Work is due to start on a £15,000 project to save Geldeston's historic lock from collapsing.
The lock was built around 1670 to enable trading wherries to reach Bungay and is one of only two on the Broads system.
Last used by wherries such as the Albion before the lock was closed in 1934, the River Waveney Trust is determined to save the lock chamber from deteriorating further and the trust's Beccles group has launched a project to restore it.
Members say the brick walls are crumbling, with trees and other vegetation growing through them, and recent surveys have confirmed that there is a risk of collapse.
Work will get under way on August 6, with help from Waterways Recovery Group volunteers, who are experts in masonry and lock restoration. Staying for a week at the Riverside Centre in Bungay, the group will restore as much as possible of the southern wall.
Bernard Watson, project manager for the River Waveney Trust, said: 'We believe we have started this essential work in the nick of time. Another bad winter threatens the chamber.
'I am delighted to have organised support from the local community. We have received the necessary permits from the Broads Authority and the Environment Agency and are now getting all the scaffolding and materials onto the site ready for the experts starting work.'
The project will cost £15,000 and the trust is busy fundraising in the Beccles and Bungay area.
Beccles co-ordinator for the River Waveney Trust, Andy Mackney, said: 'We have thought up two excellent and eye-catching fundraising initiatives. For £35 to £45 you can sponsor an engraved brick to ensure your permanent presence at this famous lock, or in memory of a loved one.
'The Trust's founding trustee, Geoff Doggett, is also skydiving from Ellough Airfield in October and your pledges to support his initiative are also very welcome.'
Anyone interested in sponsoring a brick can email rwtbricks@gmail.com or call 01379 853464.
To find out more about the scheme, other ways to donate and to sponsor Mr Doggett's skydive, visit the River Waveney Trust website at www.riverwaveneytrust.org
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here