Water Abstraction
Wye and Usk SACs
The demand for water from Wye and Usk is met, in part by the construction of reservoirs in the upper part of their catchments. Four were completed in upper Wye in 1901: Caban Goch; Garreg Dhu; Pen y Garreg and Craig Goch with a fifth, Claerwen, completed in 1952. Water is either piped from these reservoirs by gravity to Birmingham or extra flows are released down the river to be abstracted and transferred to the South Wales. Various abstraction points take water for local use too. Agricultural use includes the unlimited "trickle" irrigation, licenced abstractions and some for winter storage.
At one stage, the enlargement of the top reservoir, Craig Goch, was considered but in the late '70s demand fell away as our heavy industrial base declined. This would have created one of the bigger manmade reservoirs in Europe.
The Usk also has five storage reservoirs: Crai; Usk; Talybont; Grynne Fawr and Llandegfedd. The Monmouthshire and Brecon canal takes water at Brecon and from tributaries at various points downstream and has an historic ‘right of abstraction’ to take almost any amount of water it needs. Crai and Usk reservoirs are used to supply areas outside the Usk catchment. Two major abstractions sites at Radyr and Llantrissant plus water from the Wye transfer at Monmouth comprise the Southeast Wales Conjunctive Use System (SEWCUS). Although the upper catchments have high rainfalls (up to 2700 mm at Pumlumon) supplies are ultimately limited by storage capacity and what can be taken from the rivers without ecological damage. Nonetheless, by any definition, both rivers were over abstracted (2014).
When the two rivers were listed as Special Areas of Conservation (SACs), a mechanism was put in place to rectify any historic licences that damaged "the sites". The Review of Consents process would correct these shortcomings as a one off process. The result of this may be found here.
There are a number of other impacting issues associated with both impoundment and abstraction by reservoirs. Entrainment is the term for trapping juvenile fish and other material into the system. Abstraction plants are fitting screens (2014/5) to prevent the juveniles of SAC species (salmon, lamprey shad, and bullhead) from being lost this way.
Another problem is that gravel, stones and bed load material are progressively lost from below dams and are not replaced as the dams themselves prevent natural movement. WUF plans to restore gravels below Caban Coch, Elan. Please click here for more details.