TxDOT SAYS: “All  alternatives [of the construction project] would cause disproportionate  high and adverse impacts to minority or low-income populations... no reasonable alternatives would avoid adverse impacts or have  substantially less overall adverse impacts than other alternatives.”

This  flooding potential will be exacerbated by development in the woods and  prairies to the north of Houston, which development will result from 

TxDOT's I-45 expansion plans.

The  easier (albeit only in the short term) for those in The Woodlands and north to drive downtown, the more people will relocate there and the more development will ensue.  This will eliminate precious land to soak up rain water.