Disputing a condition score with the council ecologist

A bng condition assessment dispute usually comes down to one habitat parcel and one word. Moderate or Poor on two hectares of modified grassland changes the baseline by enough units to decide whether your scheme delivers ten per cent on site or buys credits. The council ecologist has looked at the same field and reached a different answer, and the question is what to do about it. The short version: the argument is won on the criteria sheets, the survey date and the photographs, and it is almost never won by asserting that your ecologist is more experienced.

Biodiversity net gain under the Environment Act 2021 requires the statutory metric to be completed by a competent person, and the biodiversity gain plan must be approved by the local planning authority. An AI-assisted draft is a starting point for that professional, not a substitute for the survey or the judgement.

Why condition carries the argument

Biodiversity units are the product of area, distinctiveness, condition and strategic significance. Distinctiveness is fixed by the habitat type once you have classified it, and area is measurable. Strategic significance comes from the local nature recovery strategy mapping and is not usually a matter of opinion.

Condition is the only input that rests on a field judgement made on one day by one person, and the multiplier runs from 1 for poor condition to 3 for good, with intermediate values between. Doubling the condition multiplier doubles the baseline for that parcel, and a higher baseline makes on-site gain harder to achieve. That is why the incentives cut in opposite directions: an applicant's ecologist has a reason to see poor condition in the baseline, and the authority's ecologist knows it.

Understanding that dynamic is half the work. Officers are not being obstructive when they press on condition. They are applying the one part of the calculation where the evidence is thin unless you made it thick on purpose.

What the criteria sheets actually require

Each broad habitat type in the statutory metric has a condition assessment sheet with a defined list of criteria. The assessment is mechanical: you record whether each criterion passes or fails, count the passes, and read the condition category from the stated thresholds. It is not an overall impression of the field.

That structure is your friend in a dispute, because it forces the conversation onto specifics. If the council ecologist says moderate and you said poor, ask which criterion they consider passed that your assessment recorded as failed. There will be one or two, and each of them is a factual question: sward height range, cover of undesirable species, presence of bare ground, cover of wildflower and sedge species excluding white clover and creeping buttercup, evidence of scrub encroachment, damage from vehicles or trampling.

Answering at that level of specificity moves the discussion from a difference of professional opinion to a difference about what was on the ground. And a difference about what was on the ground can be resolved by going back and looking.

Photographs, dates and viewpoints

Most disputes are actually about evidence, not about ecology. The assessments that survive scrutiny share the same features.

• Fixed photographic viewpoints, with the coordinate and the bearing recorded, so the same view can be repeated in a later season or by a different surveyor.
• Quadrat locations recorded as coordinates, with the number of quadrats stated and the results tabulated rather than summarised.
• Sward height measurements with the method and the number of readings, not a single descriptive sentence.
• Species lists with cover estimates, taken at the same time as the condition assessment rather than lifted from an earlier walkover.
• Survey date, weather, surveyor name and relevant competence, and an explicit statement of limitations.

Date is where more assessments fail than any other single factor. Grassland condition cannot be assessed properly in February, and an assessment carried out outside the growing season carries a limitation that the authority is entitled to weigh against you. If the survey was done in the wrong season, that is the weakness the council ecologist will press, and no amount of argument fixes it.

The same discipline applies across the ecology evidence base generally. The way effects are described and justified in an ecological impact assessment is judged on the same basis: recorded method, stated limitations, traceable data.

When a re-survey is worth the money

Re-surveying is the cleanest resolution and it costs less than most people assume relative to the unit difference at stake. Work out the number first.

Calculate the baseline both ways, at your condition score and at the authority's, and express the difference in units and then in the cost of off-site delivery or credits. Where that difference exceeds the cost of a day of survey time and a short addendum, re-survey. Where it does not, concede the point and move on, because officer goodwill spent on a small parcel is not recoverable later.

Two conditions make a re-survey worthwhile. The original survey was outside the optimal season and a growing-season visit would produce defensible data. Or the parcel is large enough that the criteria may vary across it, in which case splitting it into two parcels with different conditions is often the honest answer and produces a result both sides accept.

A joint site visit with the council ecologist is the single most effective step available, and it is underused. Walk the parcel together with the criteria sheet in hand and record the agreement on the day. Most disagreements dissolve within twenty minutes of standing in the same field.

Making the case in writing

Where a visit is not possible, put the case in a short technical note rather than in an email chain. Structure it like this.

1. Identify the parcel by reference to the habitat plan and the metric row.
2. State the habitat classification and confirm it is agreed, because a condition argument built on a disputed classification goes nowhere.
3. Set out each criterion, the recorded observation, the pass or fail, and the evidence reference.
4. Identify the specific criteria in dispute and explain the basis of your judgement on each.
5. State the effect on the baseline in units, both ways.
6. Propose the resolution: acceptance, re-survey, parcel subdivision or a without-prejudice sensitivity run of the metric.

The sensitivity run is worth offering. Showing that the scheme delivers the required gain on both condition scenarios removes the reason for the dispute entirely, and officers accept it readily. Where it does not deliver on the authority's figure, you at least know the size of the problem before it becomes a refusal.

Check the exemptions position at the same time. Small sites, self-build and some householder development sit outside the regime, and it is worth confirming that the biodiversity net gain exemptions do not apply before spending money on a condition argument.

Where it will not resolve

Some disputes do not close. The gain plan is approved under a condition imposed by Schedule 7A to the Town and Country Planning Act 1990, and a refusal to approve it is a decision on an application required by a condition, so the appeal route under section 78 is available in the ordinary way. Check the current procedural guidance before relying on that, because the gain plan process is newer than most condition regimes and practice is still settling.

Before appealing, consider two intermediate steps. Ask whether the authority will accept an independent review by a third ecologist, with the scope and the question agreed in advance. And check whether the difference can be absorbed by improving the post-development position rather than arguing the baseline, since an extra area of created habitat or a better condition target may cost less than the dispute.

Be careful about the degradation provisions while this is running. Where habitat has been degraded after 30 January 2020 without permission, the baseline can be taken as the position before degradation, and grazing changes or scrub clearance during a dispute can turn a condition argument into a much worse one.

Designing the assessment to survive review

The way to win these arguments is to make them unnecessary at the outset. Commission the preliminary ecological appraisal and the metric baseline together, in the growing season, with the criteria sheets completed in the field rather than reconstructed in the office. Photograph everything from recorded viewpoints. Split heterogeneous parcels. Declare limitations openly, because a declared limitation is a weakness you control and an undeclared one is a weakness the officer discovers.

Then set the biodiversity net gain assessment out so the reviewer can follow every number from the field sheet to the metric cell. Also check the strategic layer, since spatial risk multipliers in the biodiversity metric can change the off-site arithmetic more than a condition category does.

A licensed or competent professional is legally required for this work under the Environment Act 2021 regime. Enter your postcode on PlanScope to see which reports your site is likely to need. This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional 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.