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Issue: Habitat scale influences - Water Quality (for surface and groundwater) - Nutrients

This is an issue under the Inland waters theme of the Data Reporting System.

Why we need to know about this issue

Nutrients play an important role in plant growth and the enrichment of receiving waters but in excessive quantities can cause algal blooms which prevent light and oxygen from reaching other biota. This can lead to eutrophication and, ultimately, to high mortality among the river fauna.

The elements of nutrients most likely to be implicated in algal blooms are nitrogen and phosphorus. The major contributor to increased phosphorus to rivers is land clearing and erosion. Nitrogen comes primarily from fertiliser use, animal wastes and sewage discharges.

Indicators

• IW-14 Volume of sewage discharge to surface waters by treatment category (primary, secondary, tertiary) 
  Discharge from sewage treatment plants can contribute to nutrient enrichment in rivers and streams. High nutrient levels, combined with the increased periods of low flow due to river regulation and water extraction, have caused blue-green algal blooms to become a persistent problem in some dams, wetlands and lakes.
• IW-19 Exceedance of total nitrogen and phosphorus water quality triggers 
  Nitrogen and phosphorus levels can limit the availability of water resources and the indicator provides information that will help managers meet current and future needs. Eutrophication and toxic algal blooms can make surface water unsuitable for drinking or recreational purposes and can impact on ecosystems. The measure of total nitrogen and total phosphorus gives an estimate of eutrophication potential and high concentrations in surface waters are linked to algal blooms. Number of exceedences of water quality triggers for total nitrogen and total phosphorus is a direct measure of this pressure.
• CO-46 Comparative water quality of coastal lakes and lagoons (water quality gradient from north to south) 
  Comparative water quality of coastal lakes and lagoons, especially along the gradient from north to south will provide information on nutrient loads entering coastal waters.

Related issues

• Inland Waters - Catchment scale influences- Land and vegetation condition- Nutrients and sediments - sources and loads 
• Inland Waters - Response of biota- Bacteria and algae 
• Coasts and Oceans - Condition of the ocean and coastal waters- Water quality 
• Coasts and Oceans - Direct pressure of human activities on coasts and oceans- Direct pressure of coastal activities (other than shipping and fishing) 
• Coasts and Oceans - Contributions and pressures between the coasts and oceans and inland water- Effect of changes in inland waters on the coasts and oceans 
• Human Settlements - Pressures created by human settlements on the environment- Waste 
• Land - Direct pressure of human activities on the land- Pollution to and from the land