Swimming with Sewage

There are many factors which can impact water systems ranging from deforestation and damming, through to sewage overflows and nutrient run off.

Deforestation near water can change the amount of sunlight the water receives, affecting algae growth impacting water oxygenation, and also the temperature of the water and the surrounding areas through loss of shade.

Nutrient run off is where fertilisers and animal waste is washed off land and into water. This can result in too much nutrients in the water causing algae to grow out of control in an algal bloom. When there isn’t enough nutrients in the water and the algae die, bacteria will decompose the algae. This consumed oxygen in the water creating ‘dead zones’ in the water where fish and other aquatic life can’t survive as there isn’t enough oxygen.

Sewage overflows can act as a significant source for nutrients in the water. Human waste often contains lots of nitrogen and phosphorus which plants and algae need to grow. This can result in the formation of a dead zone. Sewage overflows release sewage when there is heavy rain or when treatment plants exceed capacity raw or partially treated sewage into nearby bodies of water like rivers, lakes, and coastal areas.

Factors improving water systems

Improving water systems is very hard to do considering they are naturally forming and will return to their natural state if left alone. But we can help prevent harm coming to these systems:

• Reducing nutrient run off by preventing sewage overflows and minimising fertiliser use near water bodies
• Reduce deforestation near water systems. Some areas of water are naturally covered by vegetation and some are not. We shouldn’t interfere with how these systems are naturally set up
• Routine testing of water will allow us to know when water quality is bad. This will inform when actions need to be taken as well as telling us when certain improvement strategies aren’t working

If you would like to know more about factors affecting water systems then the following resources may be useful:

Main factors affecting water quality – More factors which can harm and improve water systems than detailed above

Factors affecting patterns of water use – Talks about how water is used currently and will be used in the future in areas with scarce water supplies