Faecal indicator impacts on recreational waters: budget studies and diffuse source modelling

A series of investigations are underway which have quantified the contribut ion of faecal indicators delivered to nearshore coastal waters from the sew erage system and riverine inputs. Studies have been completed in Jersey, St aithes, Yorkshire, South Wales and the North-west. The resarch protocols ha ve involved quantification of high and low flow faecal indicator delivery f rom the sewerage system and riverine sources as well as construction of non point source models designed to predict faecal indicator delivery from diff use, catchment sources. These investigations suggest a dynamic, but predict able, balance between inputs from the sewerage system and from 'catchment' sources. The sewerage system dominates during lon flow conditions but is of ten overtaken by riverine inputs during high flow conditions after rainfall . Many bathing beach locations exhibit non-compliance after rainfall when s tream inputs, rather than sewerage inputs, commonly dominate. The implicati ons of this input pattern is that routine monitoring data may not provide i nformation relevant to new infrastructure planning designed to achieve bath ing beach compliance. This suggests that the present scientific information base is insufficient to underpin the extensive UK infra-structure investme nt programmes designed to ensure compliance with existing EU Directive 76/1 60/EEC standards. Furthermore, results to date, suggest that management att ention must expand from its historical focus on infra-structure provision t o incorporate diffuse sources of faecal indicator loading which present a n ew set of management and modelling challenges.