Increased running costs after the First World War could not be met by increasing the tolls, as the company had no statutory powers to do so, and so suggested that the Ministry of Transport should take over the navigation, which they did from 24 September 1920. Tolls were increased, and a committee recommended improvements to the river. Nottingham Corporation invested some £450,000 on building the locks authorised by the 1906 Act, starting with Holme lock on 28 September 1921, and finishing with Hazelford lock, which was formally opened by Neville Chamberlain on 25 June 1926. A loan from Nottingham Corporation and a grant from the Unemployment Grants Committee enabled the company to rebuild Newark Nether lock, which was opened on 12 April 1926.