (2013) which investigated water quality in the CLLMM region during the recent drought, data collected between August 2008 and July 2010 was examined. The report concluded that:
“water quality in the Lower Lakes at the end of the Murray-Darling Basin deteriorated substantially during the hydrological drought from 2007-09… A marked shift to a more saline, turbid and eutrophic system occurred during the drought. These water quality changes were attributed to a lack of flushing, which coupled with lake volume reductions, resulted in concentration of dissolved and suspended material and increased wind-driven re-suspension of sediments as the lakes became much shallower.
Cyanobacterial species became more dominant with one large toxic bloom recorded.
Rewetting of exposed acid sulfate soils on the lake margins also resulted in severe surface water acidification and very high soluble metal levels in over 2,000 ha of surface water.” (EPA, 2013, p 77)
Ecological monitoring of the CLLMM region is currently being undertaken as part of the CLLMM Recovery Project. Abiotic monitoring includes surface and shallow groundwater quality (salinity, pH, dissolved oxygen, temperature, metals, alkalinity/acidity, turbidity and nutrients) and acid sulfate soils.
Overall, surface water quality in the Lower Lakes has been shown to have improved as a result of the continued high water levels and inflows from the River in 2011-12. All water quality parameters are back within the Australia and New Zealand Environment Conservation Council (ANZECC) water quality guidelines.
For up to date water quality information, see the EPA’s website at http://www.epa.sa.gov.au/environmental_info/water_quality/lower_lakes_monitoring/lake_albe rt_monitoring
The high flows and cooler water temperatures kept blue green algae under control, although in Lake Albert blue green algae densities were higher than those seen in Lake Alexandrina and the tributaries.
Acid sulfate soil monitoring showed that the neutralisation (to pH >4) rate of acidic soil is highly variable. In some areas, sulfuric (pH <4) conditions continue to persist and the acidification hazard remains high in many parts of the lakes. Consequently, if water levels were to decline below 0 m AHD for a length of time, this could again pose a serious risk to the water quality of the Lower Lakes.
4.3 Salinity
4.3.1 Historic Conditions
Pre-European SettlementA palaeoecological investigation (Barnett, 1994), concluded that the results of the investigation suggested conditions have been mostly oligosaline-freshwater since the formation of Lake Alexandrina, with an overall increase in freshwater conditions. An investigation by Fluin (2007), which did not include Lake Albert, suggested that Lake Alexandrina was predominantly fresh throughout its history, with marine water indicators never dominant; thereby suggesting that Lake Alexandrina was only moderately influenced by tidal inflow. Major inputs from the River Murray were evident in the diatom assemblages, particularly in the past 2,000 years. As Lake Albert receives it’s inflows from Lake Alexandrina, this is useful to note.
A palaeoecological investigation of the Lower Lakes including Lake Albert is currently being undertaken (2012-13) by Haynes et al (unpublished), will provide information about water quality conditions during the past ~7,000 years. Fossilised diatoms are examined from sediment cores: diatoms (unicellular algae) are excellent indicators of water quality as they are very sensitive to any changes in water quality, such as salinity, and preserve very well in sediments.
In a report by the Murray-Darling Basin Commission (MDBC) in 2001, it is noted that under natural flows conditions, prior to the implementation of regulation and diversions through the Murray-Darling Basin, Lakes Alexandrina and Albert were predominantly fresh water lakes, only becoming brackish or saline at times of low river flow. This is supported by Phillips and Muller (2006) who note that “at the time of European settlement, the lakes were fresh and reliable water sources as evidenced by the importance of townships such as Clayton, Milang and Meningie, and the original intention to locate Adelaide at Currency Creek in the early years.” (Phillips and Muller, 2006, p 168)
Post-European Settlement
Phillips and Muller (2006) note that salinity levels in Lakes Alexandrina and Albert have steadily risen as a result of system levers (such as River Murray regulation, extraction, and barrage operation) and anthropogenic impacts. The authors further note that “by the late- 1800s, alternative freshwater supplies to the lakes had to be sources from underground supplies for town, stock domestic and industrial supplies.” (Phillips and Muller, 2006, p 168)
Lake Albert is naturally more saline than Lake Alexandrina and exhibits more of the original character of the Lower Lakes before their impoundment in 1940. Lake Albert salinity has been measured at Meningie since 1969 (Ebsary, 1983). Since Lake Albert is a terminal lake which experiences high evaporation rates, a salinity gradient exists from north to south. The periodic wind driven inflow of fresher Lake Alexandrina water reduces the salinity of Lake Albert’s northern waters thereby increasing the salinity gradient. As the water in the Narrung Narrows is typically fresh, winds from the north west cause a significant freshening of the north east corner of Lake Albert, which is more than 10 kilometres from the end of the Narrows.
As the edges of the lake have gentle slopes, water depths are commonly less than 0.5 metres up to 100 metres from the shore. Evaporation from these shallow areas is expected to result in lake edge salinities being higher than the body of the lake. Backwaters in the south west corner of the lake, and the appendage to the south, consistently record higher than average salinities because their isolation prevents an adequate flushing effect (Ebsary, 1983).
Ebsary (1983) notes that peaks in salinity occur during summer due to low lakes levels, peak groundwater return flows, and high evaporation rates. Meningie salinity is usually at its highest toward the end of the irrigation season (end of summer) because of the additive effects of concentration due to evaporation and highly saline return flows due to heavy irrigation. Low lake levels compound the salinity problem because they cause a greater inflow of saline groundwater. The head forcing groundwater to flow into the lake is the difference between the groundwater and lake levels. Under normal lake conditions, this driving head is only a few metres, thus lake levels have only to fall a small amount to increase the head by a relatively large amount. As groundwater inflow is proportional to the driving head, decreases in lake level can cause significant increases in the quantity of salt returned to the lake by irrigation.
Salt water intrusions into the lake environment were not common until after 1900 when significant water resource development had occurred in the River Murray system (Sim &
Muller, 2004). Short-lived intrusions would occur during periods of low flow down river, resulting in a lower lake level. However, it appears that only small areas of the lakes, around the mouth and channels, were affected (Sim & Muller, 2004).
Taylor (1931) notes that in 1930, when the report was prepared, “the water of the lake [were]
slightly saline, [with] the salinity vary[ing] with seasonal conditions…” The author further notes that in March-April 1930, Lake Albert water was “affected by incoming sea water from Lake Alexandrina, which had become very saline as a further consequence of the low river level, so that Lake Albert was not potable for humans and taken unwillingly by stock until accustomed to it”.
Phillips and Muller (2006) indicate that Lake Albert salinities typically reach conductivities of up to 3,000 EC at the end of periods of low River Murray inflows. The authors further note that the lakes were fresher prior to the closure of the Murray Mouth in 1981; for example, Lake Albert regularly recorded salinities of between 600 EC (at the end of winter) and 900 EC (at the end of summer). Since 2000, salinity levels in Lake Albert have ranged between approximately 1,300 EC and 2,300 EC (Phillips and Muller, 2006).
4.3.2 Current conditions
As water levels in CLLMM region dropped during the recent drought (2006-2010), salinity levels increased. Evapo-concentration and the influx of marine water through the barrages into Lake Alexandrina (facilitated by head difference between the higher seas and the lower water level in the lakes) and the reduction in salt export from the River Murray waters (Figure
7) led to salinity levels in both lakes increasing beyond values normally associated with freshwater environments (the normal value is generally less than 1000 EC).
River Murray Salt Export to Sea (through Barrages)
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000
75-76 76-77
77-78 78-79
79-80 80-81
81-82 82-83
83-84 84-85
85-86 86-87
87-88 88-89
89-90 90-91
91-92 92-93
93-94 94-95
95-96 96-97
97-98 98-99
99-00 00-01
01-02 02-03
03-04 04-05
05-06 06-07
Flow to sea (GL/a)
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
Salt Load to sea (Mt/a)
Flow to sea Annual Salt Load 3Yr rolling average 1975-2000 (Ave)
1997-2007 (Ave) 2002-2007 (Ave) Linear (Flow to sea)
Note reduction in salt export with reduction in flow
Figure 7: River Murray Salt Export to Sea (through Barrages)
In early 2010, salinity levels in Lake Albert peaked at around 22,000 EC (EPA, 2013). During the drought, when the Narrung Bund was constructed and water was pumped to Lake Albert from Lake Alexandrina, a distinct spatial variation in salinity was observed, with lower salinity levels observed near the Narrung Narrows, grading to higher levels in the southwest region of the lake. Following the breaching of the bund this spatial variation was accentuated. (EPA, 2013)
As seen in Figure 8, following significant rainfall and flooding in the Murray-Darling Basin throughout winter and spring 2010, the Lower Lakes refilled quickly. Salinity levels in Lakes Albert quickly dropped to approximately 10,000 EC shortly after the Narrung Bund was breached in September, predominantly as a result of dilution on refilling. While this was a dramatic decrease at this time, further salinity reduction has been a slow process. By June 2012, salinity had still only declined to between 3,400 EC and 4,300 EC. As of early October 2013, the 7-day rolling average salinity in Lake Albert was approximately 2,500-2,600 EC.
Figure 8: Lake Albert and Lake Alexandrina salinity September 2009 to August 2013
The Coorong, and Lakes Alexandrina and Albert ECD (Phillips and Muller, 2006) recommends that salinity in Lake Albert is maintained below 1,500 EC, based on a five year average. This allows for periods of higher salinity during low inflows, and for the fact that Lake Albert is always more saline than Lake Alexandrina because of its terminal nature.
4.4 Habitat
4.4.1 Historic Conditions
Phillips and Muller (2006) note that prior to European settlement, the significantly fresher waters of Lake Albert supported “extensive submerged aquatic plant beds and diverse emergent macrophyte communties that fringed the lakeshore” (Phillips and Muller, 2006, p 38). The authors further note that submerged aquatic plants are now restricted to sheltered, littoral habitats.
Prior to 2007, when water levels in the CLLMM region declined significantly, fringing wetlands in the Lower Lakes region contained diverse communities of emergent, amphibious and submergent taxa (Gehrig et. al., 2012). Fresh water impounded in Lakes Alexandrina and Albert by the barrages maintains a variety of permanent and ephemeral wetlands (DEH, 2000). The Lower Lakes are fringed with tall reeds, Phragmites sp., and bulrush or cumbungi, Typha sp., and there are sheltered flats and lagoons in places. Many wetlands also support lignum and samphire at the high water mark (behind the reeds) where evaporation provides saline conditions suitable for samphire growth. The lakeshore vegetation forms an almost unbroken habitat corridor around the lakes which has a critical role in allowing birds, fish, frogs and other animals. The Lower Lakes provide habitat for a number of nationally and internationally significant species (Phillips & Muller, 2006).
The Wetlands Atlas of the South Australian Murray Valley (Jensen et. al., 1996) provides a compilation of relevant information for wetlands in the South Australian Murray Valley,
including in the CLLMM region. Conservation values from two separate assessments are included in the wetland summaries: Thompson (1988) and Lloyd and Balla (1988).
Thompsons’s criterion for conservation evaluation included the following: the area of wetland remaining in the region; diversity of habitat; permanence of the wetland; use by waterbirds;
diversity and abundance of aquatic fauna; and regeneration of fringing vegetation. Lloyd and Balla used a point system to assess conservation value, looking at the diversity and status of aquatic fauna and aquatic vegetation; the condition and cover of marginal (fringing vegetation); the condition of the wetland; and the presence of special features. The conservation values are as follows:
- low (0-10) - moderate (10-20) - high (20-30) - exceptional (30+)
Six wetlands (as seen below in Figure 9) were identified as wetlands fringing Lake Albert, including: Narrung; Narrung Narrows; Belcanoe; West Kilbride; Marnoo Complex; and Waltowa Swamp.
Figure 9: Lake Albert’s Fringing Wetlands
Table 2 below provides a summary of the information relating to Lake Albert fringing wetlands presented in the Jensen et. al, 1996. The table lists the species present, as summarised by the authors, and the conservation valuations of Thompson and Lloyd and Balla.
Table 2: Summary of information relating to Lake Albert fringing wetlands as detailed in Jensen et. al., 1996.
Wetland Species present Thompson
Valuation
Lloyd and Balla Valuation
Narrung Samphire, abundant aquatic plants, many hundreds of waterbirds of many species and an abundance, but only a moderate diversity of aquatic invertebrates.
(Thompson Survey, 1983-85)
High 21-30
(High)
Narrung Narrows Extensive areas of bulrush and reeds. These wetlands provide important habitat for waterfowl and probably aquatic fauna. (Thompson Survey, 1983-85) Extensive areas of aquatic and large areas of open water, with small patches of lignum and a few willows. (RMWMC Comments, 1994)
High 21-30
(High)
Belancoe Sedges, dense bulrush, dense aquatic plants, a few species of waterbirds, Mitchellian freshwater hardyheads, big-headed gudgeons and an abundance of aquatic invertebrates. (Thompson Survey, 1983-85)
High 21-30
(High)
West Kilbride Sedges, reeds, several species of waterbirds, Mitchellian freshwater hardyheads, Australian smelt, blue-spotted goby and aquatic invertebrates. Black swans and purple swamphens bred on this weltand.
European carp were present. (Thompson Survey, 1983-85)
High 21-30
(High)
Marnoo Complex Sedges, reeds, aquatic plants, hundreds of waterbirds of many species, Mitchellian freshwater hardyheads, Australian smelt, redfin perch and a diversity of aquatic invertebrates. Fringing this wetland is a remnant stand of the formerly more widespread salt paperbark (Melaleuca halmaturorum). Black swans bred on this wetland.
(Thompson Survey, 1983-85)
High 21-30
(High)
Waltowa Swamp Reeds, samphire, sparse aquatic plants, hundred of waterbirds of several species, Mitchellian freshwater hardyheads and a diversity and abundance of aquatic invertebrates. (Thompson Survey, 1983-85)
High 21-30
(High)
A habitat assessment of the Coorong, and Lakes Alexandrina and Albert Ramsar site by Seaman in 2003 identified and mapped the types of habitats and the condition of them. The assessment considered ecological values such as connectivity, pest plants, human impacts, integrity of vegetation associations, and condition of core habitat areas. Habitat descriptions given included: pristine (no obvious signs of disturbance); excellent (vegetation structure intact, disturbance affecting individual species and weeds are non-aggressive species limited to 5-20% coverage); very good (vegetation structure altered, obvious signs of disturbance and 20-50% weed invasion); good (vegetation structure significantly altered by very obvious signs
of multiple disturbances); degraded (basic vegetation structure severely impacted by disturbance, intensive management required to return to a “good” condition); and completely degraded (vegetation structure no longer intact and area completely/near completely devoid of native species).
Habitat condition around Lake Albert was shown to range from Excellent to Degraded (Seaman, 2003). Most of the Narrung Narrows area was given a rating of excellent, although areas such as this were “quite isolated on a regional scale” (Seaman, 2003, p 41). The Lake Albert shoreline areas assessed were given ratings of Degraded, Very Good, and Excellent, with Excellent and Degraded being the dominant ratings. The Narrung Narrows stood out as an ecological hot spot when compared across Lakes Alexandrina and Albert; there were very few areas that were classified as Excellent habitat. Figure 10 below depicts the habitats mapped in the Ramsar site, and indicates their condition.
Figure 10: Habitat condition in the CLLMM region
The Coorong, and Lakes Alexandrina and Albert ECD (Phillips and Muller, 2006) provides a qualitative description of Lake Albert, including a summary description of its ecological value.
The authors noted that Lake Albert supported remnant patches of Gahnia filum and extensive, highly significant Phragmites australis and Typha domingensis reedbeds, which provide excellent sheltered habitat for a range of fish and other vertebrate species, as well as long-term rookery sites for ibis, spoonbill and cormorants. The authors also noted that, in
addition to species present in Waltowa Swamp listed in Table 2 above, the wetland complex also supported significant orchid species and freshwater marshes.
4.4.2 Current Conditions
Thiessen (2010) conducted a habitat assessment of Ramsar wetland types in the CLLMM region to assess the impact of the drought. The assessment was undertaken based on the methods adopted by Seaman (2003) in order that conditions in 2010 could be compared to those assessed by Seaman in 2003 (pre-drought). Only 13 of the of the 19 Ramsar wetland types were re-sampled due to low representation of the remaining six wetland types. The same value system was used for each site surveyed: excellent, very good, degraded, and completely degraded (see earlier descriptions for each value). However, due to many sites having changed in habitat community so significantly as a result of the drought, it was not possible to compare values to those given by Seaman (2003) as it was no longer a comparison of the same wetland types.
The wetland types listed in the ECD that include the Lake Albert and Narrung Narrows areas are included in those types that underwent significant change in habitat community. Most changed from reedbeds, sedge lands and/or open water habitats to introduced grassland or samphire communities; indicative of drought conditions. An example provided was Waltowa Swamp, which was a healthy reedbed and open water association in 2003 and had lost water and seen a decline in reedbed condition in 2010. The loss of water flow changed the water regime and consequently the structure of the habitat, making it impossible to continue to provide critical habitat for waterfowl, waterbirds, waders, and Murray hardyhead.
Narrung wetland was one of the few sites that experienced an improvement in condition since 2003. Thiessen (2010) notes that:
“The condition of the Narrung wetland was enhanced due to management actions that were implemented [by the Coorong District Local Action Plan (CDLAP) and the South Australian Murray Darling Basin Natural Resource Management (SA MDB NRM) Board through the Narrung Wetland Management Plan (Bjornsson, 2006)]… The strategy they applied included fencing the wetland, obtaining water licenses and approval for artificial watering of the area, and a revegetation program.” (Thiessen, 2010, p 37)
Thiessen (2010) concluded that the wetland habitat condition of the majority of wetlands surveyed declined as a result of the drought, and that “water regimes changed across the entire Lower Lakes system, and vegetation associations were altered favouring the proliferation of weed communities” (Thiessen, 2010, p 39).
Vegetation surveys conducted during a four-year period (spring 2008 to autumn 2012) as part of The Living Murray program (Gehrig et. al., 2012) demonstrate the changes in vegetation types observed at varying water levels. Gehrig et. al. noted that:
“the plant community around the edge of Lake Albert was generally dominated by terrestrial taxa between spring 2008 and autumn 2010, with some floodplain and amphibious taxa also present. From spring 2010, amphibious and emergent taxa replaced the terrestrial taxa, particularly between elevations +0.4 m AHD and +0.6 m AHD. At elevation +0.2 m AHD, there was a marked increase in emergent taxa. The lower elevations (0 and -0.5 m AHD) remained bare following inundation in winter 2010. Apart from significant increases in the abundance of Aster subulatus and Cotula coronopifolia in autumn 2012, there were no significant indicators for all remaining elevations, suggesting that the plant communities remained unchanged for the latest surveys (spring 2011 to autumn 2012).” (Gehrig et. al., 2012, p 26)
Lake Albert had the highest proportion of exotics compared to other lakeshore survey sites (Lake Alexandrina and Goolwa Channel).
Gehrig et. al. (2012) included vegetation surveys of wetlands in the CLLMM region, including Narrung and Waltowa wetlands. The plant community at the Narrung wetland was found to be unchanged during the survey period, with a mixture of terrestrial, amphibious and emergent taxa present, particularly a native salt marsh comprised of Sarcornia quinqueflora, Suaeda australis, and Frankenia pauciflora. In autumn 2012, submergent, emergent and amphibious taxa were present, with Ruppia tuberosa a significant indicator. Results indicated that the plant community in Waltowa wetlands remained largely unchanged during the survey period.
4.5 Birds
4.5.1 Historic Conditions
Limited historical information is available for bird species specifically using Lake Albert. In a literature review of bird species dependant on the habitat provided by wetlands within the Coorong, and Lakes Alexandrina and Albert Wetland of International Importance (Ecological Associates, 2009), the authors note that waterbirds constitute a fundamental component of the system, and that terrestrial bird species are reliant on wetland productivity.
4.5.2 Current Conditions
Rogers (2012) collated results from monthly waterbird surveys conducted across the Lower Lakes, Coorong and Murray Mouth Icon Site between 2001 and 2012 as part of The Living Murray program. The summarised findings are as follows:
- The drop in water level in the Lower Lakes during the period of low flows associated with the recent drought (2006-2010) resulted in sharp increases in the abundance of shorebirds in this region, including migratory shorebirds. However, this increase in habitat availability within the lakes was at least partly offset by a decline in habitat availability in the southern Coorong.
- Immediately following the return of significant River Murray inflows in 2010/2011, habitat availability for shorebirds in both the Coorong and Lower Lakes reduced to near zero, and very few shorebirds were recorded anywhere in the Icon Site. The number of shorebirds recorded in the site 12 months after the return of flows had increased from this historic low, but was still low compared to earlier survey periods.
- While increases in the abundance of a number of selected species was recorded with the return of flow, some species with quite different ecological requirements continued to decline, suggesting some ongoing issues with ecosystem function of the site.
O’Conner et al. (2012) undertook a detailed and quantitative review of the Coorong, and Lakes Alexandrina and Albert Wetland of International Importance status using bird data. An assessment was made as to whether changes in bird communities using the site have affected the site’s Ramsar status across the years. This study did not single out Lake Albert, rather examined the Ramsar Site as a whole. The findings of the report are summarised as follows:
- Ten bird monitoring datasets were available for analysis in this project, nine of which were used to justify Ramsar criteria. Annual waterbird census data were the most useful for providing total numbers of individuals across the site. Smaller, species-specific surveys within the CLLMM region provided valuable breeding records and population counts for rarer species.
