“Brine” is the industry term for the waste byproduct of Desal operations. It’s not just salt, it’s all the particulates that were present in the water.

Seawater Desal operations have already caused many ecological disasters with the stuff, but brackish groundwater would probably be even more dangerous, and including higher concentrations of radioactive material. So you get the water out, but then you’re left with the sludge of everything else that needs to be disposed of somehow.