Selway Rivers. In addition, the flooding caused by its -long reservoir would require the relocation of the Dworshak fish hatchery. The proposed fifth and sixth units of the plant were deauthorized in 1990, and the fourth unit was deauthorized in 1995. During initial filling of the reservoir, the dam developed several large vertical cracks on the upstream side – some more than long – due to the rapid change of water pressure from the rising reservoir. Workers had to drill diameter drain holes between the cracks and the dam's existing foundation drainage system, or "drainage gallery", at intervals, relieving the pressure on the dam's backside. In June 1980, the dam again experienced leakage problems when a crack opened on its upstream face, sending more than of water spraying across the downstream side of the dam. Seventy drainage holes were drilled into the crack to relieve pressure before the crack was permanently sealed by an aggregate of cement, volcanic ash, and sawdust. The cost of the repair exceeded $1 million. The suspension Dent Bridge was constructed upstream of the dam, and the deck truss Grandad Bridge was built upstream. Specifications Dworshak Dam is a concrete gravity dam with a sloped downstream face and vertical upstream face, standing high from the foundations, above the riverbed and measuring long along its crest. The top of the dam is wide at an elevation of above sea level. The main body of the structure contains approximately of concrete. High water releases are controlled by a set of outlet works with four gates, capable of releasing , and a spillway controlled by two tainter gates. The spillway has a capacity of at maximum reservoir elevation. Dworshak Reservoir is the name of the lake formed behind the dam. At normal maximum water levels of above sea level, the reservoir stretches upstream, covering and containing of water with of shoreline. The hydroelectric plant located at the base of the dam is a long concrete structure and contains one 346,000 horsepower (hp) and two turbines that power one 220 megawatt (MW) and two 90 MW generators, respectively, for a total capacity of 400 MW. The rated hydraulic head for the powerhouse is , with a maximum of when the reservoir is full and a minimum of required for power generation. Up to of water can be released through the power plant at maximum capacity. The overload capacity of the