Water from two giant reservoirs in Houston was released about 2 a.m. Monday morning, as rising levels threatened their stability despite worsening flooding in their surrounding neighborhoods. Roads near the Addicks and Barker dams will be flooded “for an extended period of time” following the release, said Col. Lars Zetterstrom, the Army Corps of Engineers district commander. Officials planned to release the dams one at a time but the dramatic increase of rainfall Sunday night left them with no choice. The Army Corps listed the reservoirs at “extremely high risk of catastrophic failure” in 2009. Collectively, they hold 410,000 acre-feet of water.