River Idle
The River Idle is a river in Nottinghamshire, England whose source is the confluence of the River Maun and River Meden near Markham Moor. The Idle flows north from its source through Retford and Bawtry before entering the River Trent at West Stockwith. Its main tributaries are the River Poulter and the River Ryton. The river is navigable to Bawtry, and there is a statutory right of navigation to Retford. Most of the land surrounding the river is a broad flood plain and the river is important for conservation, with Sites of Special Scientific Interest being designated along its course. Etymology The origin of the name is not known. River Idle is commonly taken to mean 'slow river' but this is unlikely as river names tend to be even older than settlement names, and the modern name is also at odds with the fact that it is known as a very fast flowing river. The Survey of English Placenames suggests that Idle (Idel) can mean an empty or uncultivated place. This would fit with the finding that it runs through Bassetlaw which was previously known as Bernetseatte (burnt lands). Bede (HE 2, 12) names the river 'Idla' in 617 with reference to the Battle. This preserves what might have been an earlier ending -ea (meaning river.) In 1200 (British Museum Index of Charters) the river appears as Yddil. Thoroton suggests an alternative origin for the name. He traces the name instead to the Roman - Adelocum - and says "the river Idle had its name from corn, with which the neighbouring fields ever abounded, and Adelocum was intended by the Romans for the place upon Ydel, after the broad pronunciation of Ai for I, which is still frequent in this country...Ydle signifying a granary amongst the Britains". Hydrology The River Idle is a significant tributary of the River Trent. The Rivers Maun, Meden and Poulter meet near Eaton, south of Retford to form the River Idle and are joined downstream by the River Ryton. The River Idle turns eastwards at Bawtry to its confluence with the River Trent at the village of West Stockwith. The catchment area for the River Idle covers some , which has an average annual rainfall of (based on figures from 1961 to 1990). About a third of this finds its way into the rivers. There are sources of groundwater (aquifers) across the Idle catchment area, which is dominated by Lower Magnesian Limestone, Sherwood Sandstone and Mercia Mudstone. To the west of the catchment area the underlying geology is Lower Magnesian Limestone which contains quantities of the mineral Dolomite, and is rich in Magnesium. To the east there is the Triassic Sherwood Sandstone aquifer, which is the major geological component of the area. Continuing eastwards, both are these are covered by a layer of Mercia mudstone. Where these aquifers reach the surface, they often supply water to the river system, but can also take water from it. Public water supply in the Idle catchment area is