They used to be a common sight by our rivers and streams - but in the last few decades the number of water voles in our region has plummeted.
Studies show the rodent has disappeared from 94% of sites where it was once prevalent.
Some agriculture, intensive land management, and invasive species like the American mink have contributed to the decline.
But now over two thousand water voles have been released in Kielder Forest as part of the Restoring Ratty project.
Over the past five years they have been establishing water voles in locations where the threats are limited and they should be able to thrive.
We joined them on their last Kielder release - and found out why this is not the end for the project.