River Dearne - Water Quality

Water Quality

In the late 1700s, the river held good populations of fish. Industrial development of the valley consisted of several deep coal mines, but they were fairly small, and did not significantly pollute the river. There were collieries at Smithies, Honeywell, Queens Ground and Mount Osborne. The opening of the Dearne and Dove Canal in 1810 had serious impacts on the river, as it provided a way to transport the coal to Sheffield and Rotherham, where it was used in the steelworks. This led to the rapid development of more and larger collieries. The population grew rapidly, but it was housed in small villages near the pits. With no urban infrastructure, sewage polluted the river, as did the industrial discharges from the mines.

Parts of the upper river were well suited to the woollen trade, and mills developed in the nineteenth century, at Denby Dale, Scissett and Clayton West. The valley of the upper river is quite narrow, and housing was provided by building terraces, which often backed on to the river. Again, sewage ended up in the river, as did the effluent from processing the wool, which included caustic washing agents and dyes. Water used in washing was returned to the river without adequate cooling, and the temperature rose. As early as 1896, the West Riding River Board was working hard to improve the situation, and achieved limited success by 1902, when they produced a report. They identified 44 small sewage treatment plants, none of which treated the sewage adequately, and noted that the river was "much polluted by domestic sewage and by untreated or partially treated trade refuse." By the early 1900s, the river was lifeless between Barnsley and the Don, with fish unable to survive in the cocktail of chemicals. The River Dove was also lifeless, although the Cawthorne Dyke and several other small tributaries managed to retain populations of brown trout.

The situation had not improved by the 1960s, when the Yorkshire Ouse River Board noted that industrial waste from the mining, paper making, brewing and textile industries was being dumping into the river without any treatment. Pressure from the Board and from local authorities based along the river resulted in some treatment being carried out, but by 1974 much of the river was still rated as Class E on the six-point water quality scale, which indicated it was of poor quality, with some parts rated as Class F, meaning that they grossly polluted with little or no life. Nevertheless, small pockets of fish began to appear. A small population of brown trout had survived in the upper 1.5 miles (2.4 km) of the river, but could not proceed downstream due to dams erected for the woollen mills. Moth-proofing agents were released by the mills into the water, which were highly toxic to fish, and although the discharge of these chemicals ceased in 1979, when they were routed to a sewer for treatment, the problem did not immediately go away, as the chemicals continued to seep into the river from land which had been contaminated by them for another ten years. Any progress with the re-establishment of fish stocks was destroyed by a series of releases of pollutants into the river during the 1970s and 1980s.

By 1987, water quality had improved sufficiently to try restocking the upper river, and large numbers of yearling trout were released into the river in April. A fish survey carried out by the Yorkshire Water Authority a year later showed that many of these were surviving. By 1992, there was evidence that the fish were breeding in the river, and naturally bred brown trout were found between Denby Dale and Clayton West in 1994, for the first time in over 100 years. The trout population in the upper Dearne was declared to be self-sustaining by 1996.

The river below Clayton West ceases to be a shallow, fast-flowing watercourse, and consists of deeper pools with a slower flow, which is suitable for various course fish as well as trout. By 1974, a modest improvement in water quality had been achieved by treatment of industrial effluent, and some fish managed to exist below the weir at the Star Paper Mill in Barnsley. The weir helped to oxygenate the water, and most of the fish had been washed downstream from Cannon Hall and Bretton Lakes. During flood conditions, many of the population would be washed further downstream, to be replaced by others from the lakes. A survey in 1982 found gudgeon, minnow and three-spined stickleback, which had increased by 1985, and over 10,000 course fish were released as part of a restocking programme. However, most of these were decimated by serious pollution incidents that affected the river in 1987 and 1988, and the incidents continued for a further three years. The sewage treatment works at Darton and Lundwood, on either side of Barnsley, were largely responsible.

Discharges from the Darton sewage treatment works contained residues from dyes used by a local carpet manufacturer, which reached the works by a foul sewer, but could not be adequately treated by the existing processes. As a result, the final effluent was a deep red colour, and were a major factor in the poor biochemical oxygen demand ratings for the river. Major improvements, including new primary settlement tanks and tertiary treatment lagoons, were made to the treatment works, and the carpet manufacturers installed facilities to treat their effluent before it was discharged to the sewer. By 1994, fish were again appearing below the Star Paper Mill weir, and Yorkshire Water and the Environment Agency carried out another fish restocking programme.

Improvements to water quality through Barnsley highlighted the fact that fish populations did not exist below the discharge from the Lundwood sewage treatment works to the east of Barnsley. As the population of Barnsley had increased, the volume of effluent received by the works had increased without a corresponding increase in its ability to treat it. In addition, the outfall reached the river along a 440-yard (400 m) stretch of the Cliffe Bridge Dyke, which had suffered from subsidence. This resulted in slow movement along the dyke, which sometimes caused the effluent to become septic before it reached the main channel. A major programme of refurbishment was carried out at the works between 1997 and 1998, to improve the quality of discharge. The fish populations on the lower river fluctuated, as a result of pollution incidents on the middle river, but by 1994, chub and dace were clearly breeding in the river. Breeding was assisted by re-engineering of the channel at Pastures Road, Denaby, which had been straightened in the 1960s after it was affected by subsidence. A series of bends were created, which encourage the formation of deep pools and shallow gravel riffles. These features are needed by dace and barbel for successful spawning, and prevent young fish from being washed downstream in flood conditions. Water quality has continued to improve, and the lower Dearne has become an important venue for angling.

Further improvements to the Lundwood sewage treatment works began in 2007 to enable it to comply with the Freshwater Fish Directive, and although the site was inundated during the floods of 2007, the scheme, which cost £8 million, was completed in 2008. To celebrate the opening of the new works, the poet Ian McMillan was asked to run a poetry workship at Littleworth Grange Primary Learning Centre, where children completed a poem about water treatment for which he supplied the first two lines.