The earthen dam on the outskirts of this Williamson County city certainly does not look flimsy. At 35 feet high and nearly a third of a mile long, it has done a reliable job of holding back floodwaters on Chandler Branch, a normally placid tributary of Brushy Creek, for more than 50 years.
But in a worst-case flood, like what Hurricane Harvey unleashed on parts of Texas in August, or even a flood a bit more than half as severe, Chandler would turn into a monster, eventually surging over the top of what’s known as Upper Brushy Creek Dam 10A. When rushing water and earth meet, water usually wins, and the dam would almost certainly breach, resulting in the uncontrolled release of the impounded water, more than 500 million gallons.
That would swamp a miles-long area stretching southeast into Round Rock that includes 306 houses, eight multifamily buildings, 19 commercial properties and 14 road and railroad crossings, according to a study commissioned by the Upper Brushy Creek Water Control and Improvement District. Interstate 35, about 4 miles downstream, would be under nearly 6 feet of water… Read more from the Austin American Statesman