Glaciers act as natural regulators, storing water in winter and releasing it in summer. To gain some understanding of this phenomenon and the contribution which glaciers make to streamflow, the predecessors of the Water Survey of Canada began glacier surveys in 1945. The earlier surveys offered some clue to the role of the glacier but the data collected were not sufficient to provide the overall picture. Following adoption of photogrammetric survey techniques, however, the glacier surveys have evolved to the extent that it is now feasible to produce a series of maps from which the linear, areal, directional and volumetric changes can be determined. This paper traces the glacier survey work from its inception in 1945. In addition, the results of two methods for determining the average contribution of a glacier to streamflow are summarized. The surveys have revealed that the glaciers, in general, are becoming smaller in size; hence, the regulation effect is diminishing.