U.L.C River Of Darkness

A strange river in _______ has been uncovered in 1999. Its water is completely dark and once someone attempts to touch it, their entire body melts including the bones. Right after the victim has been melted the river becomes crystal clear and has curing properties that defy logic.
People were cured from illnesses, bruises and broken bones, really anything that could harm or kill someone. Even demons stand no chance as they get burned out of commission upon contact.
But for some reason after a few hours it turns back into a dark mess as if it needs sacrifices to cure the ones in need. As divers explored the safe equivalent they discovered a large unknown submerged object that was like the Ophanim from the Bible, but this one let out electricity instead of fire and the eyes were replaced by glass compartments to supposedly control the object.
As a diver touched the object he suddenly was sucked in its center, transporting him to _______ which is a backrooms-like dimension.
As the river became dark the object began to glow a yellow color. Nobody dared to do further research as it was too dangerous and the river was surrounded by unclimbable walls. Only certain levels of U.L.C employees can enter.
The walls are only removed when the river is safe and has its curing properties.