A £740,000 bridge is rusting badly, according to local residents, despite being built less than five years ago.

Pont Tonfannau, also known locally as the Dysynni Bridge, was opened to much fanfare in spring 2013 as part of the Welsh Coastal Path project, saving an eight-mile diversion via Bryncrug. Work was completed by civil engineering Company Jones Brothers from Ruthin and was designed by YGC, Gwynedd Council’s in-house consultancy team.

However, in recent weeks and months, residents have spotted that the bridge is rusting and have raised concerns over the safety of the structure.

Gwynedd Council said there is no cause for concern, the bridge is up to the required standard and that the bridge is fit-for-purpose until at least 2033.

But Les Hunt, a steel fabricator based in Tywyn, said: “If you brought a car and it rusted in four years, you wouldn’t be happy would you? Especially if it cost three quarters of a million pounds.

“I’ve looked at the bridge and they haven’t galvanised it. That seems to be an oversight for me, especially in a marine environment with lots of salt and waves.

“The railings at the very least should have been galvanised.”

Aberdyfi resident Bob Tyrrell walks the bridge routinely and was equally nonplussed with what he saw.

“This was a flagship operation, a beautifully designed bridge, and it’s already covered in rust,” said Mr Tyrrell, who is also an Aberdyfi councillor.

“It’s an eyesore already and it will only get worse.

“I’m not speaking as an Aberdyfi councillor, just a concerned resident. They spent all that money.”

When asked about the bridge, Gwynedd Council said the bridge was up to the required standard.

“A bridge the size of the Pont Tonfannau is too large to be galvanised,” said a spokesperson.

“The paint system applied to the bridge was selected to best suit the aggressive nature of a marine­ environment.

“Any system will show signs of degradation over time, particularly where it has been damaged.

“There is no reduction to the strength of the bridge due to the visible rust spots. The paint system has an intended life to major maintenance of 20 years.”

Jones Brothers were not available for comment.