Your ecologist says you need a LERC data search. It costs £100-375 and takes up to two weeks. Is it worth it? Can you just use free data instead?
This guide explains what LERCs are, what their data searches provide, when you genuinely need one, and when free alternatives are sufficient for your purposes.
What Is a LERC?
A Local Environmental Records Centre (LERC) is a not-for-profit organisation that collects, manages, and shares biodiversity data for a specific geographic area. There are approximately 50 LERCs across the UK, each covering a county or group of counties.
LERCs aggregate data from multiple sources:
- Local recording groups and volunteer naturalists
- Professional ecological consultants
- Local planning authorities
- Conservation organisations
- Citizen science schemes
The key value of LERC data is that it includes high-resolution, locally sourced records that often don't appear on national databases like NBN Atlas. A county bat group member who records a soprano pipistrelle roost at a specific building will submit that record to the local LERC. It may never reach NBN Atlas.
What Does a LERC Data Search Include?
A standard LERC data search returns:
- Protected and notable species records within a specified radius of your site (typically 1-2km)
- Locally designated site information - SINCs, Local Wildlife Sites, County Wildlife Sites, County Geodiversity Sites
- Habitat data - local habitat inventories that may include more detail than the national Priority Habitat Inventory
- Planning consultation zone information - some LERCs provide specific planning guidance zones
Records typically include species name, date, grid reference, recorder name, and data source. LERC records often have higher spatial resolution than NBN Atlas records - 6-figure grid references (100m accuracy) or even 8-figure (10m accuracy), compared to the 1km or 10km resolution common on NBN Atlas.
How Much Does It Cost?
LERC data search costs vary by centre but typically fall in the range:
- Standard search (1-2km radius, standard turnaround): £100-250
- Extended search (larger radius, more detail): £200-375
- Urgent/fast-track: Some LERCs offer expedited searches for an additional fee
Turnaround time is usually 5-10 working days, though some LERCs can be faster and others slower during busy periods (spring and summer, when more PEAs are being commissioned).
Find your local LERC at alerc.org.uk.
When Do You Need a LERC Search?
Required for formal PEAs
CIEEM guidelines for Preliminary Ecological Appraisal state that a desk study should include a search of the local biological records centre. Most ecological consultancies include a LERC search as standard in their PEA methodology. If you're submitting a PEA to support a planning application, a LERC search is considered best practice.
Required by some LPAs
Some local planning authorities specifically require evidence that a LERC data search has been undertaken as part of the ecological information submitted with a planning application. Check your LPA's validation requirements.
Recommended for any significant development
For any development that could affect protected species or habitats, a LERC search provides the most comprehensive local species data available. The cost is small compared to the overall project cost and the risk of missing a significant species record.
When Can You Use Free Alternatives?
Initial site screening
Before commissioning a full PEA and LERC search, you can use free data sources to do a quick screening:
- NBN Atlas (nbnatlas.org) - free species records, but lower resolution and less comprehensive than LERC data
- MAGIC Map (magic.defra.gov.uk) - free designation and habitat data
- EcoCheck (ecocheck.co) - combines designation data, NBN species records, GCN risk zones, and priority habitats in a single instant search
This screening tells you whether there are likely to be significant ecological constraints at your site. If the screening shows SSSIs nearby, multiple bat records, and a GCN amber zone, you know you need a full PEA with LERC search. If it shows nothing significant, the full PEA may still be needed but the LERC search is less likely to reveal surprises.
Pre-purchase due diligence
If you're considering buying a site for development and want to understand the ecological constraints before committing, a free screening is a sensible first step. It doesn't replace a LERC search but it gives you enough information to assess risk.
ECoW site preparation
For Ecological Clerks of Works preparing for a construction site visit or rail possession, free data sources often provide sufficient context for a toolbox talk and constraint awareness. A LERC search is not typically required for construction-phase ECoW work if a full PEA was done at the planning stage.
Corridor assessments
For long linear corridors with multiple check points, commissioning a LERC search at every point along the route would be prohibitively expensive. A corridor screening using national data sources provides an efficient initial assessment, with LERC searches targeted at the most constrained sections.
LERC vs NBN Atlas: Key Differences
| Feature | LERC | NBN Atlas | |---------|------|-----------| | Cost | £100-375 per search | Free | | Turnaround | 5-10 working days | Instant | | Resolution | Often 100m or 10m | Often 1km or 10km | | Local sites | Yes (SINCs, LWS) | No | | Completeness | Most comprehensive for the area | Incomplete - many records not shared | | Accepted by LPAs | Always | Usually, but LERC preferred | | Best for | Formal PEAs, planning applications | Quick screening, initial assessment |
The Practical Approach
For most development projects, the workflow is:
- Free screening first - use EcoCheck to understand the broad ecological context of your site in seconds
- Commission a LERC search as part of your PEA if the screening identifies potential constraints (or as standard best practice)
- Combine both datasets in your desktop study report - national data from EcoCheck plus local data from the LERC gives the most complete picture
This approach is efficient and cost-effective. The free screening helps you understand what you're dealing with immediately, while the LERC search provides the detailed local data that formal assessments require.
Patrick O'Connor is a Freelance Ecologist at Kinterra Consulting and the developer of EcoCheck - an instant ecological desktop assessment tool for any GB location. Try it free for 3 days at ecocheck.co.