"So Now the lot at the mall floods?"
They may have gotten it under control. I defer to the Lubbock native to tell you the status.
About a year ago, the city began installing a drainage system city-wide where each playa lake is connected through underground pipeline, and they all spill over into each other until they spill onto a spot outside of the town--I think a city owned farm, maybe.
Consequently, it hasn't really rained much since they began this installation, but, yes, the mall parking lot DID flood a great deal when it used to rain.