Ever wondered how London prepared for the 2012 Olympics? That preparation involved a significant change to the waterways. We are standing at Three Mills Lock also known as Prescott Lock. This lock played a crucial role in the Olympic development.
Three Mills Lock stands on the Prescott Channel on the River Lea. It is a vital part of London’s waterway network. The current lock structure was built by British Waterways. It officially opened on June 5 2009.
Before this modern construction an original Three Mills Lock existed. It was built in the 1930s. This earlier lock was part of a flood prevention scheme. It also aimed to create employment. The original lock bypassed the tide mills at Three Mills. It featured a sluice to manage water levels in the Bow Back Rivers. By the mid-1960s this sluice became inoperative. It was removed in the 1980s. Funding for maintenance was non-existent. The rivers upstream became tidal again. Navigation became tricky due to water levels and the low Northern Outfall Sewer.
Fast forward to the 2012 London Olympics. The island formed by the City Mills River and the Lee Navigation became the main site. Restoring the Bow Back Rivers became essential. This restoration allowed construction materials to be delivered by barge.
The new Three Mills Lock and sluice were designed for the Prescott Channel. The Three Mills Wall River Weir was built to prevent tidal water flowing back. Before the development tidal levels reached 15.8 feet above ordnance datum. The sluice now stabilizes levels at 7.5 feet above ordnance datum.
This means the Three Mills Lock must handle varying water levels. The downstream side might be higher or lower than the upstream side. The new lock is 203 feet long and 26 feet wide. It is 7.9 feet deep. It can hold two 350-tonne barges. The nearby Lee Navigation locks limit barges to 120 tonnes. Hydraulic sector gates manage the tidal range at both ends of the lock. The structure includes rising radial gates for flood control.
Interestingly the remains of the Euston Arch rest in the river south of Three Mills Lock. The design includes a footbridge for pedestrians. It also has a fish pass for migrating fish. British Waterways planned navigation and towpath improvements as part of the Olympic legacy.
Construction wasn’t without its challenges. An unexploded World War II bomb was found on June 2 2008. It was made safe after five days of disruption.
The construction of Three Mills Lock and the weir changed the Bow Back Rivers. The section north of the House Mill ceased to be tidal. Barges could transport materials for the Olympics and Stratford City. They used a new wharf on the Waterworks River. Barges can now directly access the northern section of Bow Creek to the River Thames. The water created by the lock may allow the Three Mills tidal mill to operate again.
The Three Mills Lock officially opened on June 5 2009. The expected use for Olympic Park construction was lower than planned. The nearest stations to Three Mills Lock are West Ham and Bromley-by-Bow. Bow Church and Pudding Mill Lane are the closest Docklands Light Railway stations.
So as we stand here at Three Mills Lock remember its role in both history and the modern era. It has supported industry flood control and even the Olympic Games.