At the 40 m high Möhne cyclopean masonry dam a bottom gallery was constructed by drill and blast methods in the 1970's.
At the 48 m high Eder masonry dam a gallery was excavated by drill and blast and in 1991 – 1994 a total of 104 anchors, 65 to 75 m long, were installed each with an ultimate tensile strength of 7.5 MN.
Although it appeared to suffer only minor damage in the raid at the 69 m high Sorpe earthfill dam there was a sudden increase in leakage to 180 l/sec in January 1951 which was attributed to bomb damage to the concrete core. This required the drilling of 53,000 lin m of boreholes and the injection of 4,350 tonnes of cement grout. 1,700 tonnes of clay were also used in the repairs.