[1] After serving with the U.S. army engineers in the Civil War, Hall was assigned in the latter part of the 1860s to surveying the Western regions of the United States and preparing topographical maps.

Additionally, the outside land was covered with sand dunes which needed to be reclaimed and replaced by forest trees.

[1] Despite his new responsibilities, he retained the position of consulting engineer to Golden Gate Park until he resigned in 1890, and was replaced by his assistant John McLaren.

[2] As California's State Engineer, Hall worked on a comprehensive water supply and flood control system for the Sacramento Valley.

[3] He was also instrumental in designing projects to help San Francisco acquire adequate supplies of water from the western watershed of the Tuolumne River.