Preliminary studies on the application of regional, geochemical reconnaissance data, based on stream sediment sampling, to the assessment of water quality and estuarine pollution are encouraging. The use of the trace metal composition of tributary drainage sediments for the prediction of the upper limits of the trace metal concentration ranges in associated waters has been demonstrated, suggesting that the already available reconnaissance data may be a useful ancillary aid in the location of water monitoring sites in potential problem areas for potable water abstraction. The close association between the trace metal status of estuarine waters and sediments and their respective tributary drainage sediments allows the use of regional geochemical reconnaissance data in the selection of estuaries for aquaculture and other amenities.It must be emphasized that regional geochemical reconnaissance data, although a useful guide to the trace metal status of potable and estuarine waters, does require more detailed follow-up studies in selected areas. This is especially true for temporal studies to establish the seasonal variations in surface drainage systems. The present investigations in the United Kingdom involve areas of fairly well known characteristics and relatively small climatic and environmental scope; the extension of such studies to lesser known areas and regions of greater natural variations could well prove useful.