Organisms that tolerate lower oxygen levels are more common in this section of the stream. The benefit of monitoring in each of the upper, middle and lower sections of a catchment is that it allows you to build up a more complete understanding of your monitoring results, of the relationship between the sections and of how each one influences stream quality along its length. For example, any differences in rainfall and soil type within your catchment should be taken into account when interpreting your monitoring results, or when comparing results between catchments. It's important to consider natural geographical variations when comparing water quality indicators between different sites or catchments. Local biological communities are adapted to local conditions.
Past land uses too can have an effect.
For example, an old tip site may leach pollutants for years after it has closed so you should check for this type of information with local residents or the local Council. The physical and chemical tests section includes instructions for measuring stream flow and calculations for assessing catchment loss rates. Conducting these surveys and tests Safety considerations When selecting a site, choose one that has safe and easy access to the stream-bank or wetland and the water. You need only gain access to one bank and simply observe the other when conducting the surveys. Check that the stream-bank is stable and not too slippery.