These data identify the compliance of Welsh river Special Areas of Conservation (SACs) regarding targets for eight water quality attributes: Phosphorus, Dissolved Oxygen, Biochemical Oxygen Demand, Total Ammonia, Unionised Ammonia, Trophic Diatom Index, pH and Acid Neutralising Capacity.
The targets and methods of assessment are set at a UK level by the Joint Nature Conservation Committee as published in the Common Standards Guidance for Rivers 2016, and form part of the conservation objectives for the riverine SAC features.
There are nine SACs in Wales with riverine features (known in their respective Core Management Plans as):
• River Dee and Bala Lake
• Afon Gwyrfai a Llyn Cwellyn
• Coedydd Derw a Safleoedd Ystlumod Meirion (Afon Glaslyn)
• Afon Eden - Cors Goch Trawsfynydd
• Afon Teifi
• Afonydd Cleddau
• Afon Tywi
• River Usk
• River Wye
For the purposes of water quality reporting, Natural Resources Wales (NRW) divides rivers into units called water bodies. A total of 119 (of a possible 127) water bodies, each with a single sampling point, were assessed for one or more attribute. The River Dee and Wye were assessed in the Welsh part of the SAC only.
Water quality data collected by NRW’s routine surveillance monitoring programme for a four-year period (1st January 2020 – 31st December 2023) were extracted from the NRW water quality database (KiWQM) to assess compliance with targets.
Data was not available for all attributes for all water bodies due to the risk-based design of NRW’s monitoring programmes. For attributes/waterbodies with insufficient data to determine compliance over the period 2020-2023, but where a result was produced in the previous assessment (using 2017-2019 data), the previous result has been rolled forward.
