In the article, the vast majority of the sinking (if I'm reading it correctly) is from the leftover lever effect of the old ice ages. The ice that pushed the northeast down is gone and its rising back up. That in turn is pushing the southeast back down. The sinking due to removal of water from the acquifers (I believe) is less known but believed to be a minor contributor. I know our local water department here monitors how much water they remove and the pressures in the acquifers and don't let it get past a certain point. The water they pull from is (I think) tens of thousands of years old and is way down there...so any water that seeps into it is extremely pure. I'm going from memory here, but I don't think contamination is a concern. For example, I remember being at forums where people expressed concerns about the quality of the water in acquifers and its potential to be contaminated and they stated it was a non-issue because it was like 20,000 years old. So I guess in 19,800 years someone will have to worry about it.