New generation water quality guidelines for ecosystem protection

• Published in: Freshwater biology 1999-03, Vol.41 (2), p.347-359
• Main Authors: Hart, Barry T., Maher, Bill, Lawrence, Ian
• Format: Article
• Language: English
• Subjects: ecosystem protection; Freshwater; guidelines; risk assessment; water quality
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1046/j.1365-2427.1999.00435.x

Summary 1. Water quality guidelines are important for the management of water resources. Initially, guidelines focused on quality for domestic drinking water and for agricultural, recreational and industrial purposes. More recently, the emphasis has been on ecosystem protection, as well. 2. This paper discusses the key elements of new risk‐based water quality guidelines being developed in Australia and New Zealand, that should lead to more effective management and protection of aquatic ecosystems. 3. There are three essential elements to this new approach: (i) it is ecosystem‐based— ideally the guidelines should be, as far as possible, ecosystem‐specific; (ii) it is issue‐based— the guidelines should focus on the actual issues or problems caused by physical, chemical and biological stressors rather than on the individual indicators, as at present; and (iii) it is risk‐based. There is generally great difficulty in deciding whether adverse biological effects will result from various stressors added to an ecosystem. The new approach develops guideline ‘packages’ for each issue and, where possible, for each ecosystem type. Each ‘package’ consists of specified key performance indicators, trigger levels for these indicators (that is, levels which indicate the degree of risk that adverse biological effects may occur), and for high risk situations (where trigger levels are exceeded) a protocol for considering the effect of ecosystem‐specific factors in reducing (or enhancing) the biological effects. 4. This paper presents a case study related to a highly relevant aquatic ecosystem issue in Australia, namely the excessive growth of cyanobacteria (blue‐green algal blooms), to illustrate how the new risk‐based guidelines might be applied.