Water is abstracted from both surface (e.g. rivers) and ground water (e.g. by boreholes). The biggest main sources of abstractionors are the water company Dwr Cymru Welsh Water (DCWW) and those with licences, the Canal & Rivers Trust (CRT) and farmers. CRT operates the Monmouthshire and Brecon canal, which takes most of its water supply directly from the Usk.
Ensuring water abstraction and reservoirs are managed in a way that is beneficial to the river Usk and its fish is also another priority for UFA. As it is a technical issue, UFA supported the Wye and Usk Foundation (WUF) in its significant contribution to the resulting arrangements.
The long term trend in water demand for river water has been upwards, both for industry and household supply. The abstraction to the Monmouth and Brecon canal has varied over the years. In the early 20th century, it took the entire flow of the river at times until legal action was threatened by the Usk Board of Conservators. The abstraction by Welsh Water at Usk started in the 1960s. Concerns were raised about its impact on salmon in the late 1980s and 1990s but Welsh Water had a licence of right. It was not until a review of all existing abstractions was required under the European Union’s (EU’s) Habitats Directive in 1992, that the salmon and other species could be fully protected. Even so, it was twenty years before consented abstractions across the Usk catchment were reviewed; the results are only now being implemented.
On the Usk and Wye, reviews were undertaken by the Usk & Wye Abstraction Group (UWAG) comprising, for the Usk: Dwr Cymru Welsh Water, the Wye & Usk Foundation, the Canal and Rivers Trust and Natural Resource Wales. It was a ground-breaking exercise for which a key part was the construction of detailed computer models of the river flows at every abstraction point; the levels in reservoirs; and the demand for water for the canal and supply to industry and the Welsh population. The technical work of John Lawson, the WUF’s technical expert, was crucial to the final UWAG agreement but all parties, including the abstractors, must take credit for what has been an exceptional co-operation. Not only will salmon and other special flora and fauna in the Usk be protected from excessive abstraction but water supply for South Wales and the canal can be maintained through cleverer use of resources.
As you probably realise, too much water being taken is bad news for ecology, especially for those rivers with migratory fish such as Wye and Usk. Salmon, for instance, are lost for good if they are held up at the estuary, unwilling to migrate into a river during low flows. Research for the Environment Agency using tagged salmon showed that if they were delayed in the estuary in dry summers then up to half the run could be lost. For many years DCWW have pumped water from the lower end of the river Usk in large amounts to supply water for the industry and population of the South Wales Valleys. To minimise pumping costs, they would often pump at night when, under lower flows, salmon were most likely to run. This sometimes dropped the river by six inches. One of the effects was that salmon waiting in the estuary weren’t willing to enter the river and, though some entered in the autumn, many died. Modelling by WUF’s technical experts showed that stopping this practice will mean up to 20 percent more salmon returning to spawn in some years. The smolt run also needed protection; in dry springs too much abstraction, especially at night, could delay migration to sea and expose the smolts to increased predation.
To avoid significant ecological damage, a robust policy regarding how and when water is abstracted needed to be instigated and then enforced.
A solution that benefits all
Work by the Usk and Wye Abstraction Group (UWAG), which included representatives from WUF, found that very nearly all the demand for water could be met from the existing river flows and network of reservoirs without breaching the tough rules imposed by the Habitats Directive.
An important part of the solution was for DCWW to manage the surface waters in a different way. This includes:
- Reservoirs: a programme that makes better use of the existing reservoirs linked to the Usk, and
- Abstraction: the timing and quantity of water abstraction.
The changes will enable the water company DCWW and CRT to continue with their responsibilities. The changes will also help in getting all migratory fish up and down the river (especially salmon). Agreement has now been reached to release water in a timely fashion from the reservoirs at the top of the system so the full effects of spates can be mimicked and the period of the spate extended.
On the Usk, as well as putting new valves on the reservoirs, one of the main improvements is to the offtake at Prioress Mill, upstream of Usk town. Here water is taken from the main river and pumped to Llandegfedd reservoir. From late 2020, the plan is to fill the reservoir primarily during the winter months, keeping abstraction to a minimum throughout the salmon migration season. The rebuild and commissioning of the pumping station is nearing completion. It includes new fish screens being fitted. An interim arrangement includes spreading out the daily period over which pumping takes place to avoid sudden drops in flow at critical migration times. Also, there is much reduced pumping from May to September, except on the highest flows.
At Brecon, there are now constraints on the abstraction by both the water company and the canal. For the first time, the canal abstraction will be licensed, to be in place by 2022. The canal has spent and is currently spending its funds on fixing the leaks, which have bedevilled it for years so that demand is reduced and falls within the new licence conditions. There are negotiations with DCWW to secure additional water from Usk reservoir, so the canal can keep operating all but the severest droughts without affecting flows below Brecon.
In summary, ways have been found to change water abstraction and reservoir operation to improve the river environment, while still ensuring water is available for public supply and for the canal. Good news for all. Let’s hope the new arrangements work as well as planned.
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