The Boulder Beach area saw much activity during the construction of the dam. The U.S. Government Railroad was built from Boulder City to the dam site proceeding down Hemenway Wash in 1931. The Six Companies, Inc. Railroad branched off the U.S. Government Railroad in lower Hemenway Wash and crossed the river by a trestle bridge to the Arizona gravel pit. Another branch went from the gravel plant near the present Boulder Islands to the lower dam site.
The Six Companies, Inc. ceased operations when the dam was completed. The railroad beds and trestle bridge were covered as the lake filled. The U.S. Government Railroad was used until 1961 when the last generator was installed at Hoover Dam. The rails have been removed, but the tunnels, roadbeds and gravel stockpiles remain around Hemenway Wash.