WFD Cycle 2 river BOD classfication

annually

The Water Framework Directive classification system is risk based and focuses on where there is likely to be a problem. It uses a principle known as "one out, all out", which means the poorest individual results drive the overall classification for a water body. It reports on over 30 quality elements, grouped into ecological status and chemical status. Ecological status includes physico-chem (e.g. nutrients, pH, dissolved oxygen, ammonia) , biological elements (e.g. phytoplankton, macroalgae, fish, invertebrates) , specific pollutants (e.g. metals and compounds, organic compounds) , hydromorphology (e.g. depth, width, flow, structure). Chemical status is assessed using priority substances, priority hazardous substances and other pollutants that present a significant risk to the water environment.