Fact File

The River Calder rises on the Pennine Moors west of Todmorden. It is predominantly an urban river flowing through the West Yorkshire conurbation towns of Halifax, Brighouse, Huddersfield, Dewsbury and Wakefield, before joining the River Aire at Castleford, some 87 km from its source.

The name 'Calder' comes either from the early British meaning 'hard' or violent waters or stream, or possibly from the Celtic, meaning 'river of stones'.

A Legacy of Pollution
Until the early 19th century, the Calder's waters were home to plentiful stocks of salmon. However, with the onset of industrialisation, the river gradually became increasingly polluted. The last salmon on record was caught at Wakefield in 1850.

The Calder and its tributaries, particularly the River Colne, were particularly useful for the woollen industry in the 17th and 19th centuries and the area has long been used for the production of dyes for the textile industry. The fast flowing upland streams provided a convenient power source and proved useful for the washing of fleeces and general disposal of effluents.

The growing population associated with 19th century industrialisation of the area contributed to the pollution as sewage treatment facilities became inadequate for the increasing number of people moving into the Calder Valley.

The polluted stretches of the Colne and Calder did not even begin to recover until the 1950's when tighter controls on pollution started to bring about a marked improvement.

Water Quality Today 
Today the Calder's catchment area is home to almost 800,000 people and the river remains an important source of water for Yorkshire's industry.

Effluent from many sources causes pollution with the largest single source being treated sewage effluent. In fact, during dry summers, more than two thirds of the river's flow is treated effluent from major sewage works. Just upstream of Todmorden, the upper reaches of the Calder are polluted by discharges from long abandoned coal mines.

There are natural water quality problems in the catchment too. Many of the moorland streams at the head of the Calder valley are uncontaminated by effluents, but, they are frequently - and quite naturally - stained a tea colour by deposits of peat.

Also, upland streams, draining the high moorland gritstone area, are so acidic few fish can live either in them or the upland reservoirs. This is because there is no lime in the gritstone to neutralise rain falling on the peat. However, some of the water is treated and then used for drinking supplies.

The authority has a system for classifying the water quality of rivers. Class A and B rivers are of a high quality. They are clean enough for salmon and trout to live in and can be used for drinking water. They will also support a variety of invertebrates, including mayflies, stoneflies and most pollution sensitive insects.

Class C and D rivers are of fair quality. Course fish such as roach, chub and bream can live in them and possibly trout in some C waters. These rivers can be used for drinking water if it is treated. A good variety of invertebrate species can be found apart from the most pollution sensitive animals.

Class E rivers are of poor quality. They can still support coarse fish but cannot be used for drinking water.

Class F rivers are badly polluted. Some small animals like worms or midges can live in them, but no fish.

The target for the Calder is that most stretches will be classed as 'good' or 'fair' by 1998 below Huddersfield.

The authority's aim is to improve the polluted stretches of river by encouraging farmers,industrialists and Yorkshire Water Services Ltd to improve effluents and avoid unnecessary pollution spillage.

An initiative called the Aire and Calder Project was recently set up to show the environmental benefits of reducing industrial energy consumption and using cleaner technology. The 11 companies involved reduced waste water and saved up to
£3 million by using these methods.

Improving Fisheries
Despite the acidity, some of the upland streams in the Calder catchment are nevertheless able to support populations of trout.

Hebden Water and Cragg Brook are rich trout streams which help to maintain fish stocks in the main river.

Downstream of Brearly Weir, near Mytholmroyd, a variety of coarse fish, including roach, perch, chub, dace, minnows, gudgeon, pike and bream thrive alongside trout.
The stretch downstream of Elland is a well established and popular coarse fishery. Unfortunately, at Mirfield the river is virtually devoid of fish due to the polluting input from Huddersfield.

The main river downstream of Horbury contains some fish but the variable water quality still has considerable influence on the populations.

Coarse fishing remains popular between Brighouse the Cooper Bridge, where the Colne meets the Calder.

Geological Features
The Calder catchment lies entirely on the Carboniferous rocks of Millstone Grit and coal measures. These rocks, which are nearly 360 million years old, comprise a sequence of shales and grits, with the grits forming the prominent high moorland areas to the west of Huddersfield and Halifax.

In the coal measures, the grits are less prominent. There are coal seams that have been extensively mined in the past although deep coal mining has now moved eastwards and is no longer carried out in the Calder's catchment area.

A Vital Source of Water
Few rivers have been more heavily exploited over the last 200 years than the Calder, for both industry and drinking water supply. Today, there are 39 reservoirs in the Calder system licensed to provide water for public supply to the area. These supplies are supplemented by 'imports' from the Winscar reservoir at the head of the Don catchment, and from the rivers of North Yorkshire for the more heavily populated areas of West Yorkshire. The river remains an important source of water for the chemical and textile industries in the upper Calder valley.

The reservoirs of the Pennine uplands at the head of the valley also play a vital role in maintaining a healthy river flow. These reservoirs release water into the catchment as a compensation for that taken for public supply. Otherwise, problems could be caused when river levels fall too low during times of drought. Fish and other wildlife would suffer and there would be insufficient dilution of effluents.

Beating the Floods
The river the its tributaries flow through steep and relatively narrow valleys and so react very quickly to rainfall which causes rapid rises in water levels and danger of flooding. Over the years, flooding problems in the Calder valley have caused serious distress to local communities. During the Industrial Revolution, cities grew up close to watercourses allowing little space for rivers to expand. Houses were also built in floodplains. As industry continued to grow, there became less land available to soak up rainwater. This caused an increase in the amount of surface water draining into a watercourse.

To remedy the serious flooding problems, a considerable number of flood defence schemes have been carried out in the area and more are planned. These include channel improvements and flood defences on the River Calder at Todmorden, Mytholmroyd, Sowerby Bridge, Copley, Elland, Brighouse, Dewsbury, Horbury, Wakefield and Methley.

Pugneys Country Park near Wakefield is used as a 'safety valve', filling with water to protect the town when the Calder is in flood.

A computerised 24 hour Flood Warning Service monitors weather systems and river levels allowing the authority to give warnings of river flooding to the police. The police, in turn, warn local authorities and the public of imminent flooding so that preparations, such as sandbagging and safe storage of valuables, can be carried out well in advance.

Conservation
The upper areas of the catchment are of interest for conservationists and the Peak District National Park extends into the upper reaches of the River Colne and its tributaries. In these upland areas, woodlands, reservoirs and moorland are closely linked to the rivers providing excellent wildlife habitats. In fact, there are four Sites of Special Scientific Interest (SSSIs) in this area.

However, the nature conservation interest of the Calder and its lower tributaries, downstream of Huddersfield, is very limited due to poor water quality. Consequently, most sites of conservation interest in the area unfortunately do not include the rivers. Examples are the Southern Washlands near Wakefield and Gawthorpe Green Pond near Huddersfield. However there are a few sites which remained unspoilt and are therefore of particular interest and value from a conservation point of view because of their rarity.

These are invariably steep sided wooded valleys, which have remained unspoilt due to their inaccessibility. The value of these sites will increase further once water quality has improved. The same can be said for many other areas of the catchment, including heavily urbanised areas, where inner city regeneration is providing opportunities to reconstruct rivers with more conservation interest.

Enjoying the Calder
Although the Calder is predominantly an urban catchment, there is some spectacular scenery and note-worthy walks, including the Calderdale Way and the Pennine Way footpaths.

The countryside around the Colden and Hebden Water tributaries of the Calder attracts birdwatchers and picnicking motorists.

The Pennine Way footpath crosses both the Colne Valley Circular walk and the Calderdale Way, which skirts the catchment, passing moorland bogs, reservoirs, waterfalls, before crossing the river itself.

Hebden Water flows through an attractive wooded valley and Hardcastle Crags, owned by the National Trust, is a well-known beauty spot.

Downstream of the pretty town of Hebden Bridge, popular with day tripping motorists, there is a working clog factory, Walkleys, where traditional footwear is still made by hand.

At Sowerby Bridge, canoeists use a slalom course constructed through the race of a demolished mill complex.

Next to the river at Cromwell Bottom, by the Calderdale Way, there are old gravel pits now used for water skiing.

As it passes through Kirklees the river carries some of the leisure craft which pass this way as the river and canal are linked through Mirfield.

Where the river passes Pugneys Country Park, windsurfers, canoeists and anglers take advantage of the enclosed waters created by former open cast mine workings next to the river. Sandal Castle, perched high above the Calder on a bluff just upstream of Wakefield, has important historical connects. It was here in December 1460, that Richard, Duke of York was slain in the Battle of Wakefield during the Wars of the Roses. Two centuries later, the castle was a Royalist stronghold attacked by Oliver Cromwell during the English Civil War.

The river has literary associations too. Poet Laureate, Ted Hughes, once lived at Lumb Bank on Colden Water and the building is now used as a school for creative writing.

Main text from Fact File - River Calder National Rivers Authority,
Publication No. NY-3/95-1K-E-ANOS

The NRA is now subsumed into the Environment Agency

Courtesy of the Environment Agency.