ABSTRACTAll electricity produced in Norway originates from hydroelectric power plants, some of which utilize glacier melt-water. In a special case, a subglacial water intake was constructed under Bondhusbreen, an outlet glacier from the Folgefonni ice-cap in southwestern Norway.To remove bed load material from the meltwater a large sedimentation chamber was constructed in the bedrock under the glacier. A program of taking bottom samples from a proglacial lake was carried out to obtain data to help engineers to design the correct dimensions for the chamber.Six vertical cores were taken from a flat bottom area of the glacier lake Bondhusvatn; five of them contained clearly laminated sand, silt and clayey material. Both annualvarvesand“pseudovarves”were identified. The thickest annual layers, which have been deposited since the end of the 17th century, were used to calculate the maximum annual bed load, for engineering purposes. A calculation of extreme sediment inputs in the past indicates that a maximum annual suspended load of 9100 m3occurs about twice per century. Therefore, the volume of the sedimentation chamber had to be designed to accommodate 10000 m3to prevent bed-load material from entering the diversion tunnel system.The paper describes the cores, the correlation of varve diagrams constructed from laboratory studies of the cores, and the dating of the cores, partly through available meteorological and hydrological data. The existence of“pseudo-varves”was probably related to seasonal variations in discharge; the dominant annual layers (varves) were related to high total annual discharge or other“extreme”hydrometeorological events. Finally, a smooth curve showing annual varve thickness was compared to similar curves for meteorologic elements.