Ireland’s largely unpolluted surface waters are one of the most valuable natural resources of the island. Until the 1970’s there was very little information available on the quality of Irish water bodies. Since then, drinking water legislation has required the monitoring of certain specific parameters and the problem of eutrophication has resulted in extensive investigation of nutrient levels. In more recent years, however, the availability of modern analytical techniques has greatly assisted routine monitoring of waters for a wider range of chemical parameters. Over the period 1998-2001 thousands of samples from Irish rivers, lakes and canals were analysed by the Central Fisheries Board using Inductively Coupled Plasma - Mass Spectroscopy (ICP-MS), a method that allows for rapid and sensitive multi-element measurements. The purpose o f the analyses was primarily to increase knowledge of Irish surface water chemistry. It was also hoped that the work would assist in the understanding o f biological processes and begin the development of a database of chemical “signatures” for Irish waters. This thesis attempts to summarise and interpret a large quantity of analytical information obtained from about 230 sites chosen from the larger dataset of sampling locations on Irish lakes, rivers and canals. Sixteen elements were routinely analysed, resulting in approximately 100,000 individual measurements during this study. In Chapter 3 eighteen lakes of varying size and location are compared and contrasted. The distinctive characteristics of twenty-eight rivers to the east and west of Lough Corrib are studied in Chapter 4 and differences in the water chemistry of the four main canal systems are investigated in Chapter 5. In each of these specific areas, temporal and spatial variations in the concentrations of major and minor elements were studied. The effects of local geology was also considered and found to play a large part in the chemical composition of surface waters. It is anticipated that the knowledge gained from this preliminary investigation of trace elements in Irish waters will advance more in-depth future studies in this area.