Arizona spillway

Arizona Spillway is a Hoover Dam control facility on the east bank of the Colorado River.

Background
This facility forms an integral part of the Hoover Dam, providing the means to control the flow of water from Lake Mead into the Colorado River. Some time after the First Battle of Hoover Dam the Battle of Arizona Spillway took place here, with the Legion eventually pushing NCR away from the east banks.

Behind the Scenes

 * At one point during development, the player would've been able to visit this part of Hoover Dam. However, it was cut at some point and it's map, called HooverDamIntArizonaSpillway in the GECK, deleted. Arizona Spillway was possibly an early to mid-way cut as one of the companions, Rose of Sharon Cassidy, had a dialog to say if the player visited there. Only the exterior of the massive spillway remains in the game. Regardless of its status, the spillway is specifically indicated in the official strategy guide.
 * The actual spillway tunnel is the big pipe/ditch area which has a bridge over it by the endgame. If you look under the bridge there is a large grating, as well as a small hatch, either of which may have lead to the deleted map.

Appearance
Arizona Spillway is mentioned only in the Fallout: New Vegas Official Game Guide Collector's Edition.