The dam had to be constructed in one season so spring floods would not wash away the temporary cofferdams. The dam was actually completed in half the time estimated by the Defense Program. The construction company claims that it was also completed at half the cost. It takes a lot of force to keep a dam standing against the incredible force of the water. The strength of the Cabinet Gorge Dam lies in the outward forces the arch design places on the canyon walls.

The dam is a true arch dam, which is 208 ft high and 600 ft long. Throughout the whole dam its thickness never exceeds 40 ft. The first step in construction was the diversion of the Clark Fork River to clear a construction site. 32 tons of dynamite blasted 50,000 cubic yards of rock down the canyon walls of the river. The blast was felt 32 miles away in Sandpoint. Water was then shunted through a pair of tunnels each 1000-ft. long. Cofferdams were built above and below the site to divert the water. Half a million cubic yards of rock were excavated.