Lake Managua only in 2009 that a modern wastewater treatment plant (built and operated by the British company Biwater) was opened in Managua, but even it treats only 40% of the city's wastewater. The lake today has no stable outlet, with only occasional floods to Lake Nicaragua through the Tipitapa River. Pollutants are thus concentrated. Despite the pollution, some of the people of Managua still live along the lake's shores and eat the fish. In 2007 the "malecón" area was dredged and the sediment hauled off on barges. A strong odor which permeated the area from the sediment disappeared. A stone rip-rap
Managua 1927. A new sewer system and the redirecting of waste water to a new waste water treatment plant at Las Mercedes funded by the German government to decontaminate the lake is expected to be the largest in Central America and was inaugurated in 2009. Managua's city area extends about , essentially south from the south shore of Lake Managua. The lakeshore is at an altitude of above sea level, and the city climbs as it gets towards the Sierras de Managua further south where it is over above sea level. Geologically, the city lies on fault lines, thus seismologists predict