Hertfordshire is a county in eastern England. It is bordered by Bedfordshire to the north, Cambridgeshire to the north-east, Essex to the east, Buckinghamshire to the west and Greater London to the south. The county town is Hertford. As of 2018, the county has a population of 1,184,400 in an area of .
As of July 2019, there are 43 sites designated within this Area of Search, 36 of which have been designated for their biological interest and 7 for their geological interest. In England the body responsible for designating SSSIs is Natural England, which chooses a site "because of its flora, fauna, or geological or physiographical features".
Key
Interest
B = a site of biological interest
G = a site of geological interest
Other classifications
CAONB = Chilterns Area of Outstanding Natural Beauty
GCR = Geological Conservation Review
EWT = Essex Wildlife Trust
HMWT = Herts and Middlesex Wildlife Trust
LNR = Local nature reserve
NCR = A Nature Conservation Review
NNR = National nature reserve
NT = National Trust
Ramsar = Ramsar site
RHPG = Register of Historic Parks and Gardens of Special Historic Interest in England RSPB = Royal Society for the Protection of Birds SM = Scheduled monument SPA = Special Protection Area WT = Woodland Trust