Aldbury Nowers is a 19.7 hectares biological Site of Special Scientific Interest (SSSI) in the Chiltern Hills, north-east of Tring in Hertfordshire. The site was notified in 1990 under the Wildlife and Countryside Act 1981. It is managed by the Hertfordshire and Middlesex Wildlife Trust.
Patmore Heath is a 7.6 hectares biological Site of Special Scientific Interest in East Hertfordshire, England, 2 kilometres north-east of Albury. The site was notified in 1985 under the Wildlife and Countryside Act 1981. Patmore Heath is home to a large amount of dry grass, as well as marshy areas. Much turf throughout the site is dominated by Deschampsia, as well as occurrences of Anthoxanthum odoratum.
Wormley-Hoddesdonpark Wood North is a 143.9-hectare (356-acre) woodland area in Hertfordshire which has been designated as a biological site of Special Scientific Interest. The site is listed as Grade 1 in A Nature Conservation Review, and is also designated a Special Area of Conservation. It is in Hoddesdon in the borough of Broxbourne, but part of the site is in East Hertfordshire.
Herts and Middlesex Wildlife Trust manages over 40 nature reserves covering nearly 810 hectares north of London, in Hertfordshire and the historic county of Middlesex, part of which is divided between the London boroughs of Barnet, Enfield, Harrow and Hillingdon. It has over 21,000 members, and is one of 46 Wildlife Trusts across the UK. It is a Registered Charity, with its Registered Office in St Albans, and had an income in the year to 31 March 2014 of over £1.5 million.
Rye Meads is a 58.5-hectare (145-acre) biological Site of Special Scientific Interest (SSSI) in Rye House, Hoddesdon, Hertfordshire. It is one of series of wetlands and reservoirs situated along the River Lea, to the north-east of London. It is part of the Lea Valley Ramsar site and a Special Protection Area.
Tring Reservoirs is a group of four reservoirs close to Tring on the border of Hertfordshire and Buckinghamshire, England. Their purpose is to feed the Grand Union Canal.
Frogmore Meadows is a 4.6-hectare (11-acre) biological Site of Special Scientific Interest in Hertfordshire and Buckinghamshire, north of the village of Chenies. It consists of two meadows in the Chilterns Area of Outstanding Natural Beauty, next to the River Chess, one of which is a Hertfordshire and Middlesex Wildlife Trust nature reserve. The planning authorities are Three Rivers District Council, Dacorum Borough Council and Chiltern District Council.
Amwell Quarry or Amwell Nature Reserve is a 37 hectare biological Site of Special Scientific Interest in Great Amwell in Hertfordshire. The planning authority is East Hertfordshire District Council. It is also part of the Lee Valley Ramsar Site and Special Protection Area, and is owned and managed by the Hertfordshire and Middlesex Wildlife Trust.
Hunsdon Mead is a 34 hectare biological Site of Special Scientific Interest (SSSI) west of Harlow and east of Roydon in Essex. The site is partly in Essex and partly in Hertfordshire, and it is jointly owned and managed by the Essex Wildlife Trust and the Herts and Middlesex Wildlife Trust. The SSSI also includes part of the neighbouring Roydon Mead. The planning authorities are East Hertfordshire District Council and Epping Forest District Council. Hunsdon Mead is registered common land.
Sawbridgeworth Marsh is a 6.3-hectare (16-acre) biological Site of Special Scientific Interest (SSSI) near Sawbridgeworth in Hertfordshire, apart from a small area in the north which is in Essex. It is managed by the Essex Wildlife Trust. The planning authorities are East Hertfordshire District Council and Uttlesford District Council.
Knebworth Woods is a 120.8-hectare (299-acre) biological Site of Special Scientific Interest in Knebworth, immediately south of Stevenage in Hertfordshire. The planning authority is North Hertfordshire District Council.
Hertford Heath nature reserve is a 28 hectare biological Site of Special Scientific Interest in Hertford Heath in Hertfordshire. It is managed by the Herts and Middlesex Wildlife Trust and the local planning authority is East Hertfordshire District Council.
Thorley Wash or Thorley Flood Pound is a 17.3-hectare biological Site of Special Scientific Interest in Thorley, south of Bishop's Stortford in Hertfordshire. It was formerly a flood pound for the Stort Navigation, which was decommissioned in 2004 and converted to a more natural state. It was purchased by the Herts and Middlesex Wildlife Trust from the Environment Agency in 2011.
Tewinbury is a 7.5-hectare (19-acre) biological Site of Special Scientific Interest near Tewin in Hertfordshire. The local planning authority is East Hertfordshire District Council, and the site is managed by the Herts and Middlesex Wildlife Trust
Fox Covert is a 2.9-hectare (7.2-acre) nature reserve near Royston in North Hertfordshire. It is owned and managed by the Herts and Middlesex Wildlife Trust.
Hill End Pit is a 0.7-hectare (1.7-acre) nature reserve on the site of a former chalk pit, in St Paul's Walden in North Hertfordshire. It was formerly managed by the Herts and Middlesex Wildlife Trust (HMWT). In February 2016 HMWT announced that three sites, Barkway Chalk Pit, Hill End Pit and Pryor's Wood, which HMWT managed on behalf of their owner, North Hertfordshire District Council, were to return to Council management as the Trust was no longer able to meet the cost. It has the largest colony of Azeca goodalli snails in Hertfordshire. Plants include viper's bugloss, cowslip and marjoram, there are butterflies such as common blue and gatekeeper, and many birds including woodpeckers.
Telegraph Hill is a nature reserve near Lilley in north Hertfordshire. It is in the Chilterns Area of Outstanding Natural Beauty (AONB). According to the Chilterns AONB, the hill is owned by the Herts and Middlesex Wildlife Trust; a notice on the site says that it is managed by the trust, but it is not listed on the trust's web site as one of its reserves.
Danemead is a 5.6-hectare nature reserve west of Hoddesdon in Hertfordshire, managed by the Herts and Middlesex Wildlife Trust. It is part of the Wormley-Hoddesdonpark Wood North Site of Special Scientific Interest.
