The impact of an annual major recreational boating event on water quality in the Solent Strait

A long-term historical analysis of the impacts of recreational boating on marine surface water quality during a regatta (Cowes Week) in an internationally crucial waterway, the Solent Strait (Hampshire, UK) is presented. Water quality indicators studied included nitrogen concentration, bacterial indicators, and oxygen saturation, at three sampling sites at/near Cowes during 2001–2019. Findings include that sewage discharge from recreational boats is the key contributor to localised faecal contamination of marine surface waters, putting bathers and shellfisheries at risk. Bathing water quality monitoring and pollution warning systems should be strengthened prior to and during this type of regatta and access to bathing water areas may need to be restricted. These findings have implications for the regulation, future monitoring and management strategies for discharges from recreational boats during extended regattas. Adequate and affordable local facilities for recovering sewage wastewater from recreational boats should be provided alongside appropriate mechanisms for communication to sailors. •Historical analysis of impacts of recreational boating on marine water quality•Water quality indicators studied: N concentration, bacteria, O2 saturation•Recreational boat discharge key contributor to faecal contamination during regattas•Bathing water quality monitoring & pollution warning systems should be strengthened•During regattas access to bathing water areas may need to be restricted