About the Catchment Area : Issues & Problems

About the Catchment Area

Issues & Problems
There are range of issues and problems that are affecting the health of the creeks and rivers in the area. Basically they can be divided up into two categories - issues that relate to

Water Quality (which includes stormwater pollution and salinity )
Water Quantity

See also
Quality Monitoring in the Board's Area
Understanding Water Quality to gain a better understanding about water quality and how it is measured.
Water Quality Monitoring parameters to lean about what things are being monitored and why.
The impact of deciduous leaves on water quality.

Water Quality Issues
Urban and industrial development, farming, mining, combustion of fossil fuels, river-channel alteration, animal-feeding operations, and other human activities can change the quality of natural waters.

As an example of the effects of human activities on water quality, consider nitrogen and phosphorus fertilizers that are applied to crops and lawns. These plant nutrients can be dissolved easily in rainwater runoff. Excess nutrients carried to creels and rivers encourage abundant growth of algae, which leads to low oxygen in the water and the possibility of fish kills.

Bacteria, viruses, and other pathogens in water
The quality of water for drinking cannot be assured by chemical analyses alone.

The presence of bacteria in water, which are normally found in the intestinal tracts of humans and animals, signal that disease-causing pathogens may be present. Giardia and cryptosporidium are pathogens that have been found occasionally in public-water supplies and have caused illness in a large number of people in a few locations.

Pathogens can enter our water from leaking septic tanks, wastewater-treatment discharge, and animal wastes.

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Stormwater pollution
Any rain that falls on the roof of your house or collects on paved areas like driveways, roads and footpaths is called stormwater.

As stormwater travels over the land, it picks up all kinds of chemicals and materials that are not naturally found in our waterways. Some of these are toxic and dangerous - even in small amounts. Others, such as nutrients, are not poisonous but may be produced in such great quantities that natural systems simply can’t cope. After a dry season, the first flush of stormwater can have the same pollutant load as raw sewage. This results in the pollution of our waterways.

Factors affecting stormwater pollution
The amount of stormwater runoff produced and pollution levels are affected by:

when it last rained
iintensity of the rain
building density and other land uses in the catchment
level of vegetation cover
the cleanliness of the streets
local practices such as street sweeping, pet control and excessive garden watering.

The effect of stormwater pollution
The effects of stormwater pollution include killing plants and animals that live in the water.

For example:

sediment in the water reduces light penetration and affects photosynthesis, the process that allows plants to use light as their source of energy
litter clogs waterways and causes toxicity from the breakdown of material and has an effect on the health of birds, fish and other animals and plants that live in the waterways
organic material (green waste) uses up vital oxygen in the water

Effects of Urban and Rural Development
The more development occurs in a catchment, the more we need to take care of the environment. When new suburbs are created, the stormwater run-off increases from 5% to over 50%, and as much as 98% in fully built up areas.

The original creek network is often unable to cope with the enormous amount of extra water, and this contributes to flooding damage. Stormwater run-off also contains a large number of pollutants.

Artificial wetlands which receive urban stormwater run-off can help moderate the effects of flooding, as well as improve water quality.

Rural Development
Irrigation for agriculture and horticulture, grazing stock, spraying chemicals and fertilisers, and dam construction all impact on the catchment.

Common Pollutants
Pollutants have many origins- here are just a few:

Motor Vehicles - cars and trucks etc that drip oil and grease onto the road are a source of pollution, so too is the rubber that gets worn from the tyres and deposited on the road surface. The next time it rains, have a look at the quality of the water running in the gutters, you will probably notice the water has an oily film on it and water can be far from clear in colour.
Chemicals and paints - used around the home and office can also become pollutants if they are not disposed of properly.
Chemical pesticides and fertilizers - used on the garden can also be harmful if they are washed into local creeks and rivers via the stormwater system. For this reason it is wise to use pesticides and fertilisers sparingly and to avoid using them at all on a windy day.
Plant litter - grass clippings and the leaves of non native trees can also be very harmful to aquatic ecosystems.

Litter - the big problem
Rubbish dropped by people is a real problem. Here are some interesting statistics provided by KESAB which show various types of litter found on our streets and indicates the prevalence of that litter.

Cigarette butts - 44 %
Paper - 13 %
Confectionary wrappers - 7 %
Plastics - 6 %
Bottle and can tops - 3 %
Plastic bags and sheets - 2 %
Straws - 2 %
Cigarette packets - 2 %
Paper cups/containers - 2 %
Milk/juice cartons - 2 %
Tickets/receipts - 2 %
Clothing - 1 %

Did you know that Australians use 3.6 billion plastic shopping bags each year? Of that number less than 1% of the total number of plastic bags used each year are re-used by households.

Cigarette butts - more information
Cigarette butts are the biggest single source of pollution (by number) littering our environment.

Australians throw away 32 billion cigarette butts every year. Many of these are carried through gutters into our local waterways.
These butts placed end to end would circle the planet 16 times and fill more 475 buses.
Everyday approximately 3 million are thrown out in South Australia alone.
Filters in cigarette butts are made from a non-biodegradable plastic, which takes 15 years to break down in the environment.
Butts contain many nasty pollutants that harm our waterways and threaten animals and fish.
Wildlife can mistake cigarette butts for food. If filters block their digestive tract, animals can become ill and even starve. (Source NSW EPA)

Aren't businesses bigger polluters than residents?
Both industry and the community have an important role to play in helping to reduce stormwater pollution. Strict pollution controls on industry have helped reduce their impact on the environment in recent years. The Board helps to prevent industry stormwater through the Aware program. Cleaner production and business practices are encouraged o reduce stormwater pollution and can translate into potential financial savings for local companies. The reality is that we all have an impact on stormwater quality, and we can all take steps to make a difference.

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Salinity
The World Health Organisation currently recommends that, for humans, a salinity of 800 EC units (Electroconductivity Units) should be considered the upper limit for desirable drinking water.

Current studies show that this level is likely to be reached or exceeded for South Australian supplies in the next 50 to 100 years.

Saline groundwater is a feature of many parts of Australia. Prior to white settlement, the density of trees in the lands was considerable. Trees, with their extensive canopies and deep root systems, are effective gatherers of water from the soil. Much of the rainfall in treed areas was gathered up and transpired back in to the atmosphere. Very little water was available to seep down through the soil to join the groundwater table, and the groundwater system was able to discharge to rivers or streams at a rate that allowed a relatively static and deep water level.

Since European settlement, the large-scale clearing of native vegetation and its replacement by crops and grazing systems has substantially increased the amount of water entering the groundwater systems. The removal of trees has massively reduced the transpiration component of the water loss, resulting in additional water available to enter the groundwater system.

As the amount of water entering the groundwater system exceeds the systems capacity to discharge the additional water to rivers and streams, so the groundwater levels must rise. As the levels rise, ultimately they will come in contact with the surface and will form ponds at low points on the land.

If the soil contains salt, leakage through it to the groundwater will wash more salt to the water table. If the groundwater systems contains salt, or if it rises through salt containing strata, the salt is mobilised to the surface. As a consequence of the salt being on the surface of the land, as it rains, this salt is then washed into our rivers and streams. Therefore dryland salinity greatly influences/ river salinity.

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Water Quantity Issues
Water for human purposes
Early South Australians settled along the creeks and in areas where undergound water was very close to the surface and easily obtained from wells or shallow bores. As the population of the State increased many of these resources were exhausted or polluted and the growing population required more water than the local reservoir systems could provide from rain that fell in the Adelaide Hills catchments.

South Australia then looked to the River Murray to provide the water for the continued development of the State. The River Murray provides South Australia with:

40% of its water in a wet year.
60% of its water in an average year.
90% of its water in a dry year.

Water for the environment
All life depends on water. In aquatic ecosystems this dependence is absolute and changes in stream flow can have an almost immediate impact on the health of that ecosystem. To maintain health, aquatic ecosystems require a certain level of stream flow. The amount of flow required can be referred to as an environmental flow.

The concept of the environment being a legitimate user of water and therefore requiring its own allocation is relatively new. However, developments in catchment management and legislation indicate that the concept is becoming increasingly accepted across many parts of Australia. The Onkaparinga Catchment Water Management Plan recognises the environment as a legitimate water user through its Water For The Environment program.

Information Sources
Information on water quality sourced from
Gail E. Cordy, U.S. Department of the Interior/U.S. Geological Survey - March 2001
Website: http://water.usgs.gov/pubs/FS/fs-027-01/

Information on salinity sourced from
"Water and Salt in the Murray Darling Basin - A national environmental problem", (An Urrbrae Wetland Educational Resource), Allin Hodson 2002.

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