The primary reason for locating so many generating stations beside the Trent was the availability of sufficient amounts of cooling water from the river. This combined with the nearby supplies of fuel in the form of coal from the Nottinghamshire and Yorkshire coalfields, and the existing railway infrastructure meant that a string of twelve large power stations were originally constructed along its banks. At one time these sites provided a quarter of the electricity needs of the UK, giving rise to the epithet 'Megawatt Valley'.