A £100,000 bill could be the result of a boater's carelessness, or vandalism, which led to as part of the Kennet and Avon Canal towpath in Devizes being washed away.

A lock paddle on the Kennet Lock, at the top of the Caen Hill flight, was left open overnight on Sunday, and the weight of the water released has caused the embankment below the lock to collapse, leaving huge holes in the towpath's surface.

Staff from the Canal and River Trust visited this morning to assess the damage, with the initial estimate suggesting the repair bill could reach six figures.

The paddle is the bottom section of the lock gate, and acts like a kind of overflow valve. Because it was left open, water poured down through the lock all night, with the extra water, and the pressure and weight of the flow from the open paddle, undermining the embankment.

Mark Evans, waterway manager at the Canal & River Trust, said: “We don’t know if this was carelessness or deliberate vandalism, but either way we’re going to be left with a huge repair bill to contend with.

"As we’re a charity we’ve got finite resources, and this means we can do less of what we need to do on the rest of the canal.

"It really couldn’t have happened in a worse spot – the pound above Kennet Lock is the longest on the whole canal, so we’re talking about a lot of water rushing down the Caen Hill flight, which has caused the damage.

“The Kennet and Avon Canal is over 200 years old, and needs constant maintenance to keep it going, so to have such significant damage to deal with on top of that is very disheartening.

"At the end of the day, it’s our heritage, and is enjoyed more than ever by the communities around it, but if we don’t take care of it, we’ll lose it.

"Please, please don’t let this kind of mindlessness cost us such a valuable part of the landscape.”

The trust would like to hear from anyone who may have seen the lock, which is at the end of Northgate Street and next to Avon Terrace, being used by boats on Sunday, or spotted vandals messing about with the paddle.

If anyone has any information they should contact the Canal & River Trust on 0303 0404040.