Do you have a septic system? If so, conventional (possible leak from liquid discharge line or seepage from the drainfield) or aerobic (possible leakage from the treated water discharge line).
We have an area like that at our home on Lake Livingston. We have a broken grey water drain line either under the slab or if we are lucky, just outside the slab and under a wooden porch. Water seeps out and soil seeps into that line. This results in one flower bed and some lawn area that stay damp most of the time.
We've had the drain line jet blasted twice in the last two years and looked at with a fiber optic camera which confirmed blockage and displacement of the piping. The first symptom that pointed to a blockage was dirty water backing up into a shower drain on the lowest level. We have been quoted a price of almost $11K to find and repair/replace the broken pipe. That includes digging a 5x5x5 access hole, 14 feet of tunneling and making the repairs, the replacing and compacting the soil. If the break is not found within the quoted 14 feet of tunneling, additional charges would apply. I am going to do some investigating myself in the near future to try and pinpoint the location of the break and either repair myself if not under the slab or call in the pros if it is. But I will definitely be getting more bids if I hire it out. We have a maintenance contract (HVAC and plumbing ) with the company that diagnosed the issue and provided the bid. We trust them and they do good work but they are "pricey" on labor.
I am not the Six Million Dollar Man, but I might need that surgery. "We have the technology, we can rebuild him!"
