Otters and holts in riverside development

Otters are a European protected species, and the practical consequence for a riverside scheme is that a holt within working distance of your site can stop the programme regardless of whether an otter is in residence. The Conservation of Habitats and Species Regulations 2017 protect breeding sites and resting places whether occupied or not. There is no closed season either, because otter cubs can be born at any time of year, so the seasonal workarounds that help with bats and birds do not exist here. An otter survey for planning purposes has to happen early enough to change the design.

The protection and the offences it creates

Otters are listed under the 2017 Regulations and under Schedule 5 of the Wildlife and Countryside Act 1981. The offences that matter on a construction site are deliberate capture, killing or injury, deliberate disturbance, and damage to or destruction of a breeding site or resting place.

Disturbance is drawn widely. It covers activity likely to impair the ability of an animal to survive, breed, rear young or hibernate, and activity likely to affect the local distribution or abundance of the species. Night working with floodlights beside a used commuting route can fall within it without anyone touching a holt.

The breeding site and resting place offence has no intent requirement in the way the disturbance offence does, which is why the physical location of every holt has to be established before machinery arrives.

Surveying a watercourse properly

Otter survey is a field sign exercise. The surveyor walks both banks for a defined distance upstream and downstream of the works, traditionally 600 m in each direction from the site, recording spraints, anal jelly, footprints, slides, feeding remains, paths and any potential resting sites.

Access is the constant difficulty. Where a bank is impenetrable or in third party ownership, the report should say which sections were walked and which were assessed from the opposite bank or from a bridge. A survey that quietly covers one bank and concludes absence is not evidence.

Timing is about conditions rather than season. Low water, low vegetation and a period without heavy rain give the best chance of finding spraints, which wash away quickly in spate. Surveys after a flood event, or in high summer with dense bankside growth, carry a limitation that should be recorded and repeated later.

Expect the results to be recorded on a plan with distances from the works, not just described in text. A Protected Species Survey for otters is a mapping exercise as much as a narrative one.

Telling a holt from a couch

The distinction drives the whole mitigation approach.

A holt is an underground or fully enclosed resting site, often under tree roots on an undercut bank, in a rock cavity, a drain, or a hollow beneath a stone wall. A natal holt is one used to give birth and raise cubs, usually further from the water and in undisturbed cover.

A couch is an above-ground lying up site, commonly a flattened area in scrub, reeds or bramble, sometimes with spraints nearby. Couches are easy to miss and easy to destroy with a strimmer.

Both are resting places in law. Reports that assess holts carefully and treat couches as incidental miss the point, and a council ecologist familiar with otters will ask where the couch survey results are.

Working distances and methods that avoid a licence

Where a resting place can be avoided, a licence may not be needed. Avoidance is a matter of distance, screening, timing and the nature of the works.

Working distances are set case by case rather than by a fixed national rule. Distances in the region of 20 m to 30 m from a holt are commonly discussed for general construction, with larger separations for percussive piling, blasting and other high vibration activity, and with natal holts treated more cautiously than others. Agree the distances with the licensing authority and record the agreement, because the figure you assume at design stage is the one the contractor will rely on.

The measures that usually accompany a stand off are a fenced exclusion zone marked before any clearance, a prohibition on night working and on lighting directed at the bank, retention of a continuous vegetated corridor so animals can pass through the site, and mammal ledges or dry passage under any new or replacement culvert.

Culverts deserve their own attention. A structure that leaves no dry margin at high flow pushes otters onto the road above it, and highway authorities have taken to asking about this at consultation.

Licensing where disturbance cannot be avoided

Where a holt must be destroyed or disturbance is unavoidable, the lawful route is a European protected species licence from Natural England, applied for by a suitably licensed ecologist.

Three tests have to be satisfied. The work must be for a purpose the Regulations permit, which for development is usually imperative reasons of overriding public interest or public health and safety. There must be no satisfactory alternative. And the action must not be detrimental to the maintenance of the population at favourable conservation status.

Planning permission is normally expected to be in place first, because the no satisfactory alternative test is hard to answer while the scheme is still capable of change. Build the licence period into the programme rather than the tender, and expect it to sit on the critical path.

The survey, the mitigation design and the licence application all require someone licensed to do this work. An AI-assisted draft can structure the supporting statement, and a Preliminary Ecological Appraisal can identify that otters need considering at all, but the licensed ecologist owns the evidence.

Artificial holts and what they deliver

Artificial holts are the standard compensation where a resting place is lost. They are built from log piles, stone chambers or purpose made pipe structures, sited above the flood level, in cover, away from paths and lighting, with more than one entrance.

Be honest about uptake in the assessment. Artificial holts are not reliably occupied, and a mitigation strategy that assumes immediate transfer from a destroyed holt to a new structure overstates what the evidence supports. Build them well in advance of the works, in more than one location where the site allows, and commit to monitoring.

Monitoring should be specified with years and method, because an artificial holt with no monitoring obligation is an assertion rather than compensation. The habitat created around it can also count within a Biodiversity Net Gain Assessment, provided the same land is not double counted for two purposes.

Conditions and permits on riverside schemes

Expect a package rather than a single condition. The usual set covers a construction environmental management plan with pollution prevention and bank protection, an ecological clerk of works with authority over the exclusion zone, a lighting plan showing spill at the bank, a landscape and ecological management plan for the riparian corridor, and pre-commencement checking surveys where the gap between survey and works exceeds a stated period.

Separate consents run alongside planning. Works in, over, under or within 8 m of a main river need a flood risk activity permit from the Environment Agency, and works affecting an ordinary watercourse need consent from the lead local flood authority. Those regimes have their own ecological requirements and their own timescales.

Put the ecological controls in the Construction Management Plan rather than leaving them in an appendix nobody on site opens.

This is general guidance, not legal advice. Check the position with your local planning authority, Natural England or a qualified ecologist before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.