The otter is protected under UK and international law. As well as direct protection for the animals, protection is also provided for the places they use for shelter, giving birth and rearing young (holts); resting (loafing) areas are also protected. These places are usually located on or close to the banks of rivers and streams and are usually very well hidden with tree and shrub cover.
It is important that the presence of otters is identified on any development site where they are likely to be present as this will have implications for both the development and the construction process. A Habitats Regulations licence from NRW is required for any works with the potential to disturb otters or their habitat.
The otter is also one of the designated features of both the River Usk SAC and River Wye SAC; where developments are near to (or within) these water courses, it must be ensured that there is no likely significant effect on otters or their habitat.
There is more information on otters in the National Park here.