Eastern Yar

The Eastern Yar is the longest river on the Isle of Wight arising from the chalk downs at the southern end of the Island and flowing for some 20km to outfall into the eastern Solent at Bembridge. It comprises of two main tributaries that confluence some 8 km downstream of the village of Whitwell. Here, the Upper Yar rises as a series of springs. This upper part of the catchment is rich in a variety of wildlife habitats including old meadows. The incised river valley passes through intensively farmed land to the south and west of the village of Godshill.

Below the confluence of the Upper Yar and the Wroxall Stream near Budbridge the flood plain of the river widens to flow through a flood plain that historically supported wet grassland and marshes known locally as moors. For much of this section of the valley the old railway line follows the course of the river and it is apparent that major changes to the course of the river were undertaken in the latter half of the 18th century to facilitate the drainage of the flood plain and construction of the railway. Narrow side valleys also flow into this section of the valley supporting wet alder woodlands.

Further downstream, the valley between Newchurch and Alverstone contains some of the most important wetlands in the Yar valley including Alverstone Marshes SSSI. This section of the valley is marked by deep deposits of fen peat that have preserved archaeological remains dating back into pre‐history. To the south, the valley sides rise steeply from the flood plain to create distinctive bluffs known locally as Lynches, many of which support interesting ancient semi‐natural woodlands such as those at Lynch Copse, Newchurch.

The lower end of the Eastern Yar Moors is marked by the weir at Alverstone Mill. This historic structure backs water up along the river and creates a trap for silt. Siltation has greatly reduced the depth and area of open water and value of this reach of the river for fish. Below Alverstone Weir the valley widens further into a section – the Eastern Yar Levels. Gradients in this section of the valley are very low and a long history of regular river dredging have left the channel deeply incised below the flood plain. As a result remaining wetland habitats tend to be located around the edge of the flood plain where springs and seepages arise at the foot of the steep lynches or bluffs such as Alverstone Lynch and Borthwood Lynch. The marshes below Borthwood Lynch on the south side of the flood plain are managed by the Wight Nature Fund as a nature reserve known as Alverstone Meads whilst further areas of the flood plain are managed by the Wildlife Trust as a nature reserve.

An abstraction for public water supply and associated water treatment works is located at Burnthouse Weir, just downstream of Longwood Bridge. The abstraction of water from the river at this point can leave flows severely depleted and in summer flow can be reduced to almost a trickle. Below Longwood Bridge, the flood plain widens further to form the Sandown Levels, an extensive area of flood meadows crossed with drainage ditches and bounded by the settlements of Sandown and Yaverland to the south and chalk grassland slopes of Knighton and Brading Downs to the north. Flowing into the Eastern Yar Levels from the south is the Scotchells Brook.

The final lower reaches of the valley – the Eastern Yar Marshes and Harbour, extend downstream from Yar Bridge at Brading to the tidal outfall at Bembridge. This section of the river has mostly been reclaimed from the sea and many of the old tidal creeks can still be seen as reed-filled meanders between extensively grazed wet grasslands. The majority of this area of the flood plain is owned and managed as a nature reserve by the RSPB. Water levels are controlled to create conditions for wetland wildlife in particular wintering waterfowl, breeding waders and reed bed nesting birds such as Cetti’s, reed and sedge warbler as well as reed bunting. The river throughout these lower reaches of its course has an almost flat gradient and water levels in the adjacent marshes are maintained by control structures such as the Great Sluice at Brading and the tidal sluice gates at Bembridge. These structures act to trap sediment in the river channel which combined with the low flow rates creates a river with poor aquatic vegetation and associated invertebrate and fish populations.

The technical bits

The Upper Eastern Yar is classed as ‘’Good’ quality within the Water Framework Directive. However the Middle and Lower Eastern Yar are currently ‘Moderate’. There are a myriad of issues, discussed further here.

In 2014 we mapped all the issues we were aware of with regards to the Eastern Yar Catchment. This map can be viewed here. Please let us know if you know of other issues.