Trends in the levels of Escherichia coli in commercially harvested bivalve shellfish from England and Wales, 1999-2008

► We assess temporal trends in E. coli in shellfisheries in England and Wales. ► Average E. coli levels reduced in 12% of the shellfisheries in 1999-2008. ► Average E. coli levels increased in 9% of the shellfisheries in 1999-2008. ► Many of these sites were subject to major sewerage improvements in 2000-2005. ► Not all areas where investments were delivered evidenced improved shellfish flesh quality.