<P> On August 31 , flood levels started to subside . The water level in the city had reached that of Lake Pontchartrain , and as the lake started to drain back into the Gulf , some water in the city started to flow into the lake via the same levee breaches they had entered through . In 19th century lake floods , the water soon flowed back into the lake as there were no levees on that side . In 2005 , while the levees proved inadequate to keep the lake out of the city , even in breached form they were sufficient to keep much of the flooding from flowing back out . As breaches were gradually filled , some city pumps were reactivated , supplemented by additional pumps brought in by the United States Army Corps of Engineers . Some of the city 's pumps which survived could not be reactivated because of the failures of the canals that they pumped flood waters into . The combined task of closing breaches and pumping the flood waters out took weeks and was compounded by a setback in late September due to further flooding from Hurricane Rita . </P>
how did they get rid of the water from hurricane katrina
closing breaches and pumping the flood waters out