In 1899 a squabble over water resources between the Corporations of Derby, Leicester, Notts and Sheffield and the County Council of Derbyshire led to the passing of the Derwent Valley Water Act.
The Act authorised the construction of six reservoirs in the Derwent Valley, chosen because of its narrowness and heavy annual rainfall. These were Ronksley, Howden, Derwent and Bamford in the Derwent Valley and Haglee and Ashopton dams in the Ashop Valley.
It also divided the water to be impounded by the dams between the quarrelling parties, with Derbyshire entitled to 25%, Leicester to 35.72%, Notts to 14.28% and Sheffield to 25%.
One of the first appointments to the newly formed Derwent Valley Water Board was civil engineer Edward Sandeman, who had made his reputation on the Burrator Dam near Plymouth. He was paid an incredible salary of £1,200 a year - almost 10 times that of the Board's medical officer.
Sandeman recommended moving the Derwent dam almost 800m up the valley and increasing its height from 27m to 35m. This allowed the Ronksley dam to be dropped from the plans.
In May 1901 construction started on Howden dam, followed a year later by Derwent. Both are masonry dams, 59m thick at the base tapering to just over 3m thick at the overflow crest.
The two projects combined would require 1.25M tonnes of Derbyshire gritstone, which could have come from the Derwent Valley itself. But the Board considered that the ravages of quarrying and flooding may mean that the valley would never recover, so a quarry site was chosen in Grindleford, close to the Midland Railway Company's main line.
To get the stone up to the site of the dams, almost 14km away, the Board had to build its own standard gauge railway at a cost of £15,000. Howden dam was eventually opened at a grand ceremony by board chairman Sir Edward Fraser in September 1912. But war commitments meant Derwent's opening in 1916 passed quietly.
Nineteen years later construction of the giant Ladybower dam started. The purchase of land from the Duke of Norfolk's estate meant plans for the smaller Bamford and Ashopton dams were dropped in 1920 in favour of Ladybower. This would be the largest artificial reservoir formed by an earth dam in Europe at the time.
The dam was designed by Messrs GH Hill and Sons of Manchester and built by contractor R Baille of East Lothian. The outbreak of the Second World War forced worker's wages up and reduced the number of men on site from 312 to 218 in six months. In the same period construction material costs rose by 12.5%.
To limit costs and keep the project going Italian prisoners of war were put to work on the dam. It was eventually finished in 1945 and was inaugurated by King George VI on 25 September.