Looks like efflorescence, a result of excess moisture. Has that area been flooded?

This crawl space has been saturated for most of the year as long as I've been here. I've been scratching my head for years trying to figure out where it's coming from. I even hired a hydrologist engineer who wrote an extensive report that essentially wasn't helpful at all.

I went down there recently after heavy rains and saw water flowing and traced it to the middle of the house - coming up from the ground. One thing that has puzzled me is that the whole crawl space is completely saturated for most of the year, but there's a 200 sq ft area that stays bone dry. Several people have theorized that there may be an underground spring there, and I guess that's what it is. I dug down about five inches and there was standing water. I could see water seeping in, but couldn't find where it was coming from. So I put a sump pump in that location, and it does help a little. I had a dehumidifier there for a few years; I didn't notice much of a difference - except in my utility bill. Maybe it wasn't a big enough capacity. I've been thinking about putting a larger one in there.