6    CHAPTER:  Water Quality

6.1    Introduction

To many of us when we think about fresh water quality it is about how clean our drinking water is or in some cases whether the water is clean enough to swim in or to fish in safely.  In other words out of site out of mind.  In fact after air water is our most important ecological service, without water there can be no life.  Therefore a decrease in water quality effects not only us but the health of the natural systems we depend on; the vegetation that holds the waterway banks together, the trees that give the stock shelter and us oxygen, the insects that break down organic matter enriching the soil, the bees that pollinate the crops and so on.

6.2    Major Types of Waterway Pollution

6.2.1    Sediments

Sediment is a natural part of a healthy system however when there is excessive sedimentation is becomes one of the most damaging pollutants in a water way.  Unfortuantely because "dirt" or sediment is seen as natural the destruction it can cause is often not take seriously.

Some of the major problems associated with excessive sedimentation are:

  • Turbidity reducing light to water plants leading to damage

  • Sand slugs smothering plants and water creatures and crops

  • Negitively effecting stock drinking water

  • Filling in man made infrastructure such as dams and resevoirs

  • Causing additional flooding

6.2.2    Nutrients

Excess nutrients washed into the waterway from adjoining land in particular farm land.  The additional nutrient loads can lead to algal blooms which can smother biodiversity and effect human and stock health.

6.2.3    Chemicals

These make up the majority of pollutants that people, particularly in the city, often think of when they think of waterway pollution.  This type of pollution is much more common in urban areas where run off from streets and factories.  While this is type of pollution can be extremely damaging, in terms of overall impact this type of pollution can be considered relatively small in proportion to many other forms of pollution.  Interestingly despite the realatively small areas impacted by this type of pollution it is the only one that the EPA, the governments environmental protection agency is funded to address

6.2.4    Exotic plants

Australia is particularly vulnerable to exotic plants polluting its waterways, not only can the exotic plants choke a waterway crowding out native animals and plants and in some cases causing flooding, but deciduous trees such as willows which drop their leaves in a single season, rather than all year round with most of the Australian natives, can cause server deoxgenation which damages many native animals.

6.3    Signs of Clean Water

There are a wide range of different water testing equipment on the market and also a range of different models used to judge the quality of fresh water available in Australia.  As information associated with these methods and equipment is quite detailed aand changes regularly with time it is not appropraite to go into this mater in any detail in this book.  For up to date informtaion it is best to contact the appropriate government agency.

However for the landcare owner or interested professional who wishes to gain a snapshot of the quality of a partiular Creek a quick survey of the types of water creatures that can be found in the water can give vaualb indications about the health of the waterway.  The reason for this is that different water creatures have different levels of toleance to the levels of various pollutants in the water.

Currently the most commen assessment method for checking the quality of water is the SIGNAL method. This method checks on the type and number of macroinvertebrates (water bugs) in the water and provides a score which is dependent on the water bugs found.