HS2: On the frontline
PUBLISHED: 14:10 19 May 2011 | UPDATED: 19:24 20 February 2013
What do the water vole, great crested grebe and common spotted orchid have in common? They all need water to survive, and will be at risk if the proposed high speed rail route comes thundering through Buckinghamshire, say environmental campaigners.
The HS2 route, part of which will be on viaducts and in underground tunnels, threatens to damage the River Misbourne and two nature reserves where flooded gravel and clay pits provide tranquil refuges for wildlife. The Berks, Bucks & Oxon Wildlife Trust is calling for a comprehensive assessment of the impact on the environment and our natural heritage along the entire route, before the HS2 plans gain momentum.
Crystal clear chalk streams
The pretty River Misbourne, one of the free-flowing chalk streams of the Chilterns, runs from its source in Great Missenden to the River Colne at Denham. It is renowned for the high quality of water sourced from natural underground reservoirs in the Chilterns chalk.
This means that its perfect habitat for insects such as caddis fly species and mayfly, as well as freshwater shrimps, sticklebacks and water beetles. Fish such as the brown trout and bullheads have been found in the lower Misbourne, where water flows continuously.
In 2008 colonies of water voles were found around Chalfont St Peter and along the river to Higher Denham. Since then the Berks, Bucks & Oxon Wildlife Trust surveyed the Misbourne valley to confirm these colonies are in the section of the river where water flows continuously.
The proposed high speed rail route would include twin bore tunnels through porous chalk under the river bed of the Misbourne. This could damage the underground natural reservoirs that store water supplies. There would be a risk of the Misbourne drying up if rainfall and surface water drains away from the river, which could irreparably damage the habitats of insects, fish plants and water voles.
Wildlife lake in the Vale of Aylesbury
In a tranquil corner of the Vale a former clay pit dug for the local brickworks is now a valuable wildlife haven for birds. Calvert Jubilee is a nature reserve managed by the Berks, Bucks & Oxon Wildlife Trust.
Every winter the deep lake remains open when other lakes freeze over, and so is a key site for bittern, water rail and pochard. In spring the explosive song of the Cettis warbler can be heard, and cuckoos call from tall trees on the edge of the reserve.
These wonderful bird calls will be drowned out if the high speed rail route thunders through at 14 trains an hour. Maps show the line slicing into land running the length of the reserve, and then curving across grassland and reeds.
Colne Valley gravel pits
As the high speed rail route leaves north-west London it will launch into Bucks on a viaduct over the Mid-Colne Valley Site of Special Scientific Interest (SSSI), open water created from worked-out gravel pits.
One of these is Broadwater Lake nature reserve managed by Herts & Middlesex Wildlife Trust. This 80 hectare site is renowned internationally for the diversity of breeding wetland birds, and wintering waterbirds such as gadwall, shoveler and great crested grebe. The SSSI designation means that this site is of national importance for wildlife. Throughout the year birds congregate on the water and feed on the exposed gravel banks and fenland where yellow iris and willows have established.