Particularly, the highway's proposed route was expected to intersect the headwaters of the San Joaquin River, causing potential harm to the surrounding ecosystem.
When the High Sierra and Minarets primitive areas were designated west of the Middle Fork Valley in 1931, a legislative gap was intentionally left between them to accommodate potential highway construction.
He pointed out the need for large bridges to cross steep canyons, high snow-removal costs, and potential damage to the Devils Postpile columns due to heavy construction.
These included the visual intrusion of retaining walls on the wilderness and the possible degradation of the fragile soils, vegetation, fish, wildlife, and timber supply in recreation areas.
[1] In 1972, in a historic event held at a 9,200-foot Summit Meadow in the Sierra Nevada, Governor Ronald Reagan, on horseback, announced President Nixon's decision to halt the construction of the proposed Trans-Sierra Highway.