Helena Joyce
The Murray River is an important source of water for many communities in Australia, including Adelaide. However, the river has been facing several environmental issues that affect its health and water quality. The river has endured multiple droughts throughout history, and increased irrigation in farming has led to water being diverted from the river, affecting its flow and causing degradation. The river also faces pollution from sources such as saline water, agricultural chemicals, and other pollutants. Additionally, pest weeds and animals, as well as the overpopulation of carp, can threaten the health of the river and surrounding areas. While efforts are being made to improve the river's health and manage water quality, there are still ongoing challenges to ensuring the Murray River is clean and healthy.
| Characteristics | Values |
|---|---|
| Current status | The Murray River is doing better today, but there are still issues that can affect its health. |
| Reasons for improvement | The recovery is due to the efforts of many people after the Millennium Drought. |
| Drought impact | The Millennium Drought led to low river levels, exacerbating water quality risks and causing the lowest flows into South Australia in recorded history. |
| Flood impact | High flows can cause blackwater events, stirring up organic matter and washing it down the river. |
| Pollution sources | Septic leakage from adjacent housing, contaminated stormwater runoff, sand dumping, agricultural chemicals, and saline, low pH, metal-laden water. |
| Environmental impact | Pest weeds and animals, including overpopulation of carp, threaten the health of the river and surrounding areas, affecting crops and reducing output. |
| Salinity | The spread of salinity due to river pollution and farmland practices makes land unusable and affects water quality. |
| Water usage | Increased water usage, irrigation, and river diversions have degraded rivers and wetlands, affecting animal populations and communities that rely on these ecosystems. |
| Water quality management | The Murray–Darling Basin Authority works with communities and governments to reduce salinity and improve water quality through plans, targets, and assessments. |
| Legislation | The Environment Protection (Water Quality) Policy 2015 and other legislation aim to prevent pollution and enforce environmental duties. |
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What You'll Learn
The Millennium Drought and ongoing water quality risks
The River Murray in South Australia experienced a significant drought known as the Millennium Drought from late 2001 to 2010. The drought saw the lowest flows into South Australia in recorded history, causing severe damage to communities. The combination of low rainfall and the lowest inflows into the river resulted in flows over the border into South Australia virtually ceasing.
The Millennium Drought highlighted the issue of water being taken from the Murray-Darling Basin for too long, leaving an insufficient amount to maintain the ecosystem's health and resilience to droughts. As a result, the Murray-Darling Basin Authority was formed to develop a plan to ensure the sustainable management of the entire river system. The drought also brought attention to the risk of acidification in the Lower Lakes, with the introduction of seawater considered as a solution. However, it was found that this would lead to extreme increases in salinity and heavy metals, creating a toxic ecosystem.
The drought also exacerbated water quality risks, with modelling and water quality testing by the EPA and Department for Environment and Water (DEW) indicating plumes of saline, low pH, metal-laden turbid water entering the River Murray. These risks have been monitored since the Millennium Drought and continue to be an area of focus. Other sources of pollution that are of concern include septic leakage from adjacent housing and contaminated stormwater runoff from developed land areas.
While there have been signs of improvement since the Millennium Drought, ongoing efforts are needed to ensure the long-term health and resilience of the river system. This includes building resilience into the river system to better prepare for future droughts and ensuring sustainable water usage.
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Stormwater runoff, wastewater, and sand dumping
Stormwater runoff is a significant issue for the Murray River, as it can carry pollutants into the river and contribute to water quality degradation. When rain falls on urban areas, it picks up contaminants and becomes stormwater runoff, which often ends up in natural water bodies like the Murray River. This runoff can contain various pollutants, including heavy metals, chemicals, and debris, which can have detrimental effects on the river's ecosystem.
To address this issue, several management strategies have been implemented. Structural controls, such as detention basins, are used to collect, store, and treat stormwater before it enters the river. These basins temporarily hold the stormwater, allowing sediments and pollutants to settle and be removed before the water is released. Filtration systems are another critical structural control, using media like sand or activated carbon to remove additional contaminants.
Non-structural controls, on the other hand, promote the natural treatment of stormwater without constructed facilities. These include regulatory measures such as zoning laws and building codes that minimize impervious surface areas, encouraging infiltration and treating stormwater at its source. Community-based projects and educational programs also play a vital role in stormwater management. Initiatives like tree planting, installing rain gardens, and participating in storm drain labeling projects help reduce runoff and raise awareness about the impacts of stormwater on the environment.
Wastewater management is another critical aspect of maintaining the Murray River's health. The river receives wastewater from various sources, including agricultural, industrial, and municipal activities. To prevent pollution and ensure proper treatment, wastewater treatment facilities play a crucial role. These facilities are designed to treat sewage and reduce the environmental impact of wastewater discharge into the river. Advancements in technology have led to the development of treatment processes that focus on removing contaminants and improving the efficiency of sewage treatment.
Sand dumping is a practice that has been identified as harmful to the Murray River. It involves depositing sand on riverbanks or in the riverbed to create artificial beaches or stabilize eroding banks. While it may seem benign, sand dumping can have detrimental environmental consequences. It can lead to riverbank collapse, alter the river's natural flow, and smother aquatic habitats, negatively impacting the health of the river and its ecosystems. To address this issue, dumping sand into the river is illegal, and penalties may be imposed on individuals or companies found responsible for such actions.
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Pest weeds, animals, and overpopulation of carp
The Murray River, a part of the Murray-Darling Basin, has faced several water quality issues over the years. The Millennium Drought, for instance, exacerbated water quality risks in terms of metal exceedances of drinking water standards. The EPA and relevant authorities have been monitoring these risks since. Other sources of pollution include septic leakage from adjacent housing, contaminated stormwater runoff, and sand dumping, which is illegal and harmful to the environment.
One of the significant issues affecting the Murray River is the presence of pest weeds, animals, and an overpopulation of carp. Regarding pest weeds, the South Australian Murray-Darling Basin Natural Resources Management Board has identified several invasive weed species that could potentially enter South Australia via the River Murray. These include alligator weed and water hyacinth, which could block river systems and irrigation channels, impacting the local environment and potentially affecting the sale of produce.
In terms of animal pests, the carp (Cyprinus carpio) is a significant concern in the Murray River. Carp are an invasive species that were introduced to the Murray-Darling Basin as early as the 1920s, with the Boolara strain being the catalyst for their massive expansion in Australia. By the 1960s, the Prospect and Yanco strains were well-established, and the heavy flooding of the basin in the 1970s further facilitated the rapid spread of carp throughout the river system. The more invasive nature of the Boolara strain also contributed to their expansion.
The carp's original range is from the Amur River in eastern China to eastern Europe, and they were domesticated by the Chinese around 3,000 years ago. The species then spread across Europe with the help of the Romans and monks, becoming established by the 1200s. While there were attempts to introduce carp to Western Australia in the late 19th and early 20th centuries, these introductions were not successful. However, carp populations have been successfully eradicated from several farm dams in northwest Tasmania and functionally eradicated from lakes Sorell and Crescent in Tasmania.
The overpopulation of carp in the Murray River has negative ecological impacts. Carp are known to stir up sediment, reducing water clarity and affecting aquatic plants and other organisms that rely on clear water. They can also uproot plants, further degrading the aquatic habitat. Additionally, carp feed on algae, which can lead to increased algal growth and potentially affect water quality. The presence of carp in the Murray River contributes to the ecological challenges faced by this important water body.
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Increased water usage, droughts, and degraded wetlands
The Murray River is the main river in the Murray-Darling Basin, which has seen a huge expansion of irrigated crops since the 1970s. This has resulted in massive water extractions, leaving sensitive river wetlands and river red gum forests under stress from a lack of water and increased salinity. The Millennium Drought, which broke in 2010, saw the lowest flows into South Australia in recorded history, causing untold damage. The drought, combined with increased water usage, has led to rivers and wetlands being degraded, interrupting the breeding cycles of fish and birds and decreasing their populations.
The Murray River Commission was established in 1917 to help manage the water being taken from the river. Structures such as weirs and locks were built along the river, with weir pools providing water that could be diverted for agricultural, town, and industrial use. The barrages near the Coorong National Park help reduce water flow to the sea and also reduce salinity in the lower river. However, the increased usage of irrigation in farming has resulted in more water being taken from the river, and the effects of the Millennium Drought are still being felt.
The Murray-Darling Basin Plan, signed in 2012, aims to recover at least 2,750GL of water for the environment. This can be achieved through government buyback of water entitlements or by using the existing water in the river system more effectively. However, compulsory water buyback programs have been unpopular with rural communities due to their perceived negative economic impact. The plan also includes projects such as Nimmie-Caira, which aims to relieve environmental stress and protect the largest remaining wetland in the Murrumbidgee valley.
The health of the river is crucial for the many plants and animals that depend on it. Clean, fresh water sustains 120 waterbird species and more than 50 native fish species, many unique to Australia. The river is also central to the life and culture of the Ngarrindjeri people. The degradation of wetlands and the decrease in water quality can adversely affect water-based recreational tourism and the communities that rely on good water quality. It is essential to carefully manage water quality and availability to ensure the basin stays healthy for both humans and wildlife.
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Salinity, agricultural chemicals, and other pollutants
The River Murray is the main source of drinking water for Adelaide. However, it is polluted with salinity, agricultural chemicals, and other pollutants. The Millennium Drought, which broke in 2010, caused the lowest flows into South Australia in recorded history, and the river has not fully recovered. Modelling and water quality testing by the EPA and Department for Environment and Water (DEW) indicated that plumes of saline, low pH, metal-laden turbid water were entering the River Murray from LMRIA drains.
Salinity in the river is caused by the clearing of forests for agriculture and the excessive removal of water for irrigation. The latter also affects wetland breeding cycles for fish and birds, decreasing their populations. The clearing of forests also means that groundwater is drawn to the surface through soil that contains old marine salt, brought inland by rain and wind over millions of years. This has rendered 2.5 million hectares (6.1 million acres) of Australian agricultural land unusable, and scientists have warned that if current farming practices continue, the salinity zone will increase to 18 million hectares (30% of the total) by 2050.
Agricultural chemicals are another pollutant of the river. The use of irrigation in farming has increased, and so has the amount of water being taken from the river. Weir pools, for example, are used for agricultural, town, and industrial use. The overpopulation of carp in the river is also a problem, as they reduce the health of the river and other creatures that inhabit it.
Other pollutants include pest weeds and animals, which can affect the land of farmers, damaging crops and reducing output. Blackwater events, which are a natural phenomenon occurring when areas that don't usually have much water are inundated due to high flows, stir up organic matter like leaves and wood, washing them down the river.
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Frequently asked questions
Yes, the Murray River is polluted. The river is Adelaide's main source of drinking water, but it is contaminated with salt, agricultural chemicals, and other pollutants.
The pollution in the Murray River is caused by a variety of factors, including farm management practices, the clearing of forests for agriculture, and the removal of too much water from the river for irrigation. The river is also affected by pest weeds and animals, as well as septic leakage from housing adjacent to the river and contaminated stormwater runoff.
Communities and landholders are working together with the Murray-Darling Basin Authority (MDBA) and local and Basin state governments to reduce salinity and improve water quality. The MDBA has implemented water resource plans that include water quality management strategies and targets. There are also regulations in place, such as the Environment Protection (Water Quality) Policy 2015, to prevent and mitigate pollution.
The Murray River is doing better today thanks to the efforts of many people to help it recover after the Millennium Drought. However, there are still issues affecting its health, such as drought, flooding, and pest overpopulation.
