4. Investigating pollutants in water
HSIE Stage 2 Outcomes
The activities associated with this topic meet the following syllabus outcomes:
Patterns of Place and Location ENS 2.5.
Note: Section 4 could be appropriate at Stage 2 level if students are assisted by a trained team, such as a Streamwatch group from the local high school. Activity 4.1 has been developed specifically for Stage 2 students.
Geography Stage 5 Outcomes
The activities associated with this topic meet the following syllabus outcomes in focus areas 5A2 and 5A3:
5.1 Identifies gathers and evaluates geographical information
5.2 Analyses, synthesises and organises geographical information
5.3 Selects and uses written oral and graphic forms to communicate geographical information
5.4 Demonstrates a sense of place about Australian environments
Science and Technology K-6 Outcomes
The activities associated with this topic contribute to achievement of the following Stage 2 outcomes:
LT S2.3 identifies and describes the structure and function of living things and ways in which living things interact with other living things and their environment.
INV S2.7 conducts investigations by observing, questioning, predicting, testing, collecting, recording and analysing data, and drawing conclusions.
UT S2.9 selects and uses a range of equipment, computer-based technology, materials and other resources with developing skill to enhance investigation and design tasks.
The activities also have links to the following Stage 3 outcomes:
LT S3.3 identifies, describes and evaluates the interactions between living things and their effects on the environment.
INV S3.7 conducts their own investigations and makes judgements based on the results of observing, questioning, planning, predicting, testing, collecting, recording and analysing data and drawing conclusions.
UT S3.9 evaluates, selects and uses a range of equipment, computer-based technology, materials and other resources to meet the requirements and constraints of investigation and design tasks.
Background information compiled from:
Beachwatch and Harbourwatch State of the Beaches 1999 and 2000, NSW Environment Protection Authority, 1999, 2000.
Field Manual for Water Quality Monitoring, Mark K. Mitchell and William B. Stapp, Kendall-Hunt Publishing, 1998.
GREEN Low Cost Water Monitoring Kit, GREEN (The Global Rivers Environmental Education Network) and La Motte.
Streamwatch Manual - The Complete Streamwatch Guide to Water Quality Monitoring, Sydney Water Corporation and Department of Land and Water Conservation, 1998.
Environment Matters: Managing pesticides, Who Does What; What are pesticides? How pesticides work NSW EPA 2000
Water quality testing will enable students to obtain first hand evidence of water pollution and will assist them in identifying the sources of that pollution. The tests also provide a mechanism for monitoring water quality over time and comparing the health of different waterways.
Water quality standards have been set by the Australian and New Zealand Environment Conservation Council (ANZECC).
To access the Australian and New Zealand Guidelines for Fresh and Marine Water Quality contact the Environment Australia web site.
Collecting Water Data
If your school is a participant in the Waterwatch or Streamwatch programs (see below) then you could work with your school's coordinator to conduct water quality testing of your local waterway using the schools water quality monitoring equipment. You can also visit the Waterwatch or Streamwatch web sites to obtain water quality data collected by other schools.
Waterwatch is a national community based water monitoring program, known as Streamwatch in parts of NSW. Waterwatch assists in the monitoring and management of the local waterways and catchments of every State and Territory.
NSW Department of Infrastructure, Planning and Natural Resources
GPO Box 39, SYDNEY 2001
Phone: (02) 9228 6571 Fax: (02) 9228 6464
Streamwatch is supported by Sydney Water and Waterwatch Australia. In NSW Streamwatch operates under the umbrella of NSW WaterWatch.
Sydney Water, PO Box 756 CHATSWOOD 2057
Phone: 9952 0358 Fax: 9952 0333
Oz GREEN - Low Cost Water Testing Kit
A new low-cost water quality monitoring kit has been developed by GREEN USA and La Motte. The kit contains equipment, chemicals and simple instructions to carry out water quality testing for dissolved oxygen, biochemical oxygen demand, nitrates, phosphates, turbidity, pH, temperature and faecal coliform. The kit is available through Oz GREEN and costs approximately $66 including GST (subject to exchange rate variations).
PO Box 1378, DEE WHY, NSW 2099
Phone: (02) 9984 8917 Fax: (02) 9981 4956
Local Government Water Quality Data
Another valuable source of information about the state of your local waterways is your local government. Every year a State of the Environment report is produced by local councils. Contact the environment section at your local council. Perhaps you can arrange for a council officer to assist you with your water quality investigations.
Catchment Management Boards
Catchment Management Boards and Trusts have been established by the NSW Government to strengthen community, industry and government agency efforts to manage natural resources in an integrated way for a sustainable future. Catchment Boards and Trusts are a valuable source of information about your local waterway.
Contact the Department of Infrastructure, Planning and Natural Resources to find out the location of your nearest board.
NSW Department of Infrastructure, Planning and Natural Resources
GPO Box 39, SYDNEY 2001
Phone: (02) 9228 6506 Fax: (02) 9228 6399
Beachwatch and Harbourwatch Reports
The Beachwatch Program monitors and reports on the bathing water quality of ocean beaches from the Hunter Region in the north, Sydney metropolitan area and the Illawarra in the south. The Harbourwatch program monitors and reports on bathing water quality in Sydney Harbour, Botany Bay, Georges River, Pittwater and Port Hacking. A report is produced each year that presents a brief description of each site, an assessment of water quality over the season, pollution sources impacting on the site and any pollution reduction actions taking place.
Beachwatch reports are available from:
PO Box A290, Sydney South, NSW 1232
Phone 131 555 (information and publications) Fax (02) 9995 5999
Daily Beachwatch and Harbourwatch bulletins are also available on the Beachwatch website (www.epa.nsw.gov.au/beach).
Water Quality Tests
Physical, chemical and biological measurements combine to provide valuable tools for analysing water quality. A series of 9 water quality tests are outlined below. These tests were selected by Prof Bill Stapp, founder of the Global Rivers Environmental Education Network (GREEN), following a survey of water quality scientists from around the world. These tests form the basis of the water quality monitoring programs conducted by Waterwatch and Streamwatch , and also form basis of the Oz GREEN Low Cost Kit. These same tests are used by water quality monitoring programs around the world as an indicator of river health.
Dissolved oxygen (DO) is the amount of oxygen gas dissolved in the water. Dissolved oxygen is essential for the health of aquatic ecosystems and for the survival of most aquatic organisms. Dissolved oxygen is expressed in mg/L and per cent saturation. DO levels are dependent on the water temperature. The higher the water temperature the lower the amount of oxygen that can dissolve in the water.
Factors that cause dissolved oxygen to increase include:
- the physical mixing of water and air by waves, rapids, waterfalls and rain
- photosynthesis by aquatic plants including microscopic algae producing oxygen
- algal blooms can cause water to become super-saturated with oxygen (more than 100 per cent saturation).
Factors that cause the levels of DO to decrease include:
- the respiration of aquatic animals (and aquatic plants at night)
- the decay of organic matter such as leaves, grass clippings and sewage.
Biochemical Oxygen Demand
Biochemical oxygen demand (BOD) is a measure of the amount of organic matter in water. High BOD levels mean that oxygen is being produced during the day by aquatic plants and consumed overnight - causing the DO level to drop and animals to die.
Total Dissolved Solids (TDS) and Turbidity
Total dissolved solids are those solid materials such as salts that are dissolved in the water but have little effect on its clarity. Total Dissolved Solids (TDS) can come from a number of natural sources such as the rocks or soil in the catchment, or from man-made sources such as industrial wastes or sewage.
Turbidity is a measure of the suspended solids or cloudiness of the water.
Turbidity can effect a waterway by:
- preventing light from reaching submerged aquatic plants and reducing photosynthesis
- absorbing sunlight and raising the temperature of the water.
- clogging gills and causing harm to aquatic animal life
- causing suspended particles to act as carriers for nutrients, pesticides, herbicides and bacteria.
Factors that result in increased turbidity include:
- algae blooms
- sediment run-off from exposed or bare soil
- industrial waste
- chemical spills.
H is a measure of the acidity or alkalinity of a waterway. The optimal pH for most organisms in Australian waters is pH 6.5 to pH 8.2. Changes in pH outside this normal range will cause a reduction in species diversity. pH will vary depending on the geology of the area. Water flowing through limestone will be alkaline and water flowing through sandstone or basaltic soils will be slightly acidic. Natural seawater is slightly alkaline pH 8.2 so as the water is tested in estuarine environments the pH is naturally above fresh water levels.
Nutrients - Phosphorous and Nitrates
Phosphorus and nitrates are essential plant and animal nutrients that come from the weathering of rocks and the decomposition of organic matter. They occur naturally in very low concentrations in Australian soils and waterways. The native vegetation has adapted to these low levels and are stressed and easily displaced by phosphorous-loving 'exotic' weeds when concentrations become high.
When a waterway has an influx of nutrients, the chance of an algae bloom increases greatly. Sources of phosphate compounds in waterways include:
- sewer leaks and sewage overflows
- manure from feedlots, dairies and pet droppings
- phosphate-based detergents
- decomposing organic material
- fertilisers and industrial wastes.
Increased phosphate levels in our waterways cause the following problems:
- increase in algae growth, increasing turbidity and reducing light penetration
- blue-green algae blooms (some toxic)
- an increase in aquatic weeds that eventually choke a waterway
- the displacement of native riparian vegetation with introduced weed species
- increased BOD
- reduced DO levels leading to fish kills.
Faecal coliform are bacteria found in the faeces of humans and other warm-blooded animals. These bacteria can enter our waterways through direct discharge from mammals and birds, from agricultural and stormwater runoff carrying waste from animals and from human sewage from overflows or leaks in the sewerage system.
Faecal coliform are generally not pathogenic in low numbers but their presence may be an indication of other disease causing organisms including viruses, bacteria and parasites. Faecal coliform enter our waterways through:
- leaking sewers or septic tanks
- feedlot and dairy run-off or any other intensive animal husbandry farming
- stormwater run-off carrying animal and bird faeces (including pet droppings)
- sewage overflows during wet weather
- waterfowl and livestock defecating directly into waterways.
The ANZECC guidelines also refer to another indicator of microbiological water quality, known as enterococci. These bacteria may be a better indicator of sewage pollution when monitoring marine waters, because they survive for longer periods than coliform bacteria.
It may be necessary to investigate a wider range of water quality parameters in catchments that have industrial areas. The water may contain heavy metals or toxic organic compounds. In many waterways bottom sediments are laden with trace metals.
Trace metals or heavy metals such as: aluminium, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, silver and zinc may be toxic to aquatic organisms. Harmful effects can include death (lethal effects) or inability to reproduce. The toxicity of heavy metals will be affected by their bioavailability. Organisms uptake metals through the food they consume, through absorption onto gills and through the skin. Bioavailability in turn is affected by water hardness, pH and age of the organism. Metals are absorbed into organic material and so are found concentrated in bottom sediments.
Toxic substances can enter waterways from sewage overflows and stormwater run-off. Stormwater carries lead deposited in streets from car exhausts, oil, grease and copper worn from metal plating and brake linings.
Scientific companies such as Merck, Hach and La Motte produce kits that can be used to test for toxics in water. Contact details:
Hach suppliers: Selby Scientific
La Motte suppliers: Vendart Pty Ltd
Ph/Fax: (02) 9679 1139
Merck: Freecall 1800 335 571
Small organisms that live on the bottom of streams and rivers are known as benthic macroinvertebrates. Collecting these water bugs can provide a greater understanding of a waterway's condition. They are a useful indicator of water quality because:
- they are sensitive to physical and chemical changes in their habitat
- they are present in the water over extended periods of time and can thus indicate cumulative impacts
- they cannot easily escape pollution
- they are easy and fun to collect.
For information on how to monitor macroinvertebrates, refer to Streamwatch or Waterwatch
Interpreting Water Data
Many factors can affect the water quality of a waterway. The conditions of a river can fluctuate periodically. Hence water quality data needs to be assessed over a period of time to identify trends and patterns.
Once students have conducted their water quality testing and obtained additional water quality data from the local council and Catchment Board, the data can be studied to identify patterns and trends. Use Table 4.1 (page 6) to determine possible sources of pollution of the waterway (see student activity sheet).
Primary contact recreation (swimming, water skiing and similar body contact.) Median bacterial content should not exceed 150 faecal coliform organisms/100 mL (minimum of 5 samples taken at regular intervals not exceeding one month, with 4 out of 5 samples containing less than 600 organisms/100 mL).
Secondary contact recreation (sailing, fishing etc) Median bacterial count should not exceed 1000 faecal coliform organisms/100 mL (minimum of 5 samples taken at regular intervals not exceeding one month, with 4 out of 5 samples containing less than 4000 organisms/100 mL.
BOD (Biochemical Oxygen Demand)
Should be < 2 mg/L (Source: Pollution Control Manual for Urban Stormwater, State Pollution Control Commission 1992)
ANZECC (1992) guidelines for preventing eutrophication: (Nitrates in mg/L):
Rivers and streams 0.10-0.75
Lakes and reservoirs 0.10-0.50
Coastal waters 0.01-0.06
ANZECC (1992) guidelines for the concentration for the prevention of eutrophication (Phosphorus in mg/L):
Rivers and streams 0.01-0.100
Lakes and reservoirs 0.005-0.050
Coastal waters 0.001-0.010
TDS (Total Dissolved Solids)
Fresh waters: should not exceed 1000 mg/L
Estuarine waters: TDS will vary depending upon how far upstream tests are taken. Values at any particular point will change depending on the amount of freshwater flowing into the system.
Seasonal mean turbidity and suspended solids levels must not change by more than 10 per cent, Primary contact: < 5mg/L
DO > 6 mg/L, % saturation > 80%, < 110%
DO > 110 % saturation indicates algal activity producing super-saturation with oxygen (algal bloom).
Page last updated: 26 February 2011