Relative importance of point source contamination of surface waters: RiverCherwell catchment monitoring study.

A small catchment (100ha) has been characterised and instrumented at the he adwater of the River Cherwell in the UK to determine the relative contribut ion of point and diffuse sources of surface water contamination by the cere al herbicide isoproturon. Observation of spray activities and intensive sam pling of the spray vehicle used, yard washings and river water have shown t hat the point sources of contamination are more significant than previously recognised both in their magnitude and their duration. The preliminary fin dings of this two year project indicate that there needs to be improved tra ining and awareness of spray operators and that there are a number of physi cal or engineering possibilities which may help prevent or minimise point s ource contamination. Initial meetings with regulatory bodies and users have emphasised the need to involve all interested parties to obtain practical and acceptable solutions.