![Boulder Canyon Outlet portal of diversion tunnel No. 2 showing Stoney gate steel in place above portal and form work for concrete super-structure.; Scope and content: Photograph from Volume Two of a Boulder Canyon Outlet portal of diversion tunnel No. 2 showing Stoney gate steel in place above portal and form work for concrete super-structure.; Scope and content: Photograph from Volume Two of a](https://c8.alamy.com/comp/W5K66X/boulder-canyon-outlet-portal-of-diversion-tunnel-no-2-showing-stoney-gate-steel-in-place-above-portal-and-form-work-for-concrete-super-structure-scope-and-content-photograph-from-volume-two-of-a-series-of-photo-albums-documenting-the-construction-of-hoover-dam-boulder-city-nevada-W5K66X.jpg)
Boulder Canyon Outlet portal of diversion tunnel No. 2 showing Stoney gate steel in place above portal and form work for concrete super-structure.; Scope and content: Photograph from Volume Two of a
![Film transparency of outlet works at Hoover Dam, circa mid 1930s - Photograph Collections (1 of 2) - Welcome to UNLV's Digital Collections Film transparency of outlet works at Hoover Dam, circa mid 1930s - Photograph Collections (1 of 2) - Welcome to UNLV's Digital Collections](https://d.library.unlv.edu/digital/api/singleitem/image/pho/2198/default.jpg)
Film transparency of outlet works at Hoover Dam, circa mid 1930s - Photograph Collections (1 of 2) - Welcome to UNLV's Digital Collections
![File:Looking upstream into Black Canyon toward Hoover Dam site showing outlet portals of four diversion tunnels and... - NARA - 293789.jpg - Wikimedia Commons File:Looking upstream into Black Canyon toward Hoover Dam site showing outlet portals of four diversion tunnels and... - NARA - 293789.jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Looking_upstream_into_Black_Canyon_toward_Hoover_Dam_site_showing_outlet_portals_of_four_diversion_tunnels_and..._-_NARA_-_293789.jpg/1200px-Looking_upstream_into_Black_Canyon_toward_Hoover_Dam_site_showing_outlet_portals_of_four_diversion_tunnels_and..._-_NARA_-_293789.jpg)
File:Looking upstream into Black Canyon toward Hoover Dam site showing outlet portals of four diversion tunnels and... - NARA - 293789.jpg - Wikimedia Commons
![File:Looking upstream toward Boulder dam site showing outlet portals of all four diversion tunnels. Flow of Colorado... - NARA - 293890.jpg - Wikimedia Commons File:Looking upstream toward Boulder dam site showing outlet portals of all four diversion tunnels. Flow of Colorado... - NARA - 293890.jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/4/45/Looking_upstream_toward_Boulder_dam_site_showing_outlet_portals_of_all_four_diversion_tunnels._Flow_of_Colorado..._-_NARA_-_293890.jpg)