DEFRA does not collect this information. In 2006, the Environment Agency monitored 10,258 sewage discharges to receiving waters in England and Wales. Biological Oxygen Demand (BOD), ammonia, suspended solids and pH were monitored routinely, along with other parameters presenting a risk to the environment.
The Environment Agency also monitored 6,180 river sites for water chemistry and 5,982 river sites for biology in 2006. This covered approximately 40,000 kilometres of river length in England and Wales. Monitoring at these sites included macro-invertebrates, dissolved oxygen, BOD, ammonia and nitrate.