Everyone lives and works in a river catchment. Everything you do in your backyard, your school playground, your farm or your business then has the potential to affect waterways lower down the catchment, and ultimately the ocean and marine life.
Even little things you do in your part of the catchment can help prevent big problems like toxic algal blooms elsewhere in the system.
What is a catchment?
A catchment area or basin is land which is bounded by natural features such as hills or mountains from which all runoff water flows to a low point. This low point will be a dam, a location on a river, or the mouth of a river where the water enters a bay or the ocean.
It's just like water in a bathtub flowing to the plughole, or water that falls on a roof flowing to a downpipe.
Catchment areas vary in size and make-up. Large catchment areas such as those drained by the Burdekin and Fitzroy Rivers are bordered by mountain ranges and include major drainage networks of creeks and rivers. Large catchment areas are made up of hundreds of smaller 'sub-catchment' areas. These can be bordered by low hills and ridges and drained by only a small creek or gully.
Catchment areas are important
What happens in one part of a catchment is likely to affect the wellbeing of the rest of the catchment area, so there are many things you can do to minimise your impact on the system.
For example, since stormwater drains run straight into our waterways, heavy rainfall can wash sediments, rubbish and pollutants into the rivers and eventually into the ocean. This may impact negatively on aquatic life, coral reefs and seagrass beds. It can also affect people who use the water, for example, for irrigation or stock watering.
Development decisions under the Environmental Protection Act 1994 involving pollutant discharge to waterways must consider environmental values and water quality objectives.
The State Planning Policy (SPP) sets out State interests that must be addressed through local government planning schemes, regional plans and when making decisions about the designation of land for community infrastructure. There are 16 State interests, (including coastal environment, and water quality) that are important to protect and enhance through Queensland's continued development.
Find out more about water quality under the SPP.
Well-known contaminants include oils, animal waste, litter, fertilisers and weed sprays. But grass cuttings, leaves and soil can also upset the waterways' ecological balance. Some pollutants directly poison aquatic and marine plants and animals; others harm the environment through eutrophication or sedimentation.
Dioxins are a family of organic chemical compounds that are toxic and environmentally persistent. They are not water soluble but may attach to river and lakebed sediments, potentially entering the food web through sediment dwelling organisms to secondary consumers. 2,3,7,8- tetrachlorodibenzo para dioxin (TCDD) is considered to be the most toxic of the dioxin family.
Dioxin testing in Noosa Lakes
The Department of Environment and Science (Department) and Noosa Shire Council have been working together over the past 15 months to undertake sampling and analysis of Noosa Lakes sediment and biota to test for the presence of dioxins.
Trace levels of TCDD were detected in the sediments from Lakes Weyba and Cootharaba. The Dioxin Report was prepared by the Department in December 2020.
Following the sampling and analysis of biota from Noosa Lakes, Queensland Health prepared a report in August 2020, recommending that “no specific advice on the consumption of fish due to dioxins in the Noosa area is required.” The Queensland Health report noted the level of dioxin in fish from Noosa Lakes was below the Food Standards Australia and New Zealand limit.
Water samples from Noosa Lakes were sampled and analysed for the presence of dioxins in October 2020. No dioxins were detected in any water samples.
Trace levels of dioxins were detected in sediment samples from all Lakes. These results are consistent with the national studies by the Australian Government that found dioxins in sediment and biota in all Australian aquatic environments that were sampled and analysed under the National Dioxins Program.
In early 2021, a follow-up survey of fish samples was collected by commercial fishers in Lake Weyba, with sediment resampled from the four lakes in the Noosa Catchment—Lake Cootharaba, Lake Cooroibah, Doonella Lake and Lake Weyba.
Queensland Health again concluded that the consumption of fish from the Noosa area was unlikely to result in an unacceptable risk to public health.
Both reports mentioned can be found below:
- The Dioxin Report
- The Queensland Health Report
- Dioxin Assessment – Commercial Fishing and Sediment Report .
Find out more about Dioxin testing in Noosa Lakes .
Marine Protected Areas
Queensland marine protected areas include marine parks and declared Fish Habitat Areas. Marine parks are established over tidal lands and waters to protect and conserve special areas while allowing for the planned use of marine resources. Fish Habitat Areas protect important inshore and estuarine habitats that support local and regional fisheries against physical disturbance from coastal development, while still allowing legal fishing.
Marine protected areas conserve important natural features such as seagrass meadows, mangroves, rocky shores, reefs, sandy beaches, bays, sheltered channels, rivers, creeks and estuaries.
These areas are home to a wealth of wildlife including whales, turtles, dugong, grey nurse sharks, fish, corals, birds and more.
Land sourced runoff of sediments, nutrients and chemicals as well as the careless discarding of litter can directly affect the water quality of marine parks and Fish Habitat Areas and the health of marine wildlife.
We can improve the health of our marine environments by:
- disposing of all rubbish properly
- taking cans, glass, plastics, fishing line and non-biodegradable wastes ashore
- not discarding pollutants in stormwater drains
- reducing your use of chemicals, fertilisers and pesticides.
Remember, what goes down your stormwater drain, sink and toilet or on your garden eventually reaches our marine environments.
Find out more about Queensland’s marine parks.
Floods and cyclones are natural processes which can benefit the environment. Changes we make to our catchments can change the way they respond to flooding and cyclones.
Toxic algal blooms
The blue-green algal blooms which have caused serious damage to many of our waterways in the last few years are a result of accelerated eutrophication.
Accelerated eutrophication occurs where excess nutrients make their way into inland and coastal waters, allowing increased growth of algae. As the algae decay they deplete the oxygen content of the water and aquatic animals die in large numbers. Urban sewage and runoff from agricultural land and stormwater drains are the major causes of these damaging algal blooms.
So, we need to think of our roads, yards, farms and drains in the same way we do our creeks, remembering all stormwater eventually flows into our waterways.
Sediments in waterways are particles of soils that have been washed from farms, construction and development sites, road stockpiles, sewage effluent and other sources.
Large amounts of sediments in the water reduces the amount of light able to reach the riverbeds and bay bottoms. That means aquatic plants and marine seagrasses don't have enough light to photosynthesise and die.
Sediments cause more problems as they sink to the bottom, because they alter the shape of estuaries and shores and smother filter-feeding marine life such as coral and sponges.
The combination of increased sediments and higher nutrients have been linked to massive dieback of seagrasses in many areas.
You can help care for catchments
You can do many little things such as reducing water pollution and conserving water to reduce your impact on your catchment. Minimising erosion around your home and business will also reduce problems downstream; tree planting and mulching prevents excess soil and nutrients getting into drains and creeks.
You can also help by joining your local Coastcare or Waterwatch group and supporting programs that care for your catchment including programs being developed by your Regional Natural Resource Management Body.
Regional Natural Resource Management Bodies are a joint initiative between Queensland and Australian Governments. These groups develop regional Natural Resource Management plans and organise on-ground works and community events.
Regional Natural Resource Management depends on local people and local communities getting involved. To get involved or to find out more about Regional Natural Resource Management Bodies follow the Regional Natural Resource Management link above.
What is government doing to protect water quality?
The Reef 2050 Water Quality Improvement Plan guides how industry, government, Traditional Owners and the community will work together to improve the quality of water flowing to the Great Barrier Reef through improved land management in Reef catchments.
The plan is a joint commitment of the Australian and Queensland governments. It addresses all land-based sources of water pollution including run-off from urban, industrial and public lands; while recognising the majority of pollution comes from agricultural activities.
The Reef 2050 Plan is the overarching long-term strategy for protecting and managing the Great Barrier Reef to support its health and resilience. The Australian and Queensland governments are working with local governments, industry, land managers, scientists, Traditional Owners and the community to deliver on priority actions to protect the Reef.
Regional Natural Resource Management bodies are responsible for preparing regional water quality improvement plans that guide the implementation of local priority actions to address water quality management. For information on these refer to your Regional Natural Resource Management Body.
Coastal environment interests are included in the State Planning Policy (SPP).
Additionally, the Coastal Management Plan commenced on 18 March 2014. It is made under the Coastal Protection and Management Act 1995. The Coastal Management Plan provides non-regulatory policy guidance to coastal land managers.