Internal drainage board
IDBs are geographically concentrated in the Broads, Fens in East Anglia and Lincolnshire, Somerset Levels and Yorkshire.
Much of their work involves the maintenance of rivers, drainage channels (rhynes), ordinary watercourses, pumping stations and other critical infrastructure, facilitating drainage of new developments, the ecological conservation and enhancement of watercourses, monitoring and advising on planning applications and making sure that any development is carried out in line with legislation (NPPF).
Some IDBs may also have other duties, powers and responsibilities under specific legislation for the district (for instance the Middle Level Commissioners are also a navigation authority).
The work of an IDB is closely linked with that of the Environment Agency which has a range of functions providing a supervisory role over them.
In other parts of the country IDBs stretch in narrow ‘fingers’ up river valleys, separated by less low-lying areas, especially in Norfolk and Suffolk, Sussex, Kent, West Yorkshire, Herefordshire/Shropshire and the northern Vale of York.
The water level management activities of internal drainage boards cover 1.2 million hectares of England which represents 9.7% of the total land area.
Whilst many thousands of people outside of these boundaries also derive reduced flood risk from IDB water level management activities.
These have been extensively created in the Lindsey Marsh Drainage Board area of East Lincolnshire to accommodate the three elements of lowland watercourse sustainability.
While in-channel habitat that develops can be retained for a much longer period during the summer months, flood storage is provided for rare or extreme events and a buffer zone between the channel and any adjacent land use is created.
The Conveyance Estimating System (CES) is a modelling tool developed through a Defra / Environment Agency research collaboration.
This means in England some 635,722 hectares (2,454.54 sq mi) of land in IDB districts rely on pumping, almost 51% of the total.
A new pumping station was commissioned in April 2011 by the Middle Level Commissioners at Wiggenhall St Germans, Norfolk.
The station replaced its 73-year-old predecessor and is vital to the flood risk management of 700 km2 (270 sq mi) of surrounding Fenland and 20,000 residential properties.
Slow flowing drainage channels such as those managed by IDBs can form an important habitat for a diverse community of aquatic and emergent plants, invertebrates and higher organisms.
IDB channels form one of the last refuges in the UK of the BAP registered spined loach (Cobitis Taenia), a small nocturnal bottom-feeding fish that have been recorded only in the lower parts of the Trent and Great Ouse catchments, and in some small rivers and drains in Lincolnshire and East Anglia.
Through ADA the collective views of drainage authorities and other members involved in water level management are represented to government, regulators, other policy makers and stakeholders.
