The releases will add to flooding in areas close to Buffalo Bayou, which flows through the centre of Houston, said Jeff Linder of Harris County's flood control district.
The downtown areas of Brazoria, Sweeny and West Columbia were clear of major flooding Tuesday morning, Trower said.
Authorities outside Houston are urging residents of Brazoria County to evacuate immediately due to floodwaters from Harvey that breached a levee, the Reuters news agency reports. With rescues continuing, that number seemed certain to grow. The youngest in the family was six years old. Meanwhile, the tropical storm appeared to be gathering strength once again on the Gulf coast.
Columbia Lakes is located about 50 miles (80 km) from Houston, close to Brazos River.
Houston to open more mega-shelters to house flooded families
Some fear that may be more than the nation's fourth-largest city could bear. The US Gulf Coast has been battered by Hurricane Harvey since Saturday.
Germany to lift sanctions if Russian Federation enters ceasefire with Ukraine
As she battles for re-election, Mrs Merkel has been subjected to ridicule and protest over her laissez-faire stance on migration. But Merkel pointed out that the protesters were a small minority in the crowd of some 1,500 people.
Let's have that debate over paying for the border wall, Mr
Trump began his morning by promoting a book written by Milwaukee County Sheriff David Clarke, who has been an outspoken supporter of the president.
Donald Trump has vowed to provide "every asset" under his command to help out individuals affected by tropical storm Harvey.
Rescuers are still plucking people from vantage points around the city's submerged neighborhoods. Mayor Turner put the number saved by police at more than 3,000, while the Coast Guard said it had also rescued more than 3,000 by boat and air and was taking more than 1,000 calls per hour.
"The Brazos River is being pounded, and all of that water is coming down from the tributaries and creeks into the river", a Brazoria County official told CNN. A shortage of beds means some people will have to sleep on chairs or the floor.
"We've got a lot of low-lying areas that are experiencing flooding", Trower said.