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Flood impacts

Flood events are a natural occurrence following long periods of drought that can have significant detrimental impacts but can also provide important environmental benefits.

Floods help spread organic material, nutrients, and sediments which enrich the floodplain. They also replenish water resources and trigger life processes (such as breeding events, migration, and seed dispersal) in flora and fauna adapted to these cycles, while good soil moisture can allow crops and pastures to be established.

The time scale over which losses and benefits of a flood are a critical factor in examining the impacts of a flooding event.  In the short term, an individual flood event may appear to be an ecological disaster, with unsightly deposition of sediment and debris, destruction of plants and animals, and even local species extinctions. However, in the long term, flood events that are part of the natural cycle will ensure the long-term viability of the plants and animals adapted to flood prone environments and the functioning of those ecosystems.  They also replenish ground water, surface water and drinking water supplies.

The severity of floods is dependent on natural water movement across drainage divisions and river basins, and is affected by land use and management practices. Built infrastructure and land clearing can affect the natural flow of water across the landscape, and can increase the velocity of surface water flows and consequential damage.

The 2010-11 flood events and the Queensland Floods Commission of Inquiry

The 2010-11 wet season brought unprecedented rain and flooding to Queensland, resulting in 35 people tragically losing their lives and the declaration of 78% of the state as a disaster zone. 

The scale of the disaster led to the establishment, on 17 January 2011, of the Queensland Floods Commission of Inquiry to examine the event leading to the floods, all aspects of the response and the subsequent aftermath, and to make recommendations about things that could be improved for the future. 

The 177 recommendations contained in the Commission’s Final Report were delegated for delivery by the Queensland Government to one of five implementation groups, each chaired by a Director-General. 

The Director-General of the Department of Environment and Heritage Protection (EHP) chaired the Environment and Mines Implementation Group (EMIG), which was responsible for the delivery of all recommendations from Chapter 13 of the Commission’s report. 

During 2012-13, all Chapter 13 recommendations assigned to EHP were completed. The remaining two recommendations pertaining to the management of abandoned mines will be finalised by the end of 2013. 

In meeting its responsibilities, the Queensland Government has developed a range of responses and tools to better prepared for extreme weather events, and support the resource industry to recover from these events when they occur.  They include:

  • The implementation of new risk assessment approach and pre-wet season mine inspections which increased preparedness for the 2012-13 wet season
  • Providing assistance to mine operators in applying for amended environmental authorities
  • Incorporating model conditions for discharges to facilitate water releases whilst ensuring the protection of the environment
  • Making amendments to the Environmental Protection Act 1994 to allow for Temporary Emissions Licences to authorise the discharge of water in response to emergency events, such as those associated with ex-Tropical Cyclone Oswald in January 2013
  • Undertaking reviews of, and designing improvements to, the management of abandoned mines in Queensland
  • Improving data capture and monitoring systems across government, through the design of a new Point Source Database – the “Wastewater Tracking and Electronic Reporting System” (WaTERS) to monitor mine discharges
  • Enhanced monitoring to ensure mine water releases do not cause adverse impacts upon freshwater or marine water quality, flora or fauna.

Fitzroy Basin - A case study of the 2010-11 flood events

One of the recommendations of the Queensland Floods Commission’s Final Report, tasked EHP  “to determine, as far as possible, the impact of mine discharges during the 2010/2011 wet season on freshwater and marine water quality, and flora and fauna” (Recommendation 13.6). 

The investigation was directed by both the Commission’s recommendation and the government response to it. It led to the production of a report “Assessing the impact of mine discharges during the 2010-11 wet season: Prepared in response to Recommendation 13.6 of the Queensland Floods Commission of Inquiry Final Report and the Queensland Government Response”. 

A case study, focusing on the Fitzroy Basin was used for this investigation.  This region was selected because of the proximity of this mining region to the Great Barrier Reef, and because the Lower Fitzroy River is the source of Rockhampton’s drinking water supply.

The investigation found that most of the surface water flows that were captured on mine sites during the 2010-11 wet season were unable to be discharged to the system in this region. 

 As a result, although an estimated 6.7 million megalitres of water was reported to have flowed past Rockhampton, only 33,500 megalitres, or 0.5% of the total water flow, was sourced from coal mine releases. 

It is further estimated that more than 280,000 mega litres of water remains stored in mines pits in this region.

Due to the relatively small volume of water discharged from mines in the Fitzroy region, compared to the volume flowing during the 2010-11 wet season, the study found that mine discharges did not significantly contribute to environmental impacts. However, the report also found that because flood waters from this event were captured on mine sites, the impacts associated with their release are yet to be determined, and will require good management of mine sites to prevent further water accumulation and effective licensing to ensure that releases do not impact the aquatic environment.

Government Response and Recommendation 13.6 report (PDF, 183K)*.

The 2010-11 flood events and its impact on the environment

What were the general environmental impacts of the 2010–11 flood events in Queensland?

The 2010–11 flood events had significant impacts on terrestrial biodiversity, habitats, and wildlife.  In some areas, flood waters rose slowly, allowing many animals to escape immediate effects. However in other areas, the impact of fast flowing water, particularly on small or burrowing animals would have been more serious.

Food and habitat shortages presented longer-term impacts on those that survived, and specific programs were designed to assist some endangered species, such as the cassowary and the mahogany glider, to recover. 

The impact on freshwater systems was more positive than had been expected, with some streams and estuaries actually improving in condition as a result of the positive influence of high water flows. Similarly, inundations to wetlands supported the establishment of biological diversity, and allowed the spread and breeding of waterbirds across the state.

The major impacts on marine environments were associated with: sedimentation and turbidity; litter and human-built waste deposited from the land; toxicants, nutrients and mineral deposition; algae and phytoplankton blooms; and reduced salinity, associated with freshwater plumes to marine environments.

These impacts affected the health of the seagrass and coral communities along the coast, and those species on which they depend. Dugong and turtle strandings increased dramatically following the flood events, while dolphin deaths also increased. Other impacts were associated with stress following the displacement of fish from their former territories.

Did mine water discharges during the 2010–11 flood events have an environmental impact?

Surface water flows over cleared or mined landscapes and the discharge of captured flood waters on mine sites have the potential to cause erosion, increase the sedimentation of water courses and to contribute to freshwater flows and turbidity impacts in marine environments.

To determine the contribution of mine water discharges to observed flood impacts during this event, release volumes were compared to total water flows in the Fitzroy Basin. 

This analysis found that an estimated 6.7 million megalitres of water was reported to have flowed past Rockhampton during the 2010-11 flood events. Yet only 33,500 megalitres of this total, or 0.5% of the total water flow, related to coal mine water releases. 

Due to the relatively small contribution that mine water releases had upon total water flows during the 2010–11 flood events, the contribution of mine water to flood related environmental impacts was negligible.

How were mine water releases regulated in 2010-11?

The government regulates mining in accordance with a suite of legislation, with operational conditions for any activities that have the potential to cause environmental harm managed in accordance with the Environmental Protection Act 1994.

Under this Act, the government issues environmental authorities to resource companies which provide site-specific requirements for the release of mine-affected water. 

To take advantage of dilution opportunities, water releases were, and continue to be, generally linked to rainfall events and natural flows in receiving waters.

Environmental authority conditions are developed in consultation with resource companies using all available data to ensure that they are not only site specific, but provide protection to the environment and water users downstream of the mine. 

What was the impact of this regulatory framework upon mines?

The regulatory framework that was in place during the 2010–11 flood events was argued to have hindered the ability of mines to respond as they needed.

Transitional environmental programs (TEPs) were sought to provide a means by which mine managers could operate outside of their agreed environmental authority, allowing more flexibility in discharge arrangements. 

Once approved, TEPs allowed mines to release water during high flow events, with most TEPs allowing higher electrical conductivity in releases; an extension of time to discharge; reduced receiving water flows and amendments to monitoring requirements.  

Were the mine water releases in 2010-11 safe?

An examination was undertaken of regional data on discharges from 16 mines during the 2010–11 wet season to determine the composition of the water discharged, and to identify the metals and metalloids that the releases potentially contained. 

This analysis found that many elements were below the model water conditions for coal mines in the Fitzroy Basin, and those imposed in environmental authorities. However, for nine of the examined sites potential exceedences of trigger values were observed. These were for salinity and turbidity, as well as aluminium, ammonia, chromium, copper, iron, lead, molybdenum, nickel, selenium, sulfate, uranium, vanadium and zinc.

Because these releases occurred during times of high natural stream flow associated with flooding, the dilution effect meant that they did not result in significant environmental harm. Nevertheless, where detected, non-compliances were investigated, and penalties imposed in accordance with the department’s enforcement guidelines (PDF, 163K)*.

Was all the flood water captured on mine sites released?

Although mine water releases only contributed to 0.5% of total water flows during 2010–11, unreleased flood waters captured during this event still remain on mine sites. It is estimated that more than 280,000 megalitres of ‘legacy water’ is still stored on mines in mine pits. This equates to over 110,000 Olympic-size swimming pools of water.   

The longer this water is stored on mines, the more it will deteriorate in terms of water quality. In addition, until it is discharged, it is also preventing mines operating at their full capacity. 

The Queensland Government is undertaking a range of activities to work with industry to release this stored water in a manner that ensures the delivery of a safe and secure water supply for the community, and the protection of the environmental values of our state’s freshwater and marine environments.

Queensland Government actions to improve mine water management since the 2010-11 flood events

How has the regulatory framework been improved to prevent the accumulation of water on mines in the future?

The Queensland Government has developed a package of initiatives to improve coal mine water management, especially in times of floods. These initiatives include feasibility studies, pilot programs, enhanced water quality monitoring, the provision of increased support to industry, and the introduction of new regulatory tools.  In addition, a range of mechanisms to support the mining industry to be able to manage the impact of floods have been introduced, including:

  • model conditions that allow higher discharges of mine water during high flow events (maximising the dilution of mine affected water) have been developed
  • amendments have been made to the Environmental Protection Act 1994 to streamline assessment processes, and to allow authority condition changes during emergency and flood event.

The department also undertakes a pro-active compliance program where risk-assessed mine sites are inspected prior to the wet season each year to determine their preparedness and to identify any issues that may be present on site, prior to the wet season. This gives operators the opportunity to take any actions necessary to ensure compliance with EA conditions, to prevent the further accumulation of legacy water, and to ensure unauthorised releases do not occur.

What new regulatory tools are now available?

Temporary emissions licences (TELs) are a new authority available to be issued under the Environmental Protection Act 1994 to allow for a fast response to emergent events.

A TEL is a permit that temporarily relaxes or modifies specified conditions of an environmental authority (EA). A TEL is a flexible tool that can be used to appropriately manage the environmental impacts of contaminant releases to the environment during emergency events, where the original approval has not reasonably anticipated such an event.

For mine water releases, TELs allow a quick response to flow events that can allow for releases during the appropriate flow volumes so that the releases have very low risk of impact. TELs can also be used to reduce risks to mine water being released uncontrollably during big flow events.

In 2013, 15 TELs were issued to a range of industries and businesses including mines, sewage and water treatment plants and landfills. In the Fitzroy Basin, three TELs were issued to coal mines to allow the release of 5,231 ML of mine affected water. Since the commencement of the 2012-13 wet season, the total volume of water released from coal mines in the Fitzroy Basin equates to 0.36% of total flows past The Gap gauging station.

Managing the legacy water that remains in mine pits from the 2010-11 flood events

How is legacy water being managed?

In response to the volume of legacy flood water that remained on mine sites following the 2010–11 wet season, four coal mines in the Fitzroy region were provided approval to conduct an enhanced mine water release pilot during the 2012–13 wet season.

Under this pilot program, these mines had their environmental authorities amended to allow the release of accumulated water under certain natural water flow conditions.

Over the 2012-13 wet season there were four flow events that were sufficient to allow the release of around 10,000 megalitres of stored water without affecting drinking water quality or the marine environment.

This pilot is part of a long-term strategy to improve mine water management across the Fitzroy Basin, and it was closely regulated by the Department of Environment and Heritage Protection. 

How were the four mine sites that took part in the 2012-13 wet season pilot project selected?

The four pilot mine sites—Goonyella Riverside; Peak Downs; Saraji; and Norwich Park—in the upper Isaac River, were selected to be involved in the pilot program because they had the infrastructure to be able to remove large volumes of water from their pits. 

Further, because they were all part of the same group of companies—BHP Billiton Mitsubishi Alliance (BMA)—this provided the government with greater control over the coordination of releases, as well as their cessation, if this was necessary. 

How were risks associated with the 2012-13 wet season pilot project managed?

Legacy mine water has the potential to contain significant amounts of salt.  To monitor the effects of the 2012-13 mine water release pilot project, the Queensland Government established an expanded water monitoring program which collected, analysed and interpreted the results of water samples at key sites in the catchment independent of the mining companies.

Fitzroy River Enhanced Monitoring Program Sites (PDF)*.

The Isaac Pilot Operational Policy developed by EHP, guided the monitoring of pilot water releases to ensure downstream drinking water supplies and aquatic ecosystems of in-stream salinity levels in the Isaac River were not affected by the program.

Water quality monitoring was undertaken by the Department of Natural Resources and Mines to ensure overall compliance and also to manage the cumulative impacts of multiple releases in order to ensure regional water quality objectives were maintained.

To evaluate the potential for the program to be rolled out to other sites, data collected through the pilot program was used to inform the overall regulatory response. In addition, the four mines involved were also required to undertake additional monitoring.

Linking water quality to monitoring and regulatory activities, capacity was provided in the program to require participants to cease the release of water should monitoring indicate cause to do so. Decisions to allow releases or cessations were linked to stream flows, rainfall forecasts, and expert hydrology and water quality advice.

What did the water quality monitoring of the 2012-13 wet season pilot project find?

Monitoring associated with the 2012–13 wet season and the legacy mine water releases through the pilot project is complete. 

The results can be found on the Managing Fitzroy River water quality website.

While there was no effect on drinking water quality, some exceedences of aesthetic guidelines for the environment and drinking water were recorded.

Most of these exceedences occurred across all monitored sites in the region, not just those impacted by releases by the four mines. 

As in previous years, mine water releases would have had a minimal impact with total mine water releases during the 2012–13 wet season, representing only 0.3% of the total volume of water flows through the system.

How is legacy water on mines not involved in the 2012-13 wet season pilot project going to be managed?

In recognition of the success of the pilot program, the Queensland Government intends develop a Pilot Operational Policy for the whole of the Fitzroy Basin for the 2013-14 wet season.

As part of the development of this operational policy, the health of residents, the needs of downstream agricultural users, and the protection of the environment remain of paramount importance and will be properly balanced with the need to release legacy mine water.

The government will undertake detailed discussions with coal mine operators before the 2013-14 wet season to identify the optimal solutions that may be available for each mine.

To protect the environment, drinking water quality, and the suitability of freshwater resources for agricultural uses, releases will continue to be linked to water flows, and water quality monitoring will continue to form the basis for site specific water release authorisations. 

In addition to designing a process for its release, the cumulative impact of multiple discharges will be managed, and sufficient water quality and composition data collected and analysed to anticipate and respond to exceedences, change, or perverse outcomes should they arise in order to ensure impacts upon drinking water quality or environmental condition do not occur. 

How are the remaining residual materials at the bottom of mine pits going to be managed?

As the volume of legacy water is reduced, the soils and residual materials at the base of mine pits will be managed on a case-by-case basis under their current environmental authorities.

Currently mines have the ability to deal with certain wastes on site or to dispose of them to an appropriate facility. The treatment and disposal of residual material would be based on assessment of the content of the material. This issue will be addressed prior to the final drawn down of any legacy water pit.

Ongoing Queensland Government water monitoring activities

How are mine water releases continuing to be monitored?

The monitoring of contaminants released from mines and their potential impact on the marine environment is primarily at the release point as this is where the environmental impacts are likely to be greatest. 

Mines are required, by conditions of their EA, to monitor the impacts of any mine-affected water releases and report the findings EHP. This data is then used to develop updated conditions and to identify trends and impacts that may result in changes to a mine’s EA.

During times of heavy rainfall and flooding, EHP staff also monitor the impact of floods on mining operations located in the region, remaining in constant contact with mines and actively seeking information about impacts on production and any water management issues on site.

This allows EHP to make informed decisions within a short timeframe to potentially reduce the impact of floods on mining operations.  This monitoring work complements pre-wet season mine inspections undertaken as part of core business associated with regulating mining activities.

What other water quality monitoring activities are being undertaken by the Queensland Government?

EHP is also working with other government departments to oversee the completion of their Queensland Floods Commission of Inquiry recommendations and to improve water quality monitoring. 

This includes work undertaken by the Department of Science, Information Technology, Innovation and the Arts, to develop a point source database (the Waste Water Tracking and Electronic Reporting System (WaTERS) database) for water quality monitoring data obtained from mine operators.  This database will allow companies to submit their monitoring data electronically, and enable more rapid compliance checks, better sharing of data, and allow the cumulative impacts on water quality to be assessed by monitoring releases against the naturally occurring thresholds and Queensland water quality objectives.

More broadly, the Queensland Government is also working collaboratively with the Commonwealth Government, the Great Barrier Reef Marine Park Authority, and mine operators through the Fitzroy Partnership for River Health, to share available data, and prepare an annual report card on the health of the waters in the Fitzroy Basin.

The government’s Reef Water Quality Protection Plan also provides a strategy for improving the quality of water in the Great Barrier Reef though improved land management in reef catchments, including the Fitzroy Basin.

What are the long term water management plans to reduce salinity in the Fitzroy River catchment?

Developing a long-term solution to reduce salinity levels in the Fitzroy River catchment has been recognised as essential to safeguard water quality and sustain economic development.

The Queensland Government is committed to developing a rigorous, scientific-based program for salinity management.

Market-based instruments such as a salinity trading scheme, may provide a cost-effective long-term mechanism to improve catchment water quality. Salinity trading is premised on the fact that each river system has a capacity to accept specific salt loads under different flow conditions. Releases of water are made during flow periods when the river has the capacity to absorb a salt load without impacting on the environment. Stored mine water could then be discharged when there are good natural flows of low salt, fresh water in the river.

In these programs, results from monitoring along the river are used to determine when discharges are possible and credit trading manages the total amount of salt that can be discharged.

Building on existing information, previous studies and the information obtained from the pilot, the government is assessing the feasibility of a salinity trading scheme.

The first stage report is scheduled to be completed in 2013. This study will be an important step towards a strategic approach to improving mine water management and water quality.

More information on this initiative is available on the Managing Fitzroy River water quality website.

Queensland Government marine fauna monitoring activities

How does EHP monitor the impact of floods events on marine fauna?

In addition to water quality monitoring, EHP also monitors the impacts of flood events upon the marine environment.

This includes monitoring:

  • fluctuations in the annual breeding rates of freshwater turtle species in the lower Fitzroy as an index of turtle population dynamics in response to river conditions
  • green turtle health indices in foraging populations within Port Curtis and additional control sites removed from out flow from rivers with extensive mining in the catchment
  • the temporal and spatial occurrence of sick, injured and dead marine wildlife (turtles, dugong, whales, dolphin) in Queensland.

This monitoring data is collated in the department’s stranding database, StrandNet, along with cause of death where this has been established.  Information on marine wildlife strandings has been recorded since 1996 along the eastern Queensland coast from Mossman to the New South Wales border.

The statewide stranding data for dugong, marine turtles and cetaceans (whales and dolphin) is summarised for each year in the annual stranding reports.

Has the monitoring found any long-term impacts of the 2010-11 flood events on marine fauna?

Following observations of increased strandings post the 2010-11 wet season, EHP biologists in collaboration with university veterinarians, toxicologists and disease specialists have been monitoring the health and condition of green turtles foraging throughout eastern Queensland. In addition, fluctuations in the size of the annual nesting population are also monitored annually at multiple beaches.

While there were unprecedented high mortalities of green turtles and dugong during 2011, there has been a progressive decline in the annual stranding rate through 2012 to the present in 2013.

However the current rate of strandings for green turtles still exceeds the stranding rates recorded during the years preceding the 2010–11 floods.

Monitoring results have also established that the number of nesting female turtles visiting beaches during the 2012–13 breeding season was extremely low.  However, monitoring undertaken in the foraging areas showed green turtles in abundance, but not in breeding condition.

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Last updated
5 September 2013