This classification method enables the assessment of invertebrates in rivers in relation to general degradation, including organic pollution. Whalley, Hawkes, Paisley & Trigg (WHPT) metrics replace the Biological Monitoring Working Party (BMWP) metrics used for status classifications in the first river basin planning cycle.
Benthic invertebrate communities are good indicators of acidification which is caused by acidic pollution from precipitation and acids leaching from the surrounding soils. They are easily suited to biological monitoring as they are common, widespread and easily sampled.
Following a consultation that ended on 28th February 2013, UKTAG has finalised its recommendations on 1) biological standards for rivers, lakes, coastal and estuaries and 2) phosphorus standards for rivers.