More than 50 rivers and groundwaters have failed quality tests because they have been contaminated by toxic metals flowing from Scotland’s vast network of abandoned mines.

Coal and metal mining was a key part of Scotland’s industrial history for hundreds of years, but potentially toxic heavy metals are still being flushed out from forgotten tunnels, putting wildlife, crops and water ecology at risk.

Climate change is likely to worsen the issue, with heavier rainfall washing out even more metals from flooded mines, and less rainwater available to dilute mine water in drier summers.

Groundwaters – water found below the surface – of many of Scotland’s biggest towns and cities are contaminated with mining metals and, according to one study, mine pollution has killed off the salmon population in Midlothian’s South Esk river.

Opposition MSPs urged the Scottish Environment Protection Agency (Sepa) to set out its plans to make disused mines safe.