4f4c4942-4343-5764-6473-313136333235 English NRW_DS118585 Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2024-05-30T15:37:22.735Z NRW 1.0 wel NONE Historic General Quality Assessment (GQA) Headline Indicators of Water Courses - Chemistry Historic General Quality Assessment (GQA) Headline Indicators of Water Courses - Chemistry AfA162 Historic GQA Headline Indicators of Water Courses – Chemistry 2016-07-01 NRW_DS116325 The General Quality Assessment (GQA) Headline Indicator scheme or GQAHI (previously known as GQA) was the national indicator for water quality in rivers and canals. It was designed to provide an accurate and consistent assessment of the state of water quality and how it changes over time. These assessments were made for Biological, Chemical and Nutrients and undertaken for discrete river stretches. This datasets relates to the chemical assessments. In Wales we maintained the full GQA network until 2010 based on 800 sampling sites which provided information for approximately 4700km. Grades of river quality for the chemical GQA, Chemical grade Likely uses and characteristics:en - A: Very good, All abstractions, Very good Salmonid fisheries, Cyprinid fisheries, Natural ecosystems. - B: Good, All abstractions, Salmonid fisheries, Cyprinid fisheries, Ecosystems at or close to natural. - C: Fairly good, Potable supply after advanced treatment, Other abstractions, Good Cyprinid fisheries, Natural ecosystems, or those corresponding to good Cyprinid fisheries - D: Fair, Potable supply after advanced treatment, Other abstractions, Fair Cyprinid fisheries, Impacted ecosystems. - E: Poor Low grade abstraction for industry, Fish absent or sporadically present, vulnerable to pollution, Impoverished ecosystems - F: Bad, Very polluted rivers which may cause nuisance, Severely restricted ecosystems *Provided other standards are met where the grade is caused by discharges of organic pollution. The General Quality Assessment (GQA) Headline Indicator scheme or GQAHI (previously known as GQA) was the national indicator for water quality in rivers and canals. It was designed to provide an accurate and consistent assessment of the state of water quality and how it changes over time. These assessments were made for Biological, Chemical and Nutrients and undertaken for discrete river stretches. This datasets relates to the chemical assessments. In Wales we maintained the full GQA network until 2010 based on 800 sampling sites which provided information for approximately 4700km. Grades of river quality for the chemical GQA, Chemical grade Likely uses and characteristics:en - A: Very good, All abstractions, Very good Salmonid fisheries, Cyprinid fisheries, Natural ecosystems. - B: Good, All abstractions, Salmonid fisheries, Cyprinid fisheries, Ecosystems at or close to natural. - C: Fairly good, Potable supply after advanced treatment, Other abstractions, Good Cyprinid fisheries, Natural ecosystems, or those corresponding to good Cyprinid fisheries - D: Fair, Potable supply after advanced treatment, Other abstractions, Fair Cyprinid fisheries, Impacted ecosystems. - E: Poor Low grade abstraction for industry, Fish absent or sporadically present, vulnerable to pollution, Impoverished ecosystems - F: Bad, Very polluted rivers which may cause nuisance, Severely restricted ecosystems *Provided other standards are met where the grade is caused by discharges of organic pollution. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Environment Agency Wales Environment Agency Wales, Cambria House, 29 Newport Road, Cardiff, CF24 0TP enquiries@environment-agency.gov.uk http://www.environment-agency.gov.uk/regions/wales Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Hydrography GEMET - INSPIRE themes, version 1.0 GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme water quality monitoring NRW Thesaurus NRW Thesaurus 2023-12-31 geonetwork.thesaurus.local.theme.converted_nrw-keywords water quality Integrated Public Sector Vocabulary Integrated Public Sector Vocabulary 2013-04-03 geonetwork.thesaurus.external.theme.subjects There are no access restrictions on this data. NRW may release, publish or disseminate it freely. no limitations © CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose. Attribution statement: Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. English inlandWaters SeaVoX Vertical Co-ordinate Coverages SeaVoX Vertical Co-ordinate Coverages 2021-01-06 Wales (WLS) -5.777741 -2.608865 51.240829 51.240829 1990-01-01 2009-12-31 Documents Excel https://naturalresourceswales.sharefile.eu/d-s75a5853402c419c8 Download Data World Wide Web page Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 false Chemistry GQAHI/GQA sites were sampled twelve times a year, the samples being taken at the same spot on each sampling occasion to ensure consistency. In Wales each chemical sample was measured for biochemical oxygen demand (BOD), ammonia and dissolved oxygen (the most common types of organic pollution from sewage treatment works, agriculture and industry). A category was assigned using three years worth of samples for each sampled chemical and assigned a category assessed against chemical standards expressed as percentiles The data collected over three years were used to determine average nutrient concentrations. So the classification for the year 2008 includes the results for 2006 and 2007. Subsequently a category was assigned to each length of river according to the lowest standard achieved by any of the two or three measurements. The Chemistry GQA used in Wales described quality in terms of three chemical measurements that detect the most common types of organic pollution from sewage treatment works, agriculture and industry. In 2007 the GQA river network was reduced to the GQAHI river network. The assessment was changed to be based on total ammonia and dissolved oxygen only. Biochemical oxygen demand (BOD) was removed from the assessment and all past grades re-calculated. The data described have been amended to be consistent and comparable for all years. Chemistry GQAHI/GQA sites were sampled twelve times a year, the samples being taken at the same spot on each sampling occasion to ensure consistency. In Wales each chemical sample was measured for biochemical oxygen demand (BOD), ammonia and dissolved oxygen (the most common types of organic pollution from sewage treatment works, agriculture and industry). A category was assigned using three years worth of samples for each sampled chemical and assigned a category assessed against chemical standards expressed as percentiles The data collected over three years were used to determine average nutrient concentrations. So the classification for the year 2008 includes the results for 2006 and 2007. Subsequently a category was assigned to each length of river according to the lowest standard achieved by any of the two or three measurements. The Chemistry GQA used in Wales described quality in terms of three chemical measurements that detect the most common types of organic pollution from sewage treatment works, agriculture and industry. In 2007 the GQA river network was reduced to the GQAHI river network. The assessment was changed to be based on total ammonia and dissolved oxygen only. Biochemical oxygen demand (BOD) was removed from the assessment and all past grades re-calculated. The data described have been amended to be consistent and comparable for all years.