The environmental standards for river flows were developed from work undertaken by SNIFFER profect WFD48 . The environmental standards were developed in order to assess the risk to ecological status posed by alterations in flows across the flow regime. The study was not remitted to consider Heavily Modified Water Bodies where flow was regulated. As a consequence the standards produced did address impacts where the scale of the flow regime was altered i.e. from abstractions, but did not explicitly address situations where the pattern of the flow regime was altered through flow regulation. The project did highlight however that it would not make sense to define different sets of standards for abstractions and releases from impoundments. This point was recognised during the development of the condition limits for managed flows (UKTAG 2007) which aimed to supplement and not conflict with the environmental flow standards. It may be concluded that, in the development of the river flow standards, greater consideration was given to their application in situations where abstractions impact across the entire flow regime or at low flows, than in situations where abstractions only occur at high flows.