Why we built the scheme – 60km of polluted rivers

The high concentrations of cadmium and zinc in the mine water released from the Nent Haggs adit cause severe pollution in the River Nent, harming fish and river-flies. The pollution extends for about 60km downstream, all the way to where the River South Tyne joins the River North Tyne near Hexham. Please see the below map. 

Monitoring by the Environment Agency shows that the pollution is worst at lower river flows when the mine water provides a substantial proportion of the water in the river and the metal concentrations can be more than 200 times the safe level for wildlife. The treatment scheme captures the metal pollution at its source, from the adit, and before it reaches the river. 

The treatment scheme is designed to remove at least 90% of the harmful metals which will substantially decrease pollution levels in the river, particularly at lower river flows, and improve the environment for wildlife and people.  

The scheme will count towards the Government’s interim target, set out in the Environmental Improvement Plan in 2023, to build 8 mine water treatment schemes and 20 diffuse interventions by 2028. It will therefore help to achieve the legally-binding long-term Environment Act target to halve the length of rivers and estuaries polluted by harmful metals from abandoned metal mines by 2038.