Fog rises as the Mendenhall River flows out of Mendenhall Lake. The water is clearing up now that winter is setting in. Kate Troll, Nellie the Sheltie, and I skied around the shoreline of Mendenhall Lake to the outlet where the Mendenhall River originates.

Glacial rivers change radically from summer to winter. With summer warming, the melting glacier greatly increases the river flow, making the Mendenhall River a whitewater rafting destination for tourists. Silt from the glacier turns the water an opaque gray, and rafters can hear the hiss of silt against the rafts. In winter, flow is much less, and water more clear.

Mendenhall Glacier also causes jökulhlaups (an Icelandic term), glacial outburst floods. Meltwater builds up under the glacier, trapped by ice dams. When the ice dam melts away or breaks, the water bursts out, causing the Mendenhall River rise to flood stage very quickly. These jökulhlaups have become more predictable with sensors placed under the glacier to monitor water build-up.