The Marine chapter of the 2021 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "Pressure of Dumped Wastes".
A PDF of the full Expert Assessment, including figures and tables (where provided) is downloadable in the "On-line Resources" section of this record as "EXPERT ASSESSMENT 2021 - Pressure – Dumped Wastes"
DESCRIPTION OF PRESSURE
Dredging associated with the development or maintenance of port facilities around the coast of Australia is a necessary and unavoidable activity for port operations and safe passage of ships, and is therefore important to the continuity of the Australian economy. Materials dredged in nearshore areas (falling in the coastal environment for the purposes of SoE reporting) are most commonly disposed of by placement on the sea floor in specially designated areas. By volume, this is by far the greatest source of “dumped waste” as a pressure on the Australian marine environment.
The areas selected as disposal sites and the nature of disposed dredged material at sea are regulated to minimise the risk of marine organisms being exposed to toxic materials and that the sites chosen are the most likely to be minimally affected by the application of additional sediment (Ports Australia 2014). Pressures arising from this practice include direct burial of biota as well indirect impacts such as increased turbidity and reduced underwater light levels from resuspension of sediments placed on the sea floor. While the footprint of disposal sites is relatively small on the scale of Australia’s continental shelf, the area affected by remobilised material is potentially larger and less well known (McCook et al 2015, Mills & Kemps 2016; WAMSI 2019).
DATA STREAM(S) USED IN EXPERT ASSESSMENT
Dredging activity reported to the DAWE Sea Dumping Section by sea dumping permit holders under the Environment Protection (Sea Dumping) Act 1981.
2021 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]
• 2021 •
Assessment grade: Low impact
Assessment trend: Stable
Confidence grade: Somewhat adequate
Confidence trend: Somewhat adequate
Comparability: Grade and trends are somewhat comparable to the 2016 assessment
• 2016 •
Assessment grade: Low impact
Assessment trend: Deteriorating
Confidence grade: Adequate high-quality evidence and high level of consensus
Confidence trend: Adequate high-quality evidence and high level of consensus
Comparability: Grade and trends are somewhat comparable to the 2011 assessment
• 2011 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus
CHANGES SINCE 2016 SOE ASSESSMENT
The assessed grade is consistent with 2016, but the trend has changed from ‘deteriorating’ to ‘stable’ and confidence from ‘adequate’ to ‘somewhat adequate’. The change in trend reflect a stabilisation/decrease in at-sea dumping activity over the 2016-2021 period, based on available data. The decrease in confidence reflects the fact that state data could not be obtained for the 2016-2021 period.
