Water sources: Surface water

dam wall

As we continue our series on water sources in the lead up to National Water Week, we’re looking at one of the broader terms this week: surface water.

What is it?

Including rivers, lakes, oceans and wetlands, surface water is loosely defined as any body of water on the surface of the earth. As we’ve already covered desalinated water, to keep things simple, we will just look at fresh forms of surface water.

How is it used?

Surface water can be one of the easier and more affordable sources of water to “tap” into. Where there are fresh bodies of surface water available, they will usually be the first preference for sourcing potable water. This could be as simple as pumping water from a river, or natural lake to requiring more significant infrastructure like a dam wall. While providing potable water for a town or city, surface water plays a significant role in regulating the temperature and climate of our planet, as well as providing a great deal of aesthetic enjoyment for boating, swimming and a range of other water related activities.

Where is it being used?

Water utilities around Australia use surface water as a primary source of their potable water supply. In fact, in 2008/9 over 95% of water used in Australia was sourced from surface water. Rural water providers also use untreated surface water to supply irrigation for agriculture. The most famous surface water project in Australia is the Snowy Mountains Hydro Scheme, using water for power and irrigation in NSW.

What are some of the benefits of surface water?

  • Surface water is usually a lot easier, therefore more affordable, to access than other water sources
  • Often, there is comparatively little treatment required to make surface comply with water drinking quality standards.

water-fall

What are some of the issues with using surface water?

One of the downsides of surface water is that it can be easily lost through evaporation, especially in Summer. The Menindee Lakes in NSW lose over 400 billion litres to evaporation annually. Another downside to using surface water (as with other sources) is that there are competing needs – for example one lake may supply several towns, plus agriculture and the environment.

What is the environmental impact?

The environmental impact varies depending on where the surface water is situated. Dams have a permanent major impact on local river valleys, using water from rivers reduces environmental flows and changes seasonal flows. On the other hand, dam walls have often been needed to make the most of river supplies. This is why environmental assessments are considered each time a water provider investigates a new source of water; to weigh up whether the proposed course of action.

Have you visited the place where your water comes from?