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The updated IDF (inflow design flood) for Hyrum Reservoir could not be passed with the existing hydraulic structures. The labyrinth was the most economical alternative for an auxiliary spillway. The labyrinth spillway, a series of trapezoidal shapes in plan form, would provide the necessary spillway length and capacity within a comparatively small width. The spillway configuration was based on design curves developed in the Bureau of Reclamation Hydraulic Laboratory.

The 1:30 scale model included the upstream approach channel, the labyrinth spillway, and a transition section leading to a long sloping chute. The model confirmed the maximum discharge of the spillway and investigated different approach conditions and spillway orientations. Water surface profiles were measured over the spillway and in the chute downstream of the spillway. Splitter piers were installed to provide aeration under low flow conditions.