Horncastle floodgate fault 'did not cause flooding', said report

The Environment Agency report describes Storm Babet as an "extreme flood"

The delayed closure of a gate designed to prevent flooding did not cause 197 properties to flood, a report has found.

During Storm Babet on 20 October 2023 a reservoir sluice gate in Horncastle did not automatically close as designed.

The Environment Agency (EA) report said the flooding on 19 and 20 October 2023 was caused by "heavy rainfall downstream".

The River Bain was hit by up to two months' rain in one day, it said.

Even if the flood defence had been working properly, it wouldn't have prevented the 197 properties in Horncastle from flooding, according to the EA report.

Horncastle saw significant destruction as a result of Storm Babet

On 20 October 2023 there was a delay of around two and a half hours before the gate closed.

The £8m Horncastle flood storage reservoir scheme was completed in 2017 to reduce flood risk along the River Bain in Horncastle and villages downstream.

Analysis by Paul Murphy, BBC Environment Correspondent

When the then Flood Minister Thérèse Coffey formally opened the Horncastle Flood Defence Scheme in 2017 she said it would give local people "precious peace of mind".

The newly published Environment Agency report will go some way to shattering this assurance.

The reservoir above the town is designed to hold flood water back and buy the community valuable time during heavy rainfall.

But the Environment Agency says the events of last October were so extreme that even if this flood defence had been working properly it would not have protected people's homes.

The agency says that two months of rain fell in one day. It was "a one in one thousand year event" when the Horncastle flood defence is only designed to handle a "one in one hundred year" event.

This will be deeply concerning news for a community that once believed it was safe from floodwater.

Climate change is expected to deliver bigger storms and more extreme rainfall in the decades ahead. Horncastle remains vulnerable.

The EA report concluded: "The flooding was caused by heavy rainfall downstream of the reservoir and to the east of Horncastle, in excess of the flood storage reservoir scheme design.

"It was not caused by the delayed closure of the reservoir sluice gate."

An issue with the controls of the gate has now been resolved to prevent it from happening again, according to the report.