How to understand environmental water quality in water resources management

“Water for people and people for water” We all depend on water for life, well-being and economic prosperity. In our homes water is used for drinking, cooking and washing. In our workplaces water is used for agriculture and industry. Water provides for recreation and our need for natural beauty, and it can be part of our spiritual awareness. Water is so important and is used in so many ways that if it is overused, we risk damaging our very life source. This happens when we take too much water out of aquatic ecosystems, and put in too much waste. The South African National Water Act (NWA) (No. 36 of 1998) recognises that water resources are part of the integrated water cycle made up of water ecosystems – rivers, wetlands, lakes, dams, estuaries and groundwater – and the processes of precipitation, transpiration, infiltration and evaporation. Closely connected to the water cycle is the use that people make of water resources. The NWA promotes protection of water resources so that people can use water both now and into the future. Water is at the heart of “a better life for all”. This handbook focuses on environmental water quality (EWQ), in particular the use of water resources for waste disposal, and the effect that waste disposal has on ecosystems. The term water quality is used to describe the microbial, physical, chemical and radiological properties of water. These properties affect both ecosystem health and the “fitness for use” of the water. Managing water quality requires attention to both water resource protection – and water resource use, and requires decisions about balancing the two. Both over-protection and under-protection are expensive. Over-protection is expensive for users, and under-protection is expensive for the environment (and thus ultimately also for the users). If we really want to move towards sustainability, and to take account of social, economic and environmental costs and benefits, it is essential that we answer two questions. How much should aquatic ecosystems be protected? and How much can aquatic ecosystems be used? Ecosystem health may be expressed as one of three classes – minimally altered, moderately altered and heavily altered. Objectives for the various classes used to manage ecosystem health are termed Resource Quality Objectives (RQOs). These RQOs combine the goals/objectives for the ecosystem as well as the goals/objectives for the most sensitive user.