If the dam breaks, dozens of homes could be destroyed. abc's phillip mena is there. >> reporter: a flood emergency situating to happen. engineers racing to stop this dam southwest of dallas from breaching. workers placing heavy equipment right on top of the dam, pumping 15,000 gallons of water per minute from swollen lake padera as fast as they can. officials warning residents to prepare for the worst after days of record-breaking rains across the region, all that water draining into lakes and bayous. the fear other dams will soon reach maximum height. there are over 7,300 just in texas. accor...