It seems that the Canal and River Trust is the body responsible for the upkeep of the dam. This will be a drain on their resources (groan!) but I'm sure help will be forthcoming.
They may need it. From
the trust's last annual report:
Major Asset Failure Fund – £0.7m (2018: £nil)
The Trust has considerable exposure to major asset failures, notably in relation to reservoirs and embankments. This was aptly demonstrated during the year with the failure due to suspected vandalism at Stanthorne on the Middlewich arm of the Shropshire Union canal, which resulted in the canal being closed for around nine months and took £2.8m to repair. The Trust had to defer planned projects to be able to accommodate this within the original financial shape for this year. A fund such as this, once fully established, would allow for such additional expenditure without adversely impacting on our annual financial plans.
This designated fund will be built up over the coming years and 50% of the value of free reserves has been allocated to this fund this year.
The report lists among assets 769 major embankments. If rebuilding Stanthorne Embankment - just the side of a raised canal - cost £2.8M, they'll need the loan of a really big financial resources pump (and extraction licence).