Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, what estimate his department has made of the potential changes to the level of risk of lead contamination from flooding events due to climate change in areas downstream of historical lead mines.

Environment Agency (EA) monitoring indicates that climate change could potentially increase the mass (kg/day) of metals washed into rivers from historic metal mines. Erosion of spoil heaps during storm events can increase the mobilisation of metals into rivers and re-suspend metal-rich sediments previously deposited in river channels.

For example, on average 127 tonnes of zinc and 40 tonnes of lead enters the Tyne estuary annually (all from abandoned metal mines); however, 50% of this zinc and 80% of this lead flows into the estuary during the highest 5% of river flows. However, while the mass of metals washed into rivers increases in storm events, the severity of water pollution (metal concentrations in mg/l) may decrease due to dilution.

In flood events these metals can be washed onto floodplains, causing land contamination. Climate change is expected to increase the risk of floodplains downstream from historic mining sites being contaminated by flooding.

Through the Water and Abandoned Metal Mines Programme - a partnership between Defra, the EA and the Coal Authority – the Government is taking action to develop mine water treatment schemes and diffuse interventions to prevent metals from abandoned metal mines, including lead, from entering local river systems.