Water Quality: Definition,Testing, Guidelines and use on EIA

Water quality refers to the chemical, physical, and biological characteristics of water that determine its suitability for a specific use. Good water quality is essential for protecting ecosystems and human health.

Water quality has great significance for the environment and human health. Clean water supports healthy aquatic ecosystems and provides safe drinking water for communities. Poor water quality can lead to the spread of waterborne diseases, eutrophication, and the destruction of aquatic habitats. Monitoring and protecting water quality is thus crucial.

There is a distinction between standards for potable water versus water used for other purposes. Potable water quality standards are more stringent, as this water is used for drinking and food preparation. Parameters like turbidity, pH, dissolved oxygen, and pathogenic bacteria are especially important for judging potable water quality. Non-potable water still requires quality monitoring, but standards may vary based on factors like intended use.

Water quality testing utilises methods like pH probes, dissolved oxygen metres, chromatography, and microbiological assays. Common parameters tested include pH, turbidity, dissolved oxygen, heavy metals, and microbial pathogens. These parameters give indications of pollution, salinity, and suitability for ecosystems/human use.

International organisations like the WHO publish drinking water quality guidelines containing acceptable levels and testing methods for health-relevant parameters. Many countries base their national potable water standards on the WHO guidelines. The EPA in the US also releases recommended water quality criteria for protecting aquatic life and human health.

Water quality assessments are a key component of environmental impact assessments (EIAs). Evaluating potential project impacts on water resources informs decisions about mitigation strategies and whether/how projects should proceed. Common EIA methodologies include analysing existing data, modelling pollution inputs and impacts, and field monitoring of parameters pre- and post-project. Assessing water quality helps minimise ecosystem damage.

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What does water quality mean?

Water quality refers to the chemical, physical, and biological characteristics of water. It encompasses parameters like temperature, turbidity, nutrient levels, salinity, oxygen content, and the presence of contaminants. Good water quality means the water is chemically balanced and contains low levels of pollutants and pathogens.

Water quality is important for maintaining healthy aquatic ecosystems. Animals and plants require certain conditions to thrive. Monitoring quality helps identify pollution issues.

For human use, good water quality means water is safe for drinking, cooking, bathing, and other domestic purposes. Poor quality can endanger public health.

There are also economic implications. Clean water supports fisheries, tourism, agriculture, and industry. Treatment costs rise when source water is contaminated.

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How is the quality of water measured?

Water quality testing utilises scientific techniques to measure and analyse various physical, chemical, and biological parameters. Common tests include:

• pH - Acidity or alkalinity. Indicates chemical suitability for ecosystems and treatment needs.
• Turbidity - Cloudiness from sediment or contaminants. High turbidity can harm aquatic life.
• Dissolved oxygen - Needed by aquatic organisms to breathe. Declines can cause ecosystem damage.
• Contaminants - Toxins, heavy metals, pesticides. Compares levels to water quality guidelines.
• Bacteria - Faecal coliforms indicate disease risk. Important for drinking water.

Test results help identify pollution sources, assess ecosystems health, and determine water usage suitability. Routine testing provides vital water quality data to inform management.

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What are the methods used to test water quality?

Various physical, chemical, and biological measurements are used to analyse different aspects of water quality.

• Physical methods test physical characteristics like temperature, turbidity, colour, and solids. Higher temperatures affect dissolved oxygen and aquatic life. Turbidity and colour indicate suspended particles. Total dissolved solids influence salinity and conductivity.
• Common physical measurement techniques include thermometers for temperature, turbidimeters for cloudiness, colorimeters for colour, and gravimetric analysis for solids. These provide quantitative data on physical conditions.
• Chemical methods measure parameters like pH, oxygen, nutrients, organic matter, and toxic pollutants. pH affects toxicity and treatment needs. Dissolved oxygen is vital for ecosystems. Nutrients can cause algal blooms at high levels. Toxins pose health risks.
• Chemical testing utilises probes, test kits, titrations, chromatography, and spectrophotometry. These quantify the levels of specific chemicals in water.
• Biological methods assess bacteria levels and biological oxygen demand. High bacteria counts signal faecal contamination. High BOD indicates organic pollution and depleted oxygen.
• Together, these methods provide a comprehensive picture of water's physical, chemical, and biological quality. The results inform water monitoring, treatment needs, and environmental management.

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What affects water quality?

Water quality can be influenced by both natural factors and human activities.

• Natural factors like climate, geography, and ecology impact water quality. For example, rainfall patterns and weathering of rocks affect dissolved particles and nutrient levels. Water temperature and dissolved oxygen are also linked to climate.
• Geography determines features like water depth, flow rate, and connectivity to groundwater. These in turn influence parameters like turbidity, stratification, and salinity.
• Ecological processes like nutrient cycling, primary production, and decomposition affect oxygen, nutrient, and organic matter levels.

However, human activities often have the most significant effects on water quality issues. Major anthropogenic factors degrading quality include:

• Pollution from sewage, industry, agriculture, and urban areas. This adds excess nutrients, chemicals, toxins, and pathogens.
• Land clearing and development, which increase runoff, erosion, and sedimentation.
• Flow modification through dams, diversions, and water extraction. This alters natural hydrological regimes.
• Overfishing and introducing invasive species, impacting aquatic ecosystems.

Careful management of human activities is key to mitigating water quality issues and protecting water bodies.

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How does Human activity affect water quality?

Many human activities degrade water quality by altering the chemical, physical, and biological properties of water bodies. Common water quality issues arising from human factors include:

• Pollution from sewage, industry, farming, and urban runoff add nutrients, chemicals, and toxins to waterways. This causes issues like algal blooms, oxygen depletion, and contamination.
• Clearing land for agriculture and development increases erosion and sedimentation. Higher turbidity and excess nutrients impact aquatic habitats.
• Dams and water diversions alter natural flow regimes, temperatures, and oxygen levels. This disrupts ecosystems.
• Overfishing can unbalance food webs and change water nutrient cycles.
• Introducing invasive species impacts native ecosystems and water conditions.

Specific examples demonstrating human impacts include:

• The fertiliser runoff from agriculture in the Great Barrier Reef catchment decreases water quality and causes crown-of-thorns starfish outbreaks, damaging coral.
• Chlorine discharge from pulp mills along the Murray River produced dioxins and furans that contaminated sediments and fish.
• Gold mining in Western Australia led to acid rock drainage, degrading water quality and organisms in the river system.

Careful management of human activities is crucial for mitigating water quality issues and protecting aquatic environments.

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What are Australia's water quality management strategies?

Australia takes an integrated approach to managing water quality, with involvement from all levels of government. Key elements include:

• National Water Quality Management Strategy - provides national guidance and consistency for water quality management. Sets out principles like polluter pays, integrated decisions, and community involvement.
• National Water Quality Guidelines - scientifically-based trigger values for physical, chemical and biological indicators. Used to assess water quality for ecosystems and human use.
• State regulatory frameworks - laws regulating pollution, catchment activities, water extraction. Set quality standards and restrictions to protect water resources.
• Regional natural resource management groups - develop and implement regional water quality improvement plans. Engage community in monitoring and stewardship.
• Investments in infrastructure upgrades and water-sensitive urban design to reduce runoff and pollution.

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What are the laws and guidelines on water quality in Australia?

• National Water Quality Guidelines stipulate trigger values for water contaminants and parameters. These inform state water quality regulations.
• The Environmental Protection Act sets water pollution standards in Queensland. Offences for illegal discharge with penalties.
• Victoria's State Environment Protection Policy defines water quality objectives for regional waterways. Contains legally enforceable limits.
• Western Australia's Environmental Protection Act regulates pollution. The Department of Water and Environmental Regulation enforces regulations.
• New South Wales Protection of the Environment Operations Act regulates water pollution. EPA licensed waste discharge and fines non-compliance.
• Guidelines are implemented through monitoring, modelling, licences, and enforcement. Compliance is promoted through incentives, education, and deterrent penalties.

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What are the main components of an Environmental Impact Assessment?

Environmental impact assessments (EIAs) systematically evaluate the potential impacts of a proposed project on the environment. Main EIA components include:

• Screening - Determines if a full EIA is required for a project.
• Scoping - Identifies key issues and impacts to focus the EIA on.
• Baseline study - Describes existing environmental conditions in the project area.
• Impact analysis - Predicts and assesses the project's likely positive and negative impacts.
• Mitigation plan - Measures to avoid, minimise, and offset adverse impacts.
• Evaluation of alternatives - Compares project options to select best choice.
• Public consultation - Stakeholder engagement in the EIA process.

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Does Environmental Impact Assessment include water quality?

Yes, assessing impacts on water quality is a key part of many EIAs. It evaluates how the project could affect quality of groundwater, rivers, wetlands, coastal waters, etc. 

Common assessments include:

• Water sampling to establish baseline quality conditions.
• Hydrological modelling to predict changes to water flows.
• Estimating pollution discharges and runoff from the project.
• Testing for impacts of discharges, pipelines, dewatering, dredging etc.
• Assessing habitat, ecosystem and health impacts if quality declines.

For example, EIAs of mines evaluate acid drainage risks to water bodies. Urban development EIAs model stormwater runoff impacts.

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Why is water quality assessment important for proposed projects?

Water quality assessments during EIAs provide vital information to plan projects sustainably. For instance:

• Testing reveals quality issues needing mitigation, like high baseline turbidity or presence of toxins.
• Modelling discharge effects allows developing appropriate treatment measures.
• Understanding impacts enables modifying project plans, like realigning infrastructure away from waterways.
• Monitoring quality before and after provides accountability for preventing degradation from the project.

Undertaking water quality assessments enables proactively minimising damage to water resources and dependent ecosystems and communities. This results in more environmentally sound projects.