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 good or fail. The water quality of the Bow Brook system was as follows in 2019. Reasons for the water quality being less than good include the discharge of sewage effluent, physical barriers to the movement of fish caused by modifications to the channel for land drainage and milling, and runoff of water from agricultural land. In addition, Vyne Stream is affected by groundwater abstraction, the impounding of water, and the presence of the invasive North American signal crayfish. Bibliography References External sources Rivers of Hampshire