Sites of Special Scientific Interest (SSSI & ASSI)
Every UK SSSI and ASSI in one schema. Statutory nature sites from Natural England, NatureScot, Natural Resources Wales and DAERA, each with a stable id and a mappable point.
About this dataset
A Site of Special Scientific Interest (SSSI) is the foundation statutory nature designation in Great Britain, notified for biological or geological special interest. In Northern Ireland the equivalent is the Area of Special Scientific Interest (ASSI). This dataset holds both, so a single query returns the protected nature sites that constrain development and land use across the UK.
The statutory basis differs by nation. England, Scotland and Wales notify SSSIs under section 28 of the Wildlife and Countryside Act 1981. Northern Ireland declares ASSIs under the Environment (Northern Ireland) Order 2002. The custodians are Natural England (4,128 SSSIs), NatureScot, Natural Resources Wales (1,087 SSSIs) and the DAERA Northern Ireland Environment Agency (394 ASSIs).
We reconcile those four registers into one schema with one stable identifier per site. Every record carries valid EPSG:4326 geometry, reprojected server-side from British National Grid and the Irish Grid, plus a date_precision flag so a year-only notification date is never served as an exact day. Each record returns its custodian attribution under the Open Government Licence v3.0.
Query the data by point, radius, bounding box or polygon over REST, or fetch one site by its stable id. Use it alongside the heritage and conservation designations served from the same model to assemble a full constraints picture for a site, a title boundary or a planning application.
Everything in the box
Point, radius and polygon query
Query SSSIs and ASSIs by point, radius, bounding box or polygon over REST, or fetch a single site by its stable id.
Four registers, one schema
Natural England, NatureScot, Natural Resources Wales and DAERA reconciled into one record shape with one stable identity per site.
Stable designation id
Each site keeps a persistent id in the form design.conservation.ENG.sssi.1002340, so references stay valid across snapshots.
EPSG:4326 geometry
Every centroid is valid WGS84, reprojected server-side from British National Grid (27700) and the Irish Grid (29902).
OGL attribution per record
Each record returns the custodian and the Open Government Licence v3.0 attribution, so reuse provenance is clean.
Welsh bilingual names
Welsh sites include name_cy, the official Welsh-language site name from Natural Resources Wales.
What each record carries
Straight from the API
{
"id": "design.conservation.ENG.sssi.1002340",
"reference": "1002340",
"nation": "ENG",
"source": "Natural England",
"name": "Wytham Woods",
"name_cy": null,
"designation_type": "sssi",
"category": "biological",
"designated_date": "1986-09-01",
"amended_date": null,
"date_precision": "month",
"local_authority": "Oxfordshire",
"area_hectares": 365.2,
"source_url": "https://designatedsites.naturalengland.org.uk/SiteDetail.aspx?SiteCode=S1002340",
"centroid": {
"lat": 51.7712,
"lng": -1.3303
},
"licence": "Open Government Licence v3.0",
"attribution": "Contains Natural England data licensed under the Open Government Licence v3.0"
}What people build with it
Site due diligence
Check whether a development site or its surroundings fall within an SSSI or ASSI before committing to a scheme.
DevelopersPlanning constraint checks
Screen planning applications against statutory nature sites that trigger consultation with the relevant nature body.
PlannersValuation risk screening
Flag designated nature constraints near a security address that can affect development potential and value.
LendersUnderwriting and ESG screening
Identify protected nature sites around an asset for environmental underwriting and biodiversity reporting.
InsurersFrequently asked questions
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