As Lower has became a flooded area somewhat akin to a big sewer, and as we haven't had have many sewer areas and they're currently deeply shrinked, I think that the Optional Perks and Backgrounds that used to take effect on the sewers should have their bonuses expanded to all Lower Sanctuary area.
They're the following:
- Ooze Savant
- Sewer Dweller
- Ranger FA enemy Vermin