Potteric Carr Nature Reserve
History

A Brief History of the Reserve

The Potteric Carr basin is an area of low lying land to the south east of Doncaster. It was formerly largely bog and fen until it was drained in the mid-18th century to turn it to agriculture. During the 19th century the coal and railway industries developed on parts of the Carr and the numerous railway lines fragmented the land and made farming difficult and uneconomic. In the mid-20th century subsidence due to mining occurred under a part of the Carr and within 20 years this area had returned to its former fen and bog conditions. As a result, the associated plant, bird and insect communities returned, the plants probably having survived in the drains which criss-cross the area. During the 1960s a number of the mineral railway lines became disused, whilst ironically in 1975 new lines were constructed in connection with the introduction of high speed trains on the East Coast Main Line in 1978.

In 1968, a small area of the Carr was designated as a nature reserve by the Yorkshire Wildlife Trust. The Reserve was expanded to its current size by the mid-1970s and there are plans to increase it still further in the next few years. The Reserve has been designated by English Nature as a SSSI (Site of Scientific Interest) for its reed fen communities.

New areas of marsh and open water have been created and facilities have been provided to enable the general public to have access to the area to enjoy the wildlife and the quiet of the countryside. It relies on donations, grants and its own fund raising activities to fund the work on the Reserve and has a large voluntary input from the local community.

Water Management

Parts of the Reserve are used as a flood relief area for south Doncaster. Since the introduction of the scheme in 1980, the area has changed from a groundwater regime to a perched water table. The only substantial all year round source of water is from the Mother Drain which is fed partly from a waste water treatment works. The quality of the water in this drain can give cause for concern at times and is generally eutrophic. However, in 1998 a scheme for filtering this water using reed bed filtration, was constructed as part of Phase 1 of a development plan for the Reserve which was financed by funds from the European Union (European Regional Objective 2, Measure 22), English Partnerships (Partnerships Investment Programme) and Yorkshire Environmental Community Trust (Landfill Tax).

The scheme involved the creation of five cells through which the water, pumped from the Mother Drain, passes sequentially. The cells are planted with mainly Common Reed Phragmites australis and eventually, as the detritus from the reeds builds up, this cleans the water biologically as it passes through on a twelve hour cycle. In addition, the cells include brick rubble to strip out phosphorus.

The design team for the scheme comprised the Yorkshire Wildlife Trust, consulting ecologists Penny Anderson Associates and consulting engineers Grantham, Brundell and Farran. The cleaned water is returned to Mother Drain and eventually will provide water, through water abstraction and storage, for a new area of reed fen which will be developed on farmland to the south of the Reserve as a part of Phase 2 of the Reserve's development programme. Railways, coal and water have played a major part in shaping and continuing to shape Potteric Carr Nature Reserve.

Although the railways fragmented the land making it uneconomic for farming and, in some cases rail-locked, the coal workings in turn caused subsidence which created the conditions for the formation of the Reserve. Primarily a wetland site, it follows that an inflow of water is vital to its continued existence.

Railways, Coal and Water

Railways A feature of the Reserve is the network of used and disused railway lines which criss-cross the area. The railways were built mainly between 1840 and 1910 in response to the expansion of rail travel with the building of the Great Northern Railway linking London and the north. The proliferation of coal mines needed rail access to the important main lines which would distribute its products to industry and the domestic market. Where they had to cross Potteric Carr it was necessary to build embankments over the marshy land. These were constructed from magnesian limestone, a belt of which lies to the west and south.With the grouping of the railways into the four main companies in the 1920s, there was considerable rationalisation and some lines became disused. But these were minor lines and more dramatic closures came with Beeching in the 1960s. Ironically during the 1970s, following these major rail closures, some reconstruction work took place to enable high speed trains to be introduced on the East Coast Main Line. This included the building of new lines mainly using the old trackbeds. In addition one embankment was moved to form a new mineral line connection. Without the full co-operation of British Rail, this work could have caused considerable damage to the Reserve. Inevitably, there was some disturbance and disruption, but the scars of construction were soon healed. The lines in use now are the East Coast Main Line with a branch to Lincoln and a number of mineral lines. The disused lines have been allowed to regenerate and the limestone used in their construction has attracted a number of lime-loving plants such as Old Man's Beard Clematis vitalba. They are also used as footpaths for visitors providing raised vantage points overlooking the marshes.

The presence of live railway lines was, for many years, the cause of some difficulties with access due to the number of "rail walking permits" being limited to around 200. The Reserve's good relations with the former British Rail and now Railtrack mean that, with a special permit, all visitors can cross live railway lines at three designated points to reach a large part of the Reserve that is rail locked. As a quid pro quo, there is agreement with Railtrack to warden the area (which helps the Railway Police) and control trackside vegetation.

Coal Concurrent with the development of the railways, and closely linked with them, was the development of the coalfields around Potteric Carr. This occurred mainly during the latter part of the 19th century. The founding of the Nature Reserve occurred in the 1950s when a coal working from Rossington Colliery penetrated under the Carr causing the land to subside. The effect of this was the re-creation of conditions of 200 years earlier with extensive areas of open water and marsh with their associated plant and animal communities, notably marsh birds The local naturalists, particularly birdwatchers, were soon on the scene and, mainly at the instigation of Roger Mitchell, the Reserve was established in 1968 on about 35 acres of marsh (what is now Low Ellers Marsh). The subsidence ceased in the late 70s and, with the closure of more collieries in the 80s, the mineral lines are now less used than ever. But outside influences on the Reserve were still taking place. In the early 70s the whole area was threatened with obliteration by the proposed routing through it of the M18. This threat was averted only after four years of uncertainty, including a public inquiry. However, immediately after this threat was averted in 1974, there were proposals (as mentioned above) to build new lines across part of the Reserve. At about the same time, the Potteric Carr Internal Drainage Board produced a plan for using certain water bodies on the Reserve for flood relief for south Doncaster.

Water  The purpose of this flood relief scheme was primarily to relieve the pressure on the river systems downstream. These early designs were unsatisfactory in terms of addressing wildlife conservation. Following consultations the designs were amended to the satisfaction of both parties and work on the construction of the scheme took place from 1979 until 1981 when the system was commissioned. Part of the work involves many of the land drains being re-graded and deepened and two pumping stations were installed. The extent of disturbance was far greater than anyone anticipated but, with the promise of better control of water over the site in the future, we had to "grin and bear it". A major benefit was the construction by the Board of a new access track to their pumping station at Balby. This has provided a much more satisfactory means of access for those using the Reserve. All land drainage water now entering the Reserve from the west and the north is pumped from the lower level, which is now maintained in the drains under normal flow conditions. During times of flood, the excess water is pumped into the lakes onthe Reserve, to be released later when any flood surge has subsided. Limits are agreed on the extent of fluctuation of water levels in the Reserve.

The introduction of the scheme has resulted in a lowering of the water table over the whole area and what was a groundwater regime has now been replaced by one involving a perched water table. During the winter, given normal rainfall, all the water bodies make water naturally. Once this has happened, the clay substrate enables the water to be retained but it is inevitably lost to evaporation and transpiration during the summer months. At this time, water from the Mother Drain, the only source of water throughout the year, albeit of dubious quality at times, can be used by agreement with the Internal Drainage Board and the Environment Agency, using the IDB's pumps and the Reserve's own pumping system. (In the home page is a small section on water management and, in a forthcoming monthly update, the intriguing methods of cleaning this water will be explained in more detail.) Over the next few years with the development of land to the north and west of the Reserve for housing, light industry and leisure, there is likely to be an increase in flood flow. This is mainly because much of the land, which is now pasture, will be hard surfaced, with more rapid draining following rainfall.

Schemes for handling this are in hand so at least the nature reserve itself should be safe and indeed enhanced. For 30 years the Yorkshire Wildlife Trust through its active Management Committee at Potteric Carr has worked, in a spirit of compromise with various statutory bodies and land owners, to meet the threats identified above and to turn them to the advantage of wildlife and the visiting public.


The Doncaster Duck Decoy