More fancifully, the Jacobean antiquary Dr. Robert Thoroton suggested, before the advent of modern etymology, that the name derived instead from a supposed Roman place-name - Adelocum - claiming that "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 Britons".[2].

[3] The catchment area for the River Idle covers some 280 square miles (725 km2), which has an average annual rainfall of 24.3 inches (620 mm) (based on figures from 1961 to 1990).

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.

Public water supply in the Idle catchment area is primarily sourced from the principal aquifer of the Sherwood Sandstone with multiple borehole sites.

However, it was associated with the sea by the 12th century, when the parish church was dedicated to St Nicholas, the patron saint of seafarers, and the Hundred Rolls of 1276 listed it as a port.

[14] In order to isolate the river from Hatfield Chase, a barrier bank was constructed along the northern edge of this channel, for 5 miles (8 km) from the dam to West Stockwith.

A navigable sluice was built about 1 mile (1.6 km) from the river mouth at Misterton Soss by Vermuyden's nephew, John Liens, between 1629 and 1630, to prevent water from the Trent flooding the land to the south of Bycarrs Dike.

A petition alleging that the Participants had caused damage was brought to the Privy Council by several local authorities from Nottinghamshire, and was judged in their favour.

The Commission of Sewers decided that a new cut was needed, to carry water from Misterton, Gringley and Everton to the Trent, and so relieve the Idle, but only about 1.2 miles (2 km) was constructed before landowners objected and the work was not completed.

Nathaniel Reading, acting for the Participants, raised an 'army' in 1656, and fought a total of 31 pitched battles, including several against the men of Misterton and Gringley.

[23] The opening of the Chesterfield Canal in 1777 and the Great Northern Railway in 1849 severely affected traffic, with Piercy, a local historian from Retford reporting in 1828 that the river was "idle, as far as navigation goes, and in all probability will remain so.

Daniel Defoe visited the Idle in the early 18th century and described it as full and quick, though not rapid and unsafe...with a deep channel, which carries hoys, lighters, barges or flat-bottomed vessels.

During periods when the Trent was in flood, the gate could not be opened, and the lower reaches of the Idle acted as a pond, with water backing up as far upstream as the junction with the River Ryton, and large areas of washland becoming inundated.

Because the pumping station was thought to be essential, the Trent River Authority agreed to provide a slipway for trailable boats, which was built near Haxey Gate Bridge.

There would be a new responsibility on such authorities, who would "be placed under an obligation when constructing major works to develop amenities and assist the provision of facilities..." The immediate plans for the pumping station were shelved.

Their Recreation Officer stated in 1990 that there was no public right of navigation on the Idle, although the Retford and Worksop Boat Club were allowed to cruise on it once a year.

[38] However, in addition to requiring 48 hours notice to enter or leave the river, the Environment Agency imposed prohibitive charges to pass through the sluice gates in 2011.

A legal case from 1702 (The King v Clark) stated that the taking of money to let people pass on a navigable river was against Magna Carta clause 23, which could only be negated by an act of Parliament specifically granting such a right.

[46] The Mother Drain ran from Bawtry to Misterton, although it was authorised to continue to the Trent, and in 1812 William Jessop recommended completing the works and installing a steam pumping engine at the exit sluice.

The second, called Ada, was built in 1839, and another 34-foot (10 m) scoop wheel was powered by a beam engine supplied by Booth & Co, who were based at Park Ironworks in Sheffield.

[49] By 1910, there was a bridge at this point which included tide gates, similar to the V-gates of a lock, which were designed to shut as the level in the River Trent rose.

[52] They have been saved from dereliction by being converted to residences,[53] their function performed by the modern electric pumping station at Gringley,[54] while the tide gates have been replaced by the vertical sluice at the entrance to the river.

The low-lying region to the south of the Mother Drain was managed by the Everton Internal Drainage Board, who maintained around 34 miles (55 km) of watercourses.

The move was initiated by the Department for Environment, Food and Rural Affairs (DEFRA), who saw this and other similar amalgamations as a way to increase efficiency, and to allow them to better support Local Flood Authorities.

[24] Since the drainage works of 1981, access to the Idle is through the two sluice gates at the mouth of the river, and the Environment Agency requires 48 hours notice of intent to enter it and the payment of a £185 toll.

The tributaries of the Idle are rated at 'C' on the GQA scale, because they pass through urban areas, and there are significant discharges to the rivers from sewage treatment works.

Like most rivers in the UK, the chemical status changed from good to fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE), perfluorooctane sulphonate (PFOS) and mercury compounds, none of which had previously been included in the assessment.

[92] In early 2013, Heidelberg Materials UK, who have extracted sand and gravel near Newington and Misson for over 30 years, restored 62 acres (25 ha) of the site to benefit wildlife, creating an area of wet grassland.

[94] The Idle Valley Reserve has recorded over 250 species of birds and it is known for its breeding populations of great crested grebe, shoveler and tufted duck, as well as its starling murmurations.

The structure effectively provides a safe, wet, gradual slope so that young eels can move out of the river into the lake where they can grow until it's time for them to breed.