The River Ryton is a tributary of the River Idle. It rises close to the Chesterfield Canal near Kiveton Park, and is joined by a series of tributaries near Lindrick Common in the Metropolitan Borough of Rotherham, South Yorkshire, England. Most of its course is in Nottinghamshire, flowing through the town of Worksop. It meanders northwards to join the River Idle near the town of Bawtry on the South Yorkshire-Nottinghamshire border. While much of its route is rural, its course through Worksop is man made, a result of development and milling. It used to flow through Scrooby, where there was a mill, but was diverted northwards in the 1960s. It supplies water to the Chesterfield Canal through two feeders, and a number of the bridges which cross it are of interest architecturally, which has resulted in them becoming Listed structures. The water quality of the river is moderate, as a considerable proportion of the total flow is supplied by the processed water from sewage treatment works. Despite this, there are significant populations of fish in the river, and it is used for organised angling. Hydrology The region through which the river flows is underlaid by an extensive water-bearing porous rock structure called the Magnesian Limestone aquifer, which is near the surface in the west and dips downwards to the east. Magnesian Limestone is so called because it contains quantities of the mineral Dolomite, which is rich in Magnesium. The Triassic Sherwood Sandstone aquifer is another porous rock layer which covers this to the east, and is the major geological component of the area. Further east, they are both 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. This is affected by the extraction of groundwater, particularly for public water supply, and by fracturing of the aquifers as a result of subsidence caused by deep coal mining. The Ryton draws its water from the Anston Brook, the Pudding Dyke, the Bondhay Dyke, and to a lesser extent the Broadbridge Dyke. Prior to the construction of the Chesterfield Canal in the 1770s, the flow of the Broadbridge Dyke was much greater, but water from its catchment area was diverted to form the reservoirs at Pebley and Harthill, which supply the canal. Overflow from the reservoirs reaches the Ryton by the Pudding Dyke, but