The Murray River: Pollution's Impact And Influence

The Murray River is a critical source of drinking water for Adelaide and South Australia, as well as supporting diverse aquatic ecosystems and providing water for irrigation and recreation. However, the river has faced significant environmental challenges due to pollution and human activity. The health of the river is of utmost importance to the current and future well-being of the region. While it has improved since the Millennium Drought, there are still concerns about water quality and the impact of agricultural practices on the river system. The introduction of the Murray-Darling Basin plan in 2012 aimed to restore the river's health by recovering water diverted to irrigation and improving flows. However, compliance and water theft remain issues, and the plan has faced opposition from rural communities concerned about economic impacts. The river's health is also affected by altered river flows, vegetation clearing, and the presence of invasive species such as carp.

Septic leakage from housing near the river

The health of the Murray River is critical to the current and future wellbeing of South Australia. The river provides Adelaide with 50% of its drinking water, supports diverse aquatic ecosystems, provides irrigation and stock water, and is used for recreation activities.

One of the main water quality problems in the Murray River is water management, which includes maintaining sufficient water levels to limit upstream saline inflows and managing Lower Murray Irrigated Reclaimed Area (LMRIA) discharges. The Millennium Drought highlighted the risks of low river levels, which can lead to metal exceedences of drinking water standards.

Other sources of pollution affecting the river include septic leakage from housing near the river and floodplain areas. Septic leakage from nearby housing can contaminate the river with untreated or partially treated sewage, leading to increased bacteria and nutrient levels in the water. This can have significant environmental and health impacts, including the potential for harmful algal blooms, reduced oxygen levels, and the spread of waterborne diseases.

To address this issue, the Environment Protection Authority (EPA) of South Australia is working closely with stakeholders and industry bodies to ensure compliance with the Environment Protection Act 1993 and associated policies and codes of practice. This legislation places a general environmental duty on individuals and organizations to take all reasonable and practicable measures to prevent or minimize environmental harm from activities that pollute or may pollute the river. The EPA conducts investigations and compliance measures when apparent pollution issues or breaches of the general environmental duty arise.

In addition to regulatory measures, education and awareness about the impacts of septic leakage on water quality are crucial. Local communities and residents near the Murray River should be informed about the potential risks of septic leakage and be encouraged to implement proper wastewater treatment and disposal practices. Regular monitoring and maintenance of septic systems can help prevent leakage and reduce the potential for pollution.

By combining regulatory enforcement, community engagement, and proactive septic system management, the adverse effects of septic leakage from housing near the Murray River can be mitigated, contributing to the overall health and sustainability of this vital water source.

Contaminated stormwater runoff from developed areas

Stormwater runoff is a significant concern for the health of the Murray River. When rain falls on developed areas, such as streets, parking lots, rooftops, and sports fields, it picks up various contaminants and carries them into nearby bodies of water. This runoff can contain oil, grease, metals, and coolants from vehicles, as well as fertilizers, pesticides, and other chemicals from gardens and homes.

In the context of the Murray River, contaminated stormwater runoff from developed areas is a pressing issue. The river provides Adelaide with 50% of its drinking water, and this figure can fluctuate between 10-80% depending on rainfall and storage. Therefore, ensuring the river's water quality is critical for the wellbeing of South Australia.

One of the challenges associated with contaminated stormwater runoff is the presence of toxic chemicals, such as pesticides, that enter the river system. These chemicals can have detrimental effects on aquatic ecosystems and pose risks to human health, especially for those who rely on the river as a source of drinking water. The impact of these chemicals is further exacerbated by the increase in farming along the river, which has resulted in a greater demand for water allocation, leaving less water available for the environment.

To address the issue of contaminated stormwater runoff, effective management strategies are essential. This includes implementing best environmental management practices, such as those outlined in the Environment Protection (Water Quality) Policy 2015. Additionally, local communities, industry groups, and local governments play a crucial role in mitigating the impact of stormwater runoff through initiatives like Landcare and other projects.

By prioritizing the reduction of contaminated stormwater runoff, stakeholders can help protect the health of the Murray River and the diverse aquatic ecosystems it supports. This includes RAMSAR wetlands and other environments that are home to numerous waterbird and native fish species.

Sand dumping from creating beaches

Sand dumping is the practice of dumping beach or other sand on a river bank to create an artificial beach or embankment. Sand is often dumped when unstable mud or rocks on the river bank are exposed.

Sand dumping can cause significant harm to the environment and create safety hazards, such as riverbank collapse. It is particularly damaging when the river is low. Depositing sand into the riverbed is illegal and constitutes a breach of the Environment Protection Act 1993 and the River Murray Act 2004.

Wind, waves, and currents can pull dumped sand throughout the river, creating uncharted sandbars that pose navigational problems for boats, block irrigation channels, add weight to unstable riverbanks, and affect breeding sites for estuarine fish and animals.

The Environment Protection Authority (EPA) in South Australia has recorded more than 30 cases of illegal sand dumping in the River Murray, with 20 sites being requested for restoration. The maximum penalties for illegal sand dumping are $30,000 for individuals and $120,000 for companies.

Instead of sand dumping, alternative methods for stabilising riverbanks include the use of geotech sheets, shade cloth, temporary plastic floor tiles, retaining walls, sandbags, or synthetic turf. These methods are less harmful and dangerous and can help prevent environmental damage and safety risks associated with sand dumping.

Blackwater events

The severity of blackwater events depends on various factors, including the type and amount of plant material, air and water temperatures, and the time between high rainfalls and flooding. Prolonged dry periods, such as droughts, can lead to a build-up of organic material, which, when washed into the river during flooding, contributes to more severe blackwater events.

While blackwater events can have negative consequences, they also play a crucial role in the long-term health of the river. The organic matter washed into the river releases carbon and nutrients, boosting food supplies and supporting the breeding cycles of fish, birds, and other wildlife. Additionally, the floods that cause blackwater events are essential for the health of river, floodplain, and wetland ecosystems, especially after prolonged droughts.

To mitigate the impacts of blackwater events, environmental water holders, such as the Commonwealth Environmental Water Holder (CEWH), work with state and local water managers to develop strategies. These strategies include floodplain watering during cooler months to slow down the breakdown of organic material and reduce the severity of blackwater events during warmer periods.

The Murray–Darling Basin Authority (MDBA) is responsible for managing the River Murray water quality monitoring program. The program helps assess the impact of human development, detect sources of pollution, and respond to changes in the river's condition, including blackwater events. The Murray–Darling Basin Plan sets out water quality targets to protect and enhance water quality, restore natural flow regimes, and acquire water entitlements to return more water to the environment.

Carp overpopulation

The Murray River in Australia has been affected by the overpopulation of carp, which were introduced into Australian waters over a century ago. Carp are an invasive species that negatively impact the river's ecosystem and native fish populations. They are highly adaptable and prolific reproducers, with a mature female carp capable of producing up to 1.5 million sticky eggs, which can easily spread the population to new areas.

The carp's feeding behaviour, known as "mumbling," stirs up sediments and increases turbidity, leading to a reduction in water quality. They also damage riverbanks and contribute to algae blooms, further degrading the river's health. Additionally, carp compete with native fish species for resources and can spread diseases, impacting the biodiversity of the river.

The Australian government has recognised the issue and is working to manage the carp population through the National Carp Control Plan (NCCP). This plan aims to reduce the impact of carp on waterways by releasing a virus that is fatal to carp but won't harm other animals or affect water sources for humans. However, the project is still in the discussion phase, as there are concerns about the distribution of the virus, the number of carp it will affect, and the removal of dead carp after the virus takes effect.

In the meantime, other measures are being implemented, such as installing carp exclusion screens at wetlands and using environmental flows that benefit native species over carp. The delivery of water for the environment is helping native fish populations recover and providing greater competition for carp in the river and wetlands.

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