The Wildlife Trusts is the umbrella organisation behind a network of 47 trusts across the UK including the Yorkshire Wildlife Trust and the London Wildlife Trust.
The parent body has put together a postcard campaign, which has been sent out to the network, to help prevent the water vole population from further decline.
The campaign has arisen as trusts across the UK have recorded many cases of accidental poisoning and in one instance the extermination of an entire group of water voles.
The awareness push entitled "Know Your Vole" will aim to prevent people, including pest controllers, builders and developers, from mistaking the endangered water vole for the brown rat and accidentally poisoning them or disturbing their habitat.
Around 30,000 postcards have been printed, together with an information leaflet, which will be distributed by the trusts.
The postcard tells people how to determine a water vole from a brown rat and asks the public to inform the trust of any possible sightings of the water vole.
According to the trust, water voles have disappeared from almost 90 per cent of the sites they occupied in the UK in the last 60 years due to loss of their riverbank homes and being preyed upon by the non-native American mink.
Dr Simon Lyster, director general of the trusts, said: "The key to overcoming the problem is to build awareness of the characteristics of a water vole and for people to take an active part in reporting any water vole discoveries to the Wildlife Trusts."