Read the full story in ProPublica.
When the U.S. Army Corps of Engineers built the two reservoirs known as Addicks and Barker on what was then mostly empty prairie, their chief goal was to protect the center of the city, 20 miles downstream.
The vast basins are dry most of the time, dotted with wooded parks and sports fields, and are contained on their eastern boundaries by large, earthen dams. During rainstorms, floodwater accumulates behind those dams in areas known as “flood pools” and backs up to the west; how far it goes depends on how big the rainstorm is and where it hits.
That system worked well when the reservoirs were surrounded by prairie and rice fields. But in recent decades, development has encroached from all sides. Today, about 14,000 homes are located inside them. During Harvey, when more floodwater accumulated behind the dams than ever before, 5,138 of those homes flooded…
None of the more than half a dozen residents interviewed by The Texas Tribune and ProPublica after the floods say they knew they were living inside Addicks or Barker — many of their neighborhoods are several miles away from the dams.
Several local officials — including Houston’s “flood czar” and a neighboring county executive — said they had no idea the neighborhoods had been built inside the flood pools. Several real estate agents said they didn’t realize they were selling homes inside the pools.