Groundwater quality protection : defining strategy and setting priorities

Abstract

Groundwater, as a vital natural resource for the reliable and economic provision of potable water supply, merits protection in both the urban and rural environment. It thus plays a fundamental (but often little appreciated) role in human well-being, as well as that of some aquatic and terrestrial ecosystems. For municipal water supply, high and stable raw-water quality is a prerequisite, and one best met by protected groundwater sources. Recourse to treatment processes (beyond precautionary disinfection) in the achievement of this end, should be a last resort, because of their technical complexity, and financial cost, in addition to the operational burden they impose. However, all too widely in the past, groundwater resources have, in effect, been 'abandoned to chance'. And all too often those exploiting such resources for the provision of potable water supply, have taken no action to protect water quality. Worldwide, aquifers (geological formations containing usable groundwater resources) are experiencing an increasing threat of pollution from urbanization, industrial development, agricultural activities, and mining enterprises. Thus proactive campaigns, and practical actions to protect the natural (generally excellent) quality of groundwater are widely required, and can be justified on both broad environmental-sustainability, and narrower economic-benefit criteria. In some cases, it may take years or decades before the impact of a pollution episode, by a persistent contaminant, becomes fully apparent in groundwater supplies abstracted from deeper wells. This can lead to complacency over the pollution threat. But the real implication is that once groundwater quality has become obviously polluted, large volumes of aquifer are usually involved. Thus clean-up measures, nearly always have a high economic cost, and are often technically problematic.