A three-year programme to maintain the Grand Western Canal in Devon has begun.
Only an 11-mile section of the canal, which was built in 1812, remains open and it is now a designated country park and local nature reserve.
Devon County Council took the canal over from the British Waterways Board in 1970 and manages in partnership with Mid Devon District Council.
Specialist contractors have been employed to carry out the £330,000 programme of works.
Each of the 33 brick or stone culverts under the canal bed will be cleared of silt and vegetation, then repaired and re-pointed as necessary.
Councillor Roger Croad it was essential the culverts were properly maintained.
"The collapse of a culvert would not only seriously affect the canal, but could result in significant flooding of surrounding land, including farmland and residential areas," he said.
Des Hannon, a Devon county councillor and chairman of the Grand Western Canal's joint advisory committee, said: "The fact that the council is embarking on this vital maintenance in these hard times shows the canal's importance - both historically and to our economy today."
The canal runs from Tiverton in mid Devon to Lowdwells, near the Somerset border.
The country park is popular with walkers and cyclists and can also be used for boating and fishing.
There has been a horse-drawn passenger barge at the Tiverton canal basin since 1974.