Water dumping isn't a pleasant thing, and it's something we've been dealing with in Florida for a while, mostly since Hurricane Irma. When Irma hit, it showed specific Floridians how weak the sewer systems are after years of abuse and hard weather thanks to hurricane after hurricane over the years. Because of the severity and pure size of Irma, it destroyed many sewage systems or at least damaged them to the point of panic. That panic being that this contaminated water was going to reach retention ponds and viable bodies of water is where water dumping comes in.
So what exactly is water dumping? It's precisely what it's called; it's the dumping of contaminated water, so it doesn't affect other bodies of water. Water is physically pumped out of retention ponds and brought to public spaces because the ponds have become too high, and that's detrimental to the stormwater management system put in place. The Villages, a retirement community, known for its various golf courses, had to extract water from their retention ponds and pump it out into the golf courses themselves (not the championship courses, though). This earned the town praise as it stopped the retention pond from having incredibly high levels that could have flooded into residential areas.
It is not a short process, as it's still being done as currently as the Fall of 2019. That's two years past Hurricane Irma, and the state of Florida is still cleaning up bits and pieces after the massive storm hit. So one can only imagine the amount of damage that was indeed done to the old and outdated sewer systems that were affected and how much water dumping has helped contaminants out of our water.