the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish, and chemical status, which compares the concentrations of various chemicals against known safe concentrations. Chemical status is rated good or fail. The water quality of the Devon was as follows in 2019. Data for the middle section covers a large section of the River Smite and a small section of the Devon after the two rivers have joined. Reasons for the quality being less than good include sewage discharge for most of the river, and physical modification of the channel and poor nutrient management on adjacent agricultural land on the upper sections. Like many rivers in the UK, the chemical status changed from good to fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE) and mercury compounds, neither of which had previously been included in the assessment. However the ecological status of the upper river improved from poor to moderate, while the lower river deteriorated from moderate to poor. Points of interest Bibliography References External links Devon, River 1Devon Tributaries of the River Trent