Report No SR3104

Oct 1992

The aim of this study was to determine the extent and degree of impact of oil pollution on freshwaters. To this end a detailed questionnaire was distributed to all of the regulatory bodies throughout the UK and a literature review undertaken.

Oil and its related products are the single largest group of polluting agents. The great majority of the incidents involving oil are minor, farm pollution being the cause of most serious incidents. The study revealed large geographical differences in the prevalence of oil pollution; in general Scotland and Northern Ireland has the lowest number of incidents and England the highest.

Information was collected for the most serious acute events and the best documented inputs from each region. The most common cause of acute events was failure or absence of a protective bund surrounding a storage tank. Surface water sewers draining industrial premises accounted for over half the chronic inputs.

Selected acute events highlighted by the questionnaire were considered in some detail. The immediate effects of serious acute incidents include fish kills, tainting of fish flesh, and eradication of benthic fauna. Serious acute spills can have long lasting effects and other studies have shown that in some cases all pre-spill taxa had not returned after two years. Four chronic inputs highlighted by the questionnaire offer potential for further research. Three of these deal with complex effluents of intermittent nature from industrial estates. All of these effluents have a profound effect on receiving waterbodies leaving them grossly polluted. The review highlighted American studies that have carried out field and laboratory toxological studies in order to set safe discharge limits for effluents. These techniques could be applied to UK situations.

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