Look at a map. The Persian Gulf is a dead end, and all ocean water flow has to come through the Strait of Hormuz. There's some fresh water coming in from the Tigris and Euphrates rivers, but less each year as that fresh water is captured and used, and as global warming increases evaporation.

The San Francisco bay has to be actively managed for similar reasons. It's a large body of water with a narrow outlet, fed by a river system from which much water is captured. If too little water comes in from the Sacramento River, the delta will turn to salt water. Managing that is what the Bay Model, mentioned recently, is for.

Huh, looks like they process about 1/500 of the water in it every year. So enough to make a dent in the salinity eventually.

pardon my ignorance. But, all that salt was there already. right? Is it that we have less water there now ?

I thought the HN-way was to be more charitable than just directly calling out obvious bullshit.