Dredging is the excavation of sediments from below water. Dredging can occur on the seabed in coastal areas, or on riverbeds or in estuarine environments. There are many different ways of dredging for sediments. Common techniques use ships or vessels, which dredge sediments using suction technology or motorised cranes.
Dredging can have significant environmental impacts. For example, some common environmental risks are:
- destruction of plants and animals that live on the seabed or riverbed where dredging takes place;
- turbidity and increased sediment around the dredging, which can reduce light to marine plants;
- release of toxic chemicals, including polychlorinated biphenyls (PCBs) and heavy metals into the water column;
- destruction of plants and animals that live in, or near to, the dredging area or depend on the area for their survival, with corresponding impacts on the food chain;
- disruption to marine species and fisheries from noise associated with dredging; and
- changes in the speed and direction of tidal currents, which can erode beaches and coastal areas, or cause increased sedimentation.
The legal regime for dredging in the Northern Territory
The law treats dredging in two ways, depending on whether the sediments are being mined, or being removed for some other purpose, such as creating or maintaining a shipping channel. Dredging for non-mining purposes is regulated by a suite of Northern Territory and Commonwealth legislation. Mining for sediments by dredging is additionally regulated by the Northern Territory’s mining laws.
Dredging for non-mining purposes may be controlled by the:
- Northern Territory Planning Act;
- Northern Territory Water Act;
- Northern Territory Fisheries Act;
- Northern Territory Darwin Port Corporation Act;
- Commonwealth Environment Protection (Sea Dumping) Act 1981; and
Dredging for the purposes of mining is additionally controlled by the:
- Northern Territory Mineral Titles Act and Mineral Titles Regulations; and
- Northern Territory Mining Management Act.
In both cases, if the dredging is likely to have a significant environmental impact, environmental assessment may be required. The laws which govern environmental assessments are:
- the Northern Territory Environmental Assessment Act and the Environmental Assessment Administrative Procedures; and
- the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
Dredging for non-mining purposes
Dredging for purposes other than mining most commonly includes dredging to provide navigational channels for shipping and boating; for the development of coastal infrastructure or aquaculture; or for waterway management such as flood plain management. Depending on the location of the dredging and the scale of the works, dredging for non-mining purposes may be controlled by a variety of Northern Territory and Commonwealth legislation, the requirements of which are discussed briefly below.
Northern Territory Planning Act
The Planning Act provides for the establishment of the Northern Territory Planning Scheme. The Planning Scheme contains provisions that include:
- statements of policy with respect to the use or development of land;
- provisions that permit, prohibit or impose conditions on a use or development of land;
- provisions that provide instructions, guidelines or assessment criteria to assist the consent authority in assessing development applications; and
- other provisions in connection with planning for, or control of, the use or development of land.
In some circumstances, dredging or the disposal of dredge spoil may constitute land use which requires consent under a land use control plan. The Development Consent Authority is responsible for provisionally approving developments under the Planning Act. Information about whether the Planning Act will apply is available from the Department of Lands Planning and the Environment.
Northern Territory Water Act
Under the Water Act it is an offence to cause waste to come into contact with or to pollute water that is flowing or contained in a waterway, groundwater or tidal water. Proponents of dredging projects may need to apply for a waste discharge licence under the Water Act. Further information about waste discharge licences is available from the NT EPA website.
Northern Territory Darwin Port Corporation Act
Where dredging is to take place in the Port of Darwin, as described in the Darwin Port Corporation Act, then the dredging will be subject to any by-laws developed by the Darwin Port Corporation. Dredging within the port waters requires the permission of the port manager to ensure that the proposed dredging design, safety and operational issues are satisfactory.
Northern Territory Fisheries Act
Under the Northern Territory Fisheries Act, unless it is done in accordance with a permit, it is an offence to:
- cause or permit a shock, sound or other vibration which stuns, injures, kills or detrimentally affects fish or aquatic life; or
- directly or indirectly introduce, cast, place, discharge, or allow to fall, flow, or percolate or be carried by wind, tide, or current a substance into waters of the Territory where an effect of the substance is, or may be, that fish or aquatic life are stunned, injured, killed, or detrimentally affected.
Additional requirements may also apply if the dredging is to take place in an area subject to a fisheries management plan.
Commonwealth Environment Protection (Sea Dumping) Act 1981
Under the Environment Protection (Sea Dumping) Act 1981, it is a criminal offence to dump, or load for the purposes of dumping, any wastes or other matters into Australian waters, or from an Australian vessel or platform, anywhere at sea, accept in accordance with a permit. The Commonwealth Department of the Environment overseas the permit application and assessment process and publishes National Assessment Guidelines for Dredging which provide details of the assessment framework.
Dredging for Mining
In addition to the requirements set out above, mining for sediments by dredging is regulated by the Northern Territory’s mining laws.
Dredging for the purposes of mining is typically for sediments which are categorised as “extractive minerals”. Under the Mineral Titles Act, extractive minerals are sand, soil, gravel, rocks, peat and any other substance prescribed by regulation.
Dredging for the purposes of mining may also be for substances which are classified as “minerals”. Under the Mineral Titles Act, minerals include any naturally occurring inorganic element or compound, any organic carbonate compound, coal, lignite, oil shale or salt but do not include extractive minerals, petroleum or water. Mining for minerals on the seabed is subject to a moratorium that ends in 2015. For information about mining for minerals on the seabed, read our Fact Sheet on Seabed Mining.
Before a company can mine extractive minerals by dredging, it must hold a title under the Mineral Titles Act to explore for, extract or mine extractive minerals. The different types of titles in relation to extractive minerals are:
- an extractive mineral exploration licence (called an EMEL in the Mineral Titles Act);
- an extractive mineral permit (called an EMP in the Mineral Titles Act); and
- an extractive mineral lease (called an EML in the Mineral Titles Act).
These approvals are explained below.
All dredging activities for the purpose of mining must also hold an Authorisation under the Mining Management Act. For more information about Authorisations, read our Fact Sheet on Environment Protection and Minerals Mining.
Extractive mineral exploration licence
An extractive mineral exploration licence (EMEL) allows the holder to occupy the licence area and explore for extractive minerals and conduct any other activities reasonably necessary for the exploration.
Extractive mineral permit
An extractive mineral permit (EMP) allows the holder occupy the title area specified in the EMP and to extract extractive minerals at the natural surface of the land only. Among other things, it also allows the permit holder to:
- temporarily store and process extractive minerals in the title area; and
- remove extractive minerals from the title area.
Extractive mineral lease
An extractive mineral lease (EML) allows the holder to occupy the title area specified in the EML and to mine for extractive minerals. Among other things, it also allows the lease holder to:
Approvals, objections and submissions
The Minister for Mines and Energy is responsible for approving exploration and mining of minerals and extractive minerals by dredging. There is a process that allows people to make objections and submissions against the grant of:
- an extractive mineral exploration licence;
- an extractive mineral permit;
- an extractive mineral lease; and
- a mineral lease.
There is no right to make objections against the grant of an Authorisation under the Mining Management Act.
A detailed overview of the objections and submissions process is provided in our Fact Sheet on Mining for Minerals and Extractive Minerals.
If dredging is likely to have a significant environmental impact, it will require an environmental impact assessment. For more information about the environmental assessment of mining operations, read our Fact Sheet on Environmental assessment of mining activities.
In 2013, the Northern Territory EPA published for public comment a set of draft Guidelines for the Environmental Assessment of Marine Dredging in the Northern Territory (Guidelines). These Guidelines have been prepared primarily to apply to dredging for non-mining purposes and have not been finalised. They do however provide guidance about the obligations and requirements that proponents of dredging projects should take into account.
Commonwealth Environment Protection and Biodiversity Conservation Act 1999
At the Commonwealth level, the EPBC Act requires that a person must not take an action that has, will have, or is likely to have a significant impact on a matter of national environmental significance, unless the action is taken with Commonwealth Government approval.
Whether or not dredging will impact on a matter of national environmental significance will depend on the circumstances and scale of the activity. Further details on the assessment and approval process are provided by our Fact Sheet on Commonwealth Environmental Impact Assessment.
Environmental Assessment and Mining
In relation to mining for minerals or extractive minerals by dredging (or otherwise), there is no requirement in the Northern Territory environmental impact assessment laws, or in the Mineral Titles Act, for the Minister for Mines and Energy to take into account the outcome of an environmental impact assessment when he or she decides whether or not to grant an exploration or mining approval.
If exploration or mining is approved under the Mineral Titles Act, the law that attempts to deal with environment protection is the Mining Management Act. This requires a mining company to hold:
- an Authorisation under the Mining Management Act; and
- an approved Mining Management Plan under the Mining Management Act
The Minister for Mines and Energy must consider the outcome of an environmental impact assessment when he or she decides whether or not to grant a mining Authorisation. If the Minister for Mines and Energy decides to grant an Authorisation, he or she can put conditions on an Authorisation that relate to the protection of the environment, the outcome of an environmental impact assessment or require the operator to make an environmental mining report available to the public at specified intervals.
For more information about environment protection under the Mining Management Act read our Fact Sheet on Environment protection and minerals mining.
 Approvals under the Mineral Titles Act are not required for the extraction of extractive materials if the extraction is incidental to a construction work: see s12(3) and s50(3) Mineral Titles Act.
 Exactly which legislation will apply will depend on the circumstances of the case, the location of the dredging and the scale of the works. There is no regulatory framework for works at sea or coastal areas, such as the equivalent to Victoria’s Coastal Management Act.
 Dredging is regulated under the Mineral Titles Act and associated Regulations; see s 12(1)(c) which specifically includes dredging in the definition of mining; s 5(2) which applies the Act to all water on the land and all coastal waters of the Territory. Northern Territory coastal waters are areas within 3 nautical miles of the Northern Territory coast.
 Relevantly: s 35(3)(f) of the Mining Management Act applies to extracting resources from the surface of the land, underground, riverbeds or under the sea; s 35(k) applies to active remote sensing and seismic techniques in water.
 Water Act, s 16.
 Water Act, s 74.
 Darwin Port Corporation Act s 48
 Fisheries Act, s 15(c) and (e)
 Environment Protection (Sea Dumping) Act 1981, s 10A.
 Mineral Titles Act, s 10
 Mineral Titles Act, s 9
 Dredging is specifically included in the definition of mining in s 12 of the Mineral Titles Act.
 Mineral Titles Act ss 46(1) and 34
 Mineral Titles Act ss 50(1) and 53
 Mineral Titles Act, ss 50(1)(b) and 53
 Mineral Titles Act, ss 50(1)(b) and 53
 Mineral Titles Act, s 54
 Mineral Titles Act, s 57
 Mineral Titles Act, s 57
 The Minister is responsible for administering the Mineral Titles Act and the Mining Management Act.
 Section 82(c) of the Mining Management Act requires the Minister to consider the outcome of an EIA when exercising powers under the Act.
 Mining Management Act, s 37(3)(b)