Ordinary watercourses are a statutory type of watercourse in England and Wales. Ordinary watercourses include every river, stream, ditch, drain, cut, dyke, sluice, sewer (other than a public sewer) and passage through which water flows and which does not form part of a main river. An internal drainage board where relevant, or local authority has permissive powers to carry out flood defence works for ordinary watercourses at their discretion. This is similar to those powers the Environment Agency can use on main rivers[1].
Critical Ordinary Watercourses (COWS) are a subdivision of ordinary watercourses responsibility for which lies with the Environment Agency. They were created following Defra's Flood and Coastal Defence Funding Review published in February 2003. In many cases the day to day operational work has been contracted back to internal drainage boards and local authorities[2].