|Leader||Tree Father Birch|
|Main Local(s)|| Harold|
|Related Quests||Oasis Quest|
Oasis is located in the north-west of the Capital Wasteland in Fallout 3. It can be a very difficult place to find as it's completely surrounded by mountains with the exception of a very narrow pathway to the west of the mountain. You'll know that you're close to the entrance when you start seeing bushes and patches of grass on the ground. There are 3 ways to get the Oasis location marked on your map;
- You can kill the Drifter at the Dickerson Tabernacle Chapel and get the location off his corpse, as part of the unmarked quest High Plains Drifter.
- There is a random encounter involving 2 wastelanders arguing about the location. After you talk to them, they will turn hostile, kill them and the Oasis will be marked on your map.
- Another random encounter involves a Wasteland Merchant who has visited Oasis, he seems a little out of it and will fall dead after you talk to him. The Wasteland Merchant Note can be found on his body and will mark the Oasis location on your map.
The Oasis is the only place in the Capital Wasteland where life still grows, this is because of the effects left by Harold, who is a recurring character in the Fallout series. Harold was exposed to high amount of both Radiation and the Forced Evolutionary Virus but he didn't transform into a Super Mutant or a Ghoul like most people exposed to such dangers, he was "Special". Sometime after his exposure, a tree began to grow out the side of his head, it's the only known case of such a thing in the Fallout world. As the years went on the tree grew bigger and Harold claims the tree speaks to him inside his mind, he named the tree Bob (but sometimes calls him Herbert because, "Bob hates it"). As more years passed by, Bob became too big for Harold and eventually rooted him to the ground, he was discovered by a group of Wastelanders who hailed him as a god. While Harold was rooted to the ground, Bob began to blossom and more life started to grow around him, The Wastelanders decided to hide this secret from the rest of the wasteland and build themselves a base around Harold and name themselves as Treeminders.
By the time the Lone Wanderer arrives in Oasis, Harold has been rooted to the ground for over 20 years, he is now more tree than man and the once small patches on grass around him have grown into a full forest. In order to meet Harold you'll have to take part in a ceremony held by the Treeminders to cleanse you from the Wasteland's effects.
 Oasis Quest
- Main Article: Oasis Quest
After this you can start the quest where you're given 3 choices that could shape the future of Oasis and the Capital Wasteland. You can side with the Treeminder's leader Tree Father Birch by suppressing Harlods growth to keep him a secret from the rest of the wasteland. You can side with his wife Leaf Mother Laurel by expanding Harolds growth so the rest of the Wasteland can grow with life. You can also side with Harold by killing him, he says he's sick of being stuck in the same place for so many years and is desperate for death to come. Harold's death will stop any further life from being grown in the Oasis.