Article Index

Contaminants

Non-nutrient contaminants include metals, pesticides and petroleum hydrocarbons that are typically the result of historic and current agricultural, urban and industrial activities.

In the Swan Canning Riverpark, non-nutrient contaminants of potential concern include:

  • metals (e.g. mercury, zinc, lead and copper)
  • pesticides and herbicides (e.g. DDT and dieldrin)
  • polycyclic aromatic hydrocarbons (PAHs)
  • petroleum hydrocarbons (e.g. BTEX)
  • polychlorinated biphenyls (PCBs)
  • organotins (e.g. TBT)
  • anionic surfactants (e.g. detergents)
  • litter (e.g. plastics and fishing line)

These can enter the Swan Canning river system through drains, tributaries, groundwater, in-river activities such as recreational boating and the disturbance oacid sulphate soils.

Many contaminants bind to sediment particles and settle on to the riverbed and may persist in the environment for many years. Contaminated sediments may be re-mobilised if disturbed through activities such as dredging. Environmental conditions including low pH, decreased oxygen and increased microbial activity can also cause sediment-bound contaminants to re-enter the river system and become more biologically available.

Depending on the nature and concentration of these bioavailable contaminants, they may have an immediate (acute) toxic effect on aquatic life or they may have sub-lethal effects over longer timeframes (chronic toxicity), such as reduced reproductive capacity.

Metals and some persistent organic contaminants (e.g. organochlorine pesticides) can enter the food chain in the river through uptake by algae or filter feeders like mussels and invertebrates. Once in the food chain, these contaminants can accumulate and concentrate in the tissues of the animals that consume them such as fish. Birds, dolphins and humans may be susceptible to contaminants when they consume affected seafood.

Investigating and managing non-nutrient contaminants

The Non-Nutrient Contaminants Program (NNCP) was initiated in 2006 to investigate the nature and extent of contaminants other than nutrients in the Swan Canning estuary, its catchment and drainage network. Baseline surveys, completed in 2009, identified a range of pollutants of potential concern in the Swan Canning estuary and its tributaries.

Subsequent investigations (2009-13) focused on possible impacts of contaminants on biota at priority areas identified in the baseline surveys and guided management options to reduce the impacts of contaminants entering the river system. Notably, these investigations determined that some sediments were toxic to a range of aquatic organisms, however the Department of Health has indicated that no public health concerns were identified.

In addition, surveys of sediment and mussel tissue in the vicinity of yacht clubs suggested these sites were potential sources of environmental contaminants such as Tributyltin (TBT) and metals through historic and present-day anti-fouling practices.

Following from these investigations into environmental contaminants, Parks and Wildlife with support from the departments of Health and Fisheries developed a robust methodology for determining consumption guidance for wild-caught fish in the Swan and Canning rivers. This pilot study focused on the most popular recreational angling species in the estuary, black bream (Acanthopagrus butcheri) and confirmed that metal and organic contaminants found within the system do not restrict the consumption of this species by recreational anglers.

The Department of Health advises that the public should not consume shellfish  (e.g. mussels, clams, scallops and oysters) collected from any uncontrolled site, including the Swan Canning Riverpark.

Reducing contamination of our waterways

Working with yacht clubs: Parks and Wildlife works collaboratively with yacht clubs to maintain and implement Environmental Management Systems to ensure there is no ongoing release of TBT to the river system and best management practices are adopted to minimise contamination from other anti-fouling products.

Pollution response: Parks and Wildlife officers respond to pollution incidents (including sewage spills, fuel and oil spills and chemical spills) affecting the Swan Canning Riverpark. The department has targeted pollution response plans and officers are equipped to contain and clean up a wide variety of pollutants. Depending on the nature and extent of the pollution, the response may also involve the Department of Environment Regulation, the Department of Transport or other authorities. Officers investigate causes of pollution and are authorised under the Swan and Canning Rivers Management Act 2006 and the Environmental Protection Act 1986to commence prosecutions if warranted. Fines for pollution range from $200 infringements for minor offences up to $250,000 for major offences.

Drainage management: Under the Drainage and Nutrient Intervention Program, Parks and Wildlife has in place a series of approaches aimed at reducing the movement of nutrients through the drainage system. Many of these approaches also reduce the movement of non-nutrient contaminants.

Educating the community: There is a common misconception that stormwater drains connect to the sewer or a wastewater treatment system. The reality is that whatever enters the drains is discharged into the nearest waterway or fed into groundwater through the stormwater network without treatment. Through its Clean Drains, River Gains campaign, Parks and Wildlife is installing kerb markers and stencils at key locations throughout the catchment to help foster community awareness.

If you see pollution affecting the Swan and Canning rivers, please report it to Parks and Wildlife during office hours on (08) 9278 0900, or contact our after-hours duty officer on 0419 192 845.

If you see pollution in locations that do not affect the Swan and Canning rivers, please report it to the Department of Environment Regulation’s 24-hour pollution watch hotline on 1300 784 782 or via their website.


Downloads

Non-nutrient Contaminants Program

Phase I

Phase II

Phase III

Yacht club sediment and mussel tissue surveys

Consumption guidance