top of page

Water - The lifeblood of our ecosystems

  • Drilling is taking place in an area of abandoned mines which are already contaminating Porthleven Stream with arsenic, cadmium & mercury.

  • Improperly decommissioned boreholes from the exploratory drilling may leave conduits for contaminated water.

WATER overflowing mineshaft on the Flow stream that leads to Porthleven

Image: Continuously overflowing mineshaft at the head of Porthleven Stream in the Flow Valley

One of the unacceptable consequences of metalliferous mining is contamination of groundwater and surface water. Water is the lifeblood of our ecosystems. Metals mix with it in the depths of a mine. They find their way to the surface in abnormally high concentrations and mix with organic materials and settle in the sediments of streams and rivers.

In January 2023 Parliament approved a new legally-binding target to halve the length of rivers polluted by abandoned metal mines by 2038. This target, explained in the Environmental Improvement Plan, will be achieved through the Water and Abandoned Metal Mines (WAMM) Programme. Pollution is localised in 1500 km of rivers including some 500 km in Cornwall.

Because these mines all closed before 2000, the law says the former mine owners or operators do not have to deal with the water pollution they created. This pollution will continue for hundreds more years unless action is taken.  For more details of the government’s plan of action see this powerful article on the Environment Agency Blog : "Cleaning up rivers polluted by abandoned metal mines"

Porthleven Stream is already the second most polluted waterway in Cornwall. (The Carnon River is the most polluted in the UK.)

Micro-organisms at the base of the food chain cannot survive in this polluted environment. Organisms higher up the chain become starved and die out. Insects, invertebrates, fish, amphibians, birds and small mammals lose their food source and either die or move elsewhere. Biodiversity is eroded and will not recover until the water is de-contaminated.

Our Government’s own Climate Projections, 2018, showed that hotter drier summers, milder wetter winters, rising sea levels and more extreme weather were arriving. Droughts increase the severity of pollution because there is less dilution by cleaner water, and more erosion of mine wastes occurs after intense rainfall. Ancient shafts collapse, particularly when in-filled or capped a long time ago, releasing once-dormant pollution.  

Mining companies spend a lot of money on this problem, while they are mining. The pollution problem arises after the mining operation is abandoned, filtration systems are shut down and the mine floods. Up until 1999, mine operators could abandon a mine without notifying anyone!


Many people remember the Wheal Jane Pollution disaster that resulted in a massive and unsightly permanent treatment works that still fall short of filtering out all levels of contamination.

wheal jane pollution treatment image

Image: Pollution treatment at Wheal Jane

bottom of page