Unwanted Christmas trees are being used to provide flood defences and protect river banks from erosion, the Environment Agency has said.
Conifers, including Christmas trees which have not been sold and specimens donated by the Forestry Commission, are being used to line river banks in a trial by the agency.
Tree trunks are used to stabilise the river bank while conifers provide habitat and act as filters, catching silt from the water that would otherwise smother fish eggs and prevent them from hatching, the Environment Agency said.
Preventing the river banks from eroding should stop the river over-topping its sides so easily in case of heavy rain and flooding.
The trees are considered to be a "softer" and greener alternative for flood defences to using heavier engineering materials such as steel pilings to maintain the banks.
The technique involves securing large spruce logs at the base of eroding river banks and attaching the Christmas trees to them.
It has been successfully tested on the River Bollin in Cheshire, which has particularly sandy and easily eroded banks, as well on the Derwent, Glenderamackin and Marron rivers in Cumbria.
Mike Farrell, fisheries officer at the Environment Agency, said: "This is the ultimate green gift for people and wildlife living along our rivers.
"Homes are being protected from flooding whilst new habitats are being created for mammals, fish and invertebrates."
He added: "We hope this innovative use of Christmas trees will have great potential for reducing flood risk.
"One in six properties in England and Wales is at risk of flooding so we are urging everyone to find out if they are at risk by visiting the Environment Agency website."