***Cypermethrin is currently designated as a Priority Substance under the EU Environmental Quality Standards Directive (2013/39/EU), which is a daughter directive of the Water Framework Directive (WFD). Before December 22, 2018, it was classified as a Specific Pollutant. Upon being elevated to a priority substance, it became subject to a stricter, Europe-wide Environmental Quality Standard (EQS). This highly toxic synthetic pyrethroid insecticide is monitored to help determine the overall Chemical Status of water bodies (UK TAG)*** This dataset comprises water quality data from the NIEA water quality database from 1st January 1990 to 31st December 2024. Note that the dataset may contain results which are erroneous due to typos, sampling error or contamination. Such data points are usually several orders of magnitude above expected values. This is one of a series of water datasets being made available as Open Data. Other NIEA datasets remain available on request via waterinfo@daera-ni.gov.uk The European Water Framework Directive (2000/60/EC) has been transposed into Northern Ireland Regulations through The Water Environment (Water Framework Directive) Regulations (Northern Ireland) 2017. The Water (Amendment) (Northern Ireland) (EU Exit) Regulations 2019 ensures that the Water Framework Directive (WFD) (as transposed) and the various supporting pieces of water legislation continue to operate here after 1 January 2021. The regulations encourage the active involvement of interested parties and the general public. The regulations set out the requirement to achieve 'Good Ecological Status' and 'Good Chemical Status' for all ground and surface waters (rivers, lakes, transitional waters, and coastal waters) within Northern Ireland. Surface waters are assessed according to the following criteria: biological quality (fish, invertebrates, flora), hydromorphological, physico-chemical properties like temperature, oxygenation and nutrient conditions, chemical quality assessed against environmental quality standards for specific pollutants and priority substances.