Classification aquatic pollution

Wa.ter Qua.litySta.nda.rds, The first step in water quahty standards is stream use classification. The individual states must decide what the uses of their water will be. The four categories, as defined by the EPA, are Class A, primary water contact recreation Class B, propagation of desirable aquatic life Class C, pubHc water suppHes prior to treatment and Class D, agricultural and industrial uses. States may vary the definition of these classes to meet their own needs. The second step is to develop water-quaHty criteria. This is the specific concentration of a pollutant that is allowable for the designated use. 

Vaal M, van der Wal JT, Hoekstra J, Hermens J. Variation in the sensitivity of aquatic species in relation to the classification of environmental pollutants. Chemosphere 1997 35 1311-27. 

Special attention is given waters that are directly threatened or do not meet WQS. These receive Section 303(d) or Section 305 (threatened or impaired waters) classification. Section 303(d) includes those surface water sources impacted by pollutants, whereas nonpollutants impair Section 305 waters. Where the source of aquatic life impairment is unclear, the source receives Section 303(d) classification. Waters classified as threatened or impaired require biennial progress reporting, with prioritization of TMDL levels and WQC established accordingly. 

Eutrophication potential (EP). Eutrophication is referred to as the pollution state of aquatic ecosystems where the overfertilisation of water and soil has turned into an increased growth of biomass. EP is calculated in kg based on a weighted sum of the emission of nitrogen and phosphorus derivatives such as N2, NOx, NH, P04, P and chemical oxygen demand (COD). The classification factors for EP are expressed as phosphates equivalents. 

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