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.

Mine Pit Lakes in Australia: an International Perspective

Naresh Kumar(MiWER), Clint McCullough (MiWER), Mark Lund (MiWER)

What are the characteristics of Australian pit lakes and how do compare to those of other countries?

The MiWER team were invited to contribute a book chapter on “Mining lakes in Australia” to the book, “Acidic Pit Lakes – legacies of coal and ore mining” published by Springer. The book is a revised version of the now 10 year-old well-recognised publication by the same publishers. Our chapter will highlight knowledge of mine pit lakes in Australia. Main topics that are covered in the chapter are the total number of mine lakes, type of mining, physical, chemical and some biological characteristics, any remediation and rehabilitation approaches planned or already carried out, remediation drivers and the socio-economic aspects of the mine lakes etc. To assist us, we have contacted regulatory agencies in all states as well as a broad range of industry groups and consultants to provide information on pit lakes across the country.

Photo: Australia has many highly acidic and also highly saline lakes as a result of its arid climate. Mine from the Goldfields of Western Australia.

Map: With a mining booming in Australia, mine pits are forming larger and more ubiquitous pit lakes than ever before.


Kumar, N. R.; McCullough, C. D. & Lund, M. A. (2012). Pit lakes in Australia.In: Acidic Pit Lakes – Legacies of surface mining on coal and metal ores. (Ed W. Geller & M. Schultze). Springer, Berlin, Germany.

Kumar, N. R.; McCullough, C. D. & Lund, M. A. (2009). Water resources in Australian mine pit lakes. Proceedings of AUSIMM Water in Mining 2009Australasian Institute of Mining and Metallurgy (AusIMM), Perth, Australia. pp. 507-511.PDF

Kumar, N. R.; McCullough, C. D. & Lund, M. A. (2009). Water resources in Australian mine pit lakes. Mining Technology. 118:

Wetland riparian vegetation structure of natural wetlands as guidelines to dredge pond rehabilitation, south-western Australia

Eddie van Etten (MiWER), Clint McCullough (MiWER), Mark Lund (MiWER), Mark Gell (KSS)

What is the vegetation structure of typical seasonal wetlands of the Kemerton region?

Silica sand mining by Kemerton Silica Sand Pty. Ltd. in the Kemerton region, south-western Australia, is followed by rehabilitation of mined lands into conservation areas after ore extraction is complete. Successful rehabilitation to a natural structure is involving first studies into what type of wetland (e.g., wetland riparian vegetation structure) is typical of the area, and hence acceptable as a rehabilitation outcome. Studies are focussing on both understanding natural wetland structure, dynamics and environmental drivers, on also on understanding how rehabilitation efforts are achieving desirable rehabilitation outcomes.


Photo: A typical seasonal waterbody of the Kemerton wetlands.

Photo: Dr. Eddie van Etten surveying vegetation rehabilitation success and rehabilitated slope topography and soil structure.

Figure: Topography, vegetation structure and soil structure profile of a seasonal Kemerton wetland.


  • Van Etten, E. J. B.; McCullough, C. D. & Lund, M. A. (2014). Setting restoration goals for restoring pit lakes as aquatic ecosystems: a case study from south west Australia. Mining Technology. link
  • Van Etten, E. J. B.; McCullough, C. D. & Lund, M. A. (2011). Setting restoration goals for restoring pit lakes as aquatic ecosystems: a case study from south west Australia. Proceedings of the Eighth International Heavy Minerals Conference, Perth, Australia, 5-6 October 2011, pp. 339-350.  AusIMM, Melbourne. PDF
  • Van Etten, E. J. B.; McCullough, C. D. & Lund, M. A. (2011). Sand mining restoration on the Swan Coastal Plain using topsoil – learning from monitoring of previous rehabilitation attempts. Proceedings of the Eighth International Heavy Minerals Conference, Perth, Australia, 5-6 October 2011, pp. 323-338.  AusIMM, Melbourne. PDF
  • Van Etten, E. J. B.; McCullough, C. D. & Lund, M. A. (2012). Importance of topography and topsoil selection and storage in successfully rehabilitating post-closure sand mines featuring pit lakes. Mining Technology. 121:
  • van Etten, E.; McCullough, C. D. & Lund, M. A. (2009). Evaluation of rehabilitation efforts at the Kemerton Silica Sands Pty. Ltd. project area, November 2008. Report number 2009-02, Centre for Ecosystem Management/Mine Water Environment Research, Edith Cowan University, Perth, Australia. Unpublished commercial-in-confidence report to Kemerton Silica Sand Pty Ltd.
  • van Etten, E.; McCullough, C. D. & Lund, M. A. (2009). Riparian vegetation characteristics of seasonal wetlands in Kemerton, south-western Australia Report number 2008-17, Centre for Ecosystem Management/Mine Water Environment Research, Edith Cowan University, Perth, Australia. 50pp. Unpublished report to Kemerton Silica Sand Pty Ltd.

Geochemical Modelling of Pit Lake Water Chemistry to Support Management Decisions

Mike Mueller (Hydrocomputing, Germany), Katja Eulitz (Hydrocomputing, Germany), Clint McCullough (MiWER), Mark Lund (MiWER)

How does pit lake water quality and depth change under different management scenarios?

Stage 1. Selection of appropriate model

This model will maximise the use of the currently available data for model creation and validation. The current preference is not to focus on a single pit lake and model in detail but develop a simpler model that can be easily applied to cohorts of Collie pit lakes identified by the inventory collection and conceptual modelling. This general model would be less detailed but more suited to the low input knowledge environment of the Collie groundwater region and would support important pit lake and ground water management decisions.

Stage 2: Model parameterisation and testing.

There is no option for detailed validation of the model at this stage, other than through use of existing historic and collection of new data sets arising from Task 1.

Stage 3: Scenario testing.

A series of different scenarios will be run to demonstrate model outputs and to test alternative pit lake management and environmental strategies for the different pit lake cohorts.



Figure: Important processes in pit lakes

Model: Schematic of model coupling in MODGLUE

Modelling Tools

This project is using the model PITLAKQ which is a coupled model that combines the groundwater model PCGEOFIM, the lake hydrodynamic and water quality model CE-QUAL-W2 and the hydro-geo-chemical model PHREEQC.

PITLAKQ is capable of modelling all processes that are important to pit lake water quality. Fig. 2 shows these processes that include weather induced hydrodynamics with thermal layering, heath and gas exchange with the atmosphere as well as flow, transport and chemical changes in the subsurface. In addition, a wide variety of water quality processes in the lake water such as biological processes including algae growth and nutrient dynamics as well as equilibrium and kinetic chemical reactions can be modelled. Pit lake specific chemical reactions may be defined by means of an extendable hydro-geo-chemical database and rate limited reaction paths.

PITLAKQ has already been applied to a variety of different mining pit lakes under different scenarios, producing results to guide surface and groundwater management.

Video: Model of Lake Kepwari during filling showing temperature changes

Video: Model of Lake Kepwari showing pH changes during filling


Müller, M.; Eulitz, K.; McCullough, C. D. & Lund, M. A. (2010). Mine Voids Management Strategy (V): Water Quality Modelling of Collie Basin Pit Lakes. Department of Water Project Report MiWER/Centre for Ecosystem Management Report 2010-10, Edith Cowan University, Perth, Australia. 95pp. Unpublished report to Department of Water. link

McCullough, C. D.; Müller, M.; Eulitz, K. & Lund, M. A. (2011). Modelling a pit lake district to plan for abstraction regime changes. Mine Closure 2011: Proceedings of the Sixth International Conference on Mine Closure. Lake Louise, Canada. Fourie, A. B.; Tibbett, M. & Beersing, A. (eds.), Australian Centre for Geomechanics (ACG), Perth, Australia, 581-592pp. PDF

Müller, M.; Eulitz, K.; McCullough, C. D. & Lund, M. A. (2011). Model-based investigations of acidity sinks and sources of a pit lake in Western Australia. Proceedings of the International Mine Water Association (IMWA) Congress. Aachen, Germany. 41-45pp. PDF


Ecotoxicity limitations following liming and nutrient enrichment to remediate acid mine lakes

Clint McCullough (MiWER), Luke Neil (Curtin), Mark Lund (MiWER), Jess Sackmann (CWR, UWA), Dr. Anas Ghadouani (CWR, UWA), Dr. Yuri Tsvetnenko (Curtin), Dr. Jim Ranville (DCG-Colorado School of Mines), Prof. Louis Evans (Curtin)

Is liming and enhanced primary production able to reduce ecological toxicity and increase biodiversity of Collie lakes?

Twelve 1,200 L mesocosms at ECU have been filled with a 40 mm layer of lake sediment from the bottom of the fast river-filled Lake Kepwari. This representative sediment layer has then been covered with Lake Kepwari water. Treatments have been allocated in a randomised two-way factorial design to test the effects of liming, phosphorus enrichment and combined liming and phosphorus amendment on different aspects of the AMD water chemistry, ecotoxicity and ecology.

                             Not limed    Limed

No nutrients    U U U    U U U

Nutrients            U U U    U U U

Figure: Experimental Design

Photo: Collecting sediment from Lake Kepwari

Photo: The mesocosms back established at ECU

This was a collaborative multidisciplinary project with co-supervised students at Curtin University of Technology and University of Western Australia. The Edith Cowan University team examined water chemistry, sediment and periphyton dynamics, including the effect of liming and enhanced primary production upon dissolved heavy metal and nutrient concentrations, alkalinity and pH. Jess Sackmann examined correlations between phytoplankton community water quality, and Luke Neil examined the effect of different treatments on aquatic ecotoxicity between each other and over time.


Part of L. Neil’s Ph.D. project and J. Sackmann’s Honours Project. Partially funded by Curtin, Edith Cowan, UWA and the Centre for Sustainable Mine Lakes.


Neil, L. L. (2008). Bioassay assessment of mine pit lake water for aquaculture and biodiversity conservation, Ph.D. thesis, Curtin University of Technology, Perth, Australia. 298pp. link

Neil, L.; McCullough, C. D.; Lund, M.A.; Tsvetnenko, Y. & Evans, L. (2009). Bioassay toxicity assessment of mining pit lake water remediated with limestone and phosphorus. Ecotoxicology and Environmental Safety. 72: 2,046-2, (Highlighted article).

Neil, L.; McCullough, C. D.; Tsvetnenko, Y. & Evans, L. (2006). Toxicity assessment of limed and phosphorus amended mine pit lake water. RACI/ASE Interact 2006 conference. Perth, Australia 24-28 September. PDF

Sackmann, J. (2006). The effect of experimental liming and nutrient addition on phytoplankton of an acidic mine lake, B.E. (hons) thesis, University of Western Australia, Perth, Australia. 50pp.

Conceptual Modelling of Pit Lake Processes and Ecological Risk

Clint McCullough (MiWER), Mark Lund (MiWER)

Conceptual modelling to better understand ecological risks posed by pit lakes

To ensure greatest scientific robustness of conceptual models we held a site visit and workshop in Collie with an expert panel of scientific researchers and managers from universities and State regulatory staff to best understand how these processes are likely working in different pit lakes. This workshop identified conceptual model needs e.g., a carbon cycling model and an acidity budget model. The intent is to then present the conceptual models as diagrammatic representations highlighting the nature of relationships between parameters and processes. These models will also be used to develop cohorts of similar pit lakes for later empirical modelling.

Photo: How does acidity enter Collie pit lakes? (Lake Kepwari)

Figure: Example conceptual modelling of pit lake chemistry

Funding: Department of Water (Western Australia)


McCullough, C. D. & Lund, M. A. (2010). Mine Voids Management Strategy (IV): Conceptual Models of Collie Basin Pit Lakes. Department of Water Project Report MiWER/Centre for Ecosystem Management Report 2010-12, Edith Cowan University, Perth, Australia. 95pp. Unpublished report to Department of Water. link

McCullough, C. D. & Van Etten, E. J. B. (2011). Ecological engineering of a novel lake district: new approaches for new landscapes. Mine Water and the Environment. 30:

Assessment of the Effects of Pit Lakes on Human Health

Andrea Hinwood (CEM), Jane Heyworth (UWA), Helen Tanner (CEM), Clint McCullough (MiWER)

Do pit lakes present a hazard to human health?

Government and community stakeholders have expressed concerns about how open cut mining operations may affect human health and wellbeing through modified surface and groundwater regimes and their follow-on effects on environmental contamination and disease propagation. This project used Collie as a case-study to investigate how the formation of pit lakes may degrade or even improve health outcomes for mining communities living with these legacies.

This project aimed to examine possible impacts of human interaction with pit lakes. The project was conducted in three stages. The first was a literature review of the health effects of the aspects of pit lakes including chemical contamination, pH and also injury. The second stage of the work attained an understanding of how and how frequently the community was exposed to the pit lakes leading to the third stage, an assessment of the risks of exposure and health impacts. Stage 3 produced a screening health risk assessment identifying risks, management strategies, including management trigger levels to ensure protection of human health.


Photo: Sulfidic minerals release acidity and metals as AMD in Collie pit lakes

Photo: Black Diamond pit lake highwalls create a realised drowning risk

Stage 1:  Literature review of historic and new Collie pit lake characteristics, data collation of existing information and assessment of health impacts of identified parameters.

This stage required the compilation of existing data on the chemical, physical and biological aspects of Collie pit lakes from the peer reviewed and available grey literature. As there was little data publicly available on Collie pit lakes, this data compilation made extensive use of unpublished MiWER data. Project members from the MiWER team have an extensive dataset on water quality of most Collie pit lakes extending back more than a decade and also collected new data specifically for the health study. In addition, existing monitoring data was used to determine concentrations of relevant parameters and their likely health effects. The literature review outlined likely health effects associated with water temperature and other issues such as chemical injury. The data collated in Task 1 were used to identify potential chemical and biological human health risks associated with pit lakes in Collie. A further literature review also examined physical risks such as injury, water temperature and drowning.  

Stage 2:  Community Survey

To assess the use and perceived issues of using pit lakes a community survey was undertaken via administration of a postal questionnaire. The questionnaire was focussed on finding out how many people use the pit lakes, the purposes for which they use the lake, how often they use the lakes and for how long they have used the lakes and how they would like to use the lakes. We also obtained data on health issues that may be associated with pit lake water and other potential confounding factors. The questionnaire was designed based on the literature review. The population of Collie and surrounds is 7,194 persons and we aimed to obtain information from approximately 10% of the population. As response fractions are often low 1,500 questionnaires were posted to a random sample of residents of Collie. The selection was based on the electoral roll. A reply paid envelope was provided. The data collected via questionnaire was analysed and the information informed the screening health risk assessment in Stage 3. A report on the questionnaire was then developed and provided the Department with a variety of information on actual and perceived issues associated with pit lakes in the area. 

Stage 3:  Screening Health Risk Assessment.

Health risk assessment is a systematic, transparent process of assessing the potential risks associated with exposure to environmental and physical parameters. It uses a standard methodology which is routinely accepted worldwide and provides managers with good information on how to prevent and minimise both actual and perceived risks. Based on Stages 1 and 2 human health risks were determined based on the likelihood of them occurring, the consequence if they occur and therefore an assessment of the significance of the risk. This process also enabled the development of triggers to manage issues to prevent risks from occurring. This stage also identified any issues that required further investigation.

Funding: Department of Water (Western Australia)


Hinwood, A.; Tanner, H.; Heyworth, J.H.; McCullough, C. D. & Lund, M. (2010). Water quality of mine void pit lakes used for recreation. 2010 Joint Conference of International Society of Exposure Science & International Society for Environmental Epidemiology. Seoul, Korea. International Society of Exposure Science (ISES) and the International Society of Environmental Epidemiology (ISEE).PDF

Hinwood, A.; Tanner, H.; Heyworth, J. & McCullough, C. D. (2010). Recreational use of acid mine pit lakes. 2010 Joint Conference of International Society of Exposure Science & International Society for Environmental Epidemiology. Seoul, Korea. International Society of Exposure Science (ISES) and the International Society of Environmental Epidemiology (ISEE). PDF

Hinwood,A.; Heyworth, J.; Tanner, H. & McCullough, C. D. (2012). Recreational use of acidic pit lakes – human health considerations for post closure planning. Journal of Water Resource and Protection. 4: 1,061-1,070 link

Hinwood, A. L.; Heyworth, J.; Tanner, H. & McCullough, C. D. (2010). Mine Voids Management Strategy (II): Review of potential health risks associated with Collie pit lakes. Department of Water Project Report MiWER/Centre for Ecosystem Management Report 2010-11, Edith Cowan University, Perth, Australia. 111pp. Unpublished report to Department of Water. link

Use and Water Quality Remediation of Acidic Coal Pit Lakes by Adjacent Aquaculture

Clint McCullough (MiWER), Naresh Radhakrishnan (MiWER), Mark Lund (MiWER), Xanti Larrañaga, (MiWER), Digby Short (Premier Coal Pty Ltd)

Can a nearby aquaculture discharge be used to both remediate an acidic pit lake and also to provide a sustainable source of water for a post-mining industry?

The aim of this competitively-funded research programme is to examine how a coal mine pit lake could supply feed water and accept waste discharge from a commercial scale aquaculture venture as part of a sustainable post-mining community without significant deterioration in the lake environment e.g., water quality. This project also intends to answer whether water quality in coal mine pit lakes would be improved by accepting wastewater from a commercial scale aquaculture venture through simulation of microbial remediative processes previously inhibited by low nutrient concentrations. Specific objectives of this study therefore will determine:

  • The capacity of a coal mine pit lake to accept aquaculture waste discharges without detrimental impacts to pit lake water quality or wildlife.
  • How improvement of water quality and wildlife values might occur through aquaculture waste discharges remediating key pit lake water quality issues such as acidity by addressing insufficient nutrient concentrations.


Photo: The marron grow-out ponds adjacent to Collie pit lake WO3.

Photo: An adult marron crayfish from Collie.


Kumar, R. N.; McCullough, C. D. & Lund, M. A. (2011). Use and water quality remediation of acidic coal pit lakes by adjacent aquaculture. Report number 2011-10. Mine Water Environment Research Centre/Centre for Ecosystem Management, Edith Cowan University, Perth, Australia. 104pp. Unpublished report to Australian Coal Association Research Programme (ACARP).

Kumar, N. R.; McCullough, C. D.; Lund, M. A. & Larranãga, S. A. (2011). Evaluating the factors limiting algal biomass in acidic pit lakes of the Collie Lake District, Western Australia. Proceedings of the International Mine Water Association (IMWA) Congress. Aachen, Germany. 523-527pp.

Remediation of waters from a south-west Australian acid pit lake with oxic liming and an aerobic wetland

Clint McCullough (MiWER), Mark Lund (MiWER), David Bills (Griffin Coal)

Does treatment with oxic liming and an aerobic wetland remediate mine waters from a new acid pit lake?

A mine water treatment system was constructed at Griffin Coal Mining Company Limited in Collie Western Australia, to remediate acidified mine lake water from the nearby Chicken Creek pit lake (pH 3, containing approximately 8 million m3 of water) and make it suitable for cultivating plants or fish.

The first part of pit water treatment is a two-stage liming system utilising a fluidised bed of limestone. At each stage of liming there is a settling pond to remove particulate iron- and aluminium oxyhydroxides. From here the limed water gravity-feeds back to the lake though 5 ha constructed aerobic “polishing” wetland.

Photo: Fluidised liming of Chicken Creek pit lake water

Photo: Aerobic polishing of fluidised Chicken Creek pit lake water

This study is evaluating the way in which fluidised liming and aerobic wetland treatment can remediate pH and elevated metal concentrations in water from a typical recently groundwater-filled acid pit lake of Collie. Both water chemistry analyses and toxicity teas are being undertaken to evaluate water quality at each stage of treatment in order to better understand the processes taking place in this treatment system. The conclusions and recommendations of this project will enable better design of such systems for this mining region.

Influence of phosphorus and organic carbon on benthic productivity and ecological diversity in coal mine lakes.

Mark Lund (MiWER), Naresh Radhakrishnan (MiWER),  Clint McCullough (MiWER), Lorraine Wyse, Digby Short (Premier Coal)

Can amendments of organic matter and nutrient improve ecological values of abundance and biodiversity in coal mine lakes?

The objective of this project is to examine whether pit lake ecosystem values rather than water quality could be considered by regulators as criteria for accepting pit lake closure and relinquishment back to the state. Specifically, the project seeks to:

  • determine which nutrient is limiting in each of the two lake acidity types and what, if any, thresholds exist for the amount of nutrient that needs to be added to increase algal growth.
  • test whether additions of simple nutrients (N and P) can encourage significant improvement of ecosystem values in pit lake types  with different acidity;
  • examine the role that bankside vegetation may play in providing inputs of nutrients and habitat for increasing aquatic biodiversity environmental values.


Photo: Riparian vegetation around pit lakes is often sparse; but may be very important to lake ecosystem function.

Photo: Benthic chambers are used to measure benthic primary productivity.


Photo: Water quality data are collected by submersible logging sondes.



Lund, M. A.; Van Etten, E. J. B. & McCullough, C. D. (2013).Importance of catchment vegetation and design to long-term rehabilitation of acidic pit lakes. Proceedings of the International Mine Water Association (IMWA) Congress. Bunbury, Australia. Brown, A.; Figueroa, L. & Wolkersdorfer, C. (eds.), International Mine Water Association (IMWA), 1029-1034pp.