Factors affecting microbiological water quality at sixteen beaches in South-West Wales

Routine monitoring data from 1993 to 1999 were analysed to elucidate relationships between microbiological water quality and environmental conditions at sixteen EC identified bathing waters in South-West Wales. The objective was (a) to gain an understanding of the factors affecting non-compliance with the guideline standard of the EC Bathing Waters Directive, (b) to aid the development of action plans for improved bathing-water quality, and (c) to enable effective targeting of future investigations. The analyses demonstrated relationships between water quality and rainfall, sunshine, tidal range, tidal state, time of sampling, time of year, wind speed, wind direction, state of sea, transparency, river flows, river quality, salinity and temperature. The temporal and spatial variability In water quality shown by this study also highlights the need to ensure that monitoring programmes represent conditions at the times and locations of greatest bathing-water use.