Major flood management plans for Chesham have been delayed after part of the scheme was hampered by difficulties in getting final agreement from the Environment Agency.

Buckinghamshire Council has reluctantly confirmed that the construction of a bigger culvert in the Pednormead End area of the old town will now not be completed until next summer.

The work to upgrade and replace the culvert – the tunnel carrying the River Chess – under Church Street, which started last year, has also been made difficult due to “unusually high groundwater levels” in recent months, Bucks Council said.

The culvert is part of a major £3.4 million flood defence scheme in the historic area, which has been blighted by floods three times in the past two decades – with the last in 2014 when roads were covered in two inches of water.

More than 130 homes, businesses and a school in the Church Street area of Pednormead End are “at risk” from flooding due to excessive surface water and the nearby River Chess – which bursts its banks during heavy downpours.

A Bucks Council spokesman said: “With last winter’s significant rainfall, groundwater levels were already higher than expected at the start of spring.

“The situation was made worse with the extensive rainfall in May and has meant any construction would be increasingly difficult as attempts to get excavations dry enough to work in would be challenging and potentially dangerous.

“It’s for this reason that the work to divert a high voltage cable this week, as part of the scheme, has also been postponed.

“The second issue lies with obtaining the necessary permit from the Environment Agency for the works. The permit application has resulted in the need to update the initial flood impact estimation work to improve its accuracy.

“This could lead to potential changes in the scheme's design which need to be addressed before the works can be finalised.

“As a result of both issues, the council has no choice but to postpone work until summer 2022.”

In addition to the culvert upgrade, work to install flood resilience measures on individual homes in the area is continuing, with 11 properties now complete.

These measures include flood doors, barriers, one-way return valves and waterproofing.

Commenting on the culvert scheme, cabinet member for climate change and the environment Peter Strachan, said that he was disappointed to hear of the need for delay but hoped residents would “recognise the council’s commitment to the area”.

Mr Strachan added: “This project is crucial for reducing flood risk in Chesham and we will get this work done.

“I understand residents may feel frustrated by these further delays, but we remain committed to completing the project next year after everything has been resolved.”