The land is rising around South Padre Island. It not because of any geology, but because they're bringing in landfill by the truckload. The fill material is mainly from landfills outside San Bonito and is higher in clay, better "foundation soil." The reason is because new flood elevation laws that require new construction to be at least 5 feet above street grade (the SPI roads are about 5 feet above mean sea level).
I can see why certain elevations are needed, although with stilt houses it shouldn't matter. Look at what Mr. Fanke did on The Shores, with a blow-though garage downstairs and the living areas on the second and third floors. I don't think he used a lot of landfill material except for shaping some landscaping. You have to admit it is pretty nice.
That's a sore issue but I also fear for the land itself; it turns it into yet more impervious cover that won't replenish the shallow freshwater aquifer we have. That's important if you have a small tree or want a big bush. I don't know if anyone has thought about that. The largest freshwater lenses we have under the island are probably those empty lots along Padre Boulevard, between Isla Blanca and Schlitterbaun, and up by some rather large dunes up to the north. I have no idea if the dang aquifer is important but I do know that if we pave this island solid with impervious cover, not a speck of native green anywhere, there would be Hell to pay.