Completion of the Mossy Rock Dam flooded the valley creating Riffe Lake. The dam is the tallest in the state. The power generated by the dam supplies 40 percent of Tacoma’s electric needs. Plans were announced in 1948 but met with strong opposition. The City of Tacoma went before the US Supreme Court three times in order to get the dam approved. Construction started in 1965 and completed in 1968.

Prior to construction of the dam, the tour passed through farming and dairying country. Most of the land in this area had been under cultivation for more than a quarter century, and the farms gave evidence of considerable prosperity in the well-painted barns, large silos, and sleek cattle.