Massive flooding caused by Tropical Storm Harvey along Texas' refinery-rich coast could have long-standing and far-reaching consequences for the state's oil and gas industry and the larger U.S. economy. The storm's remnants left much of Houston underwater on Sunday, and the National Weather Service says it's not over yet: Some parts of Houston and its suburbs could end up with as much as 50 inches (1.3 meters) of rain.

With the heavy precipitation expected to last for days, it's still unclear how bad the damage will be, but there is already evidence of widespread losses. Key oil and gas facili...