Many spillways have floodgates designed to control the flow through the spillway. It is an earthfill dam with a concrete spillway. There was no overflow spillway in the original reservoir. A serious flood in September 1986 raised the reservoir above the emergency spillway. The reservoir continues for to its spillway near Olive Bridge. The concrete dam has eight floodgates, similar to those on the Gatun spillway. The water flowed directly onto the earthen hillside below the emergency spillway, as designed. The dam crest is higher to the left and to the right of the spillway. The dam was long with a long service spillway. A variety of dam and spillway types were used in the construction. The dam includes a spillway, a powerhouse, and switchyard. The design discharge of the spillway is . The flow coming into the spillway is subcritical. The trestles were completed in 1936, after construction of the Spillway. The single controlled spillway is capable of discharging .