An internal drainage board (IDB) is a type of operating authority which is established in areas of special drainage need in England and Wales with permissive powers to undertake work to secure clean water drainage and water level management within drainage districts. The area of an IDB is not determined by county or metropolitan council boundaries, but by water catchment areas within a given region. IDBs are geographically concentrated in the Broads, Fens in East Anglia and Lincolnshire, Somerset Levels and Yorkshire.
In comparison with public bodies in other countries, IDBs are most similar to the Waterschappen of the Netherlands, Consorzi di bonifica e irrigazione of Italy, wateringen of Flanders and Northern France, Watershed Districts of Minnesota, United States and Marsh Bodies of Nova Scotia, Canada.
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). IDBs are not responsible for watercourses designated as main rivers within their drainage districts; the supervision of these watercourses is undertaken by the Environment Agency.
The precursors to internal drainage boards date back to 1252; however, the majority of today's IDBs were established by the national government following the passing of the Land Drainage Act 1930 and today predominantly operate under the Land Drainage Act 1991 [1] under which, an IDB is required to exercise a general supervision over all matters relating to water level management of land within its district. 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). IDBs are responsible to Defra from whom all legislation/regulations affecting them are issued. 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.
Defra brought IDBs under the jurisdiction of the Local Government Ombudsman (LGO) from 1 April 2004, and introduced a model complaints procedure for IDBs to operate. This move was aimed to increase the accountability of IDBs to the general public who have an interest in the way that IDBs are run and operate by providing an independent means of review. At this time Defra also revised and re-issued model statutory rules and procedures under which IDBs operate. [2]
There are 112 internal drainage boards in England in 2018 covering 1.2 million hectares (9.7% of England's total land area) and Areas around The Wash, the Lincolnshire Coast, the lower reaches of the Trent and the Yorkshire Ouse, the Somerset Levels and the Fens have concentrations of adjacent IDBs covering broad areas of lowland. 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 largest IDB (Lindsey Marsh DB) covers 52,757 hectares and the smallest (Cawdle Fen IDB) 181 hectares. 24 of the county councils in England include one or more IDB in their area as do six metropolitan districts, and 109 unitary authorities or district councils.
The Association of Drainage Authorities holds a definitive record of all IDBs within England and Wales and their boundaries. [3]
The Environment Agency acts as the internal drainage board for one internal drainage district in East Sussex. In Wales internal drainage districts are managed by Natural Resources Wales.
Internal drainage districts of England and Wales | |||
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Internal drainage districts in England
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IDBs have an important role in reducing flood risk through management of water levels and drainage in their districts. 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. Reducing the flood risk to ~600,000 people who live or work, and ~879,000 properties located in IDB districts. Whilst many thousands of people outside of these boundaries also derive reduced flood risk from IDB water level management activities. Several forms of critical infrastructure fall within IDB districts including; 56 major power stations (28%) are located within an Internal Drainage District, 68 other major industrial premises and 208 km of motorway. In fact a recent publication by the Association of Drainage Authorities identified that 53% of the installed capacity (potential maximum power output) of major power stations in England and Wales are located within an IDB.
Although of much reduced significance since the 1980s, many IDB districts in Yorkshire and Nottinghamshire lie in areas of coal reserves and drainage has been significantly affected by subsidence from mining. IDBs have played an important role in monitoring and mitigating the effects of this activity and have worked in close collaboration with the coal companies and the Coal Authority.
The fundamental role of an internal drainage board is to manage the water level within its district. The majority of lowland rivers and watercourses have been heavily modified by man or are totally artificial channels. All are engineered structures designed and constructed for the primary function of conveying surplus run-off to their outfall efficiently and safely, managing water levels to sustain a multitude of land functions. As with any engineered structure it must be maintained in order to function at or near its design capacity. Annual or bi-annual vegetation clearance and periodic de-silting (dredging) of these rivers and watercourses is therefore an essential component of the whole life cycle of these watercourses.
Accommodating sustainability within the design and maintenance process for lowland rivers and watercourses has to address three essential elements:
Many IDBs are redesigning watercourses to create a two-stage or bermed channel. These have been extensively created in the Lindsey Marsh Drainage Board area of East Lincolnshire to accommodate the three elements of lowland watercourse sustainability.
Berms are created at or near to the normal retained water level in the system. It is sometimes replanted with vegetation removed from the watercourse prior to improvement works but is often left to re-colonise naturally. In all cases this additional part of the channel profile allows for enhanced environmental value to develop. The area created above the berm also provides additional flood storage capacity whilst the low level channel can be maintained in such a manner that design conveyance conditions are achieved and flood risk controlled.
By widening the channel and the berm, the berm can be safely used as access for machinery carrying out channel maintenance. 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 timing of vegetation clearance works is essential to striking a sustainable balance in lowland watercourses. The Conveyance Estimating System (CES) is a modelling tool developed through a Defra / Environment Agency research collaboration. IDBs use CES to estimate the seasonal variation of conveyance owing to vegetation growth and other physical parameters which they use to assess the impact of varying the timing of vegetation clearance operations. This is critical during the spring and early summer, the prime nesting season for aquatic birds, the breeding season for many protected mammal species such as water voles and the season when many rare species of plant life flower and seed. Many IDBs have developed vegetation control strategies in co-ordination with Natural England.
111 IDB districts require pumping to some degree for water level management and 79 are purely gravity boards (where no pumping is required). 53 IDBs have more than 95% of their area dependent on pumping. 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. When running at full capacity, it is capable of draining five Olympic-size swimming pools every 2 minutes. [15]
During times of heavy rainfall and high river levels IDBs:
An IDB's priorities during flooding are:
Some IDBs are able to provide a 24-hour contact number and most extend office hours during severe emergencies. [16]
Associated with the powers to regulate activities that may impede drainage, IDBs provide comments to local planning authorities on developments in their district and when asked, make recommendations on measures required to manage flood risk and to provide adequate drainage.
Internal drainage boards in England have responsibilities associated with 398 Sites of Special Scientific Interest plus other designated environmental areas, in coordination with Natural England. 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. [17] All IDBs are currently engaging with their own individual biodiversity action plans which will further enhance their environmental role.
Many IDBs are involved with assisting major wetland biodiversity projects with organisations such as the RSPB, National Trust and the Wildfowl and Wetlands Trust. Many smaller conservation projects are co-ordinated with Wildlife Trusts and local authorities. Current projects include: The Great Fen Project (Middle Level Commissioners), [18] Newport Wetlands Reserve (Caldicot and Wentlooge Levels IDB) and WWT Welney (MLC). Middle Level Commissioners launched a three-year Otter Recovery Project in December 2007. It will build 33 otter holts and 15 other habitat areas. [19]
All properties within a drainage district are deemed to derive benefit from the activities of an IDB. Every property is therefore subject to a drainage rate paid annually to the IDB.
For the purposes of rating, properties are divided into:
Occupiers of all "other land" pay Council Tax or non-domestic rates to the local authority who then are charged by the board. This charge is called the "Special Levy". The board, therefore, only demands drainage rates direct on agricultural land and buildings. The basis of this is that each property has been allotted an "annual value" which were last revised in the early 1990s. The annual value is an amount equal to the yearly rent, or the rent that might be reasonably expected if let on a tenancy from year to year commencing 1 April 1988. The annual value remains the same from year to year. Each year the board lays a rate "in the £" to meet its estimated expenditure. This is multiplied by the annual value to produce the amount of drainage rate due on each property. [20]
Under Section 141 of the Water Resources Act 1991 [21] the Environment Agency may issue a precept to an IDB to recover a contribution that the agency considers fair towards their expenses.
Under Section 57 of the Land Drainage Act 1991, [22] in cases where a drainage district receives water from land at a higher level, the IDB may make an application to the Environment Agency for a contribution towards the expenses of dealing with that water.
District drainage commissioners (DDCs) are internal drainage boards set up under local legislation rather than the Land Drainage Act 1991 and its predecessor legislation. The majority of the provisions of the Land Drainage Acts, do however, apply to such commissioners and they are statutory public bodies. The most important in terms of size and revenue is the Middle Level Commissioners.
The majority of internal drainage boards are members of the Association of Drainage Authorities (ADA) their representative organisation. 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. [23] At a European level ADA represents IDBs through EUWMA. [24]
In 2013 it was announced that the Caldicot and Wentlooge Levels Internal Drainage Board was to be abolished in April 2015, after officials at the Wales Audit Office detailed a series of irregularities, including overpaying its chief executive, misuse of public funds, financial irregularities, and unlawful actions. [25] [26]
The Old Bedford River is an artificial, partial diversion of the waters of the River Great Ouse in the Fens of Cambridgeshire, England. It was named after the fourth Earl of Bedford who contracted with the local Commission of Sewers to drain the Great Level of the Fens beginning in 1630. It provided a steeper and shorter path for the waters of the Great Ouse, and was embanked to prevent them flooding the low ground of the South Fens. Throughout the project, the Earl and his Adventurers faced disruption from those who were opposed to drainage schemes. The project was deemed to have succeeded in draining the fens in 1637, but that decision was reversed in 1638. After a lull during the English Civil War, when much of the work was damaged, the Dutch engineer Cornelius Vermuyden worked with William Russell, the fifth Earl of Bedford to complete the drainage. Disruption and unrest continued while the work was carried out, resulting in the Adventurers employing armed guards. A second river, the New Bedford River, was cut parallel to the first channel, which then became the Old Bedford River. At some point, the Old Bedford River was split into two parts, when the upper section was diverted into the River Delph at Welches Dam, and the lower section was joined to the Counter Drain. Both parts retain the name, but are not connected to each other. The area between the two Bedford rivers acts as a large washland, which holds floodwater when the river channels cannot cope with the volume of water in them.
The River Rother flows for 35 miles (56 km) through the English counties of East Sussex and Kent. Its source is near Rotherfield in East Sussex, and its mouth is on Rye Bay, part of the English Channel. Prior to 1287, its mouth was further to the east at New Romney, but it changed its course after a great storm blocked its exit to the sea. It was known as the Limen until the sixteenth century. For the final 14 miles (23 km), the river bed is below the high tide level, and Scots Float Sluice is used to control levels. It prevents salt water entering the river system at high tides, and retains water in the river during the summer months to ensure the health of the surrounding marsh habitat. Below the sluice, the river is tidal for 3.7 miles (6.0 km).
The River Idle is a river in Nottinghamshire, England whose source is the confluence of the River Maun and River Meden near Markham Moor. The Idle flows north from its source through Retford and Bawtry before entering the River Trent at West Stockwith. Its main tributaries are the River Poulter and the River Ryton. The river is navigable to Bawtry, and there is a statutory right of navigation to Retford. Most of the land surrounding the river is a broad flood plain and the river is important for conservation, with Sites of Special Scientific Interest being designated along its course.
The South Forty-Foot Drain, also known as the Black Sluice Navigation, is the main channel for the land-drainage of the Black Sluice Level in the Lincolnshire Fens. It lies in eastern England between Guthram Gowt and the Black Sluice pumping station on The Haven, at Boston. The Drain has its origins in the 1630s, when the first scheme to make the Fen land available for agriculture was carried out by the Earl of Lindsey, and has been steadily improved since then. Water drained from the land entered The Haven by gravity at certain states of the tide until 1946, when the Black Sluice pumping station was commissioned.
Hatfield Chase is a low-lying area in South Yorkshire and North Lincolnshire, England, which was often flooded. It was a royal hunting ground until Charles I appointed the Dutch engineer Cornelius Vermuyden to drain it in 1626. The work involved the re-routing of the Rivers Don, Idle, and Torne, and the construction of drainage channels. It was not wholly successful, but changed the whole nature of a wide swathe of land including the Isle of Axholme, and caused legal disputes for the rest of the century. The civil engineer John Smeaton looked at the problem of wintertime flooding in the 1760s, and some remedial work was carried out.
Burnt Fen is an area of low-lying land crossed by the A1101 road between Littleport in Cambridgeshire and Mildenhall in Suffolk, England. It is surrounded on three sides by rivers, and consists of prime agricultural land, with sparse settlement. It is dependent on pumped drainage to prevent it from flooding.
The Association of Drainage Authorities (ADA) is a membership body for internal drainage boards and other stakeholders in water level management in the United Kingdom.
Drainage districts occur in England and Wales, varying in size from a few hundred acres to over 100,000 acres (400 km2), all in low-lying areas of the country where flood risk management and land drainage are sensitive issues. Most drainage districts are administered by an internal drainage board (IDB), which are single purpose local drainage authorities, dealing with the drainage and water level management of clean water only. Each drainage district has a defined area, and the IDB only has powers to deal with matters affecting that area.
An ordinary watercourse is one of the two types of watercourse in statutory language in England and Wales.
The Middle Level Commissioners are a land drainage authority in eastern England. The body was formed in 1862, undertaking the main water level management function within the Middle Level following the breakup of the former Bedford Level Corporation.
The Witham Navigable Drains are located in Lincolnshire, England, and are part of a much larger drainage system managed by the Witham Fourth District Internal Drainage Board. The Witham Fourth District comprises the East Fen and West Fen, to the north of Boston, which together cover an area of 97 square miles (250 km2). In total there are over 438 miles (705 km) of drainage ditches, of which under 60 miles (97 km) are navigable. Navigation is normally only possible in the summer months, as the drains are maintained at a lower level in winter, and are subject to sudden changes in level as a result of their primary drainage function, which can leave boats stranded. Access to the drains is from the River Witham at Anton's Gowt Lock.
Witham First District IDB is an English internal drainage board which was set up under the terms of the Land Drainage Act 1930. The Board inherited the responsibilities of the Witham General Drainage Commissioners, who were first constituted by an Act of Parliament of 1762. They manage the land drainage of an area to the west of the River Witham, between Lincoln and Dogdyke, which includes the valley of the River Slea to above Sleaford.
South Holland IDB is an English internal drainage board set up under the terms of the Land Drainage Act 1930. It has responsibility for the land drainage of 148.43 square miles (384.4 km2) of low-lying land in South Lincolnshire. It is unusual as its catchment area is the same as the area of the drainage district, and so it does not have to deal with water flowing into the area from surrounding higher ground. No major rivers flow through the area, although the district is bounded by the River Welland to the west and the River Nene to the east.
Holderness Drain is the main feature of a Land Drainage scheme for the area of Holderness to the east of the River Hull in the East Riding of Yorkshire, England. Construction began in 1764, and several notable civil engineers were involved with the scheme over the years. Despite the high costs of the initial scheme, it was not particularly successful, because of the refusal of the ship owners of Hull to allow an outlet at Marfleet. They insisted that the water be discharged into the River Hull to keep the channel free of silt. Following a period of agricultural depression and the building of new docks in the early 1800s, an outlet at Marfleet was finally authorised in 1832. A high level system still fed upland water to the Hull, but the low level system discharged into the Humber, where levels were considerably lower. Following the success of steam pumping on the Beverley and Barmston Drain, the trustees looked at such a possibility for the Holderness Drain, but the development of the Alexandra Dock in the 1880s and then the King George V Dock in 1913 provided a solution, as the docks were topped up with water pumped from the drain, to lessen the ingress of silt-laden water.
Witham Third District IDB is an English internal drainage board set up under the terms of the Land Drainage Act 1930. The Board inherited the responsibilities of the Witham General Drainage Commissioners, who were first constituted by an act of Parliament of 1762. They manage the land drainage of an area to the north and east of the River Witham, between Lincoln and Dogdyke, which includes the valley of the River Bain to above Hemingby, and the valleys of Barlings Eau and most of its tributaries, to the north east of Lincoln.
The Beverley and Barmston Drain is the main feature of a land drainage scheme authorised in 1798 to the west of the River Hull in the East Riding of Yorkshire, England. The area consisted of salt marshes to the south and carrs to the north, fed with water from the higher wolds which lay to the north, and from inundation by tidal water passing up the river from the Humber. Some attempts to reduce the flooding by building embankments had been made by the fourteenth century, and windpumps appeared in the seventeenth century. The Holderness Drainage scheme, which protected the area to the east of the river, was completed in 1772, and attention was then given to resolving flooding of the carrs.
The River Till is a river in the county of Lincolnshire in England and is ultimately a tributary of the River Witham. Its upper reaches drain the land east of Gainsborough. The middle section is embanked, as the water level is higher than that of the surrounding land, and pumping stations pump water from low level drainage ditches into the river. Its lower reaches from the hamlet of Odder near Saxilby into the city of Lincoln were canalised, possibly as early as Roman times, as part of the Foss Dyke.
The Upper Witham IDB is an English Internal Drainage Board responsible for land drainage and the management of flood risk for an area to the west of the Lincolnshire city of Lincoln, broadly following the valleys of the upper River Witham, the River Till and the course of the Fossdyke Navigation.
Holgate Beck is a small watercourse that flows north-eastwards through Holgate across the west side of the City of York, England. Primarily flowing through Holgate, from which it derives its name, the beck drains a large part of Askham Bog and Hob Moor, then running underneath the various lines near York railway station. It empties into the River Ouse at Water End, being one of five main tributaries for the River Ouse in York, and consequently added to the flooding in the river and immediate environs. To counter this, some flood diversionary schemes have been implemented near to Askham Bog and Hob Moor.
Romney Marshes Area internal drainage board is the successor to a long line on organisations who have managed land drainage and flood defence on Romney Marsh in the counties of Kent and East Sussex in the south-east of England.