Passenger ferry services between Mostyn Docks in Flintshire and Dublin is to be axed - nine months after the move was first suggested.
Ferry crossings Mostyn to Dublin are to stop after less than three years
Shipping company P&O pledged its support to the docks after its £17m facelift by switching its Irish Sea crossings from Liverpool to Flintshire.
However, P&O have now sold their two ferries operating on the Mostyn to Dublin route to competitor Stena Line and stop sailings from the north Wales port from next month.
Twenty jobs are expected to be lost and bosses at the port believe the failure to dredge the estuary to allow easy access for the last two and a half years has played a part in P&O's decision.
They warn the dredging problem could leave a deal to transport wings for Airbus' new superjumbo made in nearby Broughton to Toulouse in France in jeopardy.
The wings each weight 38 tonnes and are far too heavy to be flown to France.
Without the necessary dredging, ships are unable to get in and out of the docks.
Purpose-built berths to handle the shipments are now nearing completion at Broughton and Mostyn in readiness for the first export of the wings in April.
"It's a bit late to tell us that there's a problem now," said Brian Fleet from Airbus.
"We've spent significant sums of money on this project. Our plan is still to transport from Mostyn but we still need to keep an eye on the dredging issue.
"We are always concerned when any customer goes away from a supplier but we have been speaking to the Port of Mostyn on a regular basis," he added.
Jim O'Toole, managing director of Mostyn Docks, wants the Environment Agency, Defra and the Welsh Assembly to issue the necessary dredging consents without delay.
"Maintenance of the navigation channel entails the dredging of sand from the shallower areas of the channel and placing it in the deeper areas," he said.
Mostyn Docks underwent a £17m refit in 2001
"Consents to carry out maintenance dredging of the same channel have been under consideration by the regulators for the last two-and-a-half-years," he added.
Flintshire Council Leader Alex Aldridge said P&O's withdrawal from Mostyn Docks was an "immense disappointment".
Delyn MP David Hanson said he too was very disappointed and said P&O had made a "very costly mistake" in withdrawing the service.
However, P&O say the Mostyn route is no longer viable.
The port of Mostyn was reopened with a passenger terminal in February 2001 after a £17m facelift and the awarding of the P&O contract.
Apart from the ferry services, the port of Mostyn also deals with cargo handling operations.