Eco-Classification

Eco-classification is the assignment of a water body to a status class based on biological, physico-chemical, and hydromorphological condition relative to undisturbed reference conditions. Under the EU Water Framework Directive 2000/60/EC, surface waters are placed in one of five ecological status classes: high, good, moderate, poor, or bad. Classification uses an ecological quality ratio comparing observed to reference values for biological quality elements such as phytoplankton, macroalgae, benthic invertebrates, and fish. The one-out-all-out rule sets overall status by the worst-scoring element. The directive’s objective is good status or better; failure obliges a program of measures. Heavily modified water bodies are graded by ecological potential instead.