However, the breach of the Möhne Dam in 1943 taught the Ruhrverband that such large amounts of stored energy can cause immense damage and even cost lives. About 1,500 people died from the force of the tidal wave that washed over the breached masonry dam after an air raid.
To prevent history from repeating itself, the Ruhrverband has taken measures to help prevent attacks on dams and reservoirs. However, dams can break not only as a result of human action, but also because of inadequate professional planning, construction and operation. For example, in March 2009, the dam of an impounded lake broke in Indonesia after several days of continuous rain. A tidal wave more than 2 metres high washed over a neighbouring residential area, killing at least 50 people.
As a protective measure against such disasters, the Ruhrverband conducts comprehensive routine safety checks of its dams and reservoirs on its own accord. For example, in accordance with the pertinent laws and provisions, dam movements and the amount of seepage inside the dams are measured, supplemented by regular visual inspections.
In addition to this internal oversight, the Arnsberg district authority conducts its own checks, following the "four-eyes-principle". For this purpose, the Ruhrverband submits an annual safety report for each dam and reservoir, containing all measurements and obversations for each reporting year and an assessment, to document dam safety.
Moreover, the water pipes and shutters which serve to either impound or discharge the water stored in the reservoirs, are subject to special planning, construction and maintenance requirements.
Thanks to these comprehensive safety measures, the people in the Ruhr river basin can be certain that, based on reasonable discretion, a breach of any of the Ruhrverband dams can be excluded.