Boat house on Weisenhorn Lake. A number of people, some with aprons on, are posed outside the building, which has evergreen swags decorating it. Views of the buildings and pier at Weisenhorn Lake. Weisenhorn Lake became one of the three Valmont Lakes or Reservoirs in the early 1920s when the Public Service Company purchased the land for the Valmont Power Plant. The third lake is Leggett-Owen Reservoir.