¹Scottish Environment Protection Agency, Redwood Crescent, Peel Park, East Kilbride, G74 5PP, Scotland, UK.
²Scottish Environment Protection Agency, Clearwater House, Heriot Watt Research Park, Avenue North, Riccarton, Edinburgh, EH14 4AP, Scotland, UK

*Corresponding author: calum.mcphail@sepa.org.uk

Abstract

   The Scottish Environment Protection Agency (SEPA) has developed, and runs, real-time bathing water quality predictions at ten sites throughout Scotland since 2004. Daily bathing water quality predictions are posted on electronic variable message signs at 10 beach locations networked to a central communication centre and updates are simultaneously made on the SEPA website, phone and text message service.
Antecedent rainfall and subsequent river flow can significantly increase the concentrations of faecal indicator organisms in bathing waters. The SEPA signage prediction tool, an Excel spreadsheet based model, was developed and used to set site-specific criteria for rainfall and river flow to predict bathing water quality based on historical data. Real-time predictions against the current EU Bathing Water Directive were correct or precautionary on 99% of days and correct for 82% of compliance samples during 2007, and 81% of compliance samples during the 2008 season.
The revised 2006 Directive sets out more stringent bathing water quality standards which require increased model performance. New predictive models are now being trailed using decision tree statistical software and are intended to replace the existing prediction tool by 2012.