Montara oil spill

On 21 August 2009 the Montara wellhead platform drill rig owned by PTTEP Australasia suffered a well head accident, resulting in the uncontrolled discharge of oil and gas. The discharge of oil and gas was stopped on 3 November 2009.

The Australian Maritime Safety Authority coordinated the emergency spill response in accordance with Australia's National Plan to Combat Pollution of the Sea by Oil and Other Noxious and Hazardous Substances (the national plan).

The Department of the Environment, Water, Heritage and the Arts (now known as the Department of the Environment) engaged in the response through both a Wildlife Plan of Action and by taking on the role of Environmental and Scientific Coordinator under the national plan.

Montara Commission of Inquiry

On 25 May 2011, the Minister for Resources and Energy released the Australian Government's final response to the Report of the Montara Commission of Inquiry.

More information

Environmental monitoring plan

The Australian Government, in conjunction with the company responsible for the rig, PTTEP Australasia, developed a long-term environmental monitoring program to understand the longer term impacts of the spill on the marine environment. The plan, known as the Monitoring Plan for the Montara Well Release Timor Sea, consists of five operational monitoring studies - which were implemented during the response to the incident - and seven scientific monitoring studies. Implementation of the scientific studies is determined by information provided by the operational studies and components of other scientific studies.

Experts from the Australian Institute of Marine Science, CSIRO and relevant state and territory agencies provided input into the Plan and into its implementation to ensure that the monitoring program is appropriate and robust. The Plan covers both short-term and long-term environmental effects of the Montara oil spill, and includes marine life surveys, wildlife and habitat studies, continued water quality testing and shoreline ecological assessments.

Environmental monitoring studies

The views and opinions expressed in these studies are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for the Environment.

While reasonable efforts have been made to ensure that the contents of these studies are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of these studies.

Operational monitoring studies

Operational, or Type I, monitoring is undertaken during a response to an oil spill event. It is focused on providing information of use in planning or executing the response and provides data in a time-frame that is usable in that context. The environmental monitoring plan outlines five operational monitoring studies.

Scientific monitoring studies

Scientific, or Type II, monitoring is focused on non-response objectives such as estimating environmental damage and post response recovery. Scientific monitoring studies may be undertaken over extended periods.

Implementation of the scientific monitoring component of the environmental monitoring plan is managed by PTTEP Australasia in consultation with the Department, and drawing on the advice of a Technical Advisory Group. Individual studies are undertaken by contracted companies, institutions, government agencies or other parties. The environmental monitoring plan outlines seven scientific monitoring studies.

Recently released reports

Two reports developed under the environmental monitoring plan have recently been completed and are now available:

Questions and answers - Montara environmental monitoring - results

Study S6 - Surveys of the Sea Snakes and Sea Turtles on Reefs of the Sahul Shelf

What was the aim of the study?

This study aimed to quantify the presence of sea snakes and marine turtles in areas of the Sahul Shelf that were potentially impacted by the Montara oil spill.

How was the study implemented?

Two surveys were conducted (2012 and 2013) at six reefs in the Sahul Shelf region; three of these (Ashmore Reef, Cartier Island and Hibernia Reef) were considered to have likely been impacted by the Montara spill (based on operational monitoring at the time of the spill), while the other three reefs (Scott Reef, Seringapatam Reef and Browse Island) were considered to be unimpacted. An additional ‘unimpacted’ reef (Montgomery Reef) was surveyed in 2013.

Researchers assessed sea snake populations using a range of direct observation methods including manta board, snorkel, boat and foot transects, and spotlighting. Marine turtles were observed on reefs during manta board and boat transects. Blood samples were collected from foraging sea turtles at one ‘impacted’ site (Ashmore Reef) and one ‘unimpacted’ site (Montgomery Reef) to investigate potential contamination of diet. Turtle nesting activity was also recorded at sites with islands and cays. In addition, beaches, coral reefs and seagrass beds were inspected for any evidence of hydrocarbon contamination.

Data collected during these surveys was compared to data collected during previous studies (prior to the Montara spill).

What did the study find?

There is no evidence of the Montara spill having a long term impact on sea snakes or marine turtles in the Sahul Shelf region, however the limited baseline information, especially on sea snake populations, preclude ruling out any impact. The study highlighted the dynamic nature of sea snake populations in the region. There was no evidence of hydrocarbon residue on beaches, coral reefs or seagrass beds at any of the study sites.

No sea snakes were seen at Ashmore Reef or Browse Island, corresponding with historical data. There was a decline in sea snake abundance at Seringapatam Reef between the two surveys; sea snake counts were stable between surveys at all other sites.

Turtle nesting was recorded at Scott Reef, Browse and Cartier Islands and Ashmore Reef. Previous work indicates that the major breeding seasons at these locations was well prior to the Montara spill.

Foraging sub-adult sea turtles were abundant at Ashmore Reef. Blood chemistry analysis from turtles at Ashmore Reef and Montgomery Reef showed similar results, including liver function.

Study S5 - Offshore Banks Assessment Survey

What was the aim of the study?

This study builds on previous surveys in 2010 and 2011 and aims to characterise multi-year trends in ecological assemblages (benthos and fish) to understand natural variation and investigate any long-term impacts linked to the Montara oil spill of 2009. A particular focus was given to investigating changes noted during previous surveys, including the significant loss of seagrass at Vulcan Shoal noted in the 2011 surveys.

How was the study implemented?

Three of the nine previously-surveyed shoals (Barracouta East Shoal, Goree Shoal, Vulcan Shoal) were revisited in 2013. Barracouta East Shoal was considered to have received limited exposure to the Montara spill, based on distance and oil spill modelling. Goree and Vulcan Shoals, being closer to the well head, were considered to have received higher exposure to the spill; sediment sampling indicates that exposure at Vulcan Shoal was higher than at Goree Shoal.

To facilitate comparisons, survey methods and deployment sites were the same as previous surveys wherever possible. At each shoal, towed video and still photo transects were used to collect data on benthic habitat and biota, while Baited Remote Underwater Video was used to investigate fish assemblages.

What did the study find?

This study highlights that these shoals are highly diverse and subject to high levels of natural variability affecting both benthic and fish assemblages. Some results may indicate an impact from the Montara spill, but the lack of pre-spill baseline data precludes any ability to distinguish from natural variability.

The benthic communities at these shoals are dominated by algae, sponges and hard and soft corals. The latest surveys show a decline in coverage of most benthic biota – and a corresponding increase in coverage of macroalgae, sand/silt and rubble – at broad scales across the three shoals. The seagrass loss noted at Vulcan Shoal in 2011 has not recovered. In addition, an unusual soft-coral community at Barracouta East Shoal that was noted in 2010 and 2011 was absent in 2013. The broad scale of these general and specific declines indicate that the area has been subject to a major scouring event, such as a large storm (or series of storms). Further, the analysis of long term trends highlight that benthic assemblages on these shoals are subject to high natural variability.

Changes in fish community structure varied between shoals: at Barracouta East Shoal, both abundance and diversity increased when compared to expected values based on 2011 surveys, however there was a shift to smaller individuals; at Goree Shoal, abundance, diversity and size distribution were all consistent with expected values based on 2011 results; at Vulcan Shoal, abundance and diversity were decreased compared with expected values, but size distribution was stable. All of the noted differences were relatively small, however, when compared with variation between shoals noted in the 2011 and 2013 surveys.

This study noted a decline in numbers of Whitetip Reef Sharks, compared with previous surveys; the size of decline varied between shoals and was corresponded with relative exposure to the Montara spill but was not reflected in other common species of reef sharks, and so may be due to chance.

Wildlife plan of action

The Department was responsible for the implementation of a plan of action to help any wildlife that might be affected by the oil spill in Commonwealth waters and to respond to any possible impacts in Commonwealth marine reserves in the region. The Department worked closely with the Australian Maritime Safety Authority and other relevant federal and state agencies to implement the plan of action to help any wildlife that was affected by the oil spill in Commonwealth waters and to respond to any possible impacts in nearby Commonwealth marine reserves. The plan was developed by a wildlife expert from Queensland's Department of Environment and Resource Management who coordinated the wildlife response to the Moreton Bay oil spill.

Report Wildlife: if oil affected wildlife is observed in Commonwealth waters please see below for instructions on how to report the incident. Please report wildlife found in State waters to the Oil Pollution hotline on 08 9480 9924

For more information on the region visit

EPBC Act - national environment law

The then Minister for Environment Protection, Heritage and the Arts, Peter Garrett AM MP, formally exempted the company's use of a floating jack up oil rig to relieve pressure on the leaking oil well under the Environment Protection and Biodiversity Conservation Act 1999. He did this on grounds that it was in the national interest to do so because the consequences of allowing the spill to continue whilst an environmental impact assessment was prepared would have been far worse than any impacts that might arise from actions to stem the flow of oil.

Frequently asked questions

What is the impact to wildlife?

Have birds been affected by the oil spill?

A small number of birds found in the region were affected by the oil spill. The birds were identified as common noddies, brown boobies and sooty terns.

Who cared for the birds after they were found?

Birds found in the region were treated by a qualified wildlife expert on-site at Ashmore marine reserve. The process involved capturing the animal, stabilisation and providing onsite care; birds that required additional care were transferred to a veterinary clinic.

The Australian Government and the West Australian Government established a joint wildlife response centre at Broome. A suitable site was identified and prepared. Fortunately this centre was not required.

What happened to the animals after rehabilitation?

Rehabilitated wildlife recovered from the ocean were released back into the wild once wildlife experts considered them fully recovered.

What other wildlife was affected?

There were two confirmed reports of oil affected sea snakes and one green turtle collected in the vicinity of the oil spill.

No other confirmed reports of affected wildlife were received despite extensive aerial and water-based patrols in the area. There were no confirmed reports of oil affected whales or other cetaceans. There is no available evidence at this time to suggest that the migratory or breeding patterns of any wildlife have been affected. This will continue to be monitored in the long term.

What was the impact on ocean foods (e.g. sea grass) on which fish, birds and animals feed?

There are no sea grasses known to be in the immediate vicinity of the oil spill. However, the Australian Government, in conjunction with the company, is undertaking a number of steps to assess the impact of the oil spill. These assessments will provide a clear picture of the impact of the spill on the marine environment.

How can the public help?

Who should I contact if I find oiled wildlife?

If you observe oiled wildlife or habitat, contact the relevant state environment agency immediately. Instructions will be given over the phone to suit the specific situation.

If people in WA observe oiled wildlife in a coastal area they should immediately call WA's Oil Pollution hotline on 08 9480 9924.

Information that is useful in responding includes:

  • the time of day
  • the location of the animal
  • the general condition of the animal - how much oil is on it? is movement laboured?
  • identification of the animal to species level if possible
  • photographs of affected wildlife and/or affected surrounds
  • information on how many other individuals of the same species are in the vicinity (flying, swimming, nesting etc).