Otters and Water Voles

For any development which may require planning permission from your local planning authority (LPA), the LPA need to fully consider the likely ecological impacts of the proposed works.

Both otter and water vole are fully protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) making it an it an offence to intentionally injure or capture any water voles or otters and protecting any places of shelter used by these species from disturbance, damage, destruction or obstruction. Water vole and otter are recognised as Species of Principal Importance in England under Section 41 of the Natural Environment and Rural Communities Act 2006.

If it is suspected that water voles or otters are present on a site or are nearby and may be affected by the development proposals, then surveys will need to be undertaken. Surveys will provide information regarding how the site and habitat are utilised and the likely impacts  from the proposed development.

Water voles have undergone the most extreme decline of any British mammal in the 20th century. Introduction of mink, habitat destruction and fragmentation due to farming intensification means, although they are still widespread they are now classed as vulnerable to extinction in the UK.

Water voles live in colonies strung along the banks of slow flowing rivers, streams, ditches and around lakes, reed-beds, marshes and ponds with relatively steep banks, usually in rural areas. They are also found in uplands areas and heathland. They dig burrows in steep grassy banks, which often include underwater entrances. Water vole are active during the day but infrequently observed, more likely is to hear the ‘plop’ of a water vole disappearing into the water.

Water vole are similar in appearance to the brown rat, but with a blunter nose, small ears and a furry tail. They do not hibernate but are less active during the winter. Water vole surveys are conducted between March and September when higher activity makes observations of individuals or field signs more likely to occur.

Field signs of water voles include burrows, droppings and latrines, feeding stations, runs and footprints.

Otters are secretive, semi-aquatic mammals with long slender bodies, brown fur with a pale underside and short legs with webbed paws. They are around or slightly larger than 1m in length which is considerably larger than the non-native, darker coloured mink. Otter populations declined up to the 1970’s due to pesticide use but are now increasing in distribution and numbers due to improved farming practices.

Otter live in a variety of habitats including lakes, reservoirs, rivers, streams and can occur in urban cities as well as rural areas. They can regularly travel over 20km of river habitat and will mark their territory with musky deposits known as spraints.

Otter are not usually observed during the daytime and field surveys require experienced ecologists to be able to recognise the signs that they are present. Surveys can be undertaken at any time of year, but optimal conditions would be when vegetation has died back, and rainfall is low to enable increased visual survey to be made.

enims experienced ecologists undertake:


  • Habitat assessment to evaluate likely presence and to identify further surveys if required

  • Survey visits at optimal times of the year, following good practice guidelines

  • Combined surveys for both species at suitable sites

  • Pragmatic mitigation to prevent negative impacts to protected species

  • Bespoke enhancements to increase site suitability for water vole and otter and to ensure biodiversity net gain


If you require support for your project please call the enims team on 0845 644 0196.