The dam that isn't and the great floating plug of the Colden

Hebden Bridge History Society meeting report.
Speaker: Dave Smalley

Wednesday, 1 April 2015

Dave Smalley's investigation of Noah Dale dam starts with a story and an oddity in the landscape, as he explained to the Hebden Bridge Local History Society. The story is of a catastrophic collapse of the neglected dam at the head of Colden Water in the 1930s which carried the core of the dam downstream. The oddity in the landscape is the mound of earth which stands close to the breached dam wall and has been identified as the 'plug'. But big mounds of earth don't just float. Standing in the boggy ground at this remote spot, Dave was determined to find a more convincing explanation.

Noah Dale dam

The dam itself was built between 1805 and 1810 so that water supply could be guaranteed to the spinning mills of the Colden Valley. Dave has established that the original dam was well built but it was shallow and could not hold enough water to supply all the mills. The owners took an enormous loan of £7000 in 1810 but in 1826 needed to invest in making the dam bigger. This raised the wall using rather shoddy engineering and was probably the cause of the dam's ultimate failure.

Examination of the landscape shows that the original dam had made use of existing landscape features, but had diverted the course of the Colden. The odd knoll is not a 'floating plug' but just  part of a larger mound that was cut through by the navvies to keep the Colden flowing well.

A century later there were concerns about dam safety and new regulations demanded that the dam be kept in good repair. Those responsible were loath to spend more money on this, paying a waterman just £5 a year to inspect and maintain the structure. A report found a gap in the wall of the dam that had been raised, a fault that would cost £2000 to put right. The failed dam was left to decay further.

Stories have always suggested that the dam burst because of a serious rain storm - but the rainfall statistics don't support this theory. It seems that after a steadily wet year in 1938, the reservoir was beginning to hold water again, and the owners decided to dismantle it, probably by collapsing a tunnel. All the archaeology seems to support this surmise.

Dave's talk was a masterclass in showing how archaeology, geology, engineering, detective work in archives, analysis of photographs and simply tramping through bleak boggy moorland combine to add to our knowledge of the past and bring history to life. The result was a fascinating story about the construction of the Noah dale dam and its ultimate demise.
Hebden Bridge Local History Society season of talks starts again in September, but keep in touch with other events by looking at the website www.hebdenbridgehistory.org.uk

With thanks to Sheila Graham for this report