Dam failure - Peak Forest Canal latest

Navigation on the Peak Forest Canal has now re-opened after the emergency closures following the partial failure of Toddbrook Reservoir dam.

On 1st August, the risk of the dam collapsing at Whaley Bridge resulted in the closure of the lock flights at Marple on the Peak Forest Canal and Bosley on the Macclesfield Canal. As a precaution some boats have moved away from Whaley Bridge. The following day, these lock flights were re-opened but the Upper Peak Forest Canal was closed above Bridge 26 at Disley, with stop planks placed across the canal at a number of locations. These were to minimise water loss if the dam were to burst and had the subsequent torrent caused a breach of the canal around New Mills or Furness Vale.

By 7th August, water levels in the reservoir had been reduced sufficiently that there was no longer considered to be a risk of the dam collapsing. The stop planks were removed and people who had been evacuated were allowed to return.

Heavy rain in the hills around Whaley Bridge had led to water overtopping Toddbrook reservoir, immediately upstream of the town. Although this flowed down a concrete spillway designed for this purpose, the sheer volume of water undermined the concrete with sections breaking up.

The damaged spillway at Toddbrook Reservoir. (Photo: unknown source via Twitter.)

The reservoir was opened in 1838 to supply the Peak Forest Canal. The dam is constructed mainly of earth. The Canal and River Trust warned that there was a real risk of the structure failing and hundreds of residents were evacuated from the town of Whaley Bridge. Water was pumped out of the reservoir but took several days before the level was low enough to be considered no longer a risk.