Water Quality Issues: Definition, Types and Prevention
Water quality refers to the chemical, physical, biological, and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and/or to any human need or purpose. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of pesticides and fertilisers, and more.
Water quality issues arise when the water's quality becomes reduced or degraded so that it is inappropriate for its intended use. This can occur through natural causes as well as human (anthropogenic) impacts on the water. Water quality issues negatively affect human health, aquatic ecosystems, and economic activities that depend on clean water.
Some major types of water quality issues include:
- Microbial contamination - Pathogens from human and animal waste leading to infectious diseases.
- Organic and inorganic pollution - Industrial discharge, oil spills, pesticides/fertilisers leading to toxicity.
- Sedimentation - Soil erosion causing turbidity and smothering aquatic habitats.
- Eutrophication - Excess nutrients causing algal blooms and oxygen depletion.
- Salinization - Build up of salts impacting irrigation and drinking water.
- Acidification - Changes in pH impacting aquatic life.
- Heavy metal contamination - Toxicity from metals like lead, mercury, arsenic.
- Thermal pollution - Changes in water temperature impacting dissolved oxygen.
Water quality issues can stem from natural causes such as storms, floods, and geological weathering. However, the major causes today are anthropogenic:
- Sewage and wastewater discharge - Insufficient treatment leads to microbial and nutrient pollution.
- Industrial waste - Toxic chemicals, metals, oil, heat discharged into waterways.
- Agricultural runoff - Pesticides, fertilisers and animal waste adding nutrients, bacteria and chemicals.
- Mining activities - Acid drainage and leaching of metals into ground and surface water.
- Urban stormwater runoff - Road contaminants washed into waterways during rains.
- Oil spills - Accidental leaking and waste dumping causes toxicity and smothers aquatic life.
- Atmospheric deposition - Acid rain and pollutant fallout from factories impacting water chemistry.
Degraded water quality has far-reaching consequences:
- Waterborne diseases - Contaminated drinking water spreads gastrointestinal and other infectious diseases.
- Loss of aquatic biodiversity - Sensitive species succumb to polluted and altered habitats.
- Bioaccumulation of toxins - Chemicals build up in tissues of aquatic and human populations leading to cancer and organ damage.
- Hindered recreation/tourism - Polluted waterways lose aesthetic and recreational appeal.
- Reduced crop yields - Salinity and contamination lower agricultural productivity.
- Increased water treatment costs - Additional processes needed to make water potable again.
Preventing water quality issues requires:
- Regulation and monitoring of wastewater discharges and polluting activities. International agreements like the Stockholm Convention and Basel Convention have targeted persistent organic pollutants, hazardous wastes and more. Countries have national water quality standards and pollution control policies like the Clean Water Act in the USA and European Union Water Framework Directive.
- Improved sewage and industrial wastewater treatment via primary, secondary and tertiary processes.
- Control of urban and agricultural runoff through wetlands, retention ponds, and better practices.
- Protection of landscapes and waterways from overdevelopment and pollution.
- Restoration of degraded water bodies through nutrient reduction, aeration, phytoremediation and more.
- Public education campaigns on preventing water pollution and conserving water.
- Research & technology development for cost-effective water treatment innovations.
The main water quality issues can be categorised into physical, chemical, biological and emerging issues. Each degrades water quality in different ways, posing challenges for human and environmental health as well as water-based economies.
Physical Water Quality Issues
Physical water quality issues involve physical characteristics of the water. Major issues include:
- Turbidity - Cloudiness caused by suspended solids, sediment and particulate matter impacting aquatic life. Challenging to treat for drinking water.
- Temperature - Thermal pollution from industrial discharge can alter ecosystems. Cold water pollution from dams can impact fish.
- Salinity - High salt content reducing drinkability and harming salt-sensitive crops. Caused by irrigation practices.
Chemical Water Quality Issues
Chemical issues involve contamination from harmful chemicals. Key problems are:
- Nutrient pollution - Nitrogen, phosphorus from sewage, farms causing algal blooms and oxygen loss.
- Heavy metals - Toxic metals like mercury, lead, cadmium from industrial sources accumulate in biota.
- Organic toxins - Pesticides, industrial chemicals, oil spills are dangerous at even low concentrations.
- Inorganic compounds - Acids, reactive chemicals from mining alter pH and toxicity.
Biological Water Quality Issues
Biological issues involve microbes and toxins:
- Pathogens - Bacteria, viruses, protozoa from sewage causing infectious diseases.
- Harmful algal blooms - Toxin-releasing algae dangerously contaminate drinking water sources.
- Invasive species - Disrupt and alter native aquatic ecosystems. Spread through ballast water.
Emerging Water Quality Issues
Newer issues requiring more research include:
- Pharmaceuticals - Medicines passing through bodies persist in water, impacting wildlife.
- Microplastics - Small plastic particles absorbed by aquatic life with uncertain consequences.
- Endocrine disruptors - Chemical compounds interfering with hormone systems.
- Antibiotic resistance - Resistant bacteria and genes proliferate in waterways.
Acidic Sulfate Soils
Acidic sulfate soils are soils that contain iron sulfide minerals. They are formed when sulfate is reduced to sulfide under waterlogged conditions.
The exposure of these soils to air can lead to oxidation of the iron sulfides, producing sulfuric acid. This leads to acidification and mobilisation of metals into waterways, negatively impacting water quality.
Acidification of water can be toxic to aquatic life. Mobilised metals can contaminate water supplies and bioaccumulate in fish, posing health risks to humans if consumed.
Blackwater Incidents
Blackwater events occur when heavy rainfall flushes organic carbon from the landscape into waterways. This organic material is decomposed by microbes, depleting oxygen levels in the water.
Blackwater can significantly reduce water quality, as the low oxygen levels can suffocate aquatic species. Other water quality parameters like pH and clarity are also impacted.
The hypoxic and anoxic conditions caused by blackwater can lead to fish kills and loss of other aquatic organisms vital to the ecosystem. There are also impacts to recreation and aesthetics of waterways.
Bushfires
Bushfires produce large amounts of ash and debris which can be mobilised into waterways by rainfall events. Silt, sediment and nutrients from the landscape are also washed into catchments.
Ash and debris increase turbidity and suspended solids. Sediments smother riverbeds. Nutrients contribute to algae growth. These effects degrade water quality and habitat for aquatic life.
Aside from direct ecological impacts, bushfire debris can damage infrastructure like drainage systems and reduce the quality of municipal water supplies. There are subsequent risks to humans if water treatment is compromised.
Blue-Green Algae (Cyanobacteria)
Blue-green "algae" are photosynthetic bacteria that commonly occur in waterways. Under certain conditions like sustained high nutrients and warm weather, they can rapidly multiply to form algal blooms.
Algal blooms severely reduce water quality, blocking sunlight and depleting oxygen as they decompose. Some species also produce toxins which can bioaccumulate or poison wildlife and livestock.
Contact with algal bloom waters can cause skin rashes, stomach upsets and other illnesses in humans. Toxins can also contaminate drinking water supplies drawn from affected catchments.
Soil Salinization
Salinization occurs when saline groundwater rises towards the surface and accumulates in soils. It can be caused by land clearing, irrigation practices or sea water intrusion into coastal aquifers.
Salt in soils gets washed into waterways during rainfall events or seeps into surface waters through groundwater connectivity. This increases salinity, reducing water quality for drinking, agriculture and ecosystem health.
Elevated salinity is toxic for most freshwater plants and animals. It poses risks to crop irrigation systems and can corrode infrastructure over time. Drinking water can also become unpalatable if saline intrusion occurs into supplies.
Urban Drainage Basins
Urban areas contain large expanses of impervious surfaces like concrete and rooftops which generate stormwater runoff during rain events. This runoff accumulates pollutants as it drains into constructed drainage systems.
Stormwater carries sediments, nutrients, oils/grease, debris, bacteria and other contaminants into urban creeks, rivers and wetlands - negatively impacting urban water quality.
Contaminated stormwater runoff can be toxic to aquatic wildlife while nutrient loads fuel algal blooms. Pathogens may also enter recreational waters or drinking water catchments, posing health risks if untreated.
There are both international and Australian national guidelines that set standards for water quality across various uses like recreation, irrigation and drinking water supplies. The Australian and New Zealand Guidelines for Fresh and Marine Water Quality provide specific water quality benchmark levels for parameters like nutrients, turbidity, pH, dissolved oxygen and harmful contaminants. There are also guidelines for monitoring frequencies and sampling methods.
Best practice water quality management involves regular surface water monitoring across different parts of catchments to detect any deterioration and identify pollution sources. Real-time sensors, satellite data and predictive models can supplement physical sampling. Strategic approval conditions can be applied for developments with water impacts, like requiring sediment control plans. Stormwater treatment infrastructure helps remove urban contaminants, while managed aquifer recharge can buffer supplies against drought.
Protecting riparian buffer zones around waterways limits polluted runoff from agricultural areas. Erosion control, revegetation works and wetland protections can further mitigate water quality risks at a catchment scale. Community education campaigns raise awareness on how everyday actions can impact urban waterways. Stewardship programs empower landholders to monitor water quality and preserve downstream habitats on private property.
Where guidelines are exceeded, water managers can use risk-based approaches to prioritise remediation plans across pollution sources and make the best use of available resources to achieve tangible water quality improvements.
What is Australia doing to prevent water quality issues?
Australia implements water quality improvement programs at national, state and local levels. The National Water Quality Management Strategy drives coordinated monitoring, policies, guidelines and community education to maintain waterway health. Natural Resource Management groups deliver on-ground remediation projects, while Water Sensitive Urban Design principles are integrated into developments to minimise stormwater impacts.
Successful water quality initiatives have included fertiliser management programs working with farmers to prevent nutrient runoff, major wetland rehabilitation works to filter sediments and the provision of incentives for rural landholders to retain native vegetation along waterways. Robust baseline monitoring by environmental consultants identifies pollution risks and sources early so that targeted remediation plans can be put into action before irreversible degradation occurs.
There are practical steps individuals and communities can take to prevent water pollution:
- Safely disposing of household chemicals, paints and motor oils to avoid sewer contamination.
- Reducing fertiliser and pesticides use on gardens and farms.
- Installing rain gardens, rainwater tanks and permeable paving to capture stormwater runoff.
- Joining a Landcare group to plant native vegetation along local creeks and lakes.
- Picking up litter to stop it entering waterways, drains and oceans.
On a broader level, we can advocate for stronger environmental policies, support sustainable farmers/fisheries and choose products made from recycled materials to reduce plastic waste. It is only through the collective efforts of individuals, industry and governments at all levels that we can preserve the health of our rivers, aquifers and coastal ecosystems - for the benefit of present and future generations.
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