(Adds background on water releases)
Aug 29 (Reuters) - Houston reservoirs that have contained heavy rains from Tropical Storm Harvey are starting to overflow, forcing authorities to release more water into the city’s swollen drainage system to alleviate pressure on two dams, Harris County officials said on Tuesday.
County officials are monitoring six neighborhoods around the reservoirs and encouraged residents in those areas to evacuate before the water levels rise.
The releases will add to flooding in areas close to Buffalo Bayou, which flows through the center of Houston, said Jeff Linder of Harris County’s flood control district. The downtown are has not flooded yet.
The controlled releases to ease pressure on the dams have so far not added a significant amount of water to already overflowing Houston rivers, Linder said. But continued rain has complicating efforts to distribute flood waters in a controlled way.
“This is something we’ve never seen before,” he said. “We have uncertainty in how the water is going to react,” when releases from the reservoirs hit overflowing drainage. (Reporting by Gary McWilliams; Editing by Bill Trott)