I took color pictures of natural oil seeping up from the river by the bank about half a century ago. The photograph showed the blue brown sheen of the oil on the water.
It looked like this, and neighbors visited each other with rafts:
Without the snow, though, but that is pretty much what it looked like then. Those piers were used to get around on the water.
It was riddled with palmettoes and the water smelled like sulfur from the oil underneath. This oil at Bolivar may also come from the Intracoastal Waterway that runs thorugh Bolivar. See the tugs and barges going thorugh there:
I nearly bought a plot of land on the east side of it on Bolivar. So there are several possibilities. Of course since the Shrub turned over things to private industry to inspect, and the agencies that Texans have counted on have been gutted by successive waves of GOP troglodytes, anything is likely to happen down there.
It's a Libertarian nightmare but this spill or whatever it is seems to be being dealt with now.