South West Wales

Carmarthenshire Rivers Trust on acid river project success

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Media captionBrian Jones and Catherine Orr of the Carmarthenshire Rivers Trust explain the project's success

A project tackling high levels of acidity in a river should be given the go-ahead across Wales to help improve water quality, a charity has said.

Carmarthenshire Rivers Trust is concerned Natural Resources Wales (NRW) may not allow an extension of its liming project in the River Doethie.

It claims a dramatic transformation of a catchment that was failing EU water quality and wildlife standards.

NRW said it wanted to stop pollutants reaching rivers in the first place.

With funding from Welsh Water, the trust has been releasing limestone sand into the Doethie in Upper Tywi valley - between Tregaron and Llandovery - since 2010.

The alkaline sand grains help neutralise the water's acidity, which is caused by pollutants in the atmosphere being washed into the river when it rains.

The area is important as a spawning habitat for salmon and sewin, also known as sea trout.

"I've personally taken a reading in a stream at the top of the catchment that ran the same as table vinegar," Caroline Orr, trust project officer, said.

"That was above our liming site, it's hard to imagine that anything could live up there.

"This is an ingenious project and very, very simple. We monitor quite drastically and have seen nothing but improvements in numbers of fish and the invertebrates they feed on, as well as birds and water quality generally."

Before the project began the catchment was failing standards set in the EU's water framework directive but has since been reclassified as having good ecological status.

'Symptom rather than cure'

A fifth of Wales' rivers and a third of Wales' lakes are vulnerable to acidification, according to NRW's risk assessment.

Most are located in west Wales where Afonydd Cymru, the body representing individual rivers trusts, claims commercial conifer plantations are exacerbating the problem.

Image caption The alkaline sand grains help neutralise the water's acidity in the Doethie

These plantations in upland areas were historically used for pit props for the mining industry and more recently by the timber trade.

Densely planted, they become "particularly good at scavenging air pollutants, resulting in more acid run-off into rivers", according to Frank Jones, Afonydd Cymru's technical advisor.

"We absolutely need to have an intervention to deal with those impacts," he added.

"And through this project we have demonstrated what can be done. What we need to do now is extend this approach to other streams and rivers that are affected in Wales."

Mr Jones said that though the trust had "plenty of support" from local NRW officers it was concerned "policy formers are having second thoughts about liming" and may not support an extension.

Bob Vaughan, land manager for NRW, said the organisation was very pleased with the Carmarthenshire Rivers Trust's work but argued it was important to look at different opportunities to solve the problem.

"What we don't want to do is just carry on liming in a way that's just dealing with the symptom rather than the cure," he said.

In upland areas, Mr Vaughan said NRW had invested heavily in changing the way water runs off woodland plantations and would consider further interventions "on a case by case basis".

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