Arroyo
Arroyo is a tribal village, the birthplace of the Chosen One, Fallout 2's hero. It should be located at the west of Klamath, but is inaccessible in FOnline: 2238 for reasons detailed below.
Reasons of its lack
Inaccessible in FOnline: 2238 due to its heavy role in Fallout 2, we can suppose Arroy had not to be in FOnline. As the game is in the year 2238, Arroyo already exists (The village was founded in 2167), but should also host the Chosen One, that left the village in 2241, three years after the year where we are playing. FOnline: 2238 players could meet Fallout 2's hero, or should meet him, and it would be a mistake in the Fallout canon. Who knows what players could do to the hero that would, later, save the wasteland...?
TLA
Arroyo exists, however, in TLA, described as a "Wonder village built with GECK. A true Garden of Eden." As the Chosen One is officially missing, there is no dischord about the accessability of the village to the player.