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Watercourse Surveys: Riparian Ecology & Species Analysis

Delivering specialist surveys for otters, water voles, and crayfish to identify habitat suitability and ensure robust environmental legislative compliance for your site.
E3 Ecology.

Expert surveys for environmental legal standards.

If your site contains or lies adjacent to a watercourse and it is at risk of impact as a result of the proposals, further watercourse surveys are likely to be required. There are a number of species of flora and fauna that are protected by UK legislation or listed as species of national or local importance that may need to be considered as part of a development or other works that affect a watercourse. These include:

  • Water Vole
  • Otter
  • Freshwater Pearl Mussel
  • White-Clawed Crayfish
  • Fish
  • Non-native species

 

All of these species are material considerations within the planning system and it is essential to assess when a proposed development may impact these species either directly or indirectly through pollution or disturbance. As such, when works are proposed within or in close proximity to watercourses or waterbodies which are suitable to support these species, further survey work may be required.

What do watercourse surveys involve?

Watercourses can support a wide range of habitats and wildlife, including species that are legally protected or of conservation importance.  The surveys below outline the types of assessments that may be required.

Preliminary Ecological Appraisal

During the initial PEA walkover survey, any watercourses or waterbodies on site will be appraised for their suitability to support protected species such as otter, water vole, fresh water pearl mussel, white-clawed crayfish and relevant National Priority or Local Biodiversity Action Plan species. Additional survey work will be recommended where potentially suitable watercourses or waterbodies are present nearby and may be affected by the works.

Detailed water vole surveys will be carried out by two surveyors, walking within the watercourse where possible. Water voles themselves can be difficult to find, therefore surveyors will look for evidence of the species such as latrines, burrows and feeding remains.

Typically, two surveys will be required, early and late summer, however we will advise on survey effort on a site by site basis.

Detailed otter survey is carried out by two surveyors, walking within the watercourse/body where possible. Otters themselves are rarely seen, therefore surveyors look for evidence of otter such as spraint as well as any potential holt locations.

Where potential holt sites are identified that may be affected by the development, further survey involving monitoring using camera traps may be recommended. This will allow us to gain more detailed information on whether the holt is in use and the type of holt or resting place present.

Detailed freshwater pearl mussel survey is carried out by two surveyors, working within the watercourse and using a bathyscope to view the bed of the watercourse and assess the suitability of the habitats present and checking for evidence of the species.

There are a number of different techniques that can be used to survey for white-clawed crayfish, including hand searching, trapping and torchlight survey. The survey methods used will depend on the nature of the habitat. However, in the first instance, survey work will generally include an eDNA survey to check for the presence or absence of this species.

eDNA surveys can also test for the presence of the invasive species, signal crayfish, as well as crayfish plague which is carried by signal crayfish and is fatal to the native white clawed crayfish.

To assess fish populations within a watercourse, electrofishing can be undertaken. This is completed by at least two surveyors using electrofishing equipment to stun fish and catch them with nets.

All captured animals are identified and measured, where possible, before being released. The detailed methodology employed will depend on the requirements of the scheme.

An assessment of the water quality of a watercourse or waterbody can be made by surveying the macroinvertebrate population within it. Samples on invertebrates taken prior to, during and post works can indicate water quality through the period to show that adequate care has been taken to protect the feature. 

If enhancement works are proposed the survey can also show improvements in species diversity, which can be correlated with an improvement in water quality and habitats.

When can the surveys be carried out?

Different species and habitats are most effectively surveyed at specific times of year. The list below shows when surveys are usually carried out to get the most accurate results.

Our Survey Calendar Guide
Water Vole

Water vole surveys should ideally be carried out between April and September, with one survey held between April and June, and a second survey held between July and September.

Otter surveys can be carried out year-round, although may be more successful in the winter months when vegetation has died back.

Can be completed at any time of year, however the optimal survey period is April to September as survey work can only be undertaken when water levels are low and therefore times when surveys can be undertaken during the winter months are likely to be more restricted.

The optimum survey period for traditional white-clawed crayfish survey techniques extends from July to October, with hand searching and trapping not to be undertaken between late May and June when young are being released.

The optimal period for eDNA survey work is between April and October. Survey work can be undertaken outside of these periods, but the efficacy may be reduced as crayfish activity is reduced in colder temperatures.

This survey method can only be undertaken once a permit has been obtained from the Environment Agency but can be undertaken at any time of year, although water levels need to be sufficiently low.

This survey can be undertaken at any time of year, although water levels will need to be sufficiently low.

How Can E3 Ecology Help?

E3 has been involved with numerous schemes where works have been required in or adjacent to watercourses, and have designed mitigation and compensation measures, applying for Natural England conservation licences for the relevant species where necessary.

If you think you require or have been asked for a watercourse survey, or a survey relating to one of the above species, please don’t hesitate to get in touch and we will be happy to help

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