Sometime between Jak II, and Jak 3, the Water Slums were all replaced with part of New Haven. The famous Freedom HQ stands in part of its position. There is absolutely no trace of the Water Slums in Jak 3. Due to New Haven taking the Water Slums' place, the entrance to the Pumping Station is gone leaving it inaccessible but seen from the KG War Factory. Due to map analysis, the entrance to the Freedom HQ hangar stands near where the entrance to the Pumping Station is.
This location served the purpose of containing the Oracle, which existed in its own hut (with no other inhabitants). It would reward Jak with a Dark Eco whenever he received the right amount of Skull Gems