Electrical resistivity measurements were made in a series of closely spaced holes drilled to the base of Storglaciären. Electrodes were lowered to the bottoms of the holes where they made contact with the substrate beneath the glacier. The measurements show that a layer of till, ~0.4–0.7 m thick, is present at the base of the glacier. The low resistivity of the layer indicates that it has a high water content, compared with tills of similar composition in the pro-glacial environment. A marked reduction in resistivity after a heavy rain storm demonstrates that the water content is sensitive to variations in water input at the surface.