A serpentine climb around the east end of the lake and up Mt. Judah brought the Overland to the Summit Tunnel at 7,018 feet at Donner Pass and the start of a descent to Sacramento located just above sea level. Travel over this section could be quite treacherous in the winter as the Southern Pacific had to deal with clearing as much as of snowfall as well as ice from water dripping in the tunnels. The miles of showsheds needed to keep the line passable left the impression among passengers that they were railroading in a tunnel for much of the route. The wooden snowsheds also presented another challenge of railroading over the hill, however, as fires were often started by lightning strikes or embers from steam locomotives.