Romney Lock at Windsor was due to be the last lock to reopen after the Environment Agency's winter works programme.
The EA said it was planned to reopen on Thursday (March 12th) after an extensive renovation programme.
Earlier a spokesman said: " ‘We expect to complete the installation of Romney Lock’s new gates in time to fully re-open the lock to boat traffic. This is slightly later than originally planned due to unforeseen technical issues not uncommon with complex engineering projects like this. We apologise for any inconvenience this may have caused.
‘Installed at a cost of £425,000, the new steel gates replace the 30 year old hardwood gates and are expected to remain in service for 80 years."
During the winter work has been completed at Grafton,
Marsh, Marlow, Cookham,
Boulters and Sunbury locks.
Further work at Penton Hook has been postponed until next winter.
Story updated March 11th 2015