River Dearne

The River Dearne in South Yorkshire, England flows roughly east for more than 30 kilometres (19 mi), from its source just inside West Yorkshire. It flows through Denby Dale, Clayton West, Darton, Barnsley, Darfield, Wath upon Dearne, Bolton on Dearne, Adwick upon Dearne and Mexborough to its confluence with the River Don at Denaby Main. Its main tributary is the River Dove, which joins it at Darfield. The river was one of those affected by the 2007 United Kingdom floods.

The course of the river is accessible to walkers as the Dearne Way, a long distance footpath from Dearne Head to the river's junction with the Don. Places of interest along the Dearne include the Yorkshire Sculpture Park at West Bretton, and Monk Bretton Priory. The Dearne Valley below Barnsley is a regeneration area.

The river has been subject to channel engineering to ease the problem of flooding. A new channel was constructed near its mouth in the 1950s, as the old route had been affected by mining subsidence. Washlands, which can be progressively flooded as water levels rise, were constructed in the 1960s and 1970s. A flood relief channel and a regulator to restrict the flow was built at Bolton upon Dearne. During the 2007 United Kingdom floods, the washlands filled to capacity but the regulator could not be operated as it had been vandalised.

Industrialisation caused the river and the Dearne and Dove Canal, to become grossly polluted in the early nineteenth century and fish populations died. The West Riding River Board tried to address the problems in 1896 with limited success and much of the river remained dead until the 1980s, when industrial effluents were removed before they were discharged and improvements were made to sewage treatment. Despite setbacks, fish populations had been partially reinstated by the early 1990s. Channel engineering was carried out at Denaby in the 1990s, to re-introduce bends, deep pools and shallow gravel riffles, to assist fish spawning. In June 2015, salmon were reported in the river for the first time in 150 years.

The river rises just below the 330-metre (1,080 ft) contour west of Birdsedge. Within around 1.9 miles (3 km), it reaches the A635 Barnsley Road bridge at Denby Dale, by which time it has dropped below the 175-metre (574 ft) contour, and its flow has been swelled by several springs and the output of Park Dike. Below the bridge, Munchcliffe Beck joins near a large millpond, which supplied mills at Denby Dale. Beyond the mills, the river passes under a railway viaduct near Denby Dale railway station. The curved viaduct with 21 tall arches was built by the Lancashire and Yorkshire Railway in 1884.

The river flows to the north east closely following the A636 road. It is joined by Thorpe Dike at Kitchenroyd. It passes through Scissett and west of Clayton West where it is crossed by the Kirklees Light Railway. Park Gate Dike swells the flow, before a double-arched skew bridge built in the early 19th century carries the A636 over the channel. Nearby is a hump-backed packhorse bridge with a single arch, probably built in the previous century, after which the river turns to the east to pass the upper and lower lakes in a channel from where it feed the lakes in the Yorkshire Sculpture Park. Bretton Hall lies to the north. The river turns south at the dam of the lower lake and passes over weirs before picking up the outflow from the lakes, after which the 75-metre (246 ft) contour is crossed.

Next it turns to the south east and passes under the A637 road, the M1 motorway and the sliproads which form part of Junction 38, to reach Darton. The Cawthorne Dike joins from the west as it turns to the east and passes under the Wakefield to Barnsley railway line. The B6428 crosses on Barugh Bridge, a single-span bridge made of rock-faced stone, which bears the date 1850 on the north-west buttress. As the river approaches Barnsley, the remains of the Barnsley Canal follow it on the south bank. Beyond the A61 Old Mill Lane bridge there was a mill, after which an aqueduct carried the canal over the river. Two more road bridges follow, the second of which carries the A633 Grange Lane. Just before the bridge is Priory Mill, a thirteenth-century mill which was heavily rebuilt by Sir William Armyne in 1635, and further remodelled in the nineteenth century. It was powered by a leat from the river, which supplied internal water wheels. Water from the leat was also channelled to Monk Bretton Priory, where it flushed the kitchens and the reredorter. Next there are two former railway bridges which now carry footpaths. Soon sections of the disused Dearne and Dove Canal run parallel to the river, and after passing under two more railway bridges, the course turns to the south to reach Darfield, below which the River Dove joins from the west. The river turns to the east again, passing to the north east of a series of lakes which form the Dearne Ings and Old Moor washlands. On the opposite side of the channel are the Bolton Ings washlands, which cover 110 acres (45 ha) and have been acquired by the Royal Society for the Protection of Birds (RSPB). In 2011, the site was in its early stages of development, but the reedbeds have attracted spoonbills and avocets, and are expected to act as a breeding ground for bitterns in due course. After the washlands, the river flows to the north of Wath upon Dearne, and to the south of Bolton on Dearne.

The railway to Bolton on Dearne station crosses, after which the river is flanked by the disused Bolton Common tip on the south bank. From the village of Adwick upon Dearne, which is a little further to the south, Harlington Road crosses the river at Adwick Bridge, a grade II listed twin-arched bridge built of sandstone around 1800. Denaby Ings nature reserve is separated from the river by a railway embankment on the north bank. The river sweeps round to the south to join the River Don just below Mexborough Low Lock, where Mexborough New Cut on the River Don Navigation rejoins the river. In 1903 the junction of the river with the Don was adjacent to the railway sidings of the Cadeby Main colliery, but by 1930 it had been moved further upstream, much closer to its present location.