Plymouth Marine Laboratory study finds Devon sewage monitoring gaps

Research from the Plymouth Marine Laboratory indicates that current sewage pollution monitoring in Devon may be failing to detect significant bacterial contamination spikes. A study published in Marine Pollution Bulletin suggests that reliance on rainfall-based warnings and periodic water sampling misses many short-lived contamination events.

By combining water sampling with hydrodynamic and particle-tracking computer models, researchers found that coastal currents, tides, and wind play a critical role in steering sewage-linked E. coli toward beaches and shellfish farms in areas like Plymouth Sound and Lyme Bay. The study noted that routine testing schedules captured only about 5% of exceedance events.

Analysis of 13 years of data from three Devon river catchments revealed no significant relationship between rainfall and bacteria levels, with contamination spikes occurring during both wet and dry periods. This finding challenges the effectiveness of monitoring systems that rely heavily on rainfall forecasts to predict pollution risks.