BOATERS are expected to be able to resume journeys down the River Thames on Saturday after engineers worked round the clock to repair broken lock gates.

Dozens of Environment Agency staff and contractors worked in shifts day and night to build a temporary six-metre high dam capable of holding two million litres of water at Sandford Lock, just south of Oxford.

The lock, which is the fourth largest on the Thames, had to be drained, so workmen could repair one-metre long cracks in the gates after damage was discovered by divers during a routine inspection last week.

It will have been out of action for three days by the time it is set to re-open.

The bad news for boaters is that the repair is only temporary and the lock is expected to be closed for up to six weeks this winter so replacement gates can be installed at a cost of £50,000.

The agency’s waterways improvement engineer Dave Green said: “This is the worst time of year for us because of the Bank Holiday weekend.

“We didn’t like closing the river at this time, but we had no choice. We wanted to get this repair done in time for the summer.

“I’m pleased with the way our workforce has thrown their weight behind this and everyone has been trying to get the lock open in time for the Bank Holiday.

“We couldn’t have done the whole job now, though. It would have caused too much disruption to the waterway. Boaters and owners of commercial boats would have been very unhappy if we had.”

The problem meant the lock could only be opened by the lock keeper or waterways staff who worked between the hours of 8am and 8pm.

During those hours staff could only manage one lock opening upstream and downstream per hour, and it could not be opened outside those hours.

To fix the gates workmen welded steel plates over the cracks.

The mammoth task required staff to move nearly 1,000 young fish, mostly roach, as they drained the dam.

The cause of the cracking is still unknown, however Mr Green said the damage could have been caused by wear or tear, fatigue or from the gates being struck by a boat. An investigation will now be carried out by the agency as the gates had only been in place for 14 of their expected 60 year life-span.