particularly around the town of Huddersfield. For example, portions of the BBC television series Happy Valley (2014) were filmed in Huddersfield; in addition to exteriors, some of the studio filming was done at North Light Film Studios at Brookes Mill, Huddersfield. As well, interiors for the BBC's Jamaica Inn, for the BBC's Remember Me and for ITV series Black Work, were also filmed at the studios. Many of the exteriors of the BBC series Jericho (2016) were filmed at the nearby Rockingstone Quarry and some interior work was done at North Light Film Studios. Environmental Wildlife and fish Until the 19th century, the Calder was home to large numbers of salmon but pollution from the textile and chemical industries along its banks led to the death of the salmon population by the mid 19th century. The last salmon on record was caught at Wakefield in 1850, however there is evidence that they are returning, with sightings on the lower river at Castleford in 2008 and alleged catchings much further upstream. Around Huddersfield, Mirfield and Wakefield are popular areas for coarse fishing, roach, perch, chub, dace, minnows, gudgeon, pike, bream and trout. The areas upstream of Dewsbury are quickly becoming cleaner and more suited to game and specialised river cyprinids like barbel, as well as general coarse fish that are also doing well. Alongside the river are four Sites of Special Scientific Interest. Recent improvements in reducing the amount of pollution have led to the return of native wildlife, such as the otter and kingfisher to stretches of the river. Kingfishers are easily spotted (all year round, due to its orange underbelly) all the way up and down the river's course and are quite numerous around the Mirfield area. Pollution The river has been heavily polluted by the textile industry, and, more recently, chemical works along its banks. Close to its source at Heald Foot, the water is polluted by the remains of past opencast mining activities and a landfill site. This has also led to a significant amount of soil erosion, with major mudslides into the river and its tributaries in 1947, 1982, 1991 and 2001. As the river reached Huddersfield, the traditional textile industries created a considerable amount of water pollution, particularly through the processes involved in the production of synthetic dyes and in scouring the wool clean. The enormous growth of the population over the last hundred years