http://www.swg.usace.army.mil/Portals/26/docs/2009%20Addicks%20and%20Barker%20MP.pdf
Above: Everything you ever wanted to know about Addicks and Barker.
These are giant retention reservoirs that only fill in big storms. The history is given in the report as well as how they function.
They are relatively sound but old and out dated.
They were made to protect Buffalo Bayou, downtown and the ship channel all at lower elevation. They were created and then developers built above the 100 year flood plain which certainly is not that uncommon.
There are developments abutting them that NEVER should have been built. Those reservoirs were built to spare downtown Houston and we essentially brought downtown Houston to them.
Those neighborhoods are going to be flooded for months when this is all over.