The plight of the native river rodents was exacerbated by the release of 6,000 American mink in Hampshire and 7,000 from a Staffordshire fur farm last month, Tuskforce said.
It warned that 94 per cent of water vole nesting sites would disappear by 2000, through habitat degradation and the action of predators. Mink were a principal threat.
"Voles are facing short-term extinction - within the next 10 years," said a Tuskforce spokesman.
The warning came as Tuskforce announced the first British captive breeding plan for voles, at the Wild at Heart Conservation Awards for children in London.
A small number of wild voles are to be caught and bred, so that they can be used to colonise suitable and adequately protected areas in future. Others will be rescued from threatened habitats.
The awards involve a competition in which teams of children complete five conservation challenges while raising money for Tuskforce, a charity.Reuse content