Welsh mines leak at least 500 tonnes of harmful metals each year

At least 500 tonnes of harmful metals leak into the Welsh environment each year from abandoned mines, according to government estimates obtained by the Financial Times.

A Freedom of Information request revealed that 129 sites are “certainly, or highly likely, to be causing failures of water quality criteria”, according to Natural Resources Wales (NRW).

While a “comprehensive” assessment of the amounts of metals leaking into the environment has not been made, the Welsh government body estimated “350-500 tonnes” are discharged annually from the 129 sites.

That indicates that the total discharge from Wales’ more than 1,300 abandoned sites is likely to be higher than 500 tonnes.

Overall the abandoned mines pollute an estimated 700km of river reaches with metals including lead, zinc and cadmium. The figures sparked calls for the UK government to take action to tackle the legacy of Britain’s mining past.

“The severity of these findings are a cause for national concern, and demand the urgent attention of both Welsh and UK governments,” said Plaid Cymru MP Ben Lake, who has at least 200 abandoned mines in his constituency of Ceredigion.

Metals dispersed by such mines can accumulate in soil and floodplain used for homegrown and agricultural food production.

A study funded by NRW and published last year uncovered harmful levels of lead in eggs on two small farms downstream from abandoned lead mines in west Wales.

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It found that a young child eating one to two of the eggs per day “could become cognitively impaired”. The academics behind the study told the FT the eggs were eaten on the farms and sold in local markets.

There is no level of lead exposure known to be without harmful effects, according to the World Health Organization.

The study’s findings prompted the Welsh government to convene two meetings last year with officials from across the UK, including both the Food Standards Agency and Health Security Agency.

“Government ministers, relevant public bodies and members of the scientific community should convene without delay to identify action necessary to mitigate any risk to public health. There is not a moment to lose,” Lake added.

Nine of the 10 worst metal mine-polluted catchments in the UK are in Wales, according to official estimates.

Professor Mark Macklin, from the University of Lincoln, described the situation in Wales as “the tip of the iceberg”.

“In the UK, all the recent focus has been on microplastics and sewage but metal contamination from historical mining dwarfs both from an ecosystem and probably human health perspective,” Macklin said.

There are about 8,500 disused metal mines in Great Britain, according to the British Geological Survey’s database.

As far back as 2002, the Metal Mine Strategy for Wales identified 50 abandoned metal mines causing the greatest impact on rivers. 

But since then NRW has completed just one major remediation scheme on Frongoch, a former lead and zinc mine in Ceredigion, and smaller scale remedial works on two other sites. 

In 2016, NRW calculated that 16,000kg of metals, the equivalent of 16 tonnes, were still being released into the environment by the Frongoch mine each year — down only partially from 21,000kg before the remediation.

Dealing with the historic issue is complicated in the UK because while NRW and the Environment Agency are liable for environmental water pollution from these mines, it is the responsibility of local authorities to identify contaminated land that could pose a risk to human health.

Macklin from Lincoln university led a global study, published in September 2023, that estimated as many as 557,000 people currently live on a floodplain contaminated by historic metal mining in the UK.

The area of potentially contaminated floodplain was 1,120km squared, approximately 10 times the size of the city of Manchester, according to the study’s models.

“There has . . . been little understanding that floodplains, where people live and grow things, are perhaps a more important problem than the mines and water courses immediately downstream from these mines,” said Macklin.

The cost of remediating abandoned mines primarily lies with UK authorities because until 1999, mine operators could abandon sites without having to clean up pollution.

Dave Johnston, NRW’s senior specialist adviser for abandoned metal mines, said: “Natural Resources Wales and the Coal Authority are working together to tackle this pollution and mitigate other hazards at these mines.

“We are actively working on 25 projects in the programme,” he added, noting that some projects covered more than one mine site.

In 2011, the Water and Abandoned Metal Mines Programme was established in England to develop schemes to treat abandoned metal mine water pollution. Officials said the programme currently operated three successful mine water treatment schemes that had improved 20km of rivers.

In January 2023, the UK government set a new legally-binding target to “halve the length of rivers polluted by abandoned metal mines by 2038 “.

Rebecca Sudworth, director of policy at the Food Standards Agency said: “Businesses must ensure the food they produce does not go beyond the maximum [lead] levels set by law.”

“We have a monitoring and testing regime in place to check for this and enforcement action can be taken by local authorities if the maximum levels of lead in food are exceeded,” she added. The Department for Environment, Food & Rural Affairs declined to comment separately.

A Welsh government spokesperson said: “Local authorities have a duty to identify contaminated land within their areas. If they identify land which meets the definition of ‘contaminated land’, they have a duty to ensure it is dealt with appropriately.”

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