Oldcotes Dyke was rated at 'C'. This classification system has been superseded for the water quality within the river systems in England.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. Chemical status, which compares the concentrations of various chemicals against known safe concentrations, is rated as good or fail. The water quality of the Ryton was as follows in 2019. The reasons for the ecological quality being less than good include the discharge of effluent from sewage treatment works, and drainage from the transport infrastructure. Oldcotes Dyke is also affected by runoff from agricultural land. 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), perfluorooctane sulphonate (PFOS) and mercury compounds, none of which had previously been included in the assessment. The river Ryton supports various types of fish. In 2006, very few lived in the upper reaches, including the Anston Brook, because the water was only of moderate quality. A number of small streams contribute to the improvement of water quality, so that wild brown trout thrive as far as Worksop. Some trout and various types of cyprinids inhabit the water below Worksop, although abstraction of water results in spawning grounds and the habitats where the young fry live drying out during most summers, which has resulted in a decline in their numbers. Nevertheless, the lower reaches are still used for organised angling, and are the only part of the River Idle system where this activity takes place. Points of interest Bibliography References External links Rivers of Nottinghamshire Rivers of Rotherham 2Ryton