and https://irishwaterwayshistory.com/2009/07/22/the-esb-lock-at-ardnacrusha-on-the-river-shannon/

The Electricity Supply Board (ESB) operates the lock that takes boats through the hydroelectric power station at Ardnacrusha, on the lower reaches of the River Shannon. The lock is, in Irish waterways terminology, a double: a staircase pair, which counts as one lock, with a combined drop in the two chambers of about 100 feet. It’s not the deepest lock in Europe by any means (although it is by far the deepest in these Islands: five times the depth of Tuel Lane) but it is relatively small, a fact that enhances the impressions created by a passage through the lock.

The UK's deepest single canal lock has been partially drained for a spring clean.

Canal & River Trust volunteers are removing debris and litter from Tuel Lane Lock, on the Rochdale Canal in Sowerby Bridge, West Yorkshire, in preparation for the busier boating months ahead.

The lock lowers and raises boats almost 20ft (6m) as they make their journeys over the Pennines, the trust said.

The charity said it recently launched its biggest ever volunteering campaign to ask for help protecting its 250-year-old network of waterways and historic structures.



Unlike most locks, members of the public are not allowed to operate the mechanisms themselves, because of its depth and its proximity to a tunnel.  Instead, the trust said that lock-keepers helped crews to negotiate the gates.  The lock is so deep because it replaced a pair of earlier locks when it was built in 1996 to enable the canal to tunnel under a road built on its original level and provide a more efficient route.

Volunteer Maureen Readle said: "I've enjoyed lots and lots of canal boating holidays with my husband. We wanted to help give back to the canals by volunteering when we retired.  I have also adopted a stretch of the canal, too, which my husband and I look after.  When I took part the first time two years ago, I'd never worn a pair of waders before, let alone being waist high in water, helping to look after the UK's deepest lock."



Sean McGinley, regional director, Yorkshire & North East at Canal & River Trust, said: "Lock-keepers, many of whom are volunteers, are the face of the canals and play a vital and iconic role within our charity.  Lock-keepers have been a presence on Britain's canals for hundreds of years, although the role has changed over time.  Today, they help to look after the nation's beautiful waterways, assist boaters on their journeys, provide information and advice to visitors on the towpath, and maintain historic locks."