Towards the end of the First World War, Sheffield City Council proposed a major upgrade of the navigation.
They expected the government to nationalise the waterway, and pay for the improvements, to which they would contribute, providing that the railway influence was removed.
The scheme involved deepening the channel from 6 feet (1.8 m) to 8 feet (2.4 m), and constructing 18 new locks which would be 270 by 22 feet (82.3 by 6.7 m), to replace the existing 62-by-16-foot (18.9 by 4.9 m) locks.
The locks would have multiple gates, and be capable of holding four 110-tonne barges or one 300-tonne barge.
The estimated cost was £1,483,426, but the government was unwilling to support the scheme, and Sheffield City Council was not prepared to proceed without government backing.

During the inter-war years the navigation struggled to hold its own against competition from the railways and later the roads, and was affected by miners' strikes in the coal industry.
Traffic was spasmodic, rising from 381,727 tonnes in 1926, the year of the general strike, to 815,329 tonnes in 1937, but much of the latter was short-haul traffic, rather than long-haul, and the revenues did not increase correspondingly.
In an agreement with Hatfield Main Colliery and the Aire and Calder, Bramwith Lock on the Stainforth and Keadby Canal was lengthened in 1932, to allow compartment boats to be used for the coal traffic, while straightening of a stretch near Doncaster and the construction of a new warehouse and wharf were largely funded by Doncaster Corporation in 1934.

The major traffic on the navigation had always been coal, but after the Second World War there was a steady increase in oil traffic.
By 1946, all of the mortgages that the company had used to fund expansion were repaid, and the financial position of the canal gradually improved.
Control of the navigation, as with most British canals, passed to the British Transport Commission on 1 January 1948, under the terms of the Transport Act (1947).
Some improvements continued to be made, with two coal wharfs being built at Mexborough in 1954, to serve the new Doncaster power station, and Long Sandall Lock being extended to 215 by 22 feet (65.5 by 6.7 m).
The new lock was opened on 10 July 1959, and allowed trains of 17 compartment boats to work through to Doncaster and Hexthorpe, as Doncaster Town Lock above it and Sykehouse Lock below it on the New Junction Canal were already of a similar size.

In 1961, the British Transport Commission, together with the British Iron and Steel Federation and Sheffield Chamber of Commerce considered plans to upgrade the navigation to handle 250-tonne barges, and work started on new wharfs and warehouses at Rotherham.
Control of the navigation passed on again in 1963, this time to the British Waterways Board, who submitted a proposal to the government for a £2.5 million upgrade, covering the stretch from Bramwith to Rotherham.
This would have involved the construction of ten new locks, each 225 by 25 feet (68.6 by 7.6 m), to replace the existing 12 locks.
The new main line would then have been the same size as the Aire and Calder Navigation, although some of the bridges would have had less clearance.
In 1972, a further proposal for a £2 million scheme to upgrade the waterway to handle 700-tonne barges up to Mexborough, and 400-tonne barges from there to Rotherham was submitted to the Department of the Environment.

Finally, the navigation was the subject of one of the last major attempts in the UK to attract commercial freight to the waterways.
In 1983, it was upgraded to the 700-tonne Eurobarge standard by deepening the channels and enlarging the locks as far as Rotherham.
Conisbrough lock was removed altogether, and the two Eastwood locks were combined into one.
The new lock was initially named the Sir Frank Price Lock, after the chairman of the British Waterways Board who formally opened it on 1 June 1983.
The expected rise in freight traffic did not occur, however.
At Kilnhurst and Long Sandall, the new larger locks were built alongside the original locks, and so a com
Towards the end of the First World War, Sheffield City Council proposed a major upgrade of the navigation. They expected the government to nationalise the waterway, and pay for the improvements, to which they would contribute, providing that the railway influence was removed. The scheme involved deepening the channel from 6 feet (1.8 m) to 8 feet (2.4 m), and constructing 18 new locks which would be 270 by 22 feet (82.3 by 6.7 m), to replace the existing 62-by-16-foot (18.9 by 4.9 m) locks. The locks would have multiple gates, and be capable of holding four 110-tonne barges or one 300-tonne barge. The estimated cost was £1,483,426, but the government was unwilling to support the scheme, and Sheffield City Council was not prepared to proceed without government backing.
During the inter-war years the navigation struggled to hold its own against competition from the railways and later the roads, and was affected by miners' strikes in the coal industry. Traffic was spasmodic, rising from 381,727 tonnes in 1926, the year of the general strike, to 815,329 tonnes in 1937, but much of the latter was short-haul traffic, rather than long-haul, and the revenues did not increase correspondingly. In an agreement with Hatfield Main Colliery and the Aire and Calder, Bramwith Lock on the Stainforth and Keadby Canal was lengthened in 1932, to allow compartment boats to be used for the coal traffic, while straightening of a stretch near Doncaster and the construction of a new warehouse and wharf were largely funded by Doncaster Corporation in 1934.
The major traffic on the navigation had always been coal, but after the Second World War there was a steady increase in oil traffic. By 1946, all of the mortgages that the company had used to fund expansion were repaid, and the financial position of the canal gradually improved. Control of the navigation, as with most British canals, passed to the British Transport Commission on 1 January 1948, under the terms of the Transport Act (1947). Some improvements continued to be made, with two coal wharfs being built at Mexborough in 1954, to serve the new Doncaster power station, and Long Sandall Lock being extended to 215 by 22 feet (65.5 by 6.7 m). The new lock was opened on 10 July 1959, and allowed trains of 17 compartment boats to work through to Doncaster and Hexthorpe, as Doncaster Town Lock above it and Sykehouse Lock below it on the New Junction Canal were already of a similar size.
In 1961, the British Transport Commission, together with the British Iron and Steel Federation and Sheffield Chamber of Commerce considered plans to upgrade the navigation to handle 250-tonne barges, and work started on new wharfs and warehouses at Rotherham. Control of the navigation passed on again in 1963, this time to the British Waterways Board, who submitted a proposal to the government for a £2.5 million upgrade, covering the stretch from Bramwith to Rotherham. This would have involved the construction of ten new locks, each 225 by 25 feet (68.6 by 7.6 m), to replace the existing 12 locks. The new main line would then have been the same size as the Aire and Calder Navigation, although some of the bridges would have had less clearance. In 1972, a further proposal for a £2 million scheme to upgrade the waterway to handle 700-tonne barges up to Mexborough, and 400-tonne barges from there to Rotherham was submitted to the Department of the Environment.
Finally, the navigation was the subject of one of the last major attempts in the UK to attract commercial freight to the waterways. In 1983, it was upgraded to the 700-tonne Eurobarge standard by deepening the channels and enlarging the locks as far as Rotherham. Conisbrough lock was removed altogether, and the two Eastwood locks were combined into one. The new lock was initially named the Sir Frank Price Lock, after the chairman of the British Waterways Board who formally opened it on 1 June 1983. The expected rise in freight traffic did not occur, however. At Kilnhurst and Long Sandall, the new larger locks were built alongside the original locks, and so a com
River Don Navigation